Engine turns over but doesn’t start on a Yaris VVTi

[YarisVVTi2002]

Hi everybody, new member and major Toyota owner / enthusiast here with 5 different Toyota models in the immediate family.

I got a Toyota Yaris 1.3 Auto 2002 VVTi as a run around and for the school run over a year ago, except for one problem it has been good runner until now.

I’ve been working on cars for years and normally solve most problems on my own but this one has me stumped. I have done lots of checks on this problem, listed below.

Car has been running rough for weeks – very sluggish / loss of power, engine vibration etc

Car started one morning and cut out after a few minutes after engaging drive and trying to pull away. It would not restart again despite cranking over normally. Since the break down I’ve tried many ideas and I got the car started once for about 30 seconds before it conked out- it had been left for a few days and the battery had been taken out to charge it. Sometimes when the engine is turned over, the turn over speed may increase after 10-20 seconds and it feels like it’s close to starting, but this fades away.

History and things done so far:

1. The fuel tank is nearly full, it was filled up with unleaded a few days before.
2. I tried starting it with the other key, in case of an immobiliser fault- No difference
3. Charged car battery and tried jump starting the car off a different car- No difference
4. Used Cold Start spray both in the air inlet and directly into cylinders- No effect
5. Replaced all 4 pencil coil packs with a working set with the same model number- No difference. The voltage on the 4 pins of the coil leads are 0 & 12v on the 2 outer pins and about 7v on the 2 inner pins. The resistance across all 4 pins of the coils are the same on all coils. A break down technician had checked the car, plugged in an OBD scanner and said the error codes indicated a problem with the coils or the coil driver circuit on the ECU but I can’t find any faults here.
6. I took out each spark plug, left them connected and cranked the engine – there was a good spark on all 4 plugs. On removal each plug was slightly wet, indicating fuel was getting through.
7. The fuel line was disconnected and the engine turned over, about 100ml of fuel was pumped out in one crank. Indicating the fuel pump is ok and the fuel line & filter are not blocked.
8. The pistons could be seen moving up and down as the engine was cranked. Both the tops of the pistons and the plugs were quite carbonised. The car has done about 58,000 miles and has been serviced regularly. I can’t see how there can be a problem with the starter motor if the pistons are moving. I think this model has a timing chain rather than a rubber timing belt.
9. Compression was tested by taking out the spark plug and putting a rubber valve grinder suction cup over the hole and cranking the engine, a loud popping occurred indicating pressure in all cylinders.
10. The crankshaft sensor failed about 6 months ago and was replaced. The last OBD check didn’t show any crankshaft sensor error code – which it did before.
11. The petrol had a small amount of diesel contamination about 3 months ago. Since then the car has been filled up over 4 times.
12. The yellow engine warning light has been on continuously since I got the car over a year ago. The Yaris has been to the garage many times about this issue and I was told it was related to the Catalytic converter. The error can be cleared but comes back again after some time driving; it never seemed to effect starting or performance.

If anyone has any ideas or advice on this problem I would be very glad to hear them.

[SirDigby]

sounds like you might have answered your own question.
running poorly and a check engine light for a year for catalyst? the cat has probably fallen apart and carbon clogged and plugged exhaust. go check it out. it also could have damaged o2 sensor(s)
banana in the tail pipe.

[Bluevitz-rs]

If you can get it started, monitor the O2 sensor voltage on S1 and S2 and make sure they're working. They read from 0-1V.

[jra]

If it's getting gas and spark, it should run. put a test light or volt meter on your injector wires while cranking it over and see if you have current to the injectors, light should flash on and off when cranking engine. If you have gas, spark and injectors are working, cat may be plugged, Try unbolting collar at front of cat and pry it away from exhaust pipe enough that exhaust can escape before entering cat and see if it will start.

[tmontague]

Check for corroded/faulty engine block grounds. This will cause this issue. Happened to my Echo twice

[YarisVVTi2002]

Thanks for all the great ideas which I have checked out and it’s time for a long overdue update.
It doesn’t look like it’s an exhaust obstruction. I couldn’t undo the bolts from the front of the Cat but I removed the first O2 sensor so gas could get out – no change.
I took off both battery earth straps and cleaned up the bolts and terminals, they were quite clean anyway – no change.
Since my original post I got the car working for some time, it’s not clear how. I also got a OBD2 tester and compression meter.
The car had been sitting with the battery removed for a few days. I cleaned and re-gaped the spark plugs. With a freshly charged battery I tried cranking it and as before it picked up cranking speed before fading away. I kept cranking the engine with my foot to the floor and it picked up again and eventually sparked into life. I kept my foot on the gas / accelerator pedal to give fast idle for a while before driving it. Since then it started and drove quite well and interesting the engine warning light had gone out since it was started. The OBD tester showed no error codes at first but after driving it for a while it showed a pending diagnostic trouble code DTC (mode 07): PO302 - cylinder 2 misfire. After clearing it, it never came back again. After driving 20-30 miles the DTC Catalyst System Efficiency Below Threshold error came back as the engine warning light came on. There is a minor bit of blowing near a joint on the exhaust which may cause the error. Both O2 sensors readings on the OBD tester were 0-1V.
There was still a minor tappy sound from the engine, more noticeable when cold. I was still worried there may be an issue with the valves and I checked the compression on all 4 cylinders: 1 = 11 bar, 2= 9.5 bar, 3 = 11 bar, 4 = 11 bar. I took the plugs out again and checked the compression after a few weeks and they were about the same. When I repeated cylinder 1 there was some blow back out of the loosened air intake pipe and since then the car has not started again. The compression readings are all about 3 bar on all cylinders. No trouble codes have come up on the OBD tester. It feels and sounds the same as when it first didn’t start and again the plugs are producing sparks and it won’t start on cold start spray. There is no pick up of speed at all when cranking.
So I'm back to square one and run out of ideas. Any ideas anyone?

[YarisVVTi2002]

This problem has a lot in common with this one: http://honda-tech.com/forums/honda-civic-del-sol-1992-2000-1/strange-problem-no-compression-sometimes-wont-start-2389750/
Despite changing nearly everything this guy never got to the bottom of the problem.

[YarisVVTi2002]

This problem has a lot in common with this one: http://honda-tech.com/forums/honda-civic-del-sol-1992-2000-1/strange-problem-no-compression-sometimes-wont-start-2389750/

[jra]

If it's getting spark and won't start on ether, only thing I can think of would be that maybe the plug wires got crossed when you had them off?

[jra]

One more thing you might check would be if you had a pulley stuck, would keep it from kicking off. May want to loosen your fan belt and see if anything is stuck, water pump, alt, AC, should be able to turn all the pulleys by hand except for the crankshaft.

[YarisVVTi2002]

I got the car going again about a week ago. At the end of my last update I mentioned that there was low compression (about 3 bar) in all 4 cylinders. I realised that during the last compression test when I was turning the engine over I had not disabled the fuel system and I guess the unburned petrol was washing away the oil around the piston rings and reducing the compression. All I did then was dribble about 10-20 ml of engine oil into all 4 cylinders through the spark plug holes and the compression went back up to normal. It started easily after this and it ran reasonably OK for about week.

In the last few days the car has started to lose power and run rough again, error codes came up on the OBD tester. PO300 – random / multiple cylinder misfire detected and PO301 – cylinder 1 misfire detected. This morning it started but the car hardly moved when accelerating, it then cut out and wouldn’t restart. I checked the compression again and all cylinders were 3-5 bar, so no chance of starting. As before all cylinders are getting a spark and fuel. When I was checking the spark there was a small explosion inside the engine like a large pop and some small amount of smoke came out from the front of the engine and from the oil filler cap. Perhaps this was unburnt petrol inside the engine igniting as perhaps the piston rings don’t seem to be doing their job at the moment?

I was thinking that the piston rings can’t be worn out (car has only done 58,000 miles) and the compression can be normal when the car is working. Perhaps something is wrong with the oil supply so that oil is not getting to the piston rings intermittently?

Some articles mention vacuum line problems with these error codes. I wonder if anyone had a similar problem and got to the bottom of it?

I don’t think that the problem is with the ignition system as I have been around that loop a few times, swapping coils and plugs around.

@ Jra I have marked the coils so the plug wires can't be put the wrong positions. The lengths rule that out too. The fact that it was running OK should rule out the water pump, alt, AC etc ?

[Bluevitz-rs]

At this point I'd highly suggest changing the oil as its most likely contaminated with fuel.
Do you by chance drive very short distances not allowing the engine to get up to full operating temperature?

[YarisVVTi2002]

Hi Yes it's mainly used to drive a few miles to school everyday. An oil change was my next job and am waiting for the right oil filter. Do you think fuel vapour is washing away oil from the bottom of the piston rings?

[Bluevitz-rs]

I know first hand a lot of start stops without fully warming the engine can cause a buildup of fuel in the oil. It eventually get so bad you can't start the engine. It causes flooding and low compression just as you described.

[jra]

You said you had changed the crank sensor, but could be a bad camshaft sensor? I had a Tacoma that acted like this and it turned out to be the cam sensor.

[YarisVVTi2002]

I've changed the oil and oil filter now but it still doesn't start. The old oil was surprisingly clean and red coloured. I tried pouring a little bit of new engine oil into all 4 cylinders but still no luck starting and the compression is still very low (2 bar).

I've taken off the vacuum pipes from the top of the rocker cover and cleaned them. One had a small amount of mayonnaise in it but not enough to block it.

@Jra A faulty camshaft sensor sounds like an interesting idea but would it not show up as an error on the OBD scan? I've cleared all the errors (misfire and cat) and nothing new comes up.

How about the VVT system, something has to explain the low compression?
I forgot to mention that my problem has a lot in common with this one: http://honda-tech.com/forums/honda-civic-del-sol-1992-2000-1/strange-problem-no-compression-sometimes-wont-start-2389750/

I'm thinking of taking the rocker cover off and checking the tops of valves and the timing chain as the next step.

The weather in the UK has been really cold this week, with a hard frost at night (below 0C), which won't help starting conditions, as the car is outside on the drive.

Keep the ideas coming thanks, this is a real puzzle.

[YarisVVTi2002]

I've changed the oil and oil filter now but it still doesn't start. The old oil was surprisingly clean and red coloured. I tried pouring a little bit of new engine oil into all 4 cylinders but still no luck starting and the compression is still very low (2 bar).

I've taken off the vacuum pipes from the top of the rocker cover and cleaned them. One had a small amount of mayonnaise in it but not enough to block it.

@Jra A faulty camshaft sensor sounds like an interesting idea but would it not show up as an error on the OBD scan? I've cleared all the errors (misfire and cat) and nothing new comes up.

How about the VVT system, something has to explain the low compression?

I'm thinking of taking the rocker cover off and checking the tops of valves and the timing chain as the next step.

The weather in the UK has been really cold this week, with a hard frost at night (below 0C), which won't help starting conditions, as the car is outside on the drive.

Keep the ideas coming thanks, this is a real puzzle.

[Bluevitz-rs]

Check the plugs and make sure they aren't fouled too. But I'm sure you've already done that if you've done a compression check.

When you're doing the compression check are you pulling the EFI fuse and holding the throttle wide open?

[YarisVVTi2002]

Thanks Bluevitz-rs
I put new plugs but no improvement.
I have been pulling the EFI fuse recently before the compression test. I didn't at first. I have always held the throttle open for the test.

I have taken the rocker / valve cover off now.
First impressions are the timing chain is fairly slack but I doubt it's enough for it to jump off the cogs. It is a VVTi so I'm not sure how to check the correct chain slackness?
There is quite a lot of water under the rocker cover. The car has been outside unused in the cold for weeks.
Some photos of it:
https://i.imgsafe.org/1e8898bb66.jpg
https://i.imgsafe.org/1e8e60520e.jpg

[YarisVVTi2002]

Won't low compression be due to either a problem with the cylinder pistons rings or the inlet or exhaust valves ?

I've taken out the VVT oil control valve & solenoid and tested the resistance across the 2 pins - it was 7.1 Ohms, which is normal for this one according to online info. The piston in the valve slides back and forwards ok and the spring acts normally. I can't see any obvious problems with it. I've cleaned it and sprayed it with carb cleaner in case anything is sticking. I haven't opened up the cylinder at the left end of the forward camshaft which contains the VVT gears- I'm worried I might not get it back together again.

I took out the camshaft sensor as well (to the right of forward camshaft) and cleaned it, it had a resistance across the 2 pins of about 2k Ohms, which is normal for a Hall Effect sensor according to online info. Visually it looked ok. The rotor on the right end of the forward camshaft has 3 cylindrical tabs on it (magnets?), which I guess provide magnetic timing pulses to the camshaft sensor.

I have never had any OBD errors relating to the VVT oil control valves or system so far. As I understand it the VVT system adjusts the valve timing so that it holds more exhaust gas in the cylinders at higher revs to improve fuel economy. I'm assuming that at starting conditions the VVT system is not active unless it's stuck somehow?

I've turned the engine over for short periods with the rocker cover off. The tops of the valves seem to go up and down normally. The timing chain is normally tight but in some positions it is slightly slack (droops down in the middle as in photo).

Everything inside the cover is covered with slightly sticky baked on oil deposits, which I've cleaned off as much as possible. Part of the cam lobes (the short radius part) has a baked on yellow coating which indicates that they are not running in contact with the tops of the valves. Is this normal? Also the sides of the cam lobes had carbon deposits, so they must have been running hot to carbonise oil.

I'm starting to think that the oil supply to the top half of the engine has been insufficient? Perhaps there is a small inline oil filter for the VVT oil control valve? It's mentioned in the Lexus video but is it on a Yaris ?

[jra]

I think 3 bars is around 43 psi, that's pretty low, looks like it's been pretty hot under your valve cover. Wonder if you may have a head gasket leaking between two cylinders? or carbon build up on top of valves keeping them from sealing? With only 58,000 miles, it should just be getting broke in, but if it's ever been hot, aluminum heads tend to warp and crack.

[jra]

I just reread your last post again, I don't think a head gasket of carbon on valves would cause all 4 cylinders to have low compression, especially if all cylinders have about the same psi.

[KimmoKekki]

It's either way -> missing spark or missing fuel !

58.000 driven Toyota engine just won't break up like that !
Theres no water to oil mix or oil to water mix and so head gasket is just fine ...
I would quickly put all together again and start from basics !

[mimelio]

It's either way -> missing spark or missing fuel !

58.000 driven Toyota engine just won't break up like that !
Theres no water to oil mix or oil to water mix and so head gasket is just fine ...
I would quickly put all together again and start from basics !

+1

[YarisVVTi2002]

No oil in water or water in oil that I can see. All cylinders have about the same compression, either low or normal. So it's unlikely it's the head gasket.
Currently, the car turns over fine but doesn't start no matter how much cranking is done. The cranking sometimes picks up speed and feels like it may start at some points but fades away after 15-30 secs of cranking.
I'm very sure there is a spark as I tested each HV lead with an inline spark tester.
I can smell petrol on the spark plugs after trying to start the car, so some fuel is getting through. Does the cranking rpm fading away indicate a drop in fuel pressure - fuel pump problems? Would fuel pump problems show up in the OBD test? There are no error codes today.
A test light on all the injector wires flash. So I guess the injectors should be ok, it's unlikely all 4 would go down at once.
The compression is about 5 bar today on all 4 cylinders. It's still not clear why it's so low.

[dogsridewith]

I appreciate this thread as a guide to things to check with a non-starting motor.
I'd have a multimeter reading voltage while cranking. (Can use a plug into the accessory port.) Do these cars possibly have a minimum voltage level where spark and/or fuel is cut off? (Cranking voltage would be higher w/ plugs removed for visual spark check.)

Note: IC engines need fuel, spark AND fuel, spark and valves in correct sync.

[KimmoKekki]

Compression testing gives you only information if there is huge difference in between cylinders !
Good way to test if you are guessing lack of fuel is test with brake cleaner spray or something similar highly flammable spray !
Take intake boot away from throttle body ..
Someone goes to ign key and starts crancking engine .. when it's cranking over you just start to spray cleaner into throttle body !
Engine will fire up immediately if you have fuel delivery probs !
It'll also stay running as long as you give it cleaner !
Of course you have to adjust spraying or engine will go too rich and die .....
This method works on all petrol and diesel engines !
That is the 1st thing to try when there is no clear vision what causes problems

P.S. Sorry for my really bad English ... i'm Finn and we do speak rally English 8)

[YarisVVTi2002]

@ KimmoKekki
"It's either way -> missing spark or missing fuel"
I'm 100% getting a spark. In the UK we have spray's such as Cold Start which are very flammable to help starting. I've already tried this by spraying it in the air intake. There was no improvement in starting. I really doubt there is a big fuel supply problem, as I already established that the fuel pump is pumping lots of fuel into the injector manifold pipe and that the injectors are working. The plugs are also getting wet after turning the engine over. In case the engine was flooded, the car has been left for days and it still didn't start. Your English is fine :)
@ dogsridewith I hope this thread helps others. I'm convinced that the non-starting issue is not an ignition or fuel supply problem. It is also intermittent. I've tried starting it on a fully charged battery and when it's jump starting off a second battery in another car. All no difference.
I'm afraid that leaves compression / timing as the cause.

[KimmoKekki]

I should read everything 4 times before answering :/
Did you check valve clearances when valve cover was away ??
Also did you check timing marks ?

[YarisVVTi2002]

No security light flashes after the doors are opened by the key fob. No other warning lights have come on.

[YarisVVTi2002]

I've taken the Yaris to a local garage to get an opinion and they confirm that the ignition and fuel systems are OK. They think that the timing chain is stretched and have offered to fit a timing chain kit for about £600.
I'm not sure that this is the full story. Why would this stop the car starting and be intermittent? There is no suggestion that the timing chain has jumped a cog.

[tmontague]

With a stretched timing chain it should be shown symptoms earlier like running rough engine codes etc.

Yaris' are not known to stretch chains. I would get a second opinion

[KimmoKekki]

I was thinking that same question ..
I read that 1st posting again couple of times and thinking about timing chain jumping ....
58K driven ...
Fuuuuuck ...
Your car must be fitted with O**L's timing chain in that case !
Can you remember when exactly it start to sound rough ?

[YarisVVTi2002]

Does anyone whether a stretched timing chain can cause a car not to start and a drop in compression from 11 to 2 bar? And cause this effect intermittently, so that some days the compression is normal and it starts and other days it won't start and has low compression.
I can't see the point of spending £600 changing the timing chain if there is some other problem as well. May be it's safer to change the engine?
@ tmontague Opinions cost a lot of money I'm not sure what other test the garage could do, short of stripping down the engine?
@ KimmoKekki the car was running rough for months, from my original post, but not all the time.

[Bluevitz-rs]

Can you take a picture of your timing marks on the cams so we can see it is correct. They should be lined up like mine here...

[jra]

I would doubt if a loose timing chain would cause low compression or keep it from starting, unless it's jumped a cog on the sprockets. If your valve cover is still off see if the chain has any wear where the pins connect the links together and if the rollers are loose, but it should be good with no more miles than you have on it. If you have spark it should start on ether, so that leaves not getting spark at the right time. Maybe chain jumped cog? chain sprocket sheered key and turned on shaft? inconsistent cam or crank sensor, firing plugs, then not firing for two or three revelations? had that happen to my 2.7 Tocoma truck.

[Bluevitz-rs]

The other issue might be a stuck VVTi actuator in the advanced position. It would cause too much overlap and vent compression back into the intake on the compression stroke.

[YarisVVTi2002]

Hi everybody, I'm back! I never got to find the cause of the non-starting problem in my Yaris last year, so I left it over the winter. I changed the VVTi solenoid / actuator in the spring and tried to start it and it worked almost immediately, I tried putting the old one back in (as I couldn't see anything wrong with it) and the car still worked. I've run it intermittently over the summer with the new solenoid in without any problems. I don't think the cause is the solenoid. I didn't use it for while but now that the cold weather has started the Yaris is back to the same problem as before and doesn't start but turns over OK. Nothing was done on it between when it was starting and when it was not.

I put in some cold start spray into the air inlet and it almost started for a second.

I've checked a few obvious things: there is a decent spark on all the plugs, fuel is getting through but the compression is low (5 bar / 75psi) . The battery is fully charged. It's had new plugs, air & oil filter and new oil.

I've plugged in the OBD and no error codes show up.

We never solved the problem last year and the current symptoms are the same. My best guess is something temperature or fuel related.

Any ideas anyone?

[miiser]

Hi everybody, I'm back! I never got to find the cause of the non-starting problem in my Yaris last year, so I left it over the winter. I changed the VVTi solenoid / actuator in the spring and tried to start it and it worked almost immediately, I tried putting the old one back in (as I couldn't see anything wrong with it) and the car still worked. I've run it intermittently over the summer with the new solenoid in without any problems. I don't think the cause is the solenoid. I didn't use it for while but now that the cold weather has started the Yaris is back to the same problem as before and doesn't start but turns over OK. Nothing was done on it between when it was starting and when it was not.

I put in some cold start spray into the air inlet and it almost started for a second.

I've checked a few obvious things: there is a decent spark on all the plugs, fuel is getting through but the compression is low (5 bar / 75psi) . The battery is fully charged. It's had new plugs, air & oil filter and new oil.

I've plugged in the OBD and no error codes show up.

We never solved the problem last year and the current symptoms are the same. My best guess is something temperature or fuel related.

Any ideas anyone?



Fuel pump?


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[white89gt]

How do you know fuel is getting through? Is it making it into the combustion chamber?

[KimmoKekki]

Did you make that brake cleaner test back then ???
My car pulled off fuelpump's pressure neck seal 3 weeks ago !
Fuel still flowed back to tank but there was no pressure to fire up .... With brake cleaner it fired up immediately !


Lähetetty minun ONEPLUS A5000 laitteesta Tapatalkilla

[jra]

Sounds like something temperature related, maybe a coolant or air temp. sensor giving ecm wrong info? The EGR valve can cause trouble, but Toyota's have very little trouble with them.

[YarisVVTi2002]

I've checked out the fuel system at last.
I took out the fuel pump and sender unit (located under a cover under the back seat). The fuel filter was clean and pump ran fine when connected to 12V. I then took out the complete fuel rail with injectors connected and turned it over with just one injector connector plugged in at a time - they all had a good stream of fuel shooting out of them. So it doesn't seem to be a problem with the fuel system!!
I'm waiting to get some new injector gaskets before reconnecting the fuel rail - it's really hard to find any for sale.
Perhaps I'll start looking at the inlet manifold, and clean throttle, EGR valve, IAC valve etc?

[YarisVVTi2002]

This has to be one of the craziest problems ever. I still can’t find any reason for the Yaris not starting.
In summary:
When the engine is cranked:
1. There are good sparks produced on the spark plugs
2. There is a good spray of fuel from all 4 fuel injectors

I have cleaned the PCV valve and disconnected the catalytic converter inlet pipe but it still doesn’t start. No DTC errors come up on the OBD module but I have enclosed a screenshot of the OBD live data screen when the engine is turned over. I notice that the air flow rate during cranking is between 0.2 -1.43 g/s, this seems quite low? We now know there is no blockage in the exhaust and even if the air filter is removed it won’t start.
Last autumn the car stopped starting but started again without doing anything major to it this summer, now it’s stopped starting again as before.
What do people think? Is there anything that should be checked? Timing, ECU?

[YarisVVTi2002]

Any more ideas anyone? The Yaris is still the same; not starting.

[yaris2011-07]

Hi everybody, I'm back! I never got to find the cause of the non-starting problem in my Yaris last year, so I left it over the winter. I changed the VVTi solenoid / actuator in the spring and tried to start it and it worked almost immediately, I tried putting the old one back in (as I couldn't see anything wrong with it) and the car still worked. I've run it intermittently over the summer with the new solenoid in without any problems. I don't think the cause is the solenoid. I didn't use it for while but now that the cold weather has started the Yaris is back to the same problem as before and doesn't start but turns over OK. Nothing was done on it between when it was starting and when it was not.

I put in some cold start spray into the air inlet and it almost started for a second.

I've checked a few obvious things: there is a decent spark on all the plugs, fuel is getting through but the compression is low (5 bar / 75psi) . The battery is fully charged. It's had new plugs, air & oil filter and new oil.

I've plugged in the OBD and no error codes show up.

We never solved the problem last year and the current symptoms are the same. My best guess is something temperature or fuel related.

Any ideas anyone?

75 psi is low for a 1.5L engine...I suspect it may also be low for a 1.3L engine.

The link below states that minimum compression should be 156 psi

http://workshop-manuals.com/toyota/yaris/l4-1.5l_(1nz-fe)/engine_cooling_and_exhaust/engine/compression_check/system_information/specifications/page_1821/

Try following the HINT instructions:

HINT:
^

If adding oil increases the compression, the piston rings and/or cylinder bore may be worn or damaged.

^

If the pressure stays low, the valve may be stuck or seated improperly, or there may be leakage from the gasket.

[BlueMonsoon]

YarisVVTi2002, did you manage to resolve this problem?
I ask because my 2002 Yaris 1.3 has the same problem now that the weather has turned cold. The engine turns over fine, it won't fire up. Before today it was running perfectly, but it just will not fire up now.

[YarisVVTi2002]

Sorry BlueMonsoon, I never found the cause of the cranking no start problem.
The Yaris was laid up not working since my last post. I recently tried starting it again during some nice warm weather and it started straight away. I used it everyday for about a week and it was running well. I took it for an MOT and it passed without any problems. I parked the car working for about a week and when I tried to use it again the old cranking no start problem came back.
I've been doing some checks on it and will update everyone about it soon.
Did you ever solve your cranking no start problem?

[24boosted]

I am having a similar issue with my 09 Yaris with 113k miles. I have replaced nearly everything in the car yet it will start then will stall after a few seconds. (Replaced: spark plugs, coil packs, fuel pump, fuel sender, and cleaned throttle body.) No CEL is coming on, ran a diagnostic check with BlueDriver and nothing came up. I ordered a new MAF that should be in shortly. I am hoping that might fix the issue.

Edit: I finally got a check engine light to go on after letting it idle for 15 minutes. Several misfires on all cylinders, lean on bank 1. I ran the codes and it showed that the most common issue is a vacuum leak. I checked spark, fuel, and air. Seems to be air that is the issue since I had replaced everything associated with ignition and fuel. The new maf and crankshaft sensor came in and didn't really help with the issue after replacing. So I just ordered new gaskets for the intake manifold and throttle body. Hopefully this resolves the issue and a possible solution for your vehicle.

[24boosted]

So I took the car in to a shop that was highly recommended on Yelp and by Triple A. They spent two days on it and couldn't really figure it out. All diagnostics came back within spec, all sensors are running perfectly. Better be since I replaced just about every single one.

They charged me $400 and said one of the O-rings on the fuel pump was not installed correctly and it was leaking fuel pressure. I drove it home and it ran smoothly.

A day later: It started up with some hesitation and drove smoothly, then it started to struggle the instant I turned on the AC. I am suspecting the fuel pressure regulator. Just ordered a new one and hope this last thing fixes it. The code was for a P0171 lean condition in bank 1. I have replaced just about everything except the o2 sensors and fpr. Those are the next two variables remaining that is associated with the code.

EDIT: Problem solved! After 3 weeks and with a shop not being able to figure it out. The O-ring on the fuel pump kept getting dislodged due to a missing spacer! I noticed it after taking everything apart and saw that the o-ring wasn't sitting correctly again that was after the shop had reinstalled it. Car runs great now and the motor feels really healthy. I had checked compression and came out 165-175 psi on all 4 cylinders to be sure the motor wasn't dead. Was about to scrap the car too.

[Theron777]

Please tell me this problem got resolved by someone because I'm having the exact same issue with my yaris.