Engine Delayed Start - Toyota 1NZ-FE 1.5L

[SL Runner]

Dear Experts,

I'm a victim of using contaminated petrol. Experienced engine missing at 1000RPM and later on, cleaned injectors using BG Injector cleaner. Thereafter engine missing issue was resolved. But I started experiencing engine delayed start.

Vehicle: Toyota IST - 2008 - 1NZ-FE 1.5L engine

Description:

When starting the engine, starter motor kicks in about 2 seconds to start the engine. When you turn off the engine and starts the engine within 2 - 3 minutes, it starts instantly. But when you keep it for around 5 - 10 minutes, previously explained delayed starts occurs.

What I did so far:

I took my vehicle to Toyota and they checked the fuel line pressure and said there is a pressure drop. So they advised me to replace the fuel pressure regulator in the fuel pump unit. Still I'm experiencing the same delayed start issue. When they plug their computer terminal to the vehicle OBD2 port, error is reported as "Vehicle Starting Issue".

Note: I cleaned my injectors manually, Cleaned throttle body, there are no vibrations, engine is running at optimum efficiency.

I really appreciate if somebody can at least give me a clue for the delayed starting issue.

Cheers..

[CTScott]

Someone else had a similar issue recently. I believe that you have sediment in the tank which is plugging up the fuel filter (which is a plastic mesh one, attached to the bottom of the fuel pump, in the gas tank).

[SL Runner]

Someone else had a similar issue recently. I believe that you have sediment in the tank which is plugging up the fuel filter (which is a plastic mesh one, attached to the bottom of the fuel pump, in the gas tank).

Hi CTScott,

Well, technicians removed the fuel pump unit to replace the fuel pressure regulator and I checked inside the fuel tank and there were no sediments. Plastic mesh was clean as new. Fuel was contaminated with some chemical and not with water or any other solid material. However I pumped uncontaminated fuel recently. Vehicle ODO meter reading is 20,000 Km. Any other suggestions or ideas? Please do let me know.

Cheers..

[CTScott]

If the tank is clean, then the only reason I could see for the delay in starting, but no issues once running, would be that the fuel system is bleeding off pressure when it sits, so it takes it a couple of seconds to repressurize when cold starting. The fact that it warm starts fine, reinforces that thought.

[SL Runner]

Where could be the pressure leaking points? I checked all 4 injectors with an ASNU machine. And there were no leaks. Injectors works fine. Replaced the fuel pump pressure regulator. Unable to see any leaks from the fuel line. Any other places to look for? :help:

[CTScott]

Where could be the pressure leaking points? I checked all 4 injectors with an ASNU machine. And there were no leaks. Injectors works fine. Replaced the fuel pump pressure regulator. Unable to see any leaks from the fuel line. Any other places to look for? :help:

It could be leaking back into the tank when it sits. To test that you'd have to put a fuel pressure gauge somewhere between the pump and the injectors.

[SL Runner]

Hi Scott,

Yes, the technicians checked the fuel line pressure. They installed a pressure gauge in between the fuel line and the engine and they turned on the Fuel Pump using the terminal hooked to OBD2 port. As soon as we turned on the pump, pressure increased to 3.3. then after 5 minutes it came down to 2.8. And then we waited for 1 hour and it was 2.2. Is it normal? Technicians said it is normal. But before I change the pressure regulator, pressure drastically dropped to 1.0. Thats why they suggested to replace the fuel pressure regulator. Please advise. :bow:

[CTScott]

Hi Scott,

Yes, the technicians checked the fuel line pressure. They installed a pressure gauge in between the fuel line and the engine and they turned on the Fuel Pump using the terminal hooked to OBD2 port. As soon as we turned on the pump, pressure increased to 3.3. then after 5 minutes it came down to 2.8. And then we waited for 1 hour and it was 2.2. Is it normal? Technicians said it is normal. But before I change the pressure regulator, pressure drastically dropped to 1.0. Thats why they suggested to replace the fuel pressure regulator. Please advise. :bow:

According to the service manual, it should stay at or above 1.5 kg cm2 when measured 5 minutes after turning the engine off. So if you are staying at 2.2 and hour later, then it is within spec. At an hour after turning off the engine, does it start fine? If so, how many hours does it seem to need to sit before you have the starting trouble?

[SL Runner]

Well..the issue is, when you try to turn on the engine after 5 minutes of turning off the engine - it struggles to start. I wish if can show you all this. :P . Just curious to know..Is there any non-return fuel valve available in the fuel pump? Is it exists, maybe fuel is leaking from there..But I'm worried as I witnessed the fuel line pressure back at the garage and it looked fine. Yesterday I drove the vehicle for 100Km and didnt experience any unusual issues. It has done 14Km/L. I wish if I have a tool to observe the fuel line pressure back at home. My gut feeling is fuel line pressure is dropping due to some reason...:iono:

[CTScott]

Well..the issue is, when you try to turn on the engine after 5 minutes of turning off the engine - it struggles to start. I wish if can show you all this. :P . Just curious to know..Is there any non-return fuel valve available in the fuel pump? Is it exists, maybe fuel is leaking from there..But I'm worried as I witnessed the fuel line pressure back at the garage and it looked fine. Yesterday I drove the vehicle for 100Km and didnt experience any unusual issues. It has done 14Km/L. I wish if I have a tool to observe the fuel line pressure back at home. My gut feeling is fuel line pressure is dropping due to some reason...:iono:

The check valve has to either be part of the fuel pressure regulator or part of the pump.