Car shuts off when A/C turned on...

[Howster]

Hi,

My fiance owns a 2007 Yaris 4-door. It has been a perfect car since she purchased it new at the end of 2006. However recently she purchased a Mini Cooper and the Yaris was being driven part-time by her 17 year old son.

The car stopped running one day a month or so ago. We had the car towed to our home and I began troubleshooting as I am an avionics and European car technician by trade. What I found first was the fuel gauge said it had two dashes left, however when I removed the fuel pump, the fuel tank was absolutely dry. I ordered a new sending unit and that was corrected. However it seemed the fuel pump was intermittent. I used my fluke meter, but found the fuel pump seemed to be fine.

I did find out she had not replaced plugs, or had a tune-up pretty much since new. I replaced plugs, oil, air filter, PCV valve, fuel injector o-rings and caps.
I cleaned the MAF with cleaner and checked or leaks in the vacuum system. I sprayed the throttle body and removed as much carbon as i could. After replacing all of these parts and doing the cleaning steps mentioned below, the car would drive ok for a number of miles, but then start running rough at low rpm or at idle. When the A/C is turned on, it pretty much dies. Then the car is very difficult to start unless I spray starting fluid into the air intake. Then it starts fine and idles perfectly. But when I give it a little throttle, it hesitates and wants to shut off. Once I get it past this point it will run fine. But this is all null and void when the A/C is turned on. Then all bets are off. I am stumped here.

I connected my OBD II and began getting P171 codes, which show a lean bank. This to me made sense that the fuel pump could be defective, but to not troubleshoot further and then spend the $250-300 for the pump and find out that isn't the problem was not an option just yet. I have also gotten P301-P304 codes, but these have not returned once they were cleared.

I wanted to test the fuel pressure but can't locate the test port to do this. Normally it is on the fuel injector rail, but not on the Yaris. I just replaced the battery and at least I can now get the car started without jumping it.

Can ANYONE please help me with this? I am a pretty intelligent person and can troubleshoot almost anything, but this Yaris has me going cookoo. Any help would be greatly appreciated.

A six pack will go to anyone who can help me sort this out. Understand that it is illegal to ship alcoholic beverages through the USPS system, so I will of course have to drink them for you. But a toast will be made during each new beer bottle cap being popped and we will mention your name numerous times. I won't chug it, and I won't drive while I am drinking your beer. I won't even drive afterwards. This beer would be for you. So can you/anyone give me some hints? Car has been sitting for about three weeks because of my work shift. Thanks so much to everyone for reading this really long and boring post. It is greatly appreciated.

Cheers,

Howie

P.S. Howie, Alma, and Max thank you.