damnDSM

Since the beginning of this "winter" the Lexus has been giving me some cold start and dying issues. Sometimes, it will take several attempts to start the car after it has sat overnight.

The first time it died on me, I was turning a corner at 15mph. It died almost as soon as I took my foot off the accelerator.

The second time, a few days later, it wouldn't start for me at all. I cycled the key from Off to On several times and I was able to get it to start. It did died on me later that night as I was backing out of a parking space.

Today, the car started right up. I always let the car warm up for several minutes before operation. The coolant temperature gauge had moved just a little above the first mark (idled for about 5-8 minutes) then I put it in reverse and started to roll backwards. My foot wasn't on the gas pedal and it died on me. After that, it would turn over, and even catch for a moment, long enough to maintain 1,000rpm for a second, then it would die.

I popped the hood and checked the distributor cap to make sure it wasn't loose. I checked the plug wires at the cap but nothing seemed out of place or loose. Then the car fired right up...

I am guessing it is a ECU problem or maybe a Fuel pump ECU problem.

Would that be an accurate place to start?

Also, how would I go about diagnosing these things without spare parts to test.


1992 SC300
no performance mods
unknown fuel filter age


Any ideas are greatly appreciated.



(I will continue using the search feature until I find something, but so far, I have not had any luck on this forum)

LEX_MAN

iTrader: (2)

If you want to diagnose the fuel pump ECU the search that thread.I forgot what the jumper settings are for it ,but you can use a paper clip in the diagnostic box under the hood(next to the intake manifold)

Ok i found it for you,its

connect PF and B+ with a paper clip and start the car.

damnDSM

Awesome information. I was searching the wrong part of the forum, and that's why I was getting poor search results


I am going to try jumping the diag. box first thing in the morning (if it gives me the same problem)

I just looked up the Fuel Pressure bypass modification. It seems like the cheapest alternative to replacing the FPCU.

redsc400

fuel pump ecu takes 30 mins to replace and less than $50....def sounds like thats your issue i was having similar problems with mine - got one from aliga and its been good ever since

damnDSM

The car has been starting up for me like normal until just a few minutes ago. I was waiting for it to do this again, but I expected it to be much cooler outside. The outside temp here in Orlando right now is probably around 75*

In the Diag. box I jumped FP and B+ (the orientation of each female plug is noted on the inside of the lid) with a paper clip and the car fired right up. I pulled the paper clip and the car would just turn over. It would catch for a second, then die. I put the paper clip back in a second time and the car fired right up. Pulled it, car wouldn't start.

I am going to bypass the FPCU and call it a day.

redsc400

yup, if bypassing results in a good start your problem is the fpecu.

it might be a good idea to get a fresh fuel filter on the car too

damnDSM

For future trouble shooters and researchers;

I followed this write up to bypass my my Fuel Pump Control Unit. Now the car starts flawlessly every time.



I plan on getting the fuel filter next time I am at the autoparts store. Thanks for the advice!


-Stephen