Hard Start, stalling, stumbling when hot

[Rollus]

Good news.

Twenty minutes to install, one month and a half to admit it could be this and not the CSI time switch and do the hose test..

The cold start time switch engages typically at at 15°C 60°F: http://supra-mk3.club/info/TSRM-Online_by-RR/07_FI_EFI_system/index.html#pf70

Did you check the VSV? http://supra-mk3.club/info/TSRM-Online_by-RR/07_FI_EFI_system/index.html#pf74

(the above was posted on SF)

I believe you are on the right track. Sounds exactly like heat soak is causing fuel vaporization and vapor lock is occurring on the fuel rail. You can check the FPR itself and the rest pressure by following this: http://www.cygnusx1.net/Supra/Library/TSRM/MK3/manual.aspx?S=FI&P=70

If your fuel pressure is correct and not bleeding off when the car sits the fpr vsv is the next culprit.

 

[jetjock]

What happens when a logical and analytical thinker complicates things due to not understanding how a system works. The type pops up here from time to time and the result is always the same...lots of flailing around. That said I've never seen a faulty FPU solenoid alone cause that severe of a hot start issue. Lots of people don't even have them installed.

 

[Rollus]

That said I've never seen a faulty FPU solenoid alone cause that severe of a hot start issue. Lots of people don't even have them installed.

I haven't it installed. I have hot start issue. I run E85 if that makes a difference with heat soak and vaporisation. I will install it back, one day.

 

[Nick M]

I changed mine around 2006. I pulled the vacuum line and the slight stumble after the hot restart cleared quickly. This is going back some, but I didn't see it much either.

 

[bestsupraever]

Hi Guys, just a little follow up to this thread. Drove the car quite a bit the last few days, still starting like new. I am convinced the problem is solved. Also, I grabbed the old oem vsv out of the box i threw it in just on a whim, and tested it again with a 12v battery. Still no action. I then cleaned it thoroughly with contact cleaner, blew it through all 3 nipples, shook it around a bit, pulled the filter off and cleaned that, blew air through it and then tested it again, boom, it clicked, it was working again. Tested it off and on about 20 more times on the bench, and it clicked all times as it was supposed to. Also blew air through the center inlet and watched for change of direction of the airflow, and it did exactly what it was supposed to. So I conclude that it was probably gummed up inside and is now functional again. So I will keep it as a spare should I ever need it again. Just wanted to let anyone know that doesn't already know that it seems that it is possible to clean and make functional again presuming that the solenoid is not totally burned out.
Semper Fi

 

[bestsupraever]

Next time remove the alternator and alternator belt and then it won't seem to hard to get to it.

Major Correction. Hi Guys, I wouldn't want to mislead anyone. I discovered a major piece of misinformation i gave in this thread, while I was investigating my egr valve. And I want to set it straight. In fact the vsv valve for fpu is below the alternator close to block right below the 1st runner of the intake manifold. The egr vsv is below the intake manifold below the 4th runner. Also in CA. cars there is another electrical plug near the firewall in the vicinity of the egr vsv for a temp sensor. The pictured plug in a thread on the other forum may be for that sensor. That extra plug is only for CA.spec cars. Really sorry for the bad info. I only discovered it when I was trying to figure out where the egr vsv was, and I was thinking the one I saw below the 4th runner was the vsv for fpu, it is not, it is the egr vsv. So in fact I replaced the egr vsv, and that is what made my car run and start better. BTW, the fpu vsv looks like a bear to get to. Probably have to remove the alt, as nick did say early on. I just could not see it from any angle, and did not know it was there.
Luck To All--Semper Fi.

 

[bestsupraever]

Attached are picts of the egr, and fpu vsv.

 

[jetjock]

You really ought to RTFM. Also it's very unlikely a bad EGR VSV will cause hard starting because the vacuum to it is ported.

 

[bestsupraever]

Thanks for the reply jets, I have rtfm. After discovering that I actually mistakenly replaced the egr vsv, which was not working by the way, and the car does now start and run well, I to can't really explain it. Perhaps by me mucking around with the vac lines, I inadvertantly tightened one that may have been loose, and replaced the 2 going to the vsv, so maybe that would account for the car starting, but not idling right when hot. Don't know for sure. Anyway I am glad that it is running well now.
Semper Fi