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Discussion Starter #1 (Edited)
So a new problem. Car starts cold fine. Runs great. No problems. Until you turn it off and it sits for 45 min to an hour. Then it starts and idles really rough, no throttle response and won't idle up and dies. Then won't start. Smells rich when it does this. Next morning starts just fine like nothing.

It will start no problem if it only sits for a few minutes after hot. Seems to happen after it has started to cool down about 45 min to an hour.

Just cleaned throttle body and still have the issue.

Fairly stock, MAF has been deleted and running hks vane controller. Has been in this setup for years no problem. This problem is recent. Has done this 3 times now.

No recent changes.

Mods are k&n conical, hard pipes and 3" exhaust.
 

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Discussion Starter #2
update - now after sitting overnight it still won't start. so now cold start won't start. No codes are showing?
 

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Sounds like you have a leaky injector(s) that's staying open after shutoff. Would definitely check spark plugs and change them out.

*Should change your spark plugs for fresh plugs since yours are more than likely fouled. If you have a compressor I would blow out the cylinders with air, if not leave the plugs out to let the extra fuel evaporate. Should start after you install plugs. If it does, check the plugs and/or flash a light down the cylinders to look for extra fuel after it sat for 45min to an hour.
 

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Discussion Starter #4
Plugs are newer. They have less than 3,000 miles on them.
 

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I agree with ATL sounds like a fuel problem, most likely fuel injectors or a bad fuel pressure regulator. You said it smells rich if you take a plug out are they completely black from running rich? I recently had a bad fuel pressure regulator and one leaky injector. Only had starting issues when engine was warm. Check all of that and see what you find.
 

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Discussion Starter #6
Finally was able to pull a code. Turns out I need to resoder the board for the check engine light.

Code 78

We had a couple of cooler days and the dealership couldn't replicate the problem. They were thinking coolent temperatur sensor and wanted $600 to Change coolant, the thermostat and the sensor on a guess. This weekend will be warmer again so I am guessing it will occur again. I am leaning to a bad fuel pump when it is hot out.

At least when it happens this time I should be able to hear if I have fuel running in the rails. If not I can jump the b+ and the fp terminals and that should bypass the fuel ecu to pinpoint it or the pump. Is this thinking right?

The relay is fine. I switched them out already.
 

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Discussion Starter #8 (Edited)
would a bad fuel pressure regulator throw a code 78?

Update. Pulled the vacuum line of the pressure regulator and ran the fuel pump for about 5 minutes. No leaking past the diaphragm. Any other pressure regulator test other that a pressure gauge. Where would the best place be to put one on the line?
 

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Discussion Starter #10
So I haven't been able to replicate the non start now.

Pressure is good,
relays are good
Pressure regulator has no leakage past the diaphram

only unknowns are the ecu and the pump. The closest I have come to replicating the non start is when I have gone back out 1 hr after turning it off I can start the car. let it run for 5 seconds and turn it off I get a huge and loud rushing waterfall sound / gurgling from the fuel tank. It lasts longer then the usual extended run that the relay allows. it only does this once or twice (as I start it right away again to try and get it to replicate the issue) and then everything is back to normal and it is like nothing was ever wrong. I am just waiting for it to strand me again. So here is my thought.

code 78 arose from the initial non start issue. Code 78 only comes from a open circuit failure . so a faulty pressure regulator shouldn't trip a code 78

my thought is that after the fuel pump has heated up (and it needs be a decent temperature outside) it is getting too hot and creating a vapor lock once shut down. It is fine as long as it is running because it keeps getting cool gas to keep it from getting to hot. it would only do the vapor lock after it sits, heat soaks, and can vaporize the fuel in the pump. This would be consistent with the non start issue the first couple of times. The rushing should that I am hearing now could be me not timing the vapor lock correctly and hearing it returning on the bypass/return line after the car is shut off.

It would be nice to have it just not restart so I could verify the pump not running (I believe) like it did the first time, but it hasn't yet...

not very often do people wish their car to fail. lol

my circuit test fine right now. I am hoping for a different result when I can replicate the issue.
 

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Vapor lock is pretty much non existent on FI cars. Even if you turn the gas in the line to vapor it will quickly be circulated out when the fuel pump comes on. That's why your fuel rail runs into the regulator and then to the return line. Cool, fresh fuel is always circulating.

Something you may want to look at is your EGR/EVAP system. I re-installed my EVAP (Got the car with it removed) and neglected to install the VSV the first time. Fumes would flow unchecked into the manifold and cause the engine to flood after sitting for an hour just like yours. The difference is that mine would run correctly after I finally got it running. I installed a VSV and now it works like a champ. No more lost gas, no more gas smell!
 

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Discussion Starter #12 (Edited)
So I finally got it to fail. Yippie - other than the fact it was out and not at home.

The fuel pump would not run, The car ran really rough on idle and wouldn't idle up on the residual pressure that was in the fuel rail. Once it was gone it wouldn't run. So I jumped the B+ and the FP jumpers and the fuel pump ran and the car ran. So it isn't the pump, pressure issue, etc.

I wasn't able to check to see what the reading were out of the VSV as I didn't have my multi meter with me. But it ran like garbage because of no fuel pressure and the pump not running. Once I jumped the pump, no problem running, starting, etc. remove the paper clip from the jumper and it dies as soon as it uses up the fuel pressure.

This leads me to believe it is the fuel management computer - time for the 12V mod????

I believe I am on the right track - someone want to chime in and let me know if I am thinking right or if I am missing something.

p.s. - the paper clip gets pretty hot when jumping the pump - safe to drive it home?? or maybe I need to make an insulated jumper - what gauge wire?
Thanks in advance guys.
 

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Sounds like you are on the right track. Paperclip is ok in a pinch but put something more permanent in when you get home. Also keep it away from anything that it can melt or start a fire with.
 

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Discussion Starter #14 (Edited)
Gee. I wonder why I wasn't getting power to the fuel pump. This is what happens when the previous owner does the 12volt fuel pump mod and doesn't protect the wires correctly. Lucky the car didn't burn up in a big ball of flames. Grrrrrr.

rewired, cleaned up, protected properly and the car fired right up the first time. Friends shouldn't let friends do bad mods - this is why I wanted a mint supra that hadn't been monkeyed with. At least everything else I have already cleaned up, etc.
 

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