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2G weirdest fuel issue never before heard of

Boostedtsi0521

Probationary Member
20
2
Feb 27, 2017
miami, Florida
So like the the title reads it is super weird what's going on. To begin with the car was not starting, I was driving and all of a sudden shut off. Fuel pump was bad so I changed it for a higher flow (255lph) pump and install an air fuel pressure regulator (afpr). I crank the car and it doesn't turn on and psi is at 43. I can smell the gas so I disconnect the pump and crank it and it turns on stays on for about 10 seconds before it shuts off. So I'm guessing it floods the cylinders with gas and when no gas is coming in it turns on. How is this even possible when my psi is correct? I'm all out of ideas I checked the injectors and they are firing correctly. I have spark and fuel pressure .If anyone has heard of this please let me know
 

pauleyman

DSM Wiseman
6,383
1,635
Nov 19, 2011
oklahoma city, Oklahoma
Fuel works as follows.
When ECU gets a signal for cranking it fires the fuel pump and will continue to run so long as engine is turning. If you just crank for a sec without starting fuel pump still starts then shuts off as you have observed.
How did you check injectors and how did you determine fuel pump was bad? If car shuts off immediately it likely isn't fuel pump. Even if you fuel pump shuts off you have pressure so engine doesn't just shut off. Typically
engine shuts off as if you turned key off with an electrical problem. No spark or no fuel (from injectors).
When you says floods the cylinders with gas what do you mean and why? How do you know this? Where do you smell fuel?
BTW its adjustable fuel pressure regulator not air fuel pressure regulator.
 

Boostedtsi0521

Probationary Member
20
2
Feb 27, 2017
miami, Florida
Thanks for the correction on the afpr.
so when the car initially broke down the pump went bad had no pressure with power on after checking voltage. So imagine your cranking the car and it turns over but doesn't combust and turn on. You can literally smell the gas from the engine bay. Now imagine you take off the fuse to the pump so the pump doesn't engage. Now start cranking and the car turns on and stays on for about 6 seconds and just turns off. This is everytime. I put back the fuse and crank no start then pull fuse and turns on. My theory is it's getting too much gas so and then turns on when it's not receiving it. I checked the injectors with volt meter. Psi is good at 43 while cranking. I'm thinking of putting back an 195lph pump back but I just can't get over the fact that if I have correct pressure it shouldn't be the pump
 

pauleyman

DSM Wiseman
6,383
1,635
Nov 19, 2011
oklahoma city, Oklahoma
Thanks for the correction on the afpr.
so when the car initially broke down the pump went bad had no pressure with power on after checking voltage. So imagine your cranking the car and it turns over but doesn't combust and turn on. You can literally smell the gas from the engine bay. Now imagine you take off the fuse to the pump so the pump doesn't engage. Now start cranking and the car turns on and stays on for about 6 seconds and just turns off. This is everytime. I put back the fuse and crank no start then pull fuse and turns on. My theory is it's getting too much gas so and then turns on when it's not receiving it. I checked the injectors with volt meter. Psi is good at 43 while cranking. I'm thinking of putting back an 195lph pump back but I just can't get over the fact that if I have correct pressure it shouldn't be the pump
I'm still not clear here. If you had key on and checked voltage at fuel pump you will not get voltage. If this is what you did that is not indicative of a bad fuel pump.,
2nd sentence makes sense. You are trying to start it and it doesn't start. If you can smell gas it isn't because of a fuel pump issue. Either fuel pressure regulator is bad per the last post. It will leak into the intake manifold if that's the case. Or you have injectors dumping too much fuel for whatever reason. Stuck injector is a possible suspect also (as per last post). If you removed power to fuel pump obviously fuel pump won't fire. Car starts then? If so you have residual fuel pressure (as you should) and possibly leftover fuel in the cylinders. You need to rule out pressure regulaotr ( you just installed an adjustable)? If this has happened since initial diagnosis I wouild say rule that out for now. Now...onto injectors. crank the car, i assume it's not starting. pull the spark plug and see if any are wet and does any one cylinder smell worse than others. If you have a fuel pressure gauge it will drop quickly if you have a leaking injector.
I'm still doubting all of this and I think you replaced parts that weren't bad. If car shut off while driving as if you just shut it off, you weren't missing fuel pressure (pump). You're missing spark or fuel (from injectors not firing). That seems more likely. You could rule out spark by removing injector clips and using ether to try and start car. If car starts for a few sec easily you obviously have spark.
 

shdwmsk

Probationary Member
9
2
Nov 1, 2019
Ramsey, Minnesota
Check your coolant temp sensor. I had this problem 16 years ago (holy crap...) Same symptoms as you are, not running, smelling gas. But runs when you unplug the fuel pump until the fuel rail emptied. I had ECMlink and noticed that the temp was not showing ambient temp on a cold engine, changed it and it ran fine. Bad sensor messing with the FIAV.

Bellow is my thread on tuners under my old username. I remembered I had this issue when I was bored and googled my old user name yesterday looking for a picture! Hope this helps!

https://www.dsmtuners.com/threads/another-wont-start-flooding.139409/#post-1136852
 

shdwmsk

Probationary Member
9
2
Nov 1, 2019
Ramsey, Minnesota
Cool glad that I could help!

It was a weird issue that stuck with me. Its like trying to start a car in the summer with the choke on. Computer thinks its colder out then it is, adding fuel to compensate and flooding out the engine. (That's my best guess anyways.)
 
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