Fuel Pressure Problem - Team Camaro Tech
Troubleshooting Diagnosing problems done here.

 
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post #1 of 10 (permalink) Old Mar 10th, 10, 05:23 PM Thread Starter
Mantas Galijota
 
Join Date: Feb 2010
Location: joliet
Posts: 8
Fuel Pressure Problem

Alright so i got a 95 camaro with the 3.4 sfi motor ive been having cold start issues, when i try starting the car in the morning it takes a few tries if I prime the pump 3 or 4 times it fires right up but until the motor reaches optimal temp its a very rough and shaky idle once its optimal temp idles smoothes out and runs fine the car doesnt have any problems driving on a warm motor or even on a cold motor no real driving issues so i finally hooked up a pressure tester to it and it took 3 or 4 primes to even get it close to psi range when i start the motor at idle on a warm motor it sits right at about 35-37 psi when I unplug the regulator it jumps about 8 psi so im assuming the regulator is fine.

Alright so heres the main problem once I had the tester hooked up at idle it sat in that range but as soon as I cut the ignition it drops to zero in about 5 seconds.

I smelled fuel earlier and I traced the smell to the trunk it was cut out where the fuel pump sits so im assuming its been replaced the thing is theres a really strong fuel odor if I leave it open its extremely noticeable in the vehicle.

Im stumped on what it could be I thought maybe a fuel injector but im not miss firing or anything and I did change the fuel filter so thats not the problem. Could it have anything to do with the strong odor coming from where the trunk was cut, I heard the the fuel odor from there is common if it was cut open. Any help would be a godsend
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post #2 of 10 (permalink) Old Mar 10th, 10, 05:29 PM
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Alan
 
Join Date: Oct 2007
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Re: Fuel Pressure Problem

It sounds like you might have several problems. First, if you are smelling gas, you need to pull the rear seat and see where it is coming from. As to the problem of hard cranking, the check valve in the fuel pump is probably bad (assuming the valve is at the fuel pump). This allows the system to de pressurize which makes for hard starting, the check valve should keep pressure in the fuel rail. As to the poor running until it is warm, could possibly be a bad coolant sensor giving the ECU erroneous data.

alan
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post #3 of 10 (permalink) Old Mar 10th, 10, 05:38 PM Thread Starter
Mantas Galijota
 
Join Date: Feb 2010
Location: joliet
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Re: Fuel Pressure Problem

well the smell is coming directly from where the trunk is cut, i read somewhere on hear a few people cut it there to change the fuel pump much easier anyway to put an inline check valve in somewhere else to help diagnose the problem?
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post #4 of 10 (permalink) Old Mar 11th, 10, 10:12 AM
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Alan
 
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Re: Fuel Pressure Problem

If you are smelling gas, it is external to the fuel tank!!! The gas is supposed to stay in the tank not leak to the outside. Pull the panel and look around. Something is leaking!!!

alan
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post #5 of 10 (permalink) Old Mar 11th, 10, 04:14 PM Thread Starter
Mantas Galijota
 
Join Date: Feb 2010
Location: joliet
Posts: 8
Re: Fuel Pressure Problem

thats what I was thinking, logic tells me in order to hold pressure it should be fully sealed in that case meaning no fuel odor....ill start tearing apart and looking around in the mean time any more suggestions? Oh and the temp sensor is not a problem the clip broke off so the connector falls off sometimes but whether its on or off doesnt make any difference
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post #6 of 10 (permalink) Old Mar 11th, 10, 05:42 PM
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Alan
 
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Re: Fuel Pressure Problem

Well, it might not matter to you but I bet the ECU might have a different opinion. If the ECU is getting the wrong signal when the coolant/engine is cold, it won't adjust the air-fuel mixture while the car warms up which results in a poorly running cold car which get better as the car warms up. Might be a bad connection or bad sensor. Get out the manual and see what it is supposed to read when cold and when hot. If it tests out ok, redo the connection and see where that takes you.

alan
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post #7 of 10 (permalink) Old Mar 11th, 10, 06:17 PM Thread Starter
Mantas Galijota
 
Join Date: Feb 2010
Location: joliet
Posts: 8
Re: Fuel Pressure Problem

well the thing is when its plugged in for a few days nothing changes the sensor it self seems to work fine because it shows accurate readings on my dash when its unplugged it sits below the cold line and the problems still occur regardless of how long i keep it plugged up the sensor couldnt be faulty if it gives accurate readings..?
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post #8 of 10 (permalink) Old Mar 11th, 10, 08:48 PM
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Join Date: Apr 2007
Location: iowa
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Re: Fuel Pressure Problem

the sensor for the gauge and the one for the ecu are 2 different sensors

NEVER argue with a stupid person. They bring you down to their level, and then beat you with experience.
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post #9 of 10 (permalink) Old Mar 12th, 10, 04:47 AM Thread Starter
Mantas Galijota
 
Join Date: Feb 2010
Location: joliet
Posts: 8
Re: Fuel Pressure Problem

so theres 2 coolant temp sensors? or is one called something else..? Ok so they ghetto rigged some of the hoses by the pump i put some clamps on it so my problem improved a little better now when i prime the pump i get full pressure from one prime but pressure still drops all the way down to zero fast also no more fuel odor in my trunk so that problems fixed but im still losing pressure
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post #10 of 10 (permalink) Old Mar 12th, 10, 08:04 AM
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Alan
 
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Re: Fuel Pressure Problem

Get a manual but I am pretty sure the check valve is in the fuel pump. That is what prevents bleed down of pressure. As Bighaus79 said, the coolant ECU sensor. Test it!!!!

alan
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