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Posted by abe5.0 (Member # 4784) on :
 
I am having a problem starting my 1990 gt, it rotates but will not start. I can get it to start no problem with a little spray of starter fluid, but even after running it it will not start again w/out a spray of starter fluid. I am able to drive it. I think that it is not priming after i shut it off b/c i hear a big hiss and at least 5 sec of flowing liquid (pretty sure it is fuel). I think know what a car should sound like if it is priming. So my question is, What are the possible reasons the engine isn't priming itself?
 
Posted by BlackNGold (Member # 655) on :
 
Just a guess, but the first thing I would check is your fuel pressure regulator, sounds like it's not holding pressure very well...The best thing to do is buy a fuel pressure gauge and see how much fuel pressure you actually have when you just turn the key on...

Good luck... [patriot]
 
Posted by 89FOX (Member # 4273) on :
 
check for pressure at the shrader valve on the fuel rail near the #1 cylinder. also check if you hear the pump going on. [patriot]
 
Posted by six 5.0 (Member # 3153) on :
 
My old 90 had a simalr problem. Ended up being my computer, check it out.
 
Posted by abe5.0 (Member # 4784) on :
 
checked it with a fuel pressure guage, but just to make sure: the pressure is supposed to shoot up to about 35-40psi and if i do not turn it over, slowly drop? I made sure to disconnect the vaccume hose from the fuel pressure regulator, in order to make sure that i am only testing the pump. I am assuming that the pressure slowly drops becuase the regulator isn't connected to the vaccume hose. By the way the reading i got was 39psi meaning that my pump is good, right.
 
Posted by SALEENx5 (Member # 1605) on :
 
quote:
Originally posted by abe5.0:
checked it with a fuel pressure guage, but just to make sure: the pressure is supposed to shoot up to about 35-40psi and if i do not turn it over, slowly drop?
What did it slowly drop to? After engine shut off, fuel pressure is still maintained in the fuel lines by an anti-drainback valve in the fuel pump. Attatch the fuel gauge, start and let the engine run, shut it off and check to see how much of a pressure drop there is. It shouldn't drop to zero as this will cause extra fuel pump priming in order for the fuel pressure to build up for the next start-up cycle. As far as what fuel pressure should be: KOEO (KOER w/vacuum hose disconnected) 35-45 PSI. KOER (w/vacuum hose connected) 30-40 PSI. If fuel pressure is not maintained after engine shut off, then you have a bad fuel pump. A sticking open or damaged diaphragm in the fuel pressure regulator will also cause a loss of pressure after engine shut off. However, your reading of 39 psi would not be possible with a damaged regulator so you could probably rule that out.
 
Posted by blind (Member # 3052) on :
 
my car holds its fuel pressure for about 2 hours before slowing dropping if the engine is not running.
 
Posted by abe5.0 (Member # 4784) on :
 
so the pressure dropped w/regualtor connected to 0psi, does that mean i have to replace the fuel pump?
 
Posted by 89FOX (Member # 4273) on :
 
is your fuel pump whining when you turn your key to the on position if so signs of a bad pump. [patriot]
 




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