finally tested the fuel pressure

[dlistro]

Alright i finally tested the fuel pressure on my 1996 aurora. I turned the key to the run position to and the pressure built up to about 20psi. I continued to turn the key off and then back to run a few more times to see what the maximum pressure that i could obtain would be and found that the pressure reached about 38psi but would go no higher. After reaching this pressure i proceeded to crank the engine but the car still did not start (of course not). I know the correct psi for this car is anywhere between 41 and 47psi but dont you guys think that it would at least start but run shitty with 38psi? While cranking the pressure also seems to stay pretty steady until you decided to give it some gas. When gas is given the pressure drops to about 34psi. Is this enough pressure to start the car?

[Indy8]

You need to fog the airbox with starting fluid then crank it. If there is spark, it WILL start. If it burns off the fluid and stalls again then you have inadequate fuel for it to run.

[dlistro]

Yeah i tried starter fluid before and it seemed like when i gave the car a good shot of it it would start up and then shut down again. But without it i can barely ever get the car to start up. So there probably is not enough fuel pressure. Still wondering if the computer might be killing the spark after startup for some strange reason.

[Indy8]

I'm no engine managment system engineer, but I've never heard of a circuit that was intentionally designed to shut down an engine. Just part failure. So if you have air and spark, the only thing missing is gas.

[GTP Dad]

To answer your question 34 psi is not enough to start the car. Change the fuel pressure regulator and your problem should go away. The fuel pump is obviously working correctly but the regulator is not holding pressure to enable the car to run.

[dlistro]

Yeah the fpr is going to get replaced for sure. I also should say that when i go to start the car (expsecially on the first attempt) it gives me a back fire through the intake. Is this another problem or do you think that this is also fuel related. It only backfires on the first attempt after sitting for a while. Any subsequent attempts yield no backfire.

[GTP Dad]

Fuel related. It is getting just enough fuel to fire when the valves are open and cause the backfire. Should go away when the regulator is replaced.

[dlistro]

just replaced the fpr and it did not make any difference at all. The pressure still stays around 38psi and the car still wont start up. So i guess its the fuel pump? Also when i replaced the fpr there was a little of crude in the bowl. Would it be a good idea to blow out the fuel lines?

[GTP Dad]

Before you change the fuel pump, change the fuel filter and try it again. If there is junk in the fpr then the fuel filter may be so dirty it is restricting flow to the engine. Only costs a few dollars and would be a lot cheaper than a new fuel pump if it works.

[maxwedge]

Originally Posted by dlistro

just replaced the fpr and it did not make any difference at all. The pressure still stays around 38psi and the car still wont start up. So i guess its the fuel pump? Also when i replaced the fpr there was a little of crude in the bowl. Would it be a good idea to blow out the fuel lines?

Do you have injector pulse having pressure in the lines won't help if the injectors aren't pulsing.

[dlistro]

Yes i have injector pulse and i forgot to mention that the fuel filter was the first thing that i replaced.