1994 Formula

Does this intermit not all the time.

Will start for 30 seconds run like crap and bog and die.

Then it may not start for a few times then start up and run for 30 seconds sputter and die.

Then an hour later I will start the car up and it will run fine and drive fine.

Any ideas?

 

Have you scanned it for codes? Have you checked the fuel pressure?

 

I will check fuel pressure tomorrow. What is the normal range? I am not throwing a check engine light? Does it still need to be scanned? It is a 1994

 

if I am not throwing a code, do I still need to scan it?

What is the normal range for fuel pressure on a stock car?

 

There are codes that do not turn on the SES light.

Turn key to on, do not start engine. Pump should prime for a few seconds, reaching at least 40psi, then shut off. Fuel pressure should not drop quickly.

Start engine, at idle, pull the vacuum compensation line off the fuel pressure regulator (cap end of line to prevent vacuum leak). Pressure should be 43.5psi. GM accepts anything in the range of 41-47psi.

Reattach vacuum compensation line. Pressure should drop proportional to intake manifold vacuum. Up to an 8psi drop with a stock cam, less with a more radical cam.

Tape fuel pressure gauge to windshield, take it out on the road - wide open throttle/max RPM. Pressure should not drop below 40psi.

 

I let the car sit all night. I hooked up the pressure gauge flicked on the key and got like 30 and then did the test a few times and it got a few crazy readings from 30-42. I started it and it ran for about 5 seconds at a low psi then died and dropped to zero. I tried to prime then start the car and it wouldnt start then I got nothing but zeros testing after that and the car would not start.

i will try to test it the way that you just informed me however I dont know if I will get it to start as I do not think the fuel pump is always working.

If i can not get it to start whats my next move? Im assuming its the fuel pump and not the regulator. What else could it be?

 

ok i let it sit for an hour went out the turned key on didnt hear the pump and got 43 and held 40 for a minuted then I started it and it ran for maybe 2 or 3 seconds then fuel pressure dropped rapidly and the car died.

the test then shower 0 psi 3 tests in a row and oviously could not get it started

 

Try testing it by running the pump off the "fuel pump prime connector" near the PCM. Apply 12V to the connector. That bypasses the PCM/fuel pump interlocks, and the fuel pump relay.

http://shbox.com/1/fuel_pump_prime.jpg

 

this test isolates the fuel pump to test if the pump is bad or not? if the pump works then it is good and something else is the problem?

 

Couldnt keep car running.mom flicked key before i bypassed and it read out 42 psi and started and ran for a second and died to 0. I bypassed it and it read 28psi started it and died to 0 car stalled. i got it bypassed again and it read 31 psi and when it was running it was 39 psi and I went to pull vaccum line and it stalled.

 

ran off pcm again after sitting 5 minutes

1- prime read 42 psi. started car ran for 2 seconds pressure drops to 0 car dies
2-no prime
3-no prime
4-no prime

bypassed-
1-no psi or prime
2-no psi or prime
3-no psi or prime
4-no psi or prime

 

So is it the pump pr should i do more tests?

 

Your problem is not likely the PR. Since it's only a diaphragm, it would tend to give the same result all the time. Not high one second and 0 the next. Your problem is due to either a faulty pump, or faulty connection.

Your best bet is to monitor pump voltage at the connector behind the rear seat. Outside the body just in front of the driver side rear axle. At the same time, monitor fuel pressure while you have the fuel pump prime connector jumped to 12 volts.

If you read voltage to the pump at that connector but pressure drops, you know for sure the pump is bad. If voltage drops out when pressure does, it's a connection issue.

 

car sat overnight, hooked up pressure test and there was alot of gas around the cap on the back of the engine from the cap. worth noting i did do about 15 tests yesterday

1- primed to 41 started and ran perfect
2- disconnected vacuum and sealed it obtained 43.5 psi
3- hooked vaccum up drove it regular driving 38 to 39 and at wot dropped to around 20 psi
4-sealed off vaccum hose idle at 44 to 45 driving
5- 3 wot runs dropped to 22 and 18 and 10 psi was the final one
6- car bogged out and fuel cut out lost pressure almost stalled
7- regained pressure and drove at 45 then cut out the whole way home down to 15 just driving regular

 

So in order to do this test I need to run a power line from the positive battery terminal to the pump prime connctor.

and check at the connector you explained. I will have to hop under and take a look for it