Running Problems

[85mustangGT]

I have been reading a lot of the post and think I have a bad fuel pump, but just want to ask a few questions.
I replaced my fuel pump several months ago and the 1999 Bravada has had a lower than normal idle speed, lately it has been around 450-550.
Today it started sputtering a little on take off like it was going to die.
It is also hard to start, takes 2-4 turns of the key for it to start.
Fuel pump is the much talked about Airtex and I have not checked pressure.
Would the fuel pump make it have a lower idle speed as well?

Is the Delphi the same as the Delco fuel pump?

I have learned so much reading these post, you guys are great for helping everyone out and I am sure everyone appreciates your time.

[southpole9347]

check your pressure man.. did u do a fuel filter when doing the pump last time?

[85mustangGT]

I did replace the fuel filter. Also replaced the spark plugs, dist. cap and button. Bravada has around 130,000 miles on it. I will get me a fuel pressure tester tomorrow and post it up.

[duke350]

Yes, lower pressure could affect the idle. If the engine sees it is running lean due to not enough pressure it will compensate by lowering the air volume resulting in a lower idle.

From what I have read, no matter what pump you buy, delco or delphi, you will end up with a delphi. I do not know for sure, but that is what people are saying.

[85mustangGT]

Here are the results from my pressure test:

Engine not running with key on: pressure goes straight to 61 maybe 62 psi for 2-3 seconds then drops down to the following:
49 psi after 1 minute
38 psi after 2 minutes
30 psi after 3 minutes
25 psi after 4 minutes
20 psi after 5 minutes

Also noticed that the hose from my breather cap to a valve cover was not attached which created a huge vaccum leak, that could have been the whole problem??

Engine running it stays right around 54 psi

I bought my pressure tester at Harbor Freight, wonder what the degree of tolerance is on the gauge?

Maybe a bad check valve with the pressure dropping so fast or maybe just a small leak in the gauge itself??

[Chris Stewart]

The fuel pressure is still a little low. You like to see around 60psi and it should increase a coupla lbs. if you rev the engine.
How is the starting & running after you connected the vacuum line?

[85mustangGT]

Starting still an issue, I have to crank it 2-3 times before I get it to fire, if I cycle the pump a few times it will fire right up.
Attaching the hose did help the idle come up to around 600-700 where it should be.
What should my pressure be with the engine running?

[duke350]

GM doesn't post any specs for fuel pressure while running. The starting issue is most likely due to your leak down. If it is not starting like its flooded then it probably is the check valve in the pump. I have seen where people have used cheaper pumps and the check valve has just "popped" off and was sitting in the bottom of the tank.

[Chris Stewart]

The idle pressure on my '97 was 60-61 psi and increased to 62 when I'd open the throttle suddenly.