98 Astro Fuel System Problems

[WGMashburn]

The fuel pump in my 98 Astro died last weekend, and was replaced Sunday. The van started fine Monday morning/afternoon. In the evening, after another errand, it wouldn't start yet again. You can hear the fuel pump energize when you turn the key. After 2 or 3 key turns, it builds up to 22/24PSI. When I replaced the pump last weekend, I could not get a PSI reading because no fuel pressure gages were available at any of the local auto parts stores.

I took the fuel return line out of the fitting on top of the motor. Nothing came out. So I don't think it's the regulator. I dropped the fuel tank it has 4 ft of temp. rubber hose right now, still only builds 22/24PSI.

Could it be a bad pump? Or does anyone have any ideas I have not thought of before I get another pump.

Any advice/help would be greatly appreciated.

Thanx,

Ken

[MT-2500]

Make sure it has good 12 volts to it and a good ground.
Add another 5 gallon of fuel to tank.

Hard to start cold.
Check cold start fuel pressure.
Check engine running fuel pressure.
Check engine running on the road fuel pressure.
Then shut it off and watch for fast leak down.
Pinch off at rubber part or block off return line and check full pressure.
Later V6 and V8 gm engines should have 60-66 fuel pressure.
Cold start should be 64-65 lbs of pressure.
If you do not have full fuel pressure on a cold start the injectors will not squirt fuel.
Do not leave home without it.
Engine running should be 60-66 lbs pressure depending on engine load.
Full pressure with return pinched off should be 75-85 or more.
And if it has a fast leak down after shut off you have a leak.
Post back fuel pressure readings.

[drew300]

I found my defective pump was drawing less than 7 amps.
The replacement draws about 10 - 10.5 amps.
I measured this by pulling the fuel pump relay out, and carefully putting an ammeter on the correct pins of the socket. (the pump will then run even with the key off).
I did this long ago, and can't remember which pins it was, but it was marked on the relay, if you can sort thru that. This will tell you if you've got a good connection and ground to the pump.
BTW: when I was troubleshooting, a GM Service rep said "minimum 60" psi.
I had 59 psi on the guage I had, and it wouldn't start, but after starting with a shot of carb cleaner, it would run fine.
My replacement pump had a warning page with it, to make sure you get a good, clean, non-corroded connection at the pump. I was surprised at how small that connector is, considering it carries 10 amps continously.
BTW: have you checked your fuel filter? That's cheap insurance.