Fuel feed problem
richledell
12-03-2005, 09:58 AM
I have a 1996 Blazer that was bought used ~5 years ago. The original owner informed me of a problem that when the tank is at 1/4 or less and the vehicle is parked downhill, the fuel pump sucks air and engine won't start. Roll it to level ground and it starts. The problem has gotten progressively worse even after a fuel pump replacement. Now when the tank approaches just less than 1/2 full the engine will die during prolonged braking, down hill stops, and even extended long radius turning. This is really a eye opener when you loose PS & PB. Anyone else heard of this more than annoying problem?
MT-2500
12-03-2005, 03:50 PM
What kind of a fuep pump replacement?
A complete module or just the pump?
Is the gauge working right?
MT
A complete module or just the pump?
Is the gauge working right?
MT
rlith
12-04-2005, 07:30 AM
This is a common problem. It's what we call 1/4 tank syndrome...:)
Essentially the check valve on the sending unit is pooched. It's not a serviceable part. You need to change out your sending unit. (Depending on the miledge, you may want to throw a fuel pump in there so you don't have to drop the tank again later. )
Essentially the check valve on the sending unit is pooched. It's not a serviceable part. You need to change out your sending unit. (Depending on the miledge, you may want to throw a fuel pump in there so you don't have to drop the tank again later. )
richledell
12-04-2005, 07:40 AM
What kind of a fuep pump replacement?
A complete module or just the pump?
Is the gauge working right?
MT
complete module
A complete module or just the pump?
Is the gauge working right?
MT
complete module
MT-2500
12-04-2005, 10:31 AM
Like Rlith posted.
It is usually a problem in the Module/sending unit.
Get a fuel pressure gauge on it and see if pressure is returning to the fuel tank after shut off or is pumping good pressure.
Have you got any warranty left on the module?
Also make sure the plug in at the fuel pump module is in good shape and has a good ground.
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.
MT
It is usually a problem in the Module/sending unit.
Get a fuel pressure gauge on it and see if pressure is returning to the fuel tank after shut off or is pumping good pressure.
Have you got any warranty left on the module?
Also make sure the plug in at the fuel pump module is in good shape and has a good ground.
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.
MT
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