91 Fuel Pump question.
Thread Starter
Safety Car
Joined: Jan 2004
Posts: 3,783
Likes: 15
From: Northern California
91 Fuel Pump question.
I noticed lately that I don't hear the fuel pump prime for 2 seconds before I start the engine first start in the morning.
The engine starts and runs fine with 50psi at the rail (key on engine off) and 40psi engine on.
I used to hear the fuel pump prime but, not anymore. Thanks
The engine starts and runs fine with 50psi at the rail (key on engine off) and 40psi engine on.
I used to hear the fuel pump prime but, not anymore. Thanks
Last edited by GKK; Jun 14, 2011 at 04:42 PM.
Racer
Joined: Apr 2006
Posts: 419
Likes: 1
From: Kelso WA
Been to any concerts or truck pulls lately? If the fuel pressure isn't bleeding down when the key is off and it's been sitting, the pump would already be primed? Not sure what's going on, but if it ain't broke...
Le Mans Master
Joined: Aug 2005
Posts: 7,392
Likes: 218
From: Merritt Island, FL
If the gauge is indicating that it primes, I don't think I'd worry - BUT, with that being said, the pump is so easy to change in the C4 that it's one of those peace of mind kinda things to me.
Le Mans Master
Joined: Jan 2006
Posts: 5,621
Likes: 207
From: Orlando FL
I would tend to think the fuel pump relay might be bad or not getting a signal from the ECM to close.
The engine continues to run because power for the pump is probably coming from the (oil) pressure switch.
You should get the 2 second prime, has nothing to do with if the system is primed already.
The engine continues to run because power for the pump is probably coming from the (oil) pressure switch.
You should get the 2 second prime, has nothing to do with if the system is primed already.
Thread Starter
Safety Car
Joined: Jan 2004
Posts: 3,783
Likes: 15
From: Northern California
I would tend to think the fuel pump relay might be bad or not getting a signal from the ECM to close.
The engine continues to run because power for the pump is probably coming from the (oil) pressure switch.
You should get the 2 second prime, has nothing to do with if the system is primed already.
The engine continues to run because power for the pump is probably coming from the (oil) pressure switch.
You should get the 2 second prime, has nothing to do with if the system is primed already.
I'll check the fuel pump relay. Thanks
Thread Starter
Safety Car
Joined: Jan 2004
Posts: 3,783
Likes: 15
From: Northern California
I just replaced the fuel pump with a Carter pump from Napa and replaced the fuel pump relay under the passenger side dash (looking towards the rear of the car from underneath the dash, the fuel pump relay is the one in the middle of five relays on my "91").
Now, the fuel pump primes on start up and the fuel pressure at idle went from 40psi to 42psi. Thanks, everyone!
Now, the fuel pump primes on start up and the fuel pressure at idle went from 40psi to 42psi. Thanks, everyone!
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