Fuel Pump Question
Thread Starter
Instructor
Joined: Oct 1999
Posts: 145
Likes: 0
From: San Francisco, CA, USA
Fuel Pump Question
I have a fairly stock 85 with what I think is a fuel pump problem. When I turn the key , the pump goes on for a very short period of time (approx 2-3 seconds). The pressure goes up appropriately, but then the pump turns off and the pressure drops to zero. If I run power to the connector under the dash as the manual suggest, the pump activates and stays on for as long as I have power jumped. If I continue to crank the motor the engine starts, but is harder and harder to start the more times I need to start it...i.e. run, sit, start, etc.
Is this a pump problem, or something else? I understand from reading the manual that the pump should normally turn off if the starter is not engaged as the system thinks you don't really want to start the car. Before I spend the money to buy and replace the pump, I would like to be fairly confident that that is the problem. Thanks in advance for any advice :cheers:
Is this a pump problem, or something else? I understand from reading the manual that the pump should normally turn off if the starter is not engaged as the system thinks you don't really want to start the car. Before I spend the money to buy and replace the pump, I would like to be fairly confident that that is the problem. Thanks in advance for any advice :cheers:
Team Owner
Joined: Dec 2000
Posts: 90,675
Likes: 304
From: SE NY
Cruise-In II Veteran
Re: Fuel Pump Question (OnDVirg)
Leak down can be due to external leaks in the fuel rail, leaking injectors, leaking check valve in the fuel pump (FP) or defective fuel pressure regulator (FPR).
There are two rubber lines near the top of the fuel tank. These can be clamped in turn to isolate the FP check valve or the FPR.
Will the engine start without the FP jumpered at the ALDL?
There are two rubber lines near the top of the fuel tank. These can be clamped in turn to isolate the FP check valve or the FPR.
Will the engine start without the FP jumpered at the ALDL?
Safety Car
Joined: Feb 2002
Posts: 4,212
Likes: 10
From: Sun City West Az
Re: Fuel Pump Question (65Z01)
Hook a FP guage to the schrader valve,; key on; have a friend pinch off the the outbound fuel line (at the gas tank) to the fuel rail; if pressure holds then it is the pump / check valve in the pump. If pressure still falls, then the problem is after the pump; ie: FPR ,injectors, etc.
