Fuel Pump issue
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Fuel Pump issue
Three questions. Vehicle in question is an 89 Aerostar with 3.0 V-6. It has started just dying while driving down the road. After letting it sit a while it will start up again and go on like nothing ever happened. This sounds to me like fuel pump. I ran my computer in it and got a code for bad ground to fuel pump.
Question 1) Does this sound like the fuel pump is going bad? I have not had a chance to check connections yet.
Question 2) Does this model year (89) have two fuel pumps? One low pressure in the tank for fuel delivery to the fuel system and one hight pressure along the frame rail for pressurizing the fuel rail. How do I tell which one it is?
Question 3) Is there an access point to the fuel pump in the tank or do I have to drop the tank to replace the low pressure fuel pump?
Any help will be greatly appreciated.
Question 1) Does this sound like the fuel pump is going bad? I have not had a chance to check connections yet.
Question 2) Does this model year (89) have two fuel pumps? One low pressure in the tank for fuel delivery to the fuel system and one hight pressure along the frame rail for pressurizing the fuel rail. How do I tell which one it is?
Question 3) Is there an access point to the fuel pump in the tank or do I have to drop the tank to replace the low pressure fuel pump?
Any help will be greatly appreciated.
Lead Driver
Joined: Sep 2003
Posts: 7,016
Likes: 209
From: SoCal
The Aerostar has just a single fuel pump in the tank. Before dropping the tank, get a fuel pressure gauge to attach to the fuel rail to check the pressure while idling, and if possible, while driving. The idle pressure should be 30-40 psi, while under load should be at least 40 psi. If you've determined that the pump is weak or dying, you will have to at least partially drop the tank. I did this by jacking up the driver's side, and loosening the mounting straps enough to let the tank swing down to access the mounting plate on top. You have to first disconnect the fuel line from the filter mounted on the frame rail.
The other possibility, based on your symptoms, is the TFI module that's usually screwed to the base of the distributor. They're known to overheat, and cause the engine to stall. But if you let the engine sit for a while, it can cool off long enough to let you start the engine again and run for a while. It might help to remove the dog house cover the next time this happens. But the correct solution would be to relocate the module by mounting it on a better heat-sinking surface. I did this on my 1987 Mustang as a preemptive measure:
https://picasaweb.google.com/1155523...7MustangEngine
The other possibility, based on your symptoms, is the TFI module that's usually screwed to the base of the distributor. They're known to overheat, and cause the engine to stall. But if you let the engine sit for a while, it can cool off long enough to let you start the engine again and run for a while. It might help to remove the dog house cover the next time this happens. But the correct solution would be to relocate the module by mounting it on a better heat-sinking surface. I did this on my 1987 Mustang as a preemptive measure:
https://picasaweb.google.com/1155523...7MustangEngine
Postmaster
Joined: Oct 2009
Posts: 3,432
Likes: 7
I agree, do some tests with the pump. Your symptoms are consistent with a failing pump, but it could be caused by other things too. Diagnostics are important, otherwise you are just a parts changer.
And also agreed about the TFI module if it is located on the distributor. Later models put it on the radiator support or fender for that very reason.
And also agreed about the TFI module if it is located on the distributor. Later models put it on the radiator support or fender for that very reason.
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