Fuel Problem on a 1989 F-150
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Fuel Problem on a 1989 F-150
Hello
I just bought a 1989 F-150 Truck. The truck was in pretty good condition for the price... anyhow it has a 5.0 liter engine. The problem i am having is when i turn the key the fuel pump keeps running and doesn't stop. As far as i know they are supposed to shut off after 3 sec's after turn on the key. Anyhow it will start and run good but if shut it off. Then try to start again. It won't start. Its flooded. I replaced the fuel relay. I thought that was it but it wasn't. When it floods out like that i can unplug the fuel relay while someone is starting it and plug it back. It starts up. I am wondering could the fuel pump have some kind of fuel pressure valve built in it and its went to the bad? or is there something somwhere that could be messing up? please let me know your opion.... thx a lot
I just bought a 1989 F-150 Truck. The truck was in pretty good condition for the price... anyhow it has a 5.0 liter engine. The problem i am having is when i turn the key the fuel pump keeps running and doesn't stop. As far as i know they are supposed to shut off after 3 sec's after turn on the key. Anyhow it will start and run good but if shut it off. Then try to start again. It won't start. Its flooded. I replaced the fuel relay. I thought that was it but it wasn't. When it floods out like that i can unplug the fuel relay while someone is starting it and plug it back. It starts up. I am wondering could the fuel pump have some kind of fuel pressure valve built in it and its went to the bad? or is there something somwhere that could be messing up? please let me know your opion.... thx a lot
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From: Susquehanna Valley, pa.
there is a pressure switch to turn off the pump but i'm not sure where it is located or how to test it.
If RP moves this to the pre 97 section you will get alot more help.
This area is foe posts not related to trucks
Oh welcome to f150online
If RP moves this to the pre 97 section you will get alot more help.
This area is foe posts not related to trucks
Oh welcome to f150online
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From: Starkville Mississippi
If RP moves this to the pre 97 section you will get alot more help.
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I believe on that system, (EEC IV?) that the PCM supplies a ground for the fuel pump relay, but it needs to see a tach signal of at least 400 rpm or it stops supplying the ground for the relay. In other words, if the engine isn't spinning at least 400 rpm, the PCM takes away the fuel pump relay ground. This is where you get the 3 second run of the fuel pump when the key is first turned on.
I would suspect that somewhere along the way, someone wired up a 12v (hot with ignition on) feed directly to the fuel pump.
EDIT: Or, they wired the relay ground directly (by-passing the PCM)
I would suspect that somewhere along the way, someone wired up a 12v (hot with ignition on) feed directly to the fuel pump.
EDIT: Or, they wired the relay ground directly (by-passing the PCM)
Last edited by Net Wurker; Feb 14, 2005 at 10:03 AM.
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one question.... how would i test this to find that out.....?? and one question.... ppl was telling me the computer under the dash.... could be bad..... is that possible to make this problem occur?