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Joined: Jan 2022
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From: Colorado
New To the Fordum...
Bought a 93 Ford F-150 with a 94 351 Windsor in it.
I picked this up from the same guy who swapped the engine. vacuum lines were dry rotted distributor busted and the ignition column was taken apart. I've been trying to get it to run, replaced the distributor and it ran for a split second then sputtered out. i came to the conclusion that the fuel pumps were probably bad because they didn't kick on for the usual amount of time it takes to send fuel to the fuel rail. instead of two seconds it was .5 second. so I bought the new fuel pumps and vacuum line harness and I'm ready to install. If anyone knows what more I should check out to get it running or to keep surprises from arising, I would greatly appreciate it. Thanks
I picked this up from the same guy who swapped the engine. vacuum lines were dry rotted distributor busted and the ignition column was taken apart. I've been trying to get it to run, replaced the distributor and it ran for a split second then sputtered out. i came to the conclusion that the fuel pumps were probably bad because they didn't kick on for the usual amount of time it takes to send fuel to the fuel rail. instead of two seconds it was .5 second. so I bought the new fuel pumps and vacuum line harness and I'm ready to install. If anyone knows what more I should check out to get it running or to keep surprises from arising, I would greatly appreciate it. Thanks
Last edited by Cleetis44; Jan 21, 2022 at 05:32 PM.
Senior Member
Joined: Jun 2010
Posts: 16,584
Maybe this might help,
When the key is first turned on , the ECM activates an ECM relay that provides power to the fuel pump relay.The ECM also provides that 2-3 second ground to operate the fuel pump relay. When the engine is cranked over the dist sends an RPM signal back to the ECM to keep the fuel pump relay energized.
Now we have some idea of what is supposed to happen the idea is to follow up on the relays and see if the ECM is providing that momentary ground to the fuel pump relay and that the ECM relay is providing the power to the fuel pump relay so that when that relay gets the ground signal the fuel pump runs.
B the way,,,,the ECM relay and the fuel pump relay are interchangeable and can be switched to verify which is working and go from there.
Suggest you label the relay positions so you always have an idea where you are working or want to do further checking.
To help determine which is the ECM relay, One of those relays will stay energized and the other (Fuel pump) relay will be heard/felt dropping out.
You should have at least a test light to verify what you are checking.
When the key is first turned on , the ECM activates an ECM relay that provides power to the fuel pump relay.The ECM also provides that 2-3 second ground to operate the fuel pump relay. When the engine is cranked over the dist sends an RPM signal back to the ECM to keep the fuel pump relay energized.
Now we have some idea of what is supposed to happen the idea is to follow up on the relays and see if the ECM is providing that momentary ground to the fuel pump relay and that the ECM relay is providing the power to the fuel pump relay so that when that relay gets the ground signal the fuel pump runs.
B the way,,,,the ECM relay and the fuel pump relay are interchangeable and can be switched to verify which is working and go from there.
Suggest you label the relay positions so you always have an idea where you are working or want to do further checking.
To help determine which is the ECM relay, One of those relays will stay energized and the other (Fuel pump) relay will be heard/felt dropping out.
You should have at least a test light to verify what you are checking.
Thread Starter
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Junior Member
Joined: Jan 2022
Posts: 2
From: Colorado
Awesome, this gives me a great start! Thank you.
Just to insure I understand,
Make sure the ECM is providing the ground to the fuel pump relay using the ECM relay and fuel pump relay to help trouble shoot to see if everything is working properly
Just to insure I understand,
Make sure the ECM is providing the ground to the fuel pump relay using the ECM relay and fuel pump relay to help trouble shoot to see if everything is working properly
Last edited by Cleetis44; Jan 31, 2022 at 11:57 AM.
Senior Member
Joined: Jun 2010
Posts: 16,584
Don't forget the fuel pump relay will drop out if the ECM receives no RPM signal. (Safety feature)
The ECM relay will stay closed as long as the key is on. It also provides the power to one of the fuel pump relay terminals so that when the fuel pump relay get activated , that set of contacts closes and sends power on down to the fuel pump ,,,,,,,through the inertia switch.
Probably clear as mud, huh ?
The ECM relay will stay closed as long as the key is on. It also provides the power to one of the fuel pump relay terminals so that when the fuel pump relay get activated , that set of contacts closes and sends power on down to the fuel pump ,,,,,,,through the inertia switch.
Probably clear as mud, huh ?
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