Fuel pump not working?
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Mountain Pass
Joined: Feb 2021
Posts: 180
Likes: 10
Fuel pump not working?
Hi all
I just finished replacing the thermostat on my 86 f150 5.0 4x4. It has a single tank. Afterwards, I went to start it and nothing happened. I noticed no sound going off from the fuel pump. I pulled the line and nothing came out when I turned the key on. I replaced the fuel pump relay and nothing still, no click from the both the old and new relay. I tried jumping the intertia switch with a peice of wire and still nothing. What else could this issue be?
I just finished replacing the thermostat on my 86 f150 5.0 4x4. It has a single tank. Afterwards, I went to start it and nothing happened. I noticed no sound going off from the fuel pump. I pulled the line and nothing came out when I turned the key on. I replaced the fuel pump relay and nothing still, no click from the both the old and new relay. I tried jumping the intertia switch with a peice of wire and still nothing. What else could this issue be?
FTE Legend
Joined: Nov 2015
Posts: 30,940
Likes: 4,125
From: Angier, NC
For testing bypass the pump relay and check for power back at the pump.
No power you will need to back trace from pump to relay why.
If you got power try banging on the bottom of the tank and see if the pump will start and if not bad pump.
Dave ----
No power you will need to back trace from pump to relay why.
If you got power try banging on the bottom of the tank and see if the pump will start and if not bad pump.
Dave ----
Moderator
Joined: Jan 2001
Posts: 56,999
Likes: 2,746
From: Virginia
Put everything back together and go back and beat on the bottom of the tank with a piece of wood while someone tries to start it. It will probably go. This is a important trick to know if you are out stranded somewhere with a bad pump.
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Mountain Pass
Joined: Feb 2021
Posts: 180
Likes: 10
Hi all
I actually got it working. It was that small ground cable from the negative terminal on the battery. I had it grounded in the different spot. Grounded on the battery now but it once again won't start. I have fuel coming at the injectors and spark. It was running fine before hand
I actually got it working. It was that small ground cable from the negative terminal on the battery. I had it grounded in the different spot. Grounded on the battery now but it once again won't start. I have fuel coming at the injectors and spark. It was running fine before hand
Moderator
Joined: Jan 2001
Posts: 56,999
Likes: 2,746
From: Virginia
I can tell you what will easily happen to these old fuel injected trucks. If you have been messing around with it, cranking and cranking, it is very easy to foul the plugs. When they are fouled they will not fire. So pull a plug or two, see if they are wet with fuel. If they are, pull them all out, dry them off with brake cleaner and a air hose,, and then put them back in and try again.
Tuned
Joined: Dec 2024
Posts: 448
Likes: 94
From: Texas, near Houston
Hi all
I just finished replacing the thermostat on my 86 f150 5.0 4x4. It has a single tank. Afterwards, I went to start it and nothing happened. I noticed no sound going off from the fuel pump. I pulled the line and nothing came out when I turned the key on. I replaced the fuel pump relay and nothing still, no click from the both the old and new relay. I tried jumping the intertia switch with a peice of wire and still nothing. What else could this issue be?
I just finished replacing the thermostat on my 86 f150 5.0 4x4. It has a single tank. Afterwards, I went to start it and nothing happened. I noticed no sound going off from the fuel pump. I pulled the line and nothing came out when I turned the key on. I replaced the fuel pump relay and nothing still, no click from the both the old and new relay. I tried jumping the intertia switch with a peice of wire and still nothing. What else could this issue be?
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ctflareside
1987 - 1996 F150 & Larger F-Series Trucks
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Mar 19, 2021 06:02 PM
