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(O/T)1986 Ford F-150 Lariat

G

greenmachineman

Member
A few months ago I purchased an '86 Ford F-150 with the EFI 5.0L and drove it to the spot where I parked it. The other day I went to move it and it would not start, just cranked over. I am thinking it has to be something simple since it ran great before. I sprayed some carb cleaner in the throttle body and it started right up, but would only run on that. I cannot remember correctly but I think before when I turned the ignition on I could hear the fuel pump running. I don't hear anything now, maybe I am wrong. I am hoping someone can give me some pointers as to what I should look for or what I am missing. Thanks in advance for any information.
 
Initially that is what I thought, but it has two gas tanks... so does each tank have a pump or is it a frame mounted pump with each tank having a sending unit?
 
So the probability of them both being bad is pretty slim, since it ran recently. So for some reason they are not getting power. Anything other than the relay I should be checking?
 
Is this a Fuel injected model
If so there is a fuel pump on the Frame rail
its a 2 pump system high / low pressure
Is there pressure present at the fuel rail schrader valve
 
It is the EFI 5.0L, I had an '89 that had a frame rail mounted pump. I was wondering if this was the same system, or not. I will look tonight. My '89 had a switch to choose which tank, this one does not.
 
Sean is correct on the two fuel pumps for this model.

Most likely the problem is a bad relay for the main "frame rail" pump. This relay is between the fender and the power brake booster. It should have a little plastic cover that is mounted to the firewall. You can slide the relay down, while still hooked up to the harness, from this plastic cover.

Then it is a simple test.

Good Luck.
Scott
 
It was mentioned below, replace the fuel pump relay. I have replaced several on the Fords I have owned.

One time my 1997 F-350 would not crank. Fire ants had found a home in the fuel and the ECM relays.
 
If you switch tanks and cannot hear the pump run then check the relay. If that is alright then check by your battery on the ground side to see if you have a light wire ground. If there is make sure that it has not failed. I had a 88 with the same fuel injection system that you have and that ground wire failed and I just cut it off and put a eyelet on it and fastened it to the battery post and it worked again. HTH
Bob
 
I will try the relay tonight. This truck does not have the switch to go back and forth between tanks, or is it just in a different spot than my '89?
 
Check for a switch down by the heater controls. the can on the frame rail is a fule filter.
 
Have you tried to reset the accident fuel shut off? Will shut down fuel system during an accident, can't remember on this model it is located but try behind the r/h kick panel.

Leonard
 
If it has dual tanks, it has 3 pumps. A low pressure lift pump in each tank and a high pressure pump on the left frame rail near the back of the engine/front of the transmission area. There will also be a fuel filter between the frame pump and engine. Originally, the fuel pump relay was green. Replacements could be any color. If you can locate the engine control test connector (EEC4), normally on the right side middle of the engine compartment. It's trapezoid shaped and may be in a plastic cover that says EEC TEST on it. Hold the connector so the longest side is down. The lower right terminal is the fuel pump relay ground diagnostic terminal. Ground it with the key on and it will engage the pump relay. Does the check engine light come on when you turn the key on? The EEC power relay also provides power to the fuel pump relay.
 
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