No power to fuel pumps

[shadetree 59]

I have a 1988 ford E-350 with a 460 cubic inch fuel inj. V-8. I have no power to the in tank or high pressure pump. The wires are good as I had someone jump the relays and both pumps were operational. I have replaced fuel pump relay, fuel shutoff relay, ignition switch, coolant temp sensor. I have spark and current to fuel injectors. I was told that the computer was the problem but was later told by someone that if I have spark and current to injectors the computer is good. I am leaning towards replacing the ignition igniter. If I have spark does it mean this item is working? Does this send current to fuel pumps? Would like to have a better idea what to replace instead of just throwing more money at it. I’m not good at electric stuff and can’t read a schematic. Help.

Topic

[college man]

see if this helps. I know you can’t read a schematic but try its
a simple circuit. if you jumped the relay and the pumps came on
then all that wiring is good. If the relay is not pulling in. Its
controlled by the electronic engine control or a wiring issue.

http://www.justanswer.com/rv-motorhome/4uh3r-ford-econoline-350-motor-home-1988-e350-motorhome.html

[John Hugon]

I didn’t have time to read what College Man posted… hopefully this will assist you also..

Secondary ignition (spark plugs) has nothing to do with the EEC (Computer) on your truck. However the fuel injectors do and you could have battery + voltages going to them but you also need a controlled ground from the EEC to make them function.

To check the fuel pump circuit with one fuel tank…

First you need to check the inertia switch to see if you have battery + voltage going into the switch and out of it when you first turn the key on. Recheck for battery + voltage while cranking over the engine ..(pink/ black strip wire.)

The fuel pump relay should have power to terminal 30 with the ignition off. Terminal 87 will have power for 2-3 seconds when the ignition is turned to the run position. The EEC grounds the fuel pump relay at terminal 85 through EEC terminal 22 (Tan/light green trace wire) signal to the relay for 2-3 seconds and also while cranking over the engine.

If this checks out next you need to check the fuel injector circuit…I don’t have time now to explain diagnosis…I’ll try tomorrow…sorry.

[Bill]

There is a inertia switch behind the passenger front kick panel that is meant to shut the fuel pump off in case of collision. sometimes even slamming the door will trip the switch. There is a red button on the top of it. Push it to reset it.

If that’s not the problem check all fuseable links as well as the Maxi fuses in the under hood fuse box. Sometimes the wires corrode inside of the fuse box also.

[John Hugon]

I know you stated you had limitations with electronics and reading electric diagrams but you stated someone was with you that jumped around the relays…so it was my assumption that the person with you knew something about electronics. Hopefully what was posted from everyone helped you and the person working with you understand the system you’re working on.

When I posted last night I forgot to tell you the relays will have terminal numbers embossed in the plastic where the terminals stick out the bottom of the relay and in some cases the relay will have a diagram schematic printed on the side cover for reference and diagnosis.

My post last night only was the diagnosis of the fuel system circuit of what your concern was. If your check find’s the fuel circuit ok, I would start from the beginning.

That diagnosis is going to require some skill with electronics, so hopefully the person that jumped the relays will assist you. Most of my post is from memory when I worked at Ford dealers …which is becoming foggy in my later years…so… I found this in the internet which I think will help you more than me writing it out..
No start:
http://troubleshootmyvehicle.com/ford/4.9L-5.0L-5.8L/how-to-troubleshoot-a-no-start-1
Testing the EEC relay:
http://easyautodiagnostics.com/ford/relays/eec_relay/eec_power_relay_1.php

[shadetree 59]

I have spark and the injectors are firing. Does the computer have the function of supplying the power to the fuel pumps? I heard yes from the mechanic I hired to look at it and when I went to the electrical man to have him rebuild or order a new computer he said that as long as I have spark and injectors firing it isn’t the computer.

Thanks
John

[John Hugon]

In 1988 if my memory is correct the Ignition Control Module controls the primary and secondary ignition system (spark plugs). The EEC(computer) controls the fuel pump and fuel injectors. However, The PIP signal (Camshaft sensor); is also used by the PCM to start fuel pump/fuel injector operation, injecting fuel into the cylinders.PIP Sensor located inside the Distributor.

No start:
troubleshootmyvehicle.com/ford/4.9L-5.0L…leshoot-a-no-start-1

Testing the EEC relay:
easyautodiagnostics.com/ford/relays/eec_…ec_power_relay_1.php

I forgot about this one…newer than your truck…but same principle.
http://www.youtube.com/watch?v=YmcCVQK87TU

[shadetree 59]

This is a motorhome that doesn’t get used much so I have really neglected getting back to work on it. I am back on the project and have new issues. I bought a control computer a a junkyard and do have power to the in tank fuel pump which I replaced with a new one since I had the fuel tank dropped. After cycling the ignition a few times I confirmed it was working by unscrewing the fuel cup that is on the frame rail. I have gas there. Upon trying to start I lost all lights on the dash and now the hot terminal on the battery is warm to the touch even with the key off. If it were possible I would have it towed to an electrical shop but I have it wedged in the barn and can’t hook up to it. Back to the drawing board. Help

Shadetree

[Wayne]

Just warm or hot? I’d yank the neg terminal before you chernobl if it’s more than warm, but without touching a vehicle for more than a month it’s going to be a much harder on the starter motor, thus causing a high draw for cranking. If the lights are back once you’ve stopped crankin’, and it’s only warm, you note nothing further, it’s likely normal and the battery is screaming at you for a charge..or replacing.

It’s usually pretty clear in short order if there’s something catastrophically shorted.

[shadetree 59]

I’ve kept the battery charged out of the vehicle. When I turn key to start I get no dashlights and no crank. Might it be a bad ground and if yes where?

Thanks
John

[Wayne]

Just clean all the battery terminals up, and the 2 main grounds. Should be one to frame, one to engine. Frame should be no more than a foot away from where the battery is in most cases. You can just follow the piggy-backed lines off the black (-) negative cable.

If after all that it’s still cutting out, you might want to just swap in another battery anyhow, even if you had it on a charger it may not be good; they don’t last forever.

[shadetree 59]

It was just a dirty battery connection. Alas! It started. I’ve often said while watching Eric’s video that I wished he was my next door neighbor but having this site available to me is a close second. Thanks a lot Eric and you other guys.

Shadetree

[Wayne]

Good deal, glad ya let us know the outcome.

[Author]

Replies