fuel pump, no power.

[pauledude]

6/91 build F 53 chassis, 92 Holiday Rambler 32' body.

I cant find the Power Distribution panel to check the fuse or relay. I have the chassis book. But I don't see anything that looks like in the picture.


I pulled the tank, checked the wires. the pump runs fine. but I have no power to the inertia switch. If I jumper a hot wire to the Pink wire there the pump will run. I have continuity thru the switch. Relay is next in line, but I cant find it.

Debating on putting in a new relay and fuse off a switched circuit. and just let the pump run to move it. Is that all that is left? how is the pressure regulated? electrically, or just bypass back into the tank, and the pump always runs anyway?

[subford]

Originally Posted by pauledude

I cant find the Power Distribution panel to check the fuse or relay. I have the chassis book. But I don't see anything that looks like in the picture.

You do not have one.

You do not have a fuse for the fuel pump system, you have a fuse link.
The fuse link will be located at the Starter relay and feeds a yellow wire.

Originally Posted by pauledude

how is the pressure regulated? electrically, or just bypass back into the tank, and the pump always runs anyway?

The pressure is regulated by a Fuel Pressure Regulator (FPR) and it is vacuum controlled.
Idle vacuum 30-34psi fuel pressure, WOT about 40psi, no vacuum about 45psi fuel pressure.
Yes it is bypassed back to the tank by the FPR through a shuttle valve in the FDM inside the tank.
The Pump only runs when the Computer sees a PIP pulse from the distributor and it is on a one second timer. The timer will also trigger for one second when the key is first turned on.

To run the pump all the time the key is on for testing you must ground pin #6 of the EEC self-test plug and turn on the key.

Here is your Fuel pump and power relay locations in red. The fuel pump relay has a green base and the power relay a brown base.


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[subford]

It should be wired something like this:


The EEC self-test plug:


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[subford]

Your fuel system:


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[pauledude]

AHHHH. I know where that is. Ford kept telling me the body builder moved it. I knew I wasn't going crazy. Now I think I can figure it out.

Now I got to find the test plug.

Also did they always put thefuse links on the Rad support? I have a rail above the master cylinder in the wheel well. I thought it was a dumb spot, but it is wrapped up in a rubber mat.

Thanks allot for your help.

[pauledude]

And while I am at it. How do I test for a pulse from the distributor?

[subford]

Originally Posted by pauledude

And while I am at it. How do I test for a pulse from the distributor?

Put a Noid light on one of the injector plugs and crank the engine, if it flashes the computer is seeing the PIP pulses.

Or you should have a code set in CM you can check for.

Or you should see about 4-6 VAC on the PIP wire going to the computer while you crank the engine.

Where it says NUT in the diagram above at the starter relay you will see a few wires coming off that post. They are the fuse links.

[subford]

This may be the EEC Self-Test plug on your F53.
Let me know if it is.


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[pauledude]

Pulled both relays. Checked for hot. Bench tested the relays. And when I put it back together, Everything worked fine..Rv runs.

All I can figure is the relay had some carbon build up. and when I bench tested them with direct 12v, it burned it off...

Thanks for your help. saved me a lot of time. I think I will order a new relay to keep onboard in case it acts up again. towing it was expensive.

[subford]

Glade you got it running.

Was that the EEC Self-Test plug in the diagram above?

Also keep an eye on the wires under the relay socket as they give a lot problems.