Hi, I have a 86 E350 Camper thats not getting any fuel to the carb. Also none of the instrument guages work as well. The motor will turn over and will start and run as long as I pour fuel down the carb, so that part has spark and works. The fuse box does have power on all sides of the fuse's except the lower right hand corner fuse which is completely dead on both sides. I also cannot find information on the fuse box and all of it's ID on it has worn off so don't know what fuse is what. I have taken the instrument panel out and with a test light will get a pulsing light on all guages, and when held long enough on them they will move and work, but they will not move otherwise when you turn on the key. I have had to remove the dash for other reasons and have completely taken apart every connection and cleaned as well used dieelectric grease when putting them back together. Back to the fuel issue, I have power down at "hi pressure" pump on the frame and it changes according to the dash switch to the 2 tanks. Book says there are also pumps in the 2 tanks. Why are all 3 pumps not working? It would seem to be a ground issue but can not find a good wiring diagram that tells me where to look. This is a 460 engine, wipers and lights work, but the heater fan does not when installed, but have had that out and hook to a battery and it runs fine. Does the alternater have some sort of ground to it to make this all happen, book says something about neg power, and have not replaced it yet. I am new to the site and read alot of topics in this site before joining. It seems like maybe I finally found some good help with this. Please let me know some idea's where to look. Thanks

 

Have you checked the PCM ground wire which I believe is spliced into the negative battery cable near the battery?

 

That "pump" on the frame is not a pump. It's a switching valve. You only have two pumps in the tanks, both low pressure since you have a carb. The 460 fuel system has problems because of all the wiring involved. It has a relay for the pumps and a oil pressure switch. Here's a diagram.

 

okay, so in the diagram I still do not see where the ground comes from for running these pumps, remember I have power at the switching valve as you call it. To test this I pulled the connector off the valve with a test light and get power there to each tank as per switch on dash selected, also at that connecter I also get a pulse reading for the gas guage. To 87 XLT if I didn't have a ground to the PCM would the engine start and run? There is a small ground lead coming off the - terminal at the battery that pluggs into a wire but find no lead to it, have an idea where that comes from so i can search from opposite end?

 

Unfortunately I only have the factory wiring diagrams for the 3 Fords that I own.

On my 87 Ranger voltage flows from the dash switch to the pumps & back to the dash switch which is grounded under the dash. Does your switch have a solid black ground wire?

But as you say I dont see the ground in Franklins diagram.

From looking at the diagram you should only have voltage to the switch when cranking from the "start bypass leg"

Or when running from the closed relay.

If this was fuel injected, you'd need the PCM online to fire the injectors.

Disregard what I said about the PCM ground.

Where are those pumps grounded?

 

I would not worry about the grounds just yet. Check for power at the dash tank selector switch. This is what sends power to the front or rear pump. If you do not have power there, then find the relay(I think it's over near the brake booster) and check to make sure it has power, and it is pulling in.

 

So if the relay was not working would there still be power at the switch valve. If I understand your comment above power to the switching valve and the 2 pumps in the tanks are separately fed from different sources. Because I have power at the valve down on the frame and it changes from one contact terminal to another when I throw the switch on the dash. I guess I will try tommorow night to pierce thru the wires that go from the valve to the tank and see if i have current in those wires going to the tanks. Thanks for your interest and help.

 

Yes that is correct. The pump circuit is a heavier circuit that comes from the relay and a fusible link. The current to the switching valve on the frame is a different circuit.

 

ok so I worked on all those connections around the brake booster and also what I thought were relays that had connecters on the bottom, there is one green color and another white in color, cleaned both of them, returned power and tried it, when turning the key to on nothing happened but the gas guage started to work and continued to show on both tanks. Proceeded to try and start the motor and eventually got gas to come out of the back tank, it wouldn't do it unless the motor was turning over. I had the line disconnected from the carb, so I could tell if gas was coming, don't know what the deal is with the front tank yet but happy to have one tank working. Also through this process I got the heater fan to work, so we are making progress. Besides cleaning connections there, in that same area is about 3 black(presume ground)wires that go to the chasis and cleaned those up as well. Is there a relay for both tanks? and if so which color is the front? that may help me get it working. By the way anyone find a fuse box diagram, lower right corner is still dead. Can't thank you guys enough for your help, will explain eventually what the deal is with this camper, Thanks

 

Looks like you're making progress. Maybe cleaning those connections did the trick.

Try putting it back together & see what it does.

Keep in mind that when the key is turned to start, power for the pumps comes from the solenoid.

After it starts & is running power for the pumps comes from the relay.

As you can see from looking at the wiring diagram these are 2 seperate circuits.

If it runs with the key at start but quits when you release it the problem could be a bad oil pressure switch or relay or fuse link or safety switch.

Good question on the fuse, if you go to autozone.com you can pull up the fuse info.

When I tried it for a 86 E-350 I get to the fuse box diagram, but when I click on it to enlarge it, it just comes up a blank page???

 

Also another thought if there are relays for each tank, could one swap the connecters on them and see if the other tank comes alive or not? It might determine if the relay is bad.

 

Theres only one relay & it's not in the picture until after the engine is running.

Try giving the front tank a good whack with your hand & see if the pump runs.