Hi everyone,
I'm just asking for a little help resolving my fuel system issue in my 90 Ford van. This has the older style fuel injection system with the low pressure fuel pumps in the tanks and the high pressure fuel pump on the frame rail.

The black mechanical selector valve was replaced from Ford about two years ago. This is the canister looking thing on the frame rail.

The van runs for half a mile then stalls and is hard to restart.

The high pressure fuel pump has power and appears to be working fine.

When the key is turned on, I hear the fuel pump in the front tank, but not the rear tank.

Van will run on either tank, but it's much worse with the rear tank where I don't hear the pump. It runs for a longer period on the front tank.

Disconnecting the fuel line from the incoming of the high pressure pump, no fuel is coming from the rear tanks when the key is turned on. Is this normal? Both tanks are full of fuel.

Thanks in advance.

 

If the rear fuel pump is not running you will not get any fuel from the rear tank. You will always be pumping from the front. The selector valve requires pressure from the in-tank pump to switch to that tank.

That said running for half a mile then stalls if running on the front tank you will need to find out if you have a fuel or an ignition problem to fix that problem.

The stored codes in the computer may give you a clue so you need to find out if you have any.

 

Thank you Subford. I was out of town for the weekend and just got back. I tried to pull the codes this morning but it's been years since I've pulled EEC-4 codes and wow, I need to relearn how to do that! lol

I have the tool for EEC-4, so I will try again when I get home from work tonight.

My gut feeling tells my it's not ignition. I have a somewhat of a tuned ear to how the engine sounds and behaves when it is starving for fuel, and that's how it sounds.

I grasp the theory that it will not hardly run on the rear tank since I don't hear the fuel pump in that tank, but it will run for a while on the front tank where I do hear the fuel pump work.

I'm curious of what else could be wrong rather than the obvious defective fuel pump in the rear tank.

Question about the Bosch High Pressure Fuel Pump on the frame rail. Do they usually quit and die for good, or do they get weak and cause drivability issues.

 

The High Pressure Fuel Pump on the frame rail has a thermal circuit breaker in it and if the pump gets to hot it will quit. It uses fuel for cooling, no fuel it will over heat and quit until it cools.

The thermal circuit breaker will also get hot if too much current is being used by the pump and quit until it cools. Too much current can be caused by bad bearing and that will let the armature drag on the field poles (magnets). A dragging armature can result in what would be called a week fuel pump.

 

If you are asking about the ignition causing it, it could be:
1. the PIP sensor.
2. the ICM.
3. the EEC Computer.
4. the Ignition coil.

Fuel it could be:
1. a fuel pump(s).
2. junk in the tank plugging the sock at the bottom of the tanks.
3. Bad EEC Computer turning off the pumps or injectors.
4. junk inside the fuel selector valve.
5. bad selector switch in the dash.
6. bad fuel pump relay.

Or it could be a bad Ignition switch, Ignition switch plug or power relay.

Hard to say without doing tests with a fuel gauge and driving it with the EEC-IV recorder hooked up.

 

Great info, thank you.

It seems odd that no fuel is coming out of the line going into the high pressure fuel pump coming from the selector valve, regardless of which tank is selected.

 

**UPDATE**

I replaced the High Presssure Fuel Pump and the fuel filter and now it runs great on the front tank only.

If I switch it to the rear tank, it stalls within one minute. I am going to have the rear in tank pump replaced next week.