1987 Fuel Tanks

[70Post455]

I am not getting fuel up to my fuel filter and so I am not able to start and keep my truck running. I am going to check for pinched hose or cut hose today.
If I remove the fuel filter and fill it to the brim I can start my truck and it will run for a very short while then it will idle spike and shut down. I then remove my fuel filter agian and it will be way low on diesel.
I am having this problem with my front tank, but I have not tried my back tank yet. The back tank is empty so I am going to put 5 gallons in it and see if I am having the same problem with it.
Also I am not sure if this year of Ford pickup has fuel pumps in the gas tank or just a lift pump on the engine.

TIA,
Tom

 

[towcat]

Our generation diesels never had an in-tank pump. Even the early PSD's had a mech fuel pump. you got two areas you need to look at first.
One. your fuel pump output pressure. If it reads out no more than 5psi, you're good to go.
Two. fuel switching valve. By this age, it's very likely it's going to have some sticking issues. Fill your rear tank and keep an eye on your mileage. There's actually two valves the FSV controls. One is the feed the other is the return. I've found many that are sticking in either the feed or return and you will have all sorts of entertainment.

 

[Mr_Roboto]

Right, if the rear tank is empty the tank valve could very well be letting air in.

 

[towcat]

Right, if the rear tank is empty the tank valve could very well be letting air in.

If it's working right, it shouldn't be. otherwise, if you have run down a tank to empty and switch it over, you'd still be drawing off the empty tank and that's an invitation for trouble.

 

[70Post455]

Thanks for the info.
I put 5 gallons of diesel in my rear tank this afternoon and removed the fuel filter again and filled it up to the top and reinstalled it. I then flip my switch in the cab to the rear tank and the fired it up.

The truck started on about the 3rd try and ran rough for about 10 seconds or so and then smoothed out to idle just fine, however same thing is happening with the rear tank as is with the front tank. No diesel getting up to the fuel filter so the truck runs fine for 20-30 seconds or so and then idle spikes and quits.
I pulled the filter again and same results, almost empty of diesel. I will check my fuel pump output pressure tomorrow and also the fuel switching valve.
I am also thinking of installing an electric fuel pump.

Tom

 

[chopperdaw]

i had the same thing happen to me. no fuel to the filter. i changed out the mechanical fuel pump and she runs perfect now. id start with that. they are cheap to buy.

 

[Fingers77]

I had a problem with mine starting and running then quitting after a while.. turned out to be the fuel selector valve on the frame rail