6.9l non-turbo/no fuel getting to filter

[Cainon]

I have a 1985 f350 6.9 non turbo. just installed new pump bc fuel was not getting to the filter. runs for a second and dies. removed fuel filter and is only half full. if i fill the filter it will idle forever but when driving around the block by third gear its stalled. any ideas? lots of new parts and rebuilt pump months back.

 

[gnathv]

Most likely fuel restriction from tank. Disconnect fuel line into fuel pump. Replace with line placed in 5 gallon can, see if it changes.

 

[Big Bart]

If you replaced the old pump because the truck was doing the same thing and just thinking the fuel pump must be bad. Then ditto with Gnathv

Also your fuel tank selector valve could be stuck half way between, cutting off the fuel. Had this happen to me.

If it was running good and you just thought, well I am bored today, so why not replace it! Then likely the pump is bad, its on backwards, you have a voltage drop/bad connection, or the line has a air leak or air in it and it is cavitating.

 

[Cainon]

Thank you for the information. I will look into this when i get home from work. And yes it was doing the exact same thing. Thought it was the mech pump. still same issue. can I just remove the selector and run just one tank?

 

[gandalf]

... can I just remove the selector and run just one tank?

Sure you can. However, it may not be quite as easy as you're imagining. You'll have to re-plumb the supply and returns lines, move them from the FSV to the tank of your choice. And you'll have to re-do some wiring if you want the fuel gauge to work. All those things run through the FSV as Ford built them.

You just installed a new lift pump? Are you sure you got the arm under the crank rather than riding on top? Honestly, though, your problem sounds like the classic air intrusion. They can be a ***** to find. I'd start by replacing two return lines with clear lines, fill the fuel filter, and let it idle for quite a while, all the time watching for air bubbles in the return lines. If no bubbles, hold the throttle open some and watch more.

Try disconnecting the supply line where it enters the fuel filter. Crank the engine for ~10 seconds, see whether you get fuel out the end of the open line.

What you're trying to do here is isolate any possible air intrusion.

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[gnathv]

Is your truck running right on one tank and not the other? It may be the fuel selector valve or just crud from a 30 year old fuel tank. I’m getting ready to pull rear tank on mine. Driving on rear tank and saw fuel pressure going down until it stopped running. Changed tanks still low pressure. Blew 15lbs of air pressure through inlet hose to fuel pump (back to tank) fuel pressure came back and I‘m just running on front tank till I clean rear. Fuel valves aren’t too expensive. These have been getting positive comments from those who have tried them.

 

[Cainon]

Sure you can. However, it may not be quite as easy as you're imagining. You'll have to re-plumb the supply and returns lines, move them from the FSV to the tank of your choice. And you'll have to re-do some wiring if you want the fuel gauge to work. All those things run through the FSV as Ford built them.

You just installed a new lift pump? Are you sure you got the arm under the crank rather than riding on top? Honestly, though, your problem sounds like the classic air intrusion. They can be a ***** to find. I'd start by replacing two return lines with clear lines, fill the fuel filter, and let it idle for quite a while, all the time watching for air bubbles in the return lines. If no bubbles, hold the throttle open some and watch more.

Try disconnecting the supply line where it enters the fuel filter. Crank the engine for ~10 seconds, see whether you get fuel out the end of the open line.

What you're trying to do here is isolate any possible air intrusion.

You must be registered for see images attach

What size line is that?