[mark's 1984]

i have a 1984 f350 2wd. replaced the engine in 2011. after having injector pump problems; a new problem developed. The truck will start and run fine, plenty of power etc. after driving for maybe 5-10 minutes, the engine will surge (like the metering valve sticks wide open) for a few seconds. within 20 seconds the truck will start to lose power and the engine will shut off. The truck will turn over, no smoke is coming out of the exhaust. When i take the fuel filter off, it is empty of fuel. I have replaced every component on the fuel delivery system, including fuel lines and clamps. This problem occurs on both tanks, and when it starts back up, it will reoccur within 5 minutes. I have now installed an electric fuel pump that helps it from stalling, but has not solved the problem.
Does anybody have any idea what is going on? I have puzzled many auto techs in the area. PLEASE HELP

 

[Zork]

Sounds like a fuel problem but not your simple air intrusion that causes the engine to stop after a about a minute. If any of your supply lines are wet, air will enter your system. After 5-10 minutes I'd say you may be drawing a vacuum in your tanks and when it becomes great enough it draws the fuel away from the engine. My tanks had a float check valve at the top of them, typically, these valves would be connected to the evap system. I recall my hoses ended at the frame. Maybe the tubes to these valves have been crushed or a dirt dobber has plugged them or they were removed and you have no way of permitting air into the tank as the fuel is used.

You could try removing the caps to determine if the tanks are in a vacuum. If this cures your issue, you could run home with your caps loosened.

 

[LMJD]

Check your fuel pressure and flow rate at the Shraeder valve on the filter if your '84 has one. Could be anything from a restricted fuel filter to a stuck tank switching valve. Make sure your tanks have a way to breathe and can't form a vacuum due to wrong tank caps or no tank vent.

 

[Zork]

Check your fuel pressure and flow rate at the Shraeder valve on the filter if your '84 has one. Could be anything from a restricted fuel filter to a stuck tank switching valve. Make sure your tanks have a way to breathe and can't form a vacuum due to wrong tank caps or no tank vent.

If it was the schrader valve, would he not experience this trouble within the first couple of minutes of start up after sitting over night or for a long period of time?

 

[LMJD]

If it was the schrader valve, would he not experience this trouble within the first couple of minutes of start up after sitting over night or for a long period of time?

You do the CHECKING at the Shrader valve, where else??

 

[mark's 1984]

guys, the fuel filter flange has been replaced; also using a different fuel filter (napa 4008 i think). Also have replaced the mechanical fuel pump with an electric one that has a little higher pressure and i think the same flow rate. This problem exists on both tanks, however as of late it is worse on the front tank. At this time both tanks are more than half full. Don't know when the change was, but the vent on the top of the tank is just that; no hoses attached. have never noticed a vacuum in the tanks.
One auto tech said it sounded like a fuel line was collapsing, but all rubber lines have been replaced. Any suggestions? ? ?

 

[mark's 1984]

nothing is wet anywhere on the fuel delivery. have gone over it with a bright lite and a clean towel at least 2x.

 

[Zork]

You do the CHECKING at the Shrader valve, where else??

I am saying if the schrader was leaking, you should develope your symptoms withing a matter of two minutes (after sitting over night)

guys, the fuel filter flange has been replaced; also using a different fuel filter (napa 4008 i think). Also have replaced the mechanical fuel pump with an electric one that has a little higher pressure and i think the same flow rate. This problem exists on both tanks, however as of late it is worse on the front tank. At this time both tanks are more than half full. Don't know when the change was, but the vent on the top of the tank is just that; no hoses attached. have never noticed a vacuum in the tanks.
One auto tech said it sounded like a fuel line was collapsing, but all rubber lines have been replaced. Any suggestions? ? ?

Our trucks suffer from a systemic problem in the fuel tanks. Generally, the fuel pick-up disintegrates and the fuel system sucks air anywhere around half a tank and below. If the fuel pick-up disintegrates closer to empty, it will run out of fuel or suck air closer to empty. My truck started sucking air with about 8 gallons left in each tank.

 

[mark's 1984]

no schrader valve on the new flange. front tank has been out, pickup tube was replaced. nothing has been done to the rear tank yet.

 

[mark's 1984]

guys, would the injector kit that connects the injectors together possibly be sucking air and it returning to the filter?? the engine came from Jasper; they put a used pump on it, maybe the injectors and connecting hoses were used also.

 

[Zork]

guys, would the injector kit that connects the injectors together possibly be sucking air and it returning to the filter?? the engine came from Jasper; they put a used pump on it, maybe the injectors and connecting hoses were used also.

If the fuel return kit was leaking it would cause this issue within a couple minutes IF the truck sits overnight, and once you get it started it would start and run consistently.

Do you still have the OE water separator on the driver's side firewall? The water separator is problematic for leaks, but similar to the return kit written about above. I guess you could have a major leak on the top plunger, but the fuel would siphon back to the tank every time you shut it off.

Here is my mod

 

[mark's 1984]

water separator was removed years ago

 

[bobleny]

have never noticed a vacuum in the tanks.

Sorry, I don't know what you mean by that. Did you try running without your fuel caps on?

One auto tech said it sounded like a fuel line was collapsing, but all rubber lines have been replaced.

Even if the lines are new, given sufficient vacuum, they can still collapse.


If you don't have fuel in the filter when it dies, you are clearly having a fuel delivery problem.

I have now installed an electric fuel pump that helps it from stalling, but has not solved the problem.

This would suggest to me, the new pump is able to help compensate for the problem. It is also the reason I want to be clear about the fuel cap; If you are creating a vacuum in the tanks, a stronger pump would potentially allow it to run a little longer.

Did this problem occur on both tanks simultaneously?

after driving for maybe 5-10 minutes, the engine will surge (like the metering valve sticks wide open) for a few seconds. within 20 seconds the truck will start to lose power and the engine will shut off.

Does it have this problem when held at a fast idle?

I am saying if the schrader was leaking, you should develope your symptoms withing a matter of two minutes (after sitting over night)

I believe LMJD was not suggesting Mark check the schrader valve, rather he was suggesting Mark use the schrader valve to check the fuel pressure in the system; much like you would use the schrader valve on a tire to check the air pressure in the tire. (Although, we have since found out he no longer has the schrader valve.)

 

[mark's 1984]

the engine will lose power and stop running while driving. if it sits long enough idling, it will shut down. every time the filter has been drained.

yes it started on both tanks and still occurs today.

when i take the caps off i have never noticed a vacuum. i will try running with them off and see.

i still have the OEM filter flange. have thought about putting it back on.

 

[mark's 1984]

UPDATE - UPDATE! ! !

As of Nov 6 after talking to a couple of farmers in the area, they said I have to put the electric pump back on and change the fuel line to 1/2". did that, ran better, then went and filled the auxiliary tank up, drove it for about 10 miles and . . . . . NO MORE PROBLEMS! ! ! ! ! ! ! ! ! ! ! !
fires up, purrs like a kitten, plenty of power.

just wanted to let ya'll know
Mark