84' 6.9 fuel problem

[oldblue6.9]

i have an 84 f350 single cab 4x4 with a 6.9l and a banks turbo system. yesterday at about noon when i started it up it ran nasty for a few seconds then i reved it up a little bit then it was good. it didnt do it agagin till 9 or so then it just shut off goin down the road. i got it home took off the fuel line from the low pressure pump and put it in a mason jar full of diesel and it started up. put the fuel line back on and its running rough then dying again. ive checked all the lines for rust spots and im pretty sure the tank switch is working. it is my daily driver and i work every day.

 

[Exekiel69]

If it runs well from the jar with diesel then You have an air leak somewhere down to the tank or You can also get air in through the return lines (small 1/8" ID hoses above the engine going from one injector to the other), a return line kit is about $30 from rock auto, You can buy dayco fuel hose from Ryder 25' section pretty cheap, You can get hard lines IN later.

You can have an air leak that shows wet or one that is dry and You can't see, best is what You did already and now replace the fuel lines going back to the tank to be sure, assuming You have not changed this recently.

 

[oldblue6.9]

I think my problem might be the valve to switch from rear to front tank. It starts right up now but once I'm on the road and hit a few bumps it starts actin up again. I've heard alot about those little ball valves goin bad. It ran bad then I hit on the valve and it started running right again but when I drive it starts actin up.

 

[Exekiel69]

Is the water separator still connected or bypassed?
Have You checked the fuel tank pickup front and rear?

 

[oldblue6.9]

it its bypased and i have not checked that. i took the inline switch for the fuel tanks off and there were some strands of what looked like plastic fiber coming out of the source line closest to the engine. so i switched it out with one from a 6.9 tran and it didnt even know witch tank i was on.

 

[Exekiel69]

Personally when it comes to fuel lines, if in doubt I replace them all. You can get 3/8" and 1/4" fuel line from Ryder for cheap.

 

[oldblue6.9]

so i bypassed the switch for the tanks... so far so good... i just started it up and bled the air out of the injectors. i drove it around for about 10 minutes trying to recreate the same conditions from when it first messed up. gonna let it lit then give it another go in an hour or so. i belive ive got it beat (at least i hope) went to ford today and that switch is $329.

 

[OLDBULL8]

When you say switch, do you mean the selector valve? Is it a 6 port valve? Is it a motor driven one? Take a pic of it and also the connector that plugs into it. Take a pic of how it's mounted.

The reason why I ask all these questions, is I just replaced mine on a gasser 84 MH with two tanks, but the selector will work with diesel. The one I got mounts different from the original Ford one.

This is the one from Azone. 1st one is motor driven, 2nd one is just switched.
Also had the buy the connector as mine was different. I'm pretty sure the second one is like I have on my 92 F350.

http://www.autozone.com/autozone/pa...ring=search&itemIdentifier=18894_173087_5320_

http://www.autozone.com/autozone/pa...ing=search&itemIdentifier=125310_173086_5320_

 

[built4tq1]

If u need a valve i have one you may have. It is a used valve but it worked just fine before removal. let me know and ill send it your way.And yes its free!

 

[oldblue6.9]

it was the selector valve... i bypassed it a few days ago... its runnin just right. and thank you for the offer but ill have to pass. thanks for all yalls help.