Rear tank help needed

[G. Mann]

Driving along normal today and on the rear tank on my 92 F450, 7.3 / ZF5, 212,000 mi on the truck. Suddenly fuel starvation and engine dies, I pull over, switch to front tank, crank and restart. Runs normal.

Rear tank is about 1/2 tank down, should be good for another 100 mi at least. I drop by my local diesel pump and fill the rear tank to the top. Start up and switch back to rear tank [I know it's full] truck runs for about a minute and dies, fuel starvation again. Switch to front tank and re-start.. all good.

What's the problem from anyone elses experience with this?

Did the pickup tube strainer just plug or ??

Time to pull the bed and fix things? The sending unit on the rear tank has been acting up for past 6 months...

Suggestions anyone?

 

[vegas39]

Either the strainer plugged up, or you have an air leak between the rear tank and the switching valve, cant think of what else would cause that.
I dont think it could be the pickup assembly because of how full the tank is and it still doesnt want to run on the rear.

 

[Simp5782]

Yeah your strainer could be stopped but even though they dont have much one of one. or the switch valve could be stopped up. maybe check to make sure uve got proper voltage going to the selector valve to ensure its opening all the way, pop the quick connection line off the selector valve and use an air hose and try to blow back thru into the tank with it and see if u hear the fuel bubble. Also check and see if your vent line is stopped up or the roll over valve.

 

[G. Mann]

Don't think I have an air leak, as soon as I switch tanks it picks up fuel and runs fine. If it was sucking air I think I would have to re-prime the system to get air out.

Acts more like there is a blockage in the pickup line. Question is "where". The roll over vent is working good, no problems there I don't think since I have a 3/4 inch hose from the tank to the vent at the fill cap. I'll try blowing out the hose from the selector valve back and see if that clears it. Would like to avoid pulling the bed if I can till I have a forklift available to lift it off and on.

 

[Simp5782]

forklift? jeez. just get a small electric pump with some 3/8 hose and hook it to a battery and stick it down the fill and let it pump it out till its near empty then drop the tank. only an hour job.

 

[G. Mann]

Been there, done that. I'll take the "pull the bed route. AZ has no rust issues, so the bed can be off in 20 min with the forklift.

Agreed, on pumping down the tank. I'll do that.

 

[dagreendeville]

i had this problem i had already removed my strainer and done a hose pickup turns out it was the tank selector valve they can be cleaned but are easily broken as i found out the hard way

 

[G. Mann]

Please and thank you... how do you clean the tank selector valve without destroying it?

Would it work to pump fuel backward through the selector valve and "wash " the crud out of it in the rear tank path?

 

[G. Mann]

Please and thank you... how do you clean the tank selector valve without destroying it?

Would it work to pump fuel backward through the selector valve and "wash " the crud out of it in the rear tank path?

 

[dagreendeville]

this should help you out a lil i think heres my post about a simular problem and some photos http://www.oilburners.net/forums/showthread.php?t=53194

 

[bghnkinf350]

Start with the easiest first. You mentioned that you had run the vent to the filler neck. I thought I read that there were some people having problems with that bbecause it created a vacuum. Might start with running it with the cap off.

If it continues, try disconnecting the lines at the valve. See if either is clogged or restricted.

If neither are, might as well then pull the valve and clean it. It is likely the valve, but might as well start with the easiest.

Check the condition of the lines too - mine had a repair and it let in air.