Truck will not run off of rear tank.

[condor74]

My truck will not run off of the rear tank. It started a few weeks ago. It ran then started running rough then stalled. It had a long crank then restarted but run really rough. I could keep it running by keeping my foot on the gas pedal when I was at a stop. I switched to the front tank, (which I rarely use), and the truck ran normal again after a few miles.

I run primarily off of the rear tank as the front tank's fuel sending unit does not work.

Some other issues that may or may not be related.

The vacume pump stopped working and has to be replaced.
The truck has a long crank after it sits over night. It starts dies, then long crank.
There are no visible leaks around the fuel injectors.
The truck does blow a lot of smoke under acceleration. Clear on steady throttle.

Thanks for the advise.

 

[rhkcommander]

take the gas cap off the rear tank and see if fuel starts flowing. If it does then you've got improper caps. locking gas caps wont work either.

If it still doesn't flow then the lines from the tanks could be clogged with a busted pickup tube or gunk. or maybe the selector isn't working fully.

does air come out after sitting a night at the fuel filter shrader when cranking it? if fuel comes out that is good, if air or bubbles come out it means fuel leak

 

[condor74]

Thanks, I will check the truck after sitting over night this weekend.

 

[johneich]

locking gas caps wont work either

Locking caps don't work on our trucks?

 

[Cucamongan]

how much fuel do you have in the tank?

The fuel sock may have fallen on and you dont get fuel once below 3/8 or 1/4 of a tank.

Fill up the tank and see what happens. Just a suggestion.

 

[ghunt]

Mine was doing that too, even after fixing the pickup and replacing the fuel lines, with the stock mechanical pump. After converting to an electric pump it will actually run pretty good off the rear tank.

 

[rhkcommander]

Well I've heard there isn't any diesel locking caps. So what happens is a vacuum is pulled on the tank.

What happened in my case was I used the front tank for about 6 months after getting two locking caps to keep kids / whatever from putting stuff in my tanks and maybe deter a entry level thief. Well I switched to the rear and she struggles and dies like it's low on fuel. Gauge reading full. Great a broke pickup tube I thought, then I read about the locking gas cap (GAS) doing this to someone else so I ran out popped the cap and heard a whoosh and the epump finally pulled fuel no problem.

Seems to only be a problem in my case if it sits too long. Might be able to put a vent hole in. An easier method is to install cabinet locks to the fuel doors themselves. But then you get a hole punched into the tank if they want the fuel bad enough...

 

[condor74]

The problem was the sock falling off. Filling the tank let the truck run normally again.