air intrusion, rear tank empty

[danda]

So air intrusion became an issue again, but differently than before when it would start then die immediately.

Lately it has been starting fine, running fine, and then will die after about 1/2 mile with air at the schrader valve.

The front tank is about 1/4 full and the rear tank has been on E (empty) with the fuel selector valve set to the front tank.

On a hunch, yesterday I filled the rear tank 1/2 full and switched the fuel-selector valve to the rear tank.

Today, 24 hours later it started immediately and ran perfectly with no hesitations, surging, or dying.

So my theory is that the rear tank was so low (possibly bone dry) that air was getting into the pickup tube and then sneaking past the fuel selector valve which may not be closing 100%.

Does that sound plausible, or any other theories?

I guess it could also be related to the front tank somehow, since switching the fuel selector valve seems to have cured it.

 

[WrenchWhore]

Might just be a broken shower head in the front tank sucking air at 1/4 tank.

 

[Old Goat]

X2 sounds like your Shower heads have fallen off.
They set, and suck fuel right on the bottom of the tank,
so if not there at 1/4 tank, you will start running out of
Fuel.
You will either need to remove the bed, drop the tanks,
or remove the bed bolts on the filler side, and loosen the
other side and jack bed up on filler side.
The Fuel senders need to be pulled out to replace them.

With the bed removed you can fish out the broken pieces
of SH.


Goat

 

[KansasIDI]

@danda

Fill both tanks full.

See how she does on each tank.

At least fill front tank to over 1/2.

 

[danda]

Might just be a broken shower head in the front tank sucking air at 1/4 tank.

If this were the case, wouldn't the pump stop pulling fuel?

Instead, it would pull fuel fine, but I would get air in the line after sitting some hours.

I can imagine a scenario where there is a tiny hole in the shower head (or tube) above the fuel level. So when the pump is pulling hard it gets (mainly) fuel. But still air can creep in when sitting. But this doesn't really sound plausible because I would think the pump would also be pulling in air, causing bubbles, which are not observed when its running.

 

[danda]

You will either need to remove the bed, drop the tanks,
or remove the bed bolts

Or maybe just cut hole(s) in the bed with a grinder. That's what I did on a silverado when it needed a new sending unit. worked great, and now I have easy access to the top of fuel tank.

 

[KansasIDI]

Or maybe just cut hole(s) in the bed with a grinder. That's what I did on a silverado when it needed a new sending unit. worked great, and now I have easy access to the top of fuel tank.

If your bed is currently nice, without too much rust, there are people here who would cringe if you did that.

 

[IDIBRONCO]

If your bed is currently nice, without too much rust, there are people here who would cringe if you did that.

I'd cringe anyway. That is WAY too (unmentionable word) for me!

 

[danda]

they might cringe, but but they'll also be jealous how easily I can swap out shower heads, etc.

For now though I'm still in diagnose mode. We'll see what happens as the tanks get lower.

 

[Robm45497]

1/4 tank shower head problem

 

[typ4]

It's more than plausible that the fuel selector valve is bypassing a little bit. If you've ever taken one apart, you'd wonder how they work at all.

 

[Nero]

Most likely shower head issue.

 

[topkick]

Have the same issue with my pickup, exact same symptoms. No it is not the showerhead, it's the selector valve bypassing. I just make sure to keep fuel in both tanks until I do a 38 gal rear tank and sump. I plan to keep the front tank, add a sump, and just plumb the two tanks together with a ball valve between like many semi trucks with dual tanks are set up. I'll use the rear tank as the primary and only have a sender wired from said tank. The ball valve between the two tanks will do a few things, allow me to run off just the rear tank if need be and it will allow me to get both tanks completely full when filling up. Without the ball valve closed the tanks will auto level each other thus making filling them completely with only one nozzle difficult

 

[alsjunk]

How do you deal with the big hole in the bed where you access the top of the tank. I like the idea of not removing the bed of the pick-up, but I'm not sure how to reseal or ???with the cut out.
I appreciate any comment that would be helpful. Thank you.

 

[IDIBOBS]

I have not done this with trucks but in my 80s Camaros I made a cut out. First One I welded it back in. 2nd car I used tack screws and put a few pieces under the sides and screwed it all I. Last one I made a door. It was all under carpet so never saw any of it.