'98 3500 dual tank, slow fill front tank at the pump and intermittent transfer from rear tank.

[big bird]

Rear tank is only intermittently transferring to the front tank. Gages are reading correctly. When back tank is not working, truck runs out of gas at half full on gauge. Have to stop every 125-175 miles to get gas as result. Probably won't dig into this too deeply, but if there is a quick fix, it is worth looking into. Sometimes the rear tank takes several gallons and at others, it doesn't. Maybe just the pump?

Front tank is extremely slow filling. Many gas pumps won't fill slow enough to prevent spilling gas everywhere so gas has to be dispensed into a gas can and then into the truck.

Inspected vacuum/burp line on front tank the other day, I could easily blow through it into the piping leading to tank as well as out through where it joins the fill port/gas cap. I'm thinking there is a clog or blocked valve in the doohickey on top of the tank that it leads into.

Only have a few days before I have to use the truck again, and it would be real nice to at least be able to easily fill the front tank.

Any advice is greatly appreciated!

 

[big bird]

Seeing that the front tank issue may be a purge valve.

 

[big bird]

Had a minute to look. The vent hose has a double tee in it where two fuel lines from the back tank run into it.

Didn't get a picture. I'm looking at it with an inspection mirror.

If there is some sort of stuck check valve in that tee or in the front tank, that would cause the vent hose not to work and the back tank not to fill the front.

If the valve is in the tee, I don't have to drop the tank. If it's in the tank, that's more funner, but it isn't awful to drop the tank.

 

[big bird]

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I would have taken pictures but I ended up covered in gas.

The vent line from the fill cap to the plastic tee is rubber hose secured with hose clamps as well as from the tee to the elbow welded to the tank.

The lines from the back tank are flexible fuel lines with compression fittings.

I removed the hose from the elbow into the tank, attached a hose to the elbow and easily blew into it. The detached hose from the tee blew gas all over me.

I figure that the air went up the fuel inlet and into the vent line at the cap and pushed out gas.

I don't think there is a valve in the elbow but will run something into to see.

So, maybe there is a check valve in the tee. Or maybe the vent lines need to sit above or below the fill hose to vent the tank and fuel is getting trapped in them.

 

[someotherguy]

With your setup, can you see the entire run of the front tank filler neck hose and that it's not crushed, kinked, etc. anywhere along the way?

The rear tank issue is likely just the transfer pump, though the sender needs to work too for the gauge to operate correctly and the fuel tank module to operate the transfer pump. The pump is pretty cheap.

Richard

 

[big bird]

Tank filler neck hose is not crushed or kinked.

I'm thinking the vent hose needs to be higher than the filler hose and the section with the tee needs to be at a downward angle to the elbow on the tank. I'm going to try some zip ties.

I may just change out the transfer pump if it is cheap.

 

[big bird]

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[big bird]

No check valves in anything I can find. I'm starting to think I just need to zip tie the breather line higher than the fill line to prevent gas sitting in the breather line.

Broke the plastic Tee getting it apart, don't really want to JB Weld it. Going to try and order one. Local parts store didn't even have it in their system.

 

[evilunclegrimace]

Front tank is extremely slow filling. Many gas pumps won't fill slow enough to prevent spilling gas everywhere so gas has to be dispensed into a gas can and then into the truck.

Have you checked to see that the tank is lower than the filler neck? I drove an 2007 K 2500 that had a after marker flat bed installed and the the filler tube was almost horizontal, it to forever to fill the tank unless you could find a filling station that had a lot that was on a bit of an angle so that the fuel would not pool up in the filler line causing the pump to continually shut off.

 

[big bird]

That probably has a lot to do with what is going on here. The filler line is long and horizontal and the breather line sits below it or beside it most of the distance.