Loss of power on righthand tank

[Blow Boater]

I've recently purchased 87 R-10 (half ton shortbed w6.2L). When I switch over to the righthand tank I loose power. when I switch back to the lefthand tank power is back to normal. I've replaced the tank selector valve, switch, cleaned the tank and replaced the sock over the fuel pick-up, replaced the rubber fuel hoses and clamps between the tank and the selector valve. I'm at a dead-end as to what could be causing this problem. My gut feeling is something with the valve. Do you know how the solenoid on the valve operates? I don't have a schematic for the truck yet and I was wondering if it is possible that I'm not getting enough power to the soleniod to shift the valve fully? Or do you have any other suggestions I have'nt thought of yet?

Thanks
Barry

[G. Gearloose]

Maybe the left hand tank is the normal one and the left tank has a clogged or crushed return line, causing the timing to advance.

[Dezman125]

Hi
Check your dash switch. All the gassers i have in that year range have switches that differ from the older ones.The newer ones say" depress fully to switch"
I find that you have to hold it in for a few seconds so the tank switch on the frame can power up.
Happened to my wife a few times,she would switch tanks then run out of gas shortly after.
Good snag finding a shotbox :cool:
Good luck

[CleviteKid]

Hi Barry,

I just happen to have a 1987 Shop Manual. Send me an email ( leeswanger "at" yahoo "dot" com ) and I will see about sending you the schematic of the valve wiring.

Dr. Lee :cool:

[slagona]

Barry,

Put a section of clear hose between the switching valve and injection pump. Make sure there is no air entering the system when in right-hand tank mode. Generally, if it were air, the engine would run a little rough along with the loss of power - but it's something to check...

I had something similar on my right hand tank of a previous truck - air was getting in that line. I could use the entire tank of fuel as long as I didn't try to start the truck with that tank. But it would run rough and didn't have as much power.

--Scott

[ropinfool]

Are you losing engine power? Or power to your gage? John

[ropinfool]

Well I reread your post and it seems you are losing engine power. I would make sure you used the correct valve, a diesel valve is different from a gasser valve (at least on an 83). Maybe you are restricting your return? Good luck. John

[Blow Boater]

Thanks for all your relpies. I think that I'm sucking air in somewhere. It is hard to start on the right hand tank. It will light up and die as soon as I let off the accelerator. I think I may try the clear hose trick, I have some nylabraid that will work. I can here the valve shift when the engine is off and the key is in run. There is difference in the sound between the tanks. The left tank is "louder and longer" that the right tank. Thats why I changed the selector switch. I'm emailing DR. Lee for a schematic so I can see the circuit for the valve.

Thanks
Barry

[slagona]

Does it happen at all tank levels or just when the tank goes below a certain point? There have been some members with holes in the pick-up tube, so when the fuel goes below the hole on the metal tube, it starts sucking air.....

It's been about 8 years since I fixed mine (and sold the truck about 4 years ago), I had to drop the tank and I replaced all the rubber hose. I don't remember what actually fixed it - only that it no longer sucked air after taking everything apart and putting back together with new hose.....

I put some sections of clear hose right in front of the tank switch to start off with and then worked my way to the front of the truck to be sure all the leaks were out...

--Scott

[Blow Boater]

Scott,
That was my next guess. It happens at all tank levels, So if the pickup tube has a pin hole in it, It's somewhere near the top or outside the tank. I'm waiting untill the tank is empty, Then I'll drop the tank next weekend. It's not much fun driving on the right tank, especially going up hills. I just falls on its face. I hope I can find something this time I pull the tank. I'm getting profeicent pulling the tank

Barry

[slagona]

I also replaced my tank selector valve with the JC Whitney 6 port model, currently $54.... It happened to be the OEM valve when I bought mine years ago, probably still is.

When I pulled the tank and had the sending unit out, I tested the sending unit/pickup tube and selector valve before installing them. I had an electronic lift pump which I used to test. Inserted the end of the pickup tube in a bucket of diesel and tested the sending unit and both settings on the tank selector with clear plastic tubing and dumping the fuel in a clear plastic container to be sure no bubbles were present anywhere.... Eliminated any problems before installing....

--Scott

[Blow Boater]

Well I finally found the problem. The return line in the fuel pickup was partially blocked. I pushed out a plug of dirt/scale in the short section of steel tubing where the return line goes into the tank. I Also had to replace the valve because I broke the hose barb on one of the inlet ports. The new valve is a Borg/Warner unit and it has larger ports, so I that didn't hurt either.

Barry