Solution to my fuel issues - single tank conversion or am I being to simplistic???

Folks I would like your opinions please as I valued them over the years...... I was installing a new take out light switch yesterday, ya my lights are finally working and a curious on looker stop by to check out my truck. His son is a diesel mechanic and I was telling him about my nagging fuel issue. He called his son and he suggested that I eliminate one of the tanks, plumb a new line from one of the tanks directly to the fuel filter and replumb the vent tube, bypassing the selector valve. Then cap off the tank I would not use. At about 8mpg, that would get me about 400 miles per tankful. About what I would drive the truck over 6 months! He said use the other tank, leaving it in place, treat the fuel and use it for fuel storage, i.e., for my diesel tractor, generator or even for emergency fuel for the truck using a $100 dollar dc portable fuel transfer pump. Sounds like a good idea as keeping or filling a 100 Gallons of fuel on a truck driven less than 1000 miles per year doesn't make a whole lot of sense.

Has anyone attempted this? Does it make any sense? Thanks!

Getting away from the selector valve is always a good idea. You are right about not needing all that fuel for what we use the trucks for.
It sounds like a plan to me.
Post some pics of what you end up doing.

Thanks, will do!

You will still need to replace half the hoses.

For the cost of 4 extra feet of hose and 2 orings, I would fix it to original.

Just my thoughts.

Some have eliminated the valve, and that should work too.(if it and the hoses are your issue.

Remember, the primer lines can also be your issue.

If you just replace all the lines and orings, you may be good for another 30 years.

I have an International truck with dual tanks and it is rigged where it only pulls fuel from one tank. The two tanks are connected by a hose that runs from the bottom of each. The second tank drains into the first as the fuel level changes keeping the fuel level the same in both tanks. Could you rig up something like that? I am assuming since you have a selector switch that your truck is not already set up like that. There is also a manual valve in between the tanks so that if you wanted you can shut the second fuel tank off.

Thanks for all the suggestions! I have a Cummins mechanic who actually worked on these trucks coming out on Saturday to have a look. My fear is that, due to my inability to turn a wrench now and the fact that there are several layers of paint on all the hoses and fittings, I NEED HELP! Will post an update this weekend.

Made an attempt to replaced the o-rings in the selector valve today, but after going to 4 different auto parts stores and 1 hardware store could not find a number 9, 23, and 25. Where do guys buy this little buggers?

Bearing and seal shops(industrial), the internet, good hardware stores.

Any commercial plumbing warehouse should have them.

You need a #9 & #25, only two o rings.

Simply Google, "#9 Oring" and "#25 Oring".

Thanks and thanks!

Thanks, those of you who have gone with a single tank conversion, did you replace the canister filter with a Spin-off Filter?

The dual tank set-up on my xm757 (5-ton) consists of two identical systems terminating in the single fuel line to the secondary filter. It's factory, as delivered in '69 and I like it because it offers redundancy, if one fuel pump fails, I can switch to the other side. I have replaced the selector valves, however, since the originals were inoperable.
Agree about not needing the extra fuel, though...

Update.... Well it was 12 degrees, but sunny in NH, this am and I pulled the canister filter off again and found that the square washer was not seated squarely. I filled the canister with fresh diesel with a couple of ounces of 2 cycle oil, then I loosened the petcock on the primer pump and pumped about 10 times, nothing but air! I saw some bubbles coming from the fuel line fitting (IP side) that runs from the filter to the IP. I could not believe it, but it was hand loose! I tighten the line, got down on one knee, big mistake by the way because it took me 5 minutes to get back up, hoisted my sorry butt inside the cab and turn the switches on. After about 10 seconds Zeus fired right up. I left it running for about 20 minutes and took it for a ride around my property. He was running like a new engine. So I finally felt confident enough to take it for my first ride. 2 miles later I got back home and he ran like a champ. All that for a simple loose fitting. I feel like an idiot.

I am still going ahead with my single tank conversion, once the weather warms up. Tomorrow, I hope to make the 6 mile round trip to Sunoco to fill the passenger tank.

One observation..... When I shut him down, I heard air leaking in my cab, is that normal? My passenger wiper is not working, so if it is not normal to hear air leaking, could that be the culprit?

Thanks to all who contributed to this topic. I didn't even need the mobile diesel mechanic that I contacted! Just sure hope my fuel issues are behind me. Thanks again folks!

They sell check valves, so you can switch from feed source to feed source {pump to pump} with no manual isolation valves. When we nuke a fuel pump this is how are cars are set up. Just turn on the other fuel pump and off you go. each pump is fed from a tank feed {but we only run one tank}, each pump has filters fore and after. filter outlets go to a "shower head" which is just a y fitting. in between the filter output and the showerhead are the one way valves. We use aeroquip brand. which are avail in all black so it doesnt look like hotrod stuff.

nice to be able to switch out without having to do anything more than flip a switch. we use a regular relay to select. normally closed side runs the #1 pump, in emergency you flip the switch and pump #2 comes online seamlessly. You can also wire it so if pump #1 burns up/pops the fuse pump#2 automagically resumes duty and eliminate the switch altogether.

There's no pumps.

doghead said:

There's no pumps.

Click to expand...

yes i fully understand that. the conversation had turned to adding a pump and slaving the tank {somewhere around post #7}, making it a reserve tank for this truck or offloading fuel to other vehicles.


Had you any real interest in this thread other than trying to prove me wrong, you would have read it from the top and realized that.

I was trying to educate you, not prove you wrong.

Kawgomoo said:

yes i fully understand that. the conversation had turned to adding a pump and slaving the tank {somewhere around post #7}, making it a reserve tank for this truck or offloading fuel to other vehicles.


Had you any real interest in this thread other than trying to prove me wrong, you would have read it from the top and realized that.

Click to expand...

Doghead has been posting in this thread from the beginning. He does have an interest in helping the OP fix the issue.

You are the one that highjacked the thread with adding all the additional plumbing and pumps. While that is a solution it didn't help the OP solve his problem.

The OP never said he wanted to tie the tanks together and use a transfer pump