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

[MyothersanM1]

Folks I would like your opinions please as I valued them over the years......

No bicker, just help

 

[doghead]

Joesco knows I'm here to help him, no worries.

 

[joesco]

Well I am back to square one, once again!! I have been starting the truck everyday, and with it being plug in for 3 or 4 hours, as an example it was - 5 degrees this am, a couple of seconds of cranking, it started right up. So I felt confident enough to drive 8 miles(round trip) to fill both tanks with fresh diesel. About 2 miles into my drive, I began to loose power. I immediately turned around almost stalling once, pedal to the floor, not going over 15mph. Made down my driveway and he stalled out! Tried to restart him, and it crank and cranked, but he wouldn't start. So I assuming my fuel filter canister is bone dry again. I hope I can at least get the truck enough fuel to move it off my driveway before the blizzard arrives tomorrow night! I am LOST!

 

[MyothersanM1]

My truck exhibited the same symptoms almost to the tee. When I eliminated the selector valve, I replaced EVERYTHING rubber and all the fiittngs were either replaced or tightened up. Been fine since. Many will agree, you are sucking air somewhere.

 

[joesco]

Just want to give the group a quick update on my fuel issues. I drained the driver's side tank (about 5 gallons left) to make sure there was no sludge or rust, clean as a whistle. Then using my transfer pump, I pumped about 30 gallons out of the passenger side tank, into the driver's side tank. Then I purchased 2 spin-on filter heads from the local Cummins dealer, Fleet Guard Part # FG-142784S, one Baldwin Spin-On Filter with a water drain, Part # BF1212 and one Baldwin Spin-On Filter, Part # BF957. I removed the stock filter head assembly, OMG what a pain getting the three 25 year old bolt and nuts off! Made up a quick and dirty bracket, mounted the head, filled both filters with some filtered diesel and PRI-D fuel treatment, and installed them. Then, using the prime pump, pumped about half dozen times and diesel came flowing out of the petcock which by the way is another weak link, IMHO. I am replacing the petcock tomorrow. Then I disconnect the vent line that runs up the side of the intake stake and blew it out and it was totally clogged with dust, dirt, dead creatures, etc. Got into +Zeus+, cranked the starter for about 8 seconds and he started right up. I am very hesitant to drive him on the road, so I drove him around my property for about 10 minutes. On Wednesday, I have a mobile hydraulic tech coming out and he is going to help me run new lines directly from the driver's tank to the fuel filter, a new return and a new vent line. Hopefully I will be able bring closure to this nagging fuel issue.

 

[joesco]

I have searched the TM's, but can't find the dimensions of the two fittings which attach the feed and return lines to the top of driver's side, 58 gallon tank in my M931. I need to have two new lines made. Thanks!

 

[colt45s1911a1]

i know that im new here, but i have a 67 5 ton and i did a rather large tank swap( twin 100 gal saddle tanks from a modern semi ) and found that if i didnt use the factory lift pumps that were in tank she wouldnt start. i also replace the tank selector valve with a napa replacement valve. much better built just a little difficult to mount. i have had no problem except for my left pump died, the replacement is due to arrive this week.
if i understand right you no longer have in tank pumps, or never had them, would it be to much to put one in??

 

[Carlo]

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 agree with doghead. The hoses are ready available. The selector valve can be rebuilt. I did this to my 931 and spent less than 100,00. I had this same problem and the difference in throttle response after you change out everything is well noted. Plus she will start much easier.

 

[joesco]

Thanks, the IP pumps the fuel in an M931.

 

[Carlo]

As most members who had fuel starvation problems with the 250 cummins they will agree this motor is not know for its high ability to bring fuel to the injection pump. I even added a inline 24 v on one truck even after changing lines and rebulilding the selector valve.

 

[joesco]

I want to update my fuel issues. I found one major problem, after removing the spare tire carrier (soon to be replaced with a Super Single tire carrier). As you can see from the two pictures, the tank I was using (passenger) had a severely crushed fuel line.


Yesterday, I capped off the prime pump hose line and installed a brass plug in the elbow of the intake line to the IP. This eliminates the primer pump assembly as I found the petcock was leaking also. Just in that one assembly, I could see at least four possible air leaks (hose, hose connections, petcock and plunger handle). So it's gone and it will be replaced by an inline fuel pump wired to the passenger side of the fuel gauge switch as suggested by a fellow member (thanks!!!). This weekend I hope to run two new lines from the driver's side tank directly to the fuel filter and a return from the pump to the tank, by passing the floor selector switch. Then I am may to cap the two vent ports coming from the passenger tank. The passenger tank will be used as storage for my generator, New Holland loader and emergency fuel for the Zeus.

Once fuel system is refurbished, the truck is going to a truck spring shop for an evaluation and estimate next week, as I am still up in the air as to how to redesign / modify my existing rear spring assembly.

 

[doghead]

Are you planning to use the electric fuel pump just to prime?

I don't think you can continuously pressure feed the PT pump without negative results.

 

[joesco]

Just to prime doghead, unless you have a better mouse trap. I would think turning it on for several seconds should suffice after a filter change? I guess installing an air valve in the tank cap would be an alternative to bleed after a filter change? Thanks!!!

Are you planning to use the electric fuel pump just to prime?

I don't think you can continuously pressure feed the PT pump without negative results.

 

[doghead]

I have one truck that came with a field modified fuel tank cap with a shrader valve installed.

I'll save it for a "tool".

 

[Warthog]

You can make your own fuel cap with a schrader valve. You local hardware store will have a 4" rubber pvc cap and your tire store will have a screw on air valve. Drill a hole in the center and install the valve.

The cap will slip over the threaded neck, tighten the hose clamp and apply air.

 

[joesco]

The Yankee ingenuity with you guys never ceases to amaze me! Excellent ideas, thanks!

 

[MyothersanM1]

I want to update my fuel issues. I found one major problem, after removing the spare tire carrier (soon to be replaced with a Super Single tire carrier). As you can see from the two pictures, the tank I was using (passenger) had a severely crushed fuel line.
View attachment 482562View attachment 482561

Ouch! I have replaced all that copper stuff with rubber fuel lines, both supply and return. In fact, I have replaced all copper lines to include all air lines with DOT reinforced nylon. It's all a little more expensive, but much easier to install and maintain.

 

[joesco]

Need some help guys, I have gone ahead with my plan for the single fuel tank conversion using the drivers side tank, bypassing the selector valve. I am working with a mobile hydraulic hose repair guy to assist me with the new plumbing / fuel lines. We are both stumped as to the size and type of fittings for the supply and and return line fittings on the tanks side.

Any help is greatly appreciated, thanks!!

 

[MyothersanM1]

size and type of fittings for the supply and and return line fittings on the tanks side.

Inverted flare
Supply: 1/2"
Return: 3/8"
I get them here...http://www.discounthydraulichose.com/Inverted_Flare_Hydraulic_Tube_Fittings_s/241.htm

Also, they have inverted flare to barbed push lock fittings...http://www.discounthydraulichose.com/Push_Lock_Hose_Barbs_s/60.htm

 

[joesco]

Great thanks I don't understand why we are having such a difficult time finding the fittings. They sound pretty common??