M923A2 loosing fuel prime overnight

[74M35A2]

Yes, the "transducer" is the fuel shut off valve, FSOV. It needs to pull in at crank and hols in when the engine is running. When the ignition is shut off, the FSOV releases and the shut off lever on the pump moves the rack to the zero delivery port in the pump.The FSOV will not cause prime to be lost, but if it isn't being pulled in the proper amt, the rack in the pump could still be at zero delivery. When you have the no start issue and it finally does start, does it run and idle correctly, no white smoke, just starts and idles fine?

I hear as one nears retirement, their hearing and sight start to get fuzzy.

One in a million chance to get one over on the most knowledgeable Cummins guy on this board, or more....

 

[Jbulach]

Just pulled the return fitting out, and found a rotten rubber braided line running to the bottom of the tank, if it can suck air back from this line i'm sure this one was leaking. Wow

FYI, that hose is nice but not necessary. I think I gained 3hp by deleting mine...

 

[Jbulach]

Ted, you are terrible at marketing.

Ted’s tubes are full stainless including the top male JIC fitting, and available as plug-and-play, custom length, or extra long (cut to fit). Available for suction and/or return sides. TIG welded construction. Look like they belong on the space shuttle. I’ll update this with a pic when I am back at my desk.

“Ted’s Tubes” I like it!

I think he actually builds them out of old space shuttle parts

 

[Bill Nutting]

I had the same problem on my 934. I installed an electronic fuel pump right at the tank. Powered it up, the engine started without ether. Then I saw a puddle of fuel on the floor! A plastic line had split. Replaced with copper line, removed electronics pump, all good! Has not lost prime since...

 

[WillWagner]

Trying out my new braille computer, what?

You SHOULD keep the return so it returns into a head of fuel for the reasons stated above, but you can just drop it back in w/o the stand pipe, it does airiate fuel somewhat but mostly you hear an annoying hissing noise in the return. It bothers some people, some, not so much. Another reason is IF the overflow valve fails, as in the spring goes away, it is a high frequency device, the fuel will not drain out of the pump and lines backward into the tank and create bigger issues like will not start. With a failed overflow valve there will be a hard start, maybe white smoke, low RPM and white smoke at higher RPM, but you would still be able to get off the road and to a place to get fixed instead of a tow.

Ya didn't answer the question of HOW it runs when it finally starts....

 

[Jbulach]

Sorry, I had another failed attempt at humor.

I didn’t delete my return dip hose on purpose, dragging my tank and shearing off the fitting at Haspin did it, and the truck has functioned fine since. I was just trying to let him know his rotten hose wasn’t his (only) problem. I assumed he already replaced the overflow valve, along with everything else since his last thread.

 

[Jbulach]

No on computer reboot
does have fuel
batteries OK
tires OK
Not sure if computer reboot is real or ?

No, the reboot is not real, it’s just an example of an annoyingly simple question that should be eliminated as part of troubleshooting, before we jump to conclusions and start replacing random parts.

Between my low idle of 450 rpm and my old batteries, my truck at times exhibits the exact same symptoms as yours. It always cranks fine, even at barely over 12v, when two of my batteries crapped out. When it’s colder out, I have to pull my hand throttle out a few clicks (600ish rpm) and it fires right up. I also have a very similar procedure for when my fsos extends after the engine starts and I let off the start switch.

And to the smart people, don’t forget I’m cheap and don’t like to spend money until I have time, or it’s to late. Also, I like my idle low with this low reverse geared auto.

 

[djhenley]

Thanks for all the info and humor, just got home and went out and it fired right up from 5 gal bucket with a 10 ft section of hose,(normally it would have lost prime) and return line has been disconnected while sitting. It run great on the road after it primed, but today just cranked and shut back down. Did purchase new tubes from Ted and he's sending out next week. I will replace the return and good to know its not absolutely needed but i'm sure its helpful for long periods between driving. When i get the tubes, I will slowly add parts back to find problem. I 'm thinking the idle is around 550 RPM

 

[djhenley]

Followup, got the new stainless tubes from Ted installed, new push lock hoses installed, with JIC fittings, everything was working well. Added dual filter setup back and problem reappeared. Did not wan't to have to dissemble all those fittings but I did tonight. When purchased it was assembled and my mistake for not checking each fitting as I found 3 or 4 possible areas that could be the problem, almost no tape visible and joints not as tight as I think they should have been. I cleaned all fittings and applied tape and small amount of pipe compound. Primed easily and ran few minutes. Will let sit till next Sunday and post results.

 

[djhenley]

Update- After resealing all the joints and plugs on the dual filter bracket and found a missing copper gasket on one of the banjo bolts/fillings at the cylinder head my fuel problem has now bee resolved. Fires right up after sitting for a week. Also moved my batteries from under the seat to the passenger tool box. Thanks for all the input.

 

[WillWagner]

Way cool, another issue solved!

 

[charlesmann]

guess I'm gonna have to start this troubleshooting process too. if mine sits for 2 days, it takes a few more whirls to start. more than 2 days, i have to prime it. i did find a leaking return line at the pump, replaced it, but was getting line from napa when i got called to return to work early. i will have my wife open the shutoff valve and try to crank it fri. if it needs priming, that means it between the shutoff valve, prime pump and the injector pump.

 

[Buffalobwana]

I had my diesel shop replace the one rubber fuel line with a braded line on three of my trucks. They never loose prime now. I'm sure there are other areas that could cause it, but this solved the problem. About to take the 931 in for the same.

 

[charlesmann]

evidently, the wife did not need to prime it. she turned the valve on and it fired right. could something so simple as the return the line leaking cause the pump to loose prime?

 

[jtgillich]

I make the new pickup tubes. I have one set available and more in the process right now.

Hi,
Do you have any more pick up tubers for sale? How about the return tubes?
Cheers,
JT

 

[TedCat]

Hi,
Do you have any more pick up tubers for sale? How about the return tubes?
Cheers,
JT

Hi JT. I have a few sets ready ship. PM sent

 

[jtgillich]

Hi JT. I have a few sets ready ship. PM sent

Hi TedCat,

I would like to order the the fuel tubes from you.
Please contact me at 775-848-0966

 

[jtgillich]

Hi,
Do you have any more pick up tubers for sale? How about the return tubes?
Cheers,
JT

Hi TedCat,
Need to buy a set from you. Please contact me at 775-848-0966.
Cheers,
JT

 

[dougnash]

I am having the same issue on my truck.
It took like 6 to 8 cycles of the starter before it lit up yesterday.
Today after one cycle and not starting, I cracked open the bleeder screw with a 10mm wrench and used the hand pump twice to prime it and got fuel to squirt, tightened the screw and tried to start it again and it started faster than it ever has.
I already ordered the dual fuel filters from Ken Spencer as well as a set of ted's tubes.
I gotta get the truck to start correctly

 

[Jbulach]

Replace all the rubber line while your putting Teds tubes in.