I have a newly purchased 1994 Ford L9000 with an M11. Overnight it will start and run fine but if it sits for a couple of days it will start but then quit after 20-30 seconds and won't want to start again for some time. I sprayed a small amount of starting fluid after trying several times without it and got it started again and it ran good. From looking online, I'm wondering if the check valve in the fuel line at the ECM is dirty causing it to lose prime? It has a new fuel filter and water separator. Also I had to boost it to get it going but noticed it has 2 new batteries in 1 battery box hooked up but the 2 batteries in the other battery box are disconnected. My guess is the 2 batteries disconnected need replacing and the new ones were just to get the truck started so it could be sold. I figure the 2 extra batteries will be a huge improvement but could less battery capacity have anything to do with the starting and shutting off problem?
Sure sounds like air to me. I can't see how the two batteries would make a difference vs four. Make sure there aren't loose cables bouncing around that second battery box though.
I work on a fleet of 12 m11s and just had this same issue on one. It turned out the feed line from tank to cooling plate was very old and dry. If it sat then the hose would sweat the feul out through the rubber in a couple spots. New line no more issues. If you use air to put some pressure on the feul tank it will usually show a leak pretty fast. Good luck hope this helps. Oh and all of our trucks run two or three batteries only no difference between them. They aren't your problem.
I took a look today and there is no elbow with the check valve. A hose comes straight out and goes to a water separator. Some good news is that the water separator head has a bush button on it I assume is for priming. It started up today but shut of again and I had to boost it. Got it going pretty quick. I pushed the button several times and didn't need ether but is the button supposed to get hard to push when it's fully primed? There are actually 3 batteries hooked up and only 1 that isn't but I'm wondering if they aren't in the greatest shape and were maybe partially frozen or something. There are 2 battery cut-off switches but turning one of them off makes the check engine light come on. Shouldn't these cut all battery power?
I worked on a truck like yours they couldnt get it started so i went out and tryed and it would start after it did this 2times i pluged the fuel lines off and put air presser to them i had a blond moment i sprayed soapy water on every thing and i heared a leak but no bubles. It didnt buble because there was a pinhole with fuel spraying out of it.We also had a truck that would leak some coolent and would get low and wouldnt run very long before it shut down.I would take the batterys and have them tested so it would end the guessing about if there good or not.