[cummins9612v]

ok so i have been reading and searching alot on the forum and on google. my truc has a problem that is very similar to what most people experience in cold weather.
it starts up then dies after about 10-15 min, after alot of cranking it will fire up run a bit rough, then die after a few min again. this problem only happens when it is cold out and in the morning or when the truck hasent been run in awhile (few hours)
now from my online research i have found some fixes but they did not work.
I have replaced the fuel feed and return line with the Larry B's kit.
brand new lift pump (confirmed working and priming)
new fuel filter, drain on bottom not leaking and checked.
new prefilter from Cummins.
idle is at 850-900 right now.

truck still dies, problem exists weather fuel take is full or 1/4.
problem only happens when it is cold. runs fine all summer long.

Any idea what it could be. where else can air be entering my fuel system?

 

[GAmes]

Rather than guessing and throwing parts at it the first thing you should have done is determine the fuel pressure when it is running. Without knowing that your guesses would be as good as ours. Oh, and "most" people don't experience your problem when it is cold.

https://www.cumminsforum.com/forum/94-98-engine/58777-joe-gs-fuel-system-writeup.html

 

[9297oldram]

Have you checked the fuel filter after it has sat for a while to see if there is air bubbles in it, just open the bleeder and manually pump the LP and watch for bubbles.

I had a metal 90 for the supply line on the fuel tank module on my old 97 that had rusted and let air into the system.

 

[alanack6795]

Thankfully your leak is small and intermittent.

The way I chased mine down was by watching the fuel pressure gauge while a buddy would shake the connection that was suspect.

Ended up being the quick disconnect on the fuel tank.

 

[Destroked 450]

Did you pull the fuel screen and check the fuel heater, if it's burnt up air can leak in where the wires go thru the housing.

 

[ehenle4188]

Check the metal elbow at the top of your fuel tank. They are prone to rust and can cause air in fuel.

 

[bigfish95971]

Air from an air leak in the return line fitting leaks will not run 15 minutes and then die, it would be more like 0 to 15 seconds, not minutes. So unless you can see air in a piece of clear line added, air leaked in while sitting is not your problem. Sounds more like an ECM or VP electrical problem after warm up. Maybe a sensor issue.

 

[9297oldram]

Air from an air leak in the return line fitting leaks will not run 15 minutes and then die, it would be more like 0 to 15 seconds, not minutes. So unless you can see air in a piece of clear line added, air leaked in while sitting is not your problem. Sounds more like an ECM or VP electrical problem after warm up. Maybe a sensor issue.

A 12v is a mechanical engine and has no ECM, that's why we like them so much.

 

[bigfish95971]

Sorry missed year. Can a 12 valve run 15 minutes off of fuel in the pump? Is there a return line? Maybe a leak on the intake lines from the tank? But you would think that would suck air all the time.

 

[Destroked 450]

On these engines a small leak will allow the engine to run for a while until the filter finally runs dry.

 

[bigfish95971]

Yea if the filter is before the mechanical pump. If it has the same filter and heater as 24v, there is a common leak on the plug for the heater wires. It takes an o-ring that is 5/8 id, 3/4 OD and 1/16th stock.

 

[Destroked 450]

Filter is after the pump, heater is part of the prescreen mounted to the block with the lift pump.