Archived 12 Valve Dies atfer Start & Drive

[MNye]

Have a problem with a 97 12 Valve that seems to be related to cold weather. Truck has about 215k on the engine. Injector age unknown, turned up P7100.



The truck will start fine, but once driving, under light throttle, truck sputters, blows white smoke and will stall like it's getting air in the fuel system. Primer never really gets solid on lift pump, but you can prime it enough to get it running again. After this process, it will run fine until the next morning on cold start up.



Lift pump, overflow valve, and fuel heater screen have been recently replaced, but did not fix the problem.



Anybody have ideas on diagnosis? I rely on this truck daily and would like to get this issue fixed asap.



Thanks in advance

Mitch

 

[The patriot]

Change your fuel filter and rubber return line.

 

[MNye]

Fuel filter has been changed... Will go after the rubber return line next. I'm assuming it's possible for it to draw air in and not leak fuel out??? No noticable fuel leaks anywhere.

 

[surfbeetle]

Do a search in the 12 valve 2nd gen engine section. There's lots of info. The fuel supply and return rubber hoses in the area from the transmission area to the engine get cracked and don't leak but will lose the fuel prime and cause your symptoms. The other issue could be your fuel shutdown solenoid not staying up and causing the engine to die. The hose issue is more common. I've changed my hoses at least four times in 210,000 miles. Don't get the cheap hose either or you'll be doing it more often, it's a pain it the backside to do.

 

[The patriot]

J30R9 is the spec for the hose. 5/16". IIRC a foot should be enough.
I got the Goodyear with the blue in the middle. It's bio diesel rated.
In the original post it sounded like you just did the primary filter.....

Unless you got a new one, your fuel heater can be a source of introducing air into the system.

 

[surfbeetle]

I think inlet and return hoses are two different sizes. Larry B's LarryBs.com Dodge is where I got my hose. I didn't see it on the site just now, you may have to call.

 

[wcjp]

On my 96' I replaced the two different size hoses with Coast Guard approved diesel fuel line from a Marine supply store. It's twice the thickness. My main problem turned out to be the fuel preheater/lift pump soft line. It had serious dryrot. Once off the vehicle I could see daylight through the hose sidewall. It did not leak. The dealer was at least two weeks out to order a new soft line. I bought a long section of standard line from the Marine supply store. Installed it with a large loop to avoid kinks. Had to slightly shorten the line to avoid rubbing on the steering shaft. This is a good time to replace the starter contacts when changing all three soft lines.

 

[MNye]

Awesome guys. Thanks for jumping on this for me. Looks like I have a weekend project now!

 

[surfbeetle]

Hopefully you have long arms with small hands or at least a flexible ratchet extension. Those hoses are a real pain to remove. It's not very fun laying on your back trying to reach up around the transmission.

 

[Sticks]

Diesel repair by braille.

 

[Missouri Mule]

I took off the fuel filter and did hoses from top side. (Keep scrolling down on LarryB's site the hoses are down near the bottom of the page. )



Try turning up your idle. Auto trans, 750 to 800 rpm in drive and A/C On.

Manual trans, 780 rpm in neutral with A/C on.



Also make sure your linkage is moving correctly.

 

[GAmes]

I replaced my lift pump once and had starting and running problems. It turned out that the fitting that I had removed from the old pump and installed in the new pump needed one more revolution to fully seal. Also, while you are doing hoses don't forget the L shaped hose between the prefilter and the lift pump. Only about $7 from Dodge, a lot more (so I've heard) from Cummins.

 

[HHhuntitall]

Worked on one Friday... well started on it Friday... Finished it up yesterday. The steel fuel line where it clips in the holders on the bellhousing had a hole rubbed in it from the clips. The truck has repeatedly had the stalling problem when first started in the morning. It puffs white smoke until it warms up. We've been tracking o-rings, fuel level canister, return lines, check valve, lift pump. It finally started leaking a little diesel from the fuel line, I saw it, pulled the line, and sure enough, it had a pinhole leak. Seems it didn't leak much when it did leak. We cut it, slid some Gates Fuel Injection line over it, clamped it, and she runs much better! Owner is extremely happy, and I'm happy to get it out of my shop!!!

 

[EWalshak]

I had the same symptoms as you described. It turned out to be my lift pump. It was loosing prime and really became a problem when it got cold.