Slow starting

[JMcCarthy]

I have a 96 2500 that is giving me trouble at start up. It seems to bleed off fuel while it is shut down. It has to reprime itself each time I start it after it has been shut down more than a few hours. I have been told that it may be the return fuel valve ir the Lift pump. My problem is I don't have much experiance with the Cummins and I would like to fix the problem befor the new set of manuals I orderd shows. Could someone tell me where these components are, and a way to test them. Is there a way to narow down the possibilities between the two? Ive already been all over it looking for leeks. I hate to just throw parts at a problem. Any diagnostic help would be apreciated.

 

[illflem]

It sounds like the notorious leaking fuel return line might be your problem. $2 worth of parts to fix, but a big pain to get at. Dealer wants around $125 for the job, but you can do it with a little cussing yourself. Check the archives in 12 valve for return line, you will find much info.

 

[Missouri Mule]

JMcCarthy,



Ok double check for leaks. The return fuel line hose (rubber section) is the most common problem. I looked at mine for 4 months never saw it leaking. Toward the time I did decide to change the hoses out I saw that the top of starter had been dripped on. Also found diesel on the cover cap of battery cable connector on the bottom of starter. The rubber hose(line) cracks toward head so you can't see cracks or leaks. Even if not leaking air can get in to system causing hard starting. I replaced mine all is well.



If the truck was parked up hill it had problems starting, down hill or on flat service it would start fine.



Usually a fuel pressure test will identify problem between fuel retrun valve and liftr pump. While doing test reach between injector pump and fuel filter with hand or pliers and squeeze rubber return line (if low/mormal pressure is shown) if pressure comes up bad return fuel valve, if pressure stays the same bad lift pump. I don't know if pressure test wil lindicate bad check valves in pump.



I confirmed not fuel return valve by primming system by hand( push pump under lift pump, lift pump under fuel filter and in front of starter). As pressure built up the valve would make a sqeeking noise while allowing excess fuel thru it.



Return fuel valve on front-back of injector has metal line attached to it, the line runs behind injector pump.



Injector pump could be cause too. Let's hope not (most expensive).



I used transmission hose(will take the heat) cost about 5 bucks 4 ft. ($1. 25 a ft) used about 3 with return and supply lines. Job is long and a pain.



Fuel valve 2nd most costly around 100 bucks(with tax).

Lift pump I understand about 150 bucks.



I agree don't waste money by replacing parts. But if your hoses have never been changed do it. Try to get hold of previous owner to see if they were changed. ( Do not use fuel line(rubber hose) or it will crack again. The fuel hose can not take heat from head.



I think one could take off rubber hose at pre filter/heater. Leave attached to lift pump put the side of hose that came of pre filter into bottle let sit over night see a how much fuel drains in bottle. None should the check valves should keep fuel in pump and fuel filter.



Which reminds me have you checked fuel filter around area where it screws in might have fuel leak or air leak. Also check fuel drain valve on fuel filter.



Hope this helps