hey yall, im new to this site but i have heard good things, thought i would give it a shot!! heres my situation. i bought a used 05 gmc dmax, 112000 miles, about two months ago. when i went to the dealer it would crank over but not start, you could prime it and it would run all day. next morning the same thing. they replaced a fuel line with a check valve in it near the fuel tank, and all was good for about two months. no performance issues, no smoke just pure duramax power! yesturday i drove to work with no issues, sat all day, when i went to go home it started rite up, ran for 15 sec. then quit. i pushed the primer on top of the filter housing, no pressure. so i pushed till it got hard maybee ten pumps, cranked for 5 sec then ran for 15 sec and stalled again. every time i prime it i get the same result, no smoke or anything once started it ran great durring thoes 15 sec but i allways get the same reult. no visible leaks, i craked the bleder screw and turned the key on but no fuel comes from it unless i prime it by hand. i am terrified that it may be the ip, or injectors?? what do u guys think it could be? i have read allot of posts but i cant find any that are simmilar to the symptoms i am having. any help is greatly appreciated, because the daler that sold me the truck is not willing to help. thanks again
LLY: please help!! wont stay running
- Thread starter all4gmc
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the filter housing itself could need a rebuild, ive read about these same kinds of issues with them. You could get yourself a lift pump and delete the filter housing under the hood.
Could your CP3 of failed? The CP3 sucks the fuel, so that would be my first place to look. Have you changed your fuel filler.
I highly highly doubt its the CP3... You are sucking in air from somewhere. Look into the filter housing
i put my money on a cp3 only because i have dealt with this issue 4 other times and it was the cp3
Yeah I would definitely start with something like this: http://www.merchant-automotive.com/completefilterheadrebuildkit.aspx
Don't let a dealer tell you that you have to get a new filter head, they're expensive. You didn't get any fuel at the bleeder when you were cranking because it is a suction design, but you will get pressure in the head by priming it with the priming button.
Don't let a dealer tell you that you have to get a new filter head, they're expensive. You didn't get any fuel at the bleeder when you were cranking because it is a suction design, but you will get pressure in the head by priming it with the priming button.
thanks guys, gives me a good place to start, i have not changed the fuel filter the dealer i purchased the truck from said they did.
is there any good way to narrow it down between cp3 and filter housing? i really dont want to take it to the dealer due to they r expensive. i have read about cracks in the filter housing and leaking orings, if this was the case wouldnt i see fuel leaking somewhere, why would it hold prime, run good then stall if there was a bad oring or cracked housing? yhis is my first gm product i was allways a powerstroke fan, so this may sound kinda strange but what is the cp3? injection pump?
is there any good way to narrow it down between cp3 and filter housing? i really dont want to take it to the dealer due to they r expensive. i have read about cracks in the filter housing and leaking orings, if this was the case wouldnt i see fuel leaking somewhere, why would it hold prime, run good then stall if there was a bad oring or cracked housing? yhis is my first gm product i was allways a powerstroke fan, so this may sound kinda strange but what is the cp3? injection pump?
Yes the cp3 is the injection pump. You wouldn't necessarily see fuel leaking, its a suction design and can suck in air without leaking out. Another thing to check is also the Water in Fuel sensor plastic connector on the bottom of the filter. They can crack and suck in air. You can get it scanned to check actual vs. desired rail pressure to check the Cp3 but you need to know for sure that you are not sucking in air. Sometimes they are erratic because with temperature changes the o-rings expand and contract etc, sometimes they start and sometimes they just crank sucking in air. It is worth "rebuilding" the filter head and checking the WIF plug for the low costs regardless if it is the ultimate problem or not.
i live in michigan, last week it was allmost 60 today its like 30, so heres a fun fact, just went outside to get the truck in the barn to start lookin. when i untrailerd it last night where it quit it sat, all day today, hasnt been touched. anyways i started it for sh*t's and grins (without priming it first) fired rite up, ran for probly 1 min then died in the barn. yall have been very helpfull if anything else comes to mind please let me know, you guys are awsome!!:woott:
i would try unhooking the the return and inlet line on the drivers side of the motor fill up a 1 gallon jug of diesel run the two lines into the bottle and see if it runs. The one fitting youll need another fuel line with the correct end on it and connect it the inlet side of the injectors or else it wont seal correctly. If im not mistaken this is how you can tell if the filter housing maybe cracked?? I hope someone can back me up on this, its worth a shot. That way youll know how to run the upper cylinder cleaner to try and bring injectors in spec
Let me know if you need a filter housing. I bought three of them off a memeber here and I only need one of them. The two extra ones I have I am sure are for your truck. I am not sure how to test if they hold prime.
