Have a 2003 Duramax 6.6. Truck will not start unless it is plugged in over night, once its warmed up I can shut it off and restart it all day. My mechanic replaced the fuel filter and all the glow plugs, that didn't help. The dealer said the new fuel filter was leaking and replaced it , that didn't help. Back at the dealer, was told that it needed an injection pump for $3700. I decided for a second opinion. At a diesel repair shop I was told it needed injectors for $3350. Again I decided to wait. To this point it cost me about $3000 for towing, mechanics and DIAGNOSTICS. When the truck is running it runs great, it has plenty of power and at 80 mph it doesn't have a skip or a sputter. It is getting harder to start now even when plugged in. Does any one have any ideas what could be wrong.

 

there is a bus bar that ties the glow plugs together, check that.

glow plugs are bad.


does it start up when you plug it in? if so, then I would think jelling

 

The bus bar and the glow plugs have been replaced. This problem has been ongoing since last October and I have been using additive in every tank of fuel, so I don't think it is jelling. I think it may be the glow plug relay or fuse? Does anyone know where they are and how to test them? thanks

 

i dont think its a glow plug problem mine will fire up without letting my glow plugs worm up at all in the winter without it being plugged in. my friend is having a similar problem with his 03 but his fuel filter is just loosing prime so if it sits for like 2 days he just has to pop the hood and pump the fuel filter housing a few times then it starts right up. i would try doing that next time and see how that works for you. then you just need to search for where its getting air in the system

 

I pumped the fuel filter housing about 20 times but the truck still would not start.

 

when the truck first starts up does it run bad for a little bit?

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did either of the shops check the commanded rail pressure vs the actual rail pressure?, run a balance rate test? it could be something as simple as fuel pressure regulator or if all of the rail pressure's check out it could even be that the dowl pin on the crank gear has broken and which would put it slightly out of time and make it hard to start, i have seen this happen twice on local trucks

 

I check with the mechanic and he said that the the rail pressures were not the same but the actual pressure was good enough to start the truck. Also asked about the crank gear dowl pin and he told me that it would be a big job to check it. The truck is getting harder to start - needs a little ether in the mornings to get it going, so I think its time to look for a different truck. thanks for your responses.

 

if he was watching the rail pressure at crank then no they wouldnt be the same commanded should be in the 4800psi range and the actual pressure has to reach 1400psi to start the engine if its not getting there then you have a problem in the fuel system

since it is getting harder to start it really sounds like a rail pressure issue being an LB7 if it has the orginal injectors in it your best bet is probally going to be to replace all 8 of them just sucks that the warrenty is out on them now

yes checking the crank gear is hard to do thats why you really have to check out the fuel system good first and rule that possibility out

 

I would think if its out of time then it would not run very good and it would smoke alot more. I am leaning more toward fuel problem. I know it might be a long shot but my friends truck that I was talking about ended up being the neutral and reverse safety switch on the tranny. After I replaced that it starts good now along with a bad shifter cable also. his would not start unless he primed his system manually though. And it stopped going into gear. It was a around 40 bucks for the part if your truck is the four speed if its the five speed they are a bit more expencive. But you might give that a try

 

As much as I hate to do it, I decided to change the injectors. I'll have to do it myself so I hope that once its apart I can get it back together. thanks for the help, jim