gfmccutc77

I have a 2008 6.7l that won't start unless I use starting fluid. After I finally get it started it blows a cloud of black smoke everywhere I go. It is doing this no matter how fast I'm going, what gear I'm in or how hard I'm mashing on the throttle. Any suggestions would be greatly appreciated. I have used a scan tool and shut down each injector, each changing the way the truck runs, but not changing the smoking. No showing any codes regarding injectors or fuel system at this point.

2006BLKMegacab

is it stock? if not was it deleted properly?

Lary Ellis (Top)

Sounds like the turbo vanes may be sooted shut...if you don't keep the exhaust brake on all the time to keep the variable vanes moving they clog up with soot.

Also a intercooler boot may have come off or got a hole in it, black smoke means too much fuel and not enough air.

carl48

my bet is on a stuck injector. you can not kill a stuck injector with a scan tool, you must cap each one off at a time to find it. if that is what it is, you are going to ruin the engine. if not already. the giveaway is the ecm will not let the truck start unless the rail is above 3,500 psi, the stuck injector prevents the rail from reaching 3,500 psi until the engine rpm is high enough to get it. that is what the starting fluid does.

gfmccutc77

Megacab, as far as I know the truck is totally stock.

Carl48, I think you are on the right track with that. I noticed the fuel pressure was not getting above 1000 Psi while trying to start. The question is, what do I use to cap off the injectors?? I am fairly new to working on these 6.7's so I am out of my realm with this one. All your help, and further help is greatly appreciated from everyone.

carl48

rail cap I have I got from miller special tools 800-801-5420, not near my shop now to get you the part # but they are very helpful. I bought it and three special banjo bolts to do leak down test all was about $120 so the cap should be about $30 loosen the injector nut and remove the dampener (or isolator) bolt then remove the nut from the rail and place the cap on the rail. it will instantly start once you find the right one. nuts are 19mm clamp bolt 10mm

Big Will

You can also use a infared thermometer to check which cylinder is running cold once started. Works like a charm.

carl48

big it will not work on his problem. the easiest way if you do not have a rail cap is to loosen the bolts in the exhaust manifold where you have about a 0.020 to a 0.030 gap and start the engine, very apparent witch one then.

gfmccutc77

Ok guys here is what I have done so far. Started trying to narrow down if it is an injector, truck will not start now. No pressure from the injection pump, so replaced it. Now I have pressure from the pump, but the pressure sensor was reading 0. Replaced that and I am getting a pressure reading but truck still won't start. Still haven't figured out if there is a bad injector either.

gfmccutc77

I had a question asked to me, and I am going to ask you guys because I don't know the answer. If an injector is dumping 3500 pound worth of pressure into a cylinder, wouldn't it hydralock the engine?? I don't have a clue what the answer is, but it seems like a logical question. Any help is appreciated, I'm at a loss on this one.