UVC harness pinout

[SMOKNZ]

I have an old thread in the 7.3 power and performance (accidently put in wrong forum) for my truck that died. Back in December I was towing my snowmobile to a friends house to go play around. Along the way over about 5 miles I was loosing power bad till the truck would barely idle and then died completely never to start again. I had this problem before when I had a bunch of water in my tank, so I assumed I had the same problem. I drained the fuel bowl and put in a new filter, but it would not start. I had a small amount of bio-diesel left in the tank, but I filled up to a 3/4 tank just prior to this. I also verified that the fuel pump pumped fuel by emptying the fuel bowl and turning the key. Thus far I have replaced both batteries, added oil (was 2 quarts low) and also bypassed glow plug relay just to rule it out and still no start. I know the fuel pump is pumping, though don't know at what pressure. I have to hook up my fuel gauge yet. I remember reading in the past about the valve cover harness coming undone on the inside of the cover. I figured if I knew the pinout that I could narrow it down to which one it is. My glow plugs are pretty new, and I know the resistance should be around .2 ohms. Does anyone know what resistance the injectors are? and what pins everything is located at. I only have a few weekends left before camping starts and I need to be able to pull the old camper. I figure that I could narrow it down to the valve cover harness or it must be something else, like the IDM or HPOP. The truck seems to want to start but just won't catch. It blows some nice smoke while cranking so it seems to bet some fuel. Any help appreciated!

Bill

 

[BJS]

can't say that I've ever resistance checked the injectors to verify that they are plugged in. The glow plugs will be the outer 2 pins on each end of the connectors on your SD.

when you say that you've bypassed the glow plug relay are you saying that you have jumped it so that you are manually engaging the glow plugs or that you've completely disabled the GPR?

 

[SMOKNZ]

Just to make sure it was working I used a jumper cable across the relay, still didn't start. I'm pretty sure the relay is working though, i can hear the tone of the fuel pump change slightly when it turns on. I've had this fail enough that I can tell when the tone doesn't change that the relay is shot.

Bill

 

[SMOKNZ]

Googled it and found this info for the plug:

GGIICIIGG
G - Glow Plug
I - Injector +
C - Injector -
Ohms between the G and block Ground should be 0.1 - 2.0 ohms.
Ohms between the I and C one at a time if one or more is > 5 ohms, it will point to the side's gasket connector or UVC harness being shorted.

I'm going to check it out and see if everything has continuity. Also saw a You-tube video that uses a ground down quarter to secure the harness instead of buying a new one. I'm going to look hard before doing this as I sure wouldn't want a quarter jumping around valve springs.

Bill

 

[93turbo_animal]

do you have a cel on by any chance? I don't really think it is a valve cover harness cause these trucks will run with just one bank of injectors and it just seems to unlikely that both harness came unplugged at the same time

 

[SMOKNZ]

No light came on as power went away. The truck seems to want to start and I have had it start for like a second once since then but would not stay running. I get some nice smoke out the exhaust while cranking so something has to be getting fuel I would think. Will the truck start with only 1 bank firing when it's cold out?

Bill

 

[BJS]

I will suggest pulling the DP tuner chip to eliminate it as a possibility. The next step in my mind would be to pull one of the valve cover gaskets (choice is yours) and look for oil shooting from the injectors to see if they are firing. You should be getting some white smoke from the exhaust when you're trying to start the truck if they are shooting fuel.

I will also suggest checking or double checking all of the fuses under the hood, you may have blow the maxi-fuse that supplies power to the IDM

 

[93turbo_animal]

yes they will start with just one bank even cold if the glow plugs on that side are working. If you are getting a lot of white smoke out the exhaust then you are getting fuel and its not the wire harness cause if its shorted out you wouldn't get any fuel. How cold is it maybe you should plug in the block heater for a few hours just to eliminate that. My relay is sticky and doesn't always engage and it won't start even when its 70 out if the relay doesn't engage for the first start. If your getting smoke from fuel the only other thing needed to start is heat

 

[SMOKNZ]

Everytime it gets above 50 or so I have tried to start it. The way the truck went away slow over a few miles makes me shy away from the blown fuse, but I will check anyway. I will be going into the valve cover this weekend to see if I can figure out what the hell is going on. The truck was plenty warm when it was running in December, glow plugs shouldn't have been a factor in what happened at that time. Also I will be checking fuel pressure from the lift pump to make sure thats ok. I know it is moving fuel but I don't know if it is adequate.

Bill

 

[93turbo_animal]

another member just had problems close to this truck dropped off then died although he could get his truck running again it was barely running but his threw a cel so he put a scanner on it and the ICP sensor went bad.