Rough Idle - Injectors, Harness, Or...?

[bbressler]

Just started having a very rough idle today. Sounds like it's running on 6 cylinders.

My truck has a bit over 292K on it, still with original injectors & harnesses.

I've thought for a long while I should rebuild the injectors, but this has me wondering what I should do next to figure out what's going on here.

Any ideas? Is the UVC harness such that I can figure out if it's bad based on visual inspection, or with a volt-meter?

 

[94f450sd]

open your oil filler and see if you can smell burnt wireing.when was the last fuel filter change?what color was the fuel?any gunk in the bottom of the filter housing?ever clean the fuel pressure regulator screen?

 

[bbressler]

I'll go smell here after a bit.

Fuel filter should be easy to test -- I've got two (one veg oil and one regular diesel). I noticed it on regular diesel, I'll switch to veg and see if the problem persists. If it doesn't, I'll replace that filter and see what we get.

The one that's on there has probably got 10K on it or so.

Haven't checked the FPR screen lately, I'll do that tonight.

 

[94f450sd]

check the color of the fuel in the housing.black and oily looking usually indicates bad injector orings.gunk in the bottom of the housing usually indicate orings as well.

 

[bbressler]

Well -- I am noticing some burnt wire smell -- ever since I put my new Stancor relay in (long time ago).

If it is the UVC harness, is it usually burn out on the gasket itself, or the harness that goes under the VC? (Or does it happen equally either way?)

I know I've seen some pinouts somewhere that I could use to test the harnesses, any idea where I can find one of those?

I'll have to check the other stuff when I get back home.

 

[Crumm]

Well -- I am noticing some burnt wire smell .

If it is the UVC harness, is it usually burn out on the gasket itself, or the harness that goes under the VC?

The harness will be melted but many times the connections on the gasket will also be bad.

 

[bbressler]

Here's what I've found so far.

Both connectors into the VC gasket on the passenger side are melting. Back one seems to be melted on both sides, the front one is melting on the rear-most side of the connector.

I unplugged the front one and started the truck, it didn't seem very much worse than when it was plugged in.

So, I think I'm going to replace those two connectors, along with the UVC gasket on that side, all four glow-plugs on that side, and take a look at the harness inside the valve cover.

Anything else I should check?

 

[95_stroker]

Sounds like you are the right track Ben.

 

[94f450sd]

So, I think I'm going to replace those two connectors, along with the UVC gasket on that side, all four glow-plugs on that side, and take a look at the harness inside the valve cover.

Anything else I should check?

replace all 8 glowplugs!!i bet the harnesses and gasket on the other side is melted as well or atleast starting.

 

[bbressler]

I may do that...got the GPs when they were on sale at Autozone, so I've got the parts. I inspected the plugs on the drivers side, they look perfect, that's the only reason I was just going to let sleeping dogs lie and not do them....