Bizarre Electrical Problem

[quinryan]

I have an 82 Jimmy with the 6.2. For once, the engine isn't the problem.

I took the instrument panel apart in order to replace a broken fuel gauge. While I had it apart, I replaced the bulbs (red ones. Looks cool) and before I put it back together, I made SURE that everything worked right.

Then, I had to fiddle with the headlights. I have the 4-light system, and the new high/low lamp on the passenger side had a bad high. As the lamp was new, I figured that something was up with the wires there. Took it down, played with the wires a bit, and it lit right up.

Put together the I panel, and all was right with the world. Until...I turned the lights on later that night, and lots of odd stuff occurred.

-Fuel gauge goes to zero.
-No panel lights at all.
-the passenger side Low beam is inop.
-The I/? arrow for left turn stays on constantly, while the right side arrow doesn't glow at all. The turn signals work properly though, as do the tail and brake lights.
-Oh, here's the really weird thing: the little lights that indicate High Beam come on when the Low beams are on, and when the High Beam comes on, the lights go out.

Any ideas?

 

[Russell]

Bad ground! Classic symptoms, esspecially that left turn signal, haha

The ground is the one in the main harness that runs to the ground distribution block just to the left of the instrument cluster. Take the bezel off and you'll see it right away (may be behind vent ducting if you have AC)

Fix up that ground wire and all your trouble will go away

 

[63chevyll]

i second the ground issue,

Do get crazy and try to diag what ground is bad, just add grounds to each circuit until its fixed. Just a quick way to repair it

 

[quinryan]

Thanks very much! It was a ground issue. One of the lamp plugs for the I/P was bad. I DX'd it, and the I/P works great.

Now if I could just fix the smoke-screen generator that is my engine...

 

[Russell]

What color is the smoke? Dark blue, grey, white, black? All indicate something different. Does it only happen during certain conditions or is it all the time?

 

[quinryan]

smoke job

82 GMC Jimmy 6.2, 700R4, 208.

New air and fuel (both) filters, glow plugs (and solanoid and controller) and injectors. Air filter is a cold-air kit.

Rebuilt injector pump, mechanical lift pump replaced with electric fuel pump from Mr. Gasket.

Fuel tank is clean.

Okay. Smoke is black! She starts fine and it takes less than a minute for it to start idling smoothly. Some blue smoke (oil) before she hits operating temp (showing about *175 on the factory gauge). then that stops. Not too worried about that.

At idle, some smoke is coming out of the pipes, kinda like a haze. Looks black, but is thin and see-through. There's a lot of this at idle when in D, much less in N or P.

But...touch the throttle at anything past tip-in, and it starts to look like I'm laying a smokescreen. Mid-throttle on up and I cannot see behind me (good for tailgaters, though).

If I keep the RPMs up (3rd at 65 MPH or the like), there's very little smoke because I am hardly on the "gas" pedal.

My guess is that my fuel pump is just pumping too much fuel; it often feels like a gasser does when it's bogging down.

I also wonder if I'm running a bit too cold, and the mixture is not combusting fully.

I do not know how to adjust the pump. I do know how to change a t-stat.

Any ideas would be appreciated.

Thanks,

Skip Ryan
Colorado Springs, CO

82 GMC Jimmy, 6.2
93 Jeep YJ, 2.5 Low Output 4cyl
97 Ford Expedition, 4.6 (wife's)
89 Ford Taurus, 3.8 (kid's).


Go Rockies!

 

[Russell]

Sounds like your injection pump is set way too high for your engine. Black smoke is always associated with very high exhaust gas temperatures (EGTs). High EGTs can melt pistons and crack heads, so I would deal with this problem sooner than later!


A small bit of greyish smoke (tough to tell between blue and grey) is infact normal, especially on a cold start but it should clear up shortly after the engine starts to idle smoothly.

Adjusting the injection pump is not as scary of a job as it may sound like. To start, you need to remove all the glow plugs to reduce the amount of resistance to turning the engine over by hand. Next, remove the top plate on the injection pump. You will see a round shaft going straight down and at the bottom of it will likely be just a rod visible. You need to turn the engine over by hand using the bolt on the alternator pulley (do not under any circumstances try and turn the engine over using the balancer bolts!) until a hole appears in that shaft exposing the fuel adjust screw below. Turn the screw 1/8th of a turn counterclockwise to lower the fuel rate.

If you are careful when you pull the top plate off, you should be able to re-use the gasket. Make sure you put the top plate back on before you start the engine again, as there may be the potential for fuel to be sprayed around with it off.

You'll know your fuel is set right when you lay down a light black haze at wide open throttle going up an incline. Any more than that and you are simply wasting fuel and risking low melting point aluminum components / overheating the engine. Always adjust the injection pump by an 1/8th of a turn or less, a little goes a long ways with that adjustment screw. Keep in mind that it is not possible to run a diesel engine too lean. They use exactly as much air as they need to run as lean as possible, you'll simply loose power if you turn the fuel too low, and just blow black smoke if you turn the fuel too high (and will not gain extra power doing so, it just burns in the exhaust instead after the compression stroke)

 

[zombie1969]

Ive only worked on the newer tec2 compatible models and always had to set the injector pump timing with the tec2 after replacing it.Not sure about this one but if it needs to be timed and it hasn't you need to do that.Also wondering about your lift pump and what the pressure is.5 psi is the norm for what Ive worked on so I would make sure the Mr gasket one is correct.