Alright, seems easy enough. Maybe I can re-do my ground on my voltage gauge while I'm at it.

 

Couldn't even get at the sending unit wiring. Gonna have to figure out something else.


Soooo I replaced the belts. Damn cantankerous old truck!

 

i would have waited for the old belts to brake before changing them. keep the old ones as a backup. they crack with age but they don't really wear out like a serpentine belt.

since you can't get to the sending unit you will most likely have to try testing the gauge. could possible use 2 good AA batteries and a piece or 2 of wire to test the gauge. 2 AA batteries should not be enough to get it to peg but it should get it to slowly and smoothly make it up to half a tank area. just have to run power to the terminal that is shared with all the other gauges and then negative to the one that is all by itself from the gauge. just whatever you do, do not put 12v to the gauge or you will kill it. they only run on 5V which is why there is a small metal box on the back of the gauges.

 

I replaced them because one on the alt. was too slack and the other on the alt. was too tight, so I replaced the both of them and tightened the others.
Idler and PS belt are nice and tight now and no more squeal from the alt. belts.

I'll try the battery trick tomorrow I guess, if I can get the cluster out.

 

Didn't mess with the cluster, gauge mysteriously started working again.

In other news, I started looking at the vacuum advance. Truck loses the off-idle stumble it has with the advanced disconnected. It becomes harder to start and idles a littler rough, but not too bad.

 

could just have a bad connection somewhere. very common problem with old trucks. i know i occasionally have a bad connection at the sending unit.

timing could be off if it runs butter with the vacuum advance disconnected. shouldn't effect how it starts. did you plug the vacuum line when you disconnected it? a vacuum leak could cause it to idle rougher.

 

Good chance that your ground to the sending unit is losing contact. Mine did the same thing in my '78. Would work one week, not the next, then fix itself... I soldered an eye connector to the end of my ground wire (tank side), cleaned a spot on the frame (cross member under the bed, near the tank) with a grinding wheel, and attatched it with a self-tapping screw. Then I shot some battery terminal protector on it, to keep it clean. Its an 18 gauge, white wire, coming from the top of your fuel tank assuming ours are the same, which I'm fairly sure they are. Ill bet that will fix any future issues. If you'd like, I can get a picture for you.

 

Yeah, just started magically working.

I did plug the carb where the vacuum hose was attached. It did idle a little less-smooth (since it idles SO.DAMN.SMOOTH. for a 76) but I think just upping the idle speed would fix that. I am likely going to try that trick again this week and see how it starts.
I'll see if I can find it, but would you please get a picture for me? My Haynes ain't got nothin'! Pictures help greatly.

 

You got it. Ill catch one before I go to work this afternoon.

 

Thanks so much.