83 FJ60 and now we are here.....

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Apr 4, 2009
Jackson Wyoming
Ok I am 2 weeks into my project find. Many kudos to all who have responed to my prev posts. All good info and suggestions so far.
I rebuilt the carb and traded a few emails with JimC ( I think the c stands for carbuerator). It runs!!! In order to get it to idle at all I advanced the timing. Still diesels an cugs and needs choke to idle but it idles. I advanced the timing because it had no power on a spin around the block. Advanced timing and now she has some pull and actually runs smooth above 1500rpm or so.
Spent a few hours chasing oil leaks and cleaning things too. Pulled the plugs today and found #3 and #5 fairly well fouled. This could be legacy from the 2 year nap the truck took before it was mine.?? Anywho read the thread on vacuum analysis. Hooked up a quality vac guage to the vac switch hose (small one) which shares the finned valve and larger hose to the brake booster/manifold path. Pulling 5-7 inches of vac at 6250' elevation. It bounces from 5-7 inches as she chugs and idles with the choke out a click. Exhaust smells clean. Oil looks good. No clacking or tapping noises from the block. Sprayed more than my earth day share of carb cleaner all around seeking the elusive vac leak none found. Solenoid is good -bu the vac switch IS bad. Can this switch cause this problem? Any other paths to follow? I am open......I am having fun chasing away the old ghosts in this machine....I will make it run....I willl make it run........all I need is a lifting platform and a lighting stormmmmmm.....ah hahahahaha!!!! OPPs sorry wrong movie.....ahem ........can a brother get a clue here?

Thanks. :steer::hmm:
The vacuum switch that attaches to the small port on the finned manifold access is for the AC idle up. If that hose is properly connected and the ac idle up diaphragm is not broken it should cause rough idle problems.

When you say "solenoid is good but vac switch is bad" what exactly are you talking about and how do you know what's good and bad.

Here's a vacuum diagram to get you started, but you should really purchase the emissions manual and get prepared to replace all the vacuum tubing, if you haven't already.



  • vacuum piping.pdf
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Thanks 2mbb. I tested the solenoid in and out of the carb. Its clean, clicks when it is supposed to and has a new oring. The vacuum switch fails its continuity test. Case to connector beeps. Case to connector still beeps when sucking on a hose connected to the vac switch hose end. Are you suggesting that I connected the vac guage to an incorrect hose?. The small two hose switch on the fender with the black plastic cover is the one I disconnected and used for the vac guage. The AC compressor has no belt connected to it. Was that way when I got it. Not an issue, I think, were I live no one uses AC. What is the AC diaphram idle connection about thats a new one for me. Thanks for your response! BTW already replaced almost all the vac hoses on the rig. Double checked all of them for clogs and leaks. :cheers:
No I think you tested the vacuum correctly, and it's low. I thought you were asking whether the broken vacuum switch would cause the low vacuum, but I still don't know which switch you are taking about. If it's the one that's simply called "vacuum switch" on the linked diagram, then it's the switch associated with the decel fuel cut solenoid. If I read the diagram correctly, if the vacuum switch is shorted out (telling the computer it's always "on", then the decel fuel cut valve will always be open, which is not the problem you are describing.
decel fuel cut schematic.JPG
More suggestions:

Have you adjusted your valves?

You didn't find any vacuum leaks with carb cleaner. You should also check the PCV valve for proper operation and try and cap off the brake booster line to see if the booster is leaking.

Thanks 2mbb. No I have yet to venture under the valve cover. I will also try blocking off the brake booster vacuum line from the engine, good suggestion. Probably check/set valve clearance this weekend. I will keep you posted. I am dying to get her out on the road! :steer:

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