LUVTruck.com

my idle goes up then down up then down can someone enliten me it is a 1980 luv please help!

vacuum leak, standard feature

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Dr. Frankenstein

Is it a constant up and down? or does it just drop once the truck has warmed?

I gonna go with vacuum leak too. start the truck and take a can of carb cleaner and spray it around the carb by fittings and gaskets and whatnot. If you hear a noticeable increase in the rpm. you have a genuine standard vacuum leak. good luck let us know how it goes.

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Resident lurker

That is hilariously accurate. I think Isuzu could have used perforated pipe in the factory for vac lines and it wouldn't make a lot of difference.

I'd also try pulling and capping off all the vac lines off too. The truck should run ok with everything except the distributor disconnected. Just be sure the label or map out where the lines go. I've had the most trouble with the flapper valve in the air cleaner inlet and the thermal valve that controls it, but you could have a leak in the EGR valve, smog pump control valve, or just about anywhere along the hoses.