1988 Mighty Max will not idle, help please!

Hi all, new here. I'm at my wits end. Problem with my 88 Mighty Max (5 speed, 2.0, no A/C). After driving 25 or 30 miles it will not idle at stop lights. Runs fine as lone as it's moving but when I stop it cuts off unless I hold the gas pedal down enough to keep it around 2000 rpm. It will idle fine at stop lights until I get 25 or 30 miles then starts it's cutting off when I stop. I have changed all the hoses from the fuel tank to the carburetor. New fuel pump and fuel filter. New plugs, wires, distributor cap and rotor button. Sprayed carburetor cleaner in and around the carburetor. I'm lost, any ideas?

THANKS!

Did you change the hoses from the carb to the box on the drivers inner fender? Those lines go to a sensor that the computer controlled carb uses to adjust the carb. They usually are split or chewed on by mice.

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Originally Posted by pennyman1

Did you change the hoses from the carb to the box on the drivers inner fender? Those lines go to a sensor that the computer controlled carb uses to adjust the carb. They usually are split or chewed on by mice.

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Had not checked these, most all of the lines show a lot of being air dry, the largest one that connects from the manifold to the center of the box pulled apart pretty easy when I tried to remove it. Cut it back 1/2" and reconnected it. No time to try it this evening, will update after I try driving it tomorrow.

Thanks

that one is the usual suspect. May not be the total problem, but it's a start.

Quote:

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Originally Posted by pennyman1

Did you change the hoses from the carb to the box on the drivers inner fender? Those lines go to a sensor that the computer controlled carb uses to adjust the carb. They usually are split or chewed on by mice.

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Thought that had done the trick, dang truck ran flawless two days. Then on the way home this evening, same thing. After driving 20 - 25 flawless miles, pulled up to a stop sign and it wouldn't idle. Had three more stops before I got home and it wouldn't idle at any of them. About ready to get rid of this headache.

Forgot to say what I had done, bought 20' of 5.32 hose and 18" of 1/2" and changed all the vacuum hoses.

clean the egr valve and replace the PCV valve - those will stick and choke the motor out.

Will try that this evening. Getting lots of advice from coworkers as well. Most say to run a can or two of Seafoam through it. One says he thinks it sounds like the idle air control valve.

88 carbed trucks don't have an Idle air control valve.

Update ... on my second tank of 93 octane with Seafoam mixed in. Seems to take longer to get to the point of not idling, but it's still doing the same thing. About ready to sell this POS.

EGR and PCV on the menu for this weekend

Maybe try purging the carb. Carb cleaner will remove fuel gum and some garbage from the throats but if you have a clogged jet it won't help much. Take the air filter off, start the engine and cup your hands over the throats of the carb. Do it enough to starve the engine of air but not enough to stall it. You may need to do this a few times. Be aware that if the carb hasn't been overhauled in over 10 years, it is due. Fouled air bleeders, clogged jets and leaking seals will make it near unbearable to drive. Also check that the fuel cut solenoid is working. With the ignition on but not running, unplug the black wire with the white stripe hooked up to the carb and listen for the solenoid kicking on and off as you reconnect it. Could have either a dirty connection or the windings in it are breaking. Had one with an intermittent fault - it would kill the engine at the worst times (like crossing an intersection or taking off at the lights...) Might not be the reason why you're not getting idle but at least you can cross it off as a potential problem.