So, now that summer's here the engine starts right up but it seems it doesn't like to stop anymore.

I don't even need to drive very far (not over-heating) for the engine to diesel for a good 15-30 seconds. It used to be that the truck would sort of die-down after i cut the ignition, but now it chugs along happily for an embarrassingly long time. What happened?

EDIT: just did some research online, and found it might be running lean thereby causing the cylinder to become overly hot. YIKES. Could this also be the reason behind the occasional puffs of black exhaust being blown out the pipe?

EDIT: seems black smoke means I'm running rich. Waahhh?

 

Sounds a lot like ignition problem to me. I'd start with ignition plugs and may be wires. When they were replaced?

Yes, black smoke means you have it running reach, but it may be not the cause, but the result.

 

One of the first things I did after buying the truck this Winter was to replace the plugs and wires. So they're reaching the 6 month old mark just about now. I figger I've only put about 5-600 miles on the truck since purchase the swap so they're pretty new.

 

Okay Oxi, the problem is you need to decoke the engine, the valves, and the head and tops of the pistons are badly coked with burnt and unburnt fuel deposits. When the engine starts these deposits get hot and glow, acting as your spark, that's why the motor "runs on"

A quick and temporary fix, which will partially prove my point is to get the engine running on fast tickover, get some upper cylinder lubricant and gently trickle that into the carb intake not too quickly or it will stall, just run her gently like that for 5-10 minutes, just before you turn it off make sure you give it a heavy dose. Let it soak overnight, add some Upper cylinder lubricant to your gas as per manufacturers instructions, take her for a long run, open her well up through the gears and get up to max speedand that will partially cure it. Also it sounds as if you need to tune the carburetter, there should be a mixture screw on the side, fast tickover again, turn screw in until she starts to "hunt", out half a turn or until she runs sweet again, all should be well!

Good luck, and keep us posted. Billabong

 

I was takinga look for the mixture screw and found some curious looking hoses coming out of the vacuum bus. One of them is plugged with a bolt and another one is wide open. When the engine is running and i cover the wide open one with my finger is produces some pretty good suction on it and the engine idles smoother. BUT when I take my finger away it releases a whisp of smoke.

Why were these mods done?

 

you have a serious vacuum leak. it needs to be plugged. that should help your truck run at least a little better.

 

Hi Oxi,

THe Vacuum line powers the brakes, sometimes the heater/AC controls and Cruise Control, Blank that outlet off or find where it has becaome detached from!!! I t will run a lot sweeter then. Happy motoring Billabong!!

 

Yup,
I put a 1/4" dia bolt in there and the deiseling is much better, although it still does it after a real long drive.

 

Good job, if no other intake leaks are causing the higher idle, turn it down a touch to eliminate the dieseling.

 

Sorry, I didn't realize you could hear it from there.

Wait, did you mean turn it down on the idle screw?