Quote:
Originally Posted by jetfiremuck
Ive followed your detailed pump overhaul blog.
Regarding the relationship between the fuel limiter screw and idle speed at idle under load my issue is that i get a gray black haze at idle with ac on, ac off and the smoke lessens. The engine is in a conversion and idles around 900rpm in drive ac off. l When i snap the throttle in neutral there is no delay or engine rpm hangup coming back to idle. The crimp collar is still there so its setting is within 1/2 turn of the locknut.
Is this a fueling issue injector wise or does the fuel limiter screw needs backing out with the corresponding idle restored with the idle screw?
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First of all, your idle speed is a bit high. Spec is about 750 RPM, IIRC. As you seem to be aware, there are two ways to decrease the idle speed:
1. Turn the fuel limiter screw outward.
2. Adjust the idle screw on the inner side of the Injection Pump cover.
Sorry to rain on your parade, but neither of those two adjustments is likely to improve your smoky exhaust. That's because fuel is fuel, regardless of which adjustment is used to regulate that fuel.
It appears to me that you have either bad injectors or bad compression, and from your description, combined with my experience, I'm leaning toward bad compression. So, my recommendation is to check your compression before you try anything else.
Explanation: When you apply more load to the engine, two things happen:
1. The engine slows down.
2. The Injection Pump, via the governor mechanism, supplies more fuel in an attempt to maintain engine speed.
The effect of decreased engine speed, in an engine with compression issues, is for the compression to also decrease. That causes a decrease in combustion efficiency, which, combined with the increased fuel delivery, results in more smoke.
Tom