JD 48 B Carb Pulsing

CPeter

Some time back, an older gentleman posted a simple test on the YT Forum -- namely, that you could test your carb's passageways by manipulating the IDLE & LOAD needles. Here is how it goes: CAUTION: This test involves radical adjustment of both the LOAD & IDLE needles. Before starting the engine, observe the position of each needle lever, and count the number of turns OUT that each of the two needles is at so that you can put them back where they were before this test is run. (1) IDLE SYSTEM TEST: With the tractor running at least at half-full engine speed, turn the LOAD needle all the way in. The engine will continue to run if the IDLE SYSTEM is open, and if it stops running, -- the idle system IS NOT open! Assuming this test is a pass, reset the LOAD needle where is was and go on to test two below. (2) LOAD SYSTEM TEST: With the engine running at least at half-full engine speed, turn the IDLE needle all the way in. The engine will continue to run provided the LOAD FUEL system is open, however, in this mode, engine operation will be a throttling pattern. As engine speed drops, the governor will open the throttle to draw LOAD FUEL because the idle path is closed. This pattern, however, indicates the LOAD FUEL channel is open & working as it should. If the engine stops running, the LOAD FUEL channel is blocked.

If the LOAD SYSTEM TEST describes how you tractor is running, then it will probably fail the IDLE SYSTEM TEST.

Now -- if this all turns out to be the revealing truth, go to www.robertscarbrepair.com to make contact with Robert's Carb --could be that you will elect to order the 6-inch long drill bits that are needed to clear those idle passage ways of the rust that forms in cast iron carbs over the years -- or you may elect to let someone else repair your carb. No rocket science here -- just have to do some study and then some work. Let us know how the testing comes out & we can take it from there.