Re: OT, 93 F-350 Diesel problem

Posted by Bob on December 02, 2004 at 11:49:42 from (66.163.134.177):

In Reply to: OT, 93 F-350 Diesel problem posted by ChadS on December 02, 2004 at 11:22:16:

1.) The mechanical "advance" lever on the side of the pump is actually a "retard". When you put the pedal to the metal, and the pump goes into full fuel delivery, the start of injection is earlier (advanced) because the pump plungers are pushed out farther by the greater charge of fuel, so they contact the cam ring sooner, causing earlier injection timing. THE MORE THE LEVER PUSHES THE PIN "IN", THE MORE THE INJECTION TIMING IS RETARDED. This works AGAINST the speed advance, which uses the increase in fuel pressure as the engine speeds up to ADVANCE injection timing.

On the Ford and GM light diesels, the Roosa pump was fitted with this "retard" mechanism to prevent blowing the engine apart due to the start of injection being to early at high throttle positions, when the speed advance has the cam ring advanced, and the plungers go to full stroke also, effectively giving even more advance.

You say the little pin that extends out through a seal, and contacts the external lever was sticking. Was this "on the bench", or on a running engine? if it was "on the bench", it's somewhat normal. When on a running engine, the internal pump pressure assists the little internal spring in pushing the pin out against the lever.

2.) As far as the "start and die" problem. you are getting air in the fuel system.

These Fords leak at the plastic injector "tees" (there's 2 "O" rings under each fitting. Any leak in the fuel suction lines, or lift pump, or at the filter base, or anywhere in the return system will allow air to enter the system when it sits overnight, or whatever. Since you are getting fuel in the oil, you may have a leak at the pump shaft seal, or a bad mechanical lift pump. Even a bad injector can let air in the system.

I doubt your pump advance at starting or idle is too early, unless you've noticed a LOT of diesel rattle at idle. Usually if the pump is even a couple of degrees early, the increase in rattle is VERY noticeable.

With the engine running and warmed up (at idle), carefully use a screwdriver to push on the "retard" lever, to push the little pin inward. Diesel rattle should get less, and as you continue to push the pin inward, the engine will began to smoke because the timing is too late. This will verify that the mechanism is working.

Find the source of your fuel leak into the engine, and fix any places where fuel seeps out of fitting (which also cause air leaks with the engine "off", and you'll most likely fix MOST of your problems with one repair.

Follow Ups:

• Re: OT, 93 F-350 Diesel problem ChadS 15:09:05 12/02/04 (3)
  • Re: OT, 93 F-350 Diesel problem Bob 15:25:57 12/02/04 (2)
    • Re: OT, 93 F-350 Diesel problem ChadS 17:44:23 12/02/04 (1)
      • Re: OT, 93 F-350 Diesel problem ChadS 20:14:49 12/02/04 (0)

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