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Cummins 250 Fuel Pump, Died Hot, Crazy Fix

DampLemonade

Member
34
43
18
Location
Cannon AFB, New Mexico
A few months ago I replaced the injection pump on my 923. At first, everything was running great. Then, after about an hour of the engine running, it died. It would always run just fine if the engine was cold, or I had some time in between cranking the starter. Thus began a multi-month adventure of figuring out what was going on...

We finally figured out what happened today. I wanted to share just in case anyone else might come across this issue, and also just to share the relief. The shutoff solenoid that came included with the pump was apparently a 12v unit. It was getting cooked by the 24v supply and that's what was causing it to act up after 15-60 minutes. It would heat up from voltage. Back in the colder months when I first changed the pump, it wouldn't act up as often because it would be cooled by the colder winter/spring ambient air. But as it heated up for summer, it would die sooner and sooner after engine start. I bought the pump from Boyce Equipment, though they have their pumps rebuilt for them, so maybe someone at that rebuild place misplaced a 12v solenoid? The listing specifically stated the 939-series, so I assumed that it would work with the 24v of the 939. The folks I talked to at Boyce were super nice and shipped a new 24v solenoid for free. This wasn't to bash on them at all, they were very helpful. The guy on the phone even sounded surprised when I told him it was a 12v solenoid. It just seems like a crazy coincidental mistake. I'm not even sure what the lesson learned here is, I'm just happy to finally have this whole thing figured out.

Time for a Busch...
 
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