Dying on initial start of day. Fine thereafter. Slight chop in RPM. (Solved)

   / Dying on initial start of day. Fine thereafter. Slight chop in RPM. (Solved) #1  

hardhat

Silver Member
Joined
Jan 24, 2011
Messages
118
2011 F-series. Has had a rapid but small fluctuation in engine speed at certain rpm's and loads for years. Changed fuel filter and finally wrote it off to software like HP management. It did not affect operation. I could just hear it and see the tach bouncing 20-50 rpm. Gave up on this problem and figured it was just the way it was.
In last few months, machine would start up and then immediately die on first start of day with no codes and no warning lights. Might do it again on second try, but never took more than 3 starts and it would be good for rest of day. Some days would start and run fine. Did some research and fuel shutoff solenoid was suggested. Took solenoid off and stuck my finger in hole where the solenoid was and I could feel the lever in there but it was spongy. Looked with a snake light and everything looked ok. Messed with lever with my finger for a little bit and it freed up. Almost like it had grease or sludge on it that was making it stick and move slowly although I've had no fuel or oil problems.

Anyways, ohmed out old solenoid and it was fine. Replaced with new solenoid and now starts on first try and rpm is rock solid. I think that somehow this sticking fuel shutoff lever was starving the engine somewhat and maybe erratically making the rpm's surge.

So if anyone has dying after initial start and maybe a mild but rapid chop in the rpms, consider fuel shutoff solenoid. Very easy to replace and not very expensive. Kept the old solenoid as I think I may be fine and the whole problem might have been a partially stuck fuel shutoff lever.

That lever inside the hole has a weak spring. The fuel shutoff solenoid is extended when not energized and has a stronger spring than the fuel shutoff lever so it pushes on the shutoff lever when engine is off. When you start cranking engine, the solenoid energizes and retracts. This allows the spring on the fuel shutoff lever to push the lever in the other direction and lets fuel flow. I think my shutoff lever was sticking and not coming all the way out when the shutoff solenoid was energized (retracted).

Counterintuitive but fuel shutoff solenoid is in run position when energized and in kill position when denergized. So when you energize the fuel shutoff solenoid it allows the engine to run.
 
   / Dying on initial start of day. Fine thereafter. Slight chop in RPM. (Solved) #2  
Thanks for the great explanation on your problem and fix. It always feels good when an annoying problem gets fixed by your own hand. (y)
 
   / Dying on initial start of day. Fine thereafter. Slight chop in RPM. (Solved) #3  
Thanks for letting us know you solved the issue. These machines are complicated enough to try to diagnose a problem and with a small knowledge base that we have here it helps all of us.
 
 
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