Engine Quitting Intermittantly

[ozzyrral]

First off, hello from SE Kansas and thanks for the forum. I've had my B7800 for about 5 years now, it has close to 400 trouble free hours on it. I use it mainly for brush hogging.

So recently, while cutting brush, the engine will briefly die, for like a second, then start right back to running normal. This has happened several times now. It's like it's suddenly briefly starved for fuel or like the key is turned off, but the momentum of the brush hog keeps it turning long enough for it to start back up after a second or two. None of the dash lights come on when the symptoms are occurring.

Any ideas?

 

[Stubbyie]

Description sounds like what I sometimes experience.

Note any noises like clicks that might be associated with the event.

My first guess, based on the information presented, is the fuel cutoff solenoid is momentarily closing. Could be due to imminent failure, bad electrical connection(s), or a safety swich somewhere in the circuit momentarily tripping.

Confirm too clean fuel sediment bowl and clean filter and free flow of fuel from tank into sediment bowl.

Could be as simple as hitting a bump or stump and the operator momentarily becoming light in the seat. Seems like seat safety switches come in three varieties: never work, work correctly, or highly sensitive to movement.

Short spouse had the habit of standing to see over the steering wheel; doing so tripped the safety and the engine would click and die. She'd quickly sit back down and the machine would re-fire and keep going. If I was within hearing distance I could hear her progressing across a pasture: run run run stop run run run stop run run run stop. Got her a cushion for the seat and problem solved.

Please post back your ultimate diagnosis and resolution along with continuing experiences so we may all learn.

 

[North Idaho Wolfman]

Second Stubbyie's take on it.
Seat switch is probably the #1 cause, next would be wiring to the stop solenoid, bad relay, bad solenoid.
Simple test light attached to the fuel solenoid will tell you if that is what's stalling it.

 

[ozzyrral]

Thanks for the feedback. At first I thought it was the seat switch as it seemed to happen when I was backing up or changing direction. However, this morning I started it up just to move it and it happened several times as it idled. Haven't had a chance to follow up on your suggestions. Guess I might have to break down and buy a service manual.

 

[D2Cat]

Had similar results on a Grasshopper zero turn. Removed switch under the seat and jumped the two wires together. After a few hours of no more momentary dying I purchased a new switch.

Always hope for an easy solution. Oh, welcome aboard.

 

[ozzyrral]

So an update, the problem got progressively worse until today I was going to move it into my shop to work on it. It finally died while idling.

Now when I turn the key on or off I can hear the fuel shutoff solenoid clicking but the starter motor does nothing. It's an HST model and I made sure the HST pedal was in the neutral position. Tried a jumper on both the seat switches with no help.

Checked the battery, it's good, and besides, it started right up first thing this morning. Both the oil and alternator idiot lights came on after it quit running and they're nice and bright when the key is turned on. The glow plug light comes on like normal when trying to start, just nothing from the starter.

Is there another safety switch that will keep the starter from turning over? I've got the clutch pedal depressed while trying to start it like normal. Any other ideas will be appreciated.

Larry

 

[WadeCat]

I had the same problem and it was the pto safety switch. Replaced it and everything was fine.

 

[ozzyrral]

I had the same problem and it was the pto safety switch. Replaced it and everything was fine.

Thanks, Is that one of the switches under the seat? I think I eliminated those by temporarily replacing them with a jumper wire.

 

[Kanook]

Try 'jiggling' your PTO engagement lever.

 

[CaveCreekRay]

Been there. Done that.

One day moving some stuff around my barn with the loader and after shutting down for a few minutes, the machine is mort. D.O.A. No starty. Not even a crank. Nadda. Huh?

After running through the basics and peeking under the hood, I got back in the seat and looked around. Somehow, when getting out of the seat, I just tapped the PTO lever enough to knock out of OFF. I reset the thing and she fired right up. I bet if I had set my parking brake, it would have started and then died the minute I tried to move the HST pedal.

I was slightly pissed but, I FELT SO SAFE!!!!

 

[ozzyrral]

This morning I cleaned a bunch of grass and brush form under the seat around the PTO linkage and got it started but it immediately started to cut out like before. I put jumpers on both the seat safety switches and went out and mode for an hour with no issues. Tomorrow I'll remove one jumper at a time to determine which switch his the problem.

Thanks everyone for your input.

 

[WadeCat]

The switch is left of the seat back side of the lever itself. I have had luck with contact cleaner spray and also canned air.

 

[Buck8one2]

I had this exact same problem, it turned out to be fuel starvation. I replaced the fuel filter and cleaned out the bowel.....no more problem!