18hp starts, runs 2-5 min, dies, restarts, over & over

[ILENGINE]

Jeff, I am talking about the plastic piece on the end of the solenoid plunger. It will come loose from the solenoid stem and shut off the fuel flow through the carb, effectively killing the engine. But turning off the key will reseat the cap on the plunger stem.

Remove the fuel solenoid from the bottom of the carb, and pull on the cap on the end of the plunger stem and see if it easily slips off.

 

[jeffnsusan123]

ILENGINE - did as you suggested. The plastic cap did come off, but I would not say easily. I had to pull a bit on it. I replaced the fuel lines and removed the fuel solenoid altogether (replaced it with a bolt) just as a test. I know I can't run it that way long-term as the carb & engine will just flood with gas. I also replaced the fuel lines.

Started and ran for 10 minutes with blades disengaged. Engaged the blades and it has run for 10 minutes - so we're into new territory here! I'm guessing it is a bad fuel solenoid and the problem with the plastic cap as you had mentioned. Either that or the plunger mechanism just isn't strong enough so after a while it gives out and the plunger moves back up. I'll pick one up and replace it. Correct me if I'm wrong, but I can't just remove the plastic cap and run that way, right? That would cause the same carb & engine flooding situation when it is off?

I'm going to go and try some actual mowing & will report back.

 

[Tinkerer200]

I think you left a number out of your model number - 31P777. Not all fuel solenoids have plastic caps on the end of the solenoid plunger, in fact the majority of those I encounter do not. I would remove the solenoid, depress the plunger, wedge a tooth pick beside it to hold the plunger retracted, break off the tooth pick and re-install the solenoid. This allows you to check the solenoid without damaging the solenoid and you can return it to normal. IF this clears things up, you may have a wiring problem OR solenoid problem.

NO difference, remove the air cleaner and dribble some gas in when it starts to show signs of stopping. Let us know.

Walt Conner

 

[jeffnsusan123]

You're correct 31P777. The '1' was very lightly stamped and nearly invisible. But under strong light, it was there.

Mowed for 60 minutes. Ran well. At one point, I turned it down to idle to answer a phone call. Engine started smoking & eventually sputtered & died. After sitting 15-20 minutes and with some coaxing with starting fluid and a few drips of gas into the carb, it fired up and mowed for another 30 minutes until it got too dark. There was some smoking again just before I turned it off. Smelled like burning belts, so I may have a coincidental unrelated problem also. Yard is 2/3 done at least. Tomorrow, I'll reinstall the solenoid and see if the problem comes back (if it doesn't, I'll know it was just the fuel lines after all).

 

[jeffnsusan123]

Reinstalled the fuel solenoid and restarted. Engine ran fine for 15 minutes and is still going strong, so it musta been either bad fuel lines or else the little plastic cap wasn't well-seated on the fuel solenoid and is now. I think I'll pick up a new one anyway - just in case.

I also looked into the smoking situation and traced it to an idler pulley on the mower deck. It barely turns and once the blades are engaged, starts complaining and smoking within 30 seconds. So....I can't even do my "under load" test. But I'm pretty sure the engine running situation is solved now. Will just need to replace that idler pulley (and probably the other one while I'm in there).

Thank you everyone for your time, assistance, and suggestions. Much appreciated!

Jeff

 

[jeffnsusan123]

Update - it ended up being the fuel solenoid after all. Good thing I got one "just in case". After replacing the idler pulleys, and found that the bearings in one of the mandrels were bad so replaced the mandrels also along with new blades & belt, I put it to a mowing test. Five minutes in, it died again. So replaced the fuel solenoid and now all is well. Little plastic cap was seated nicely in the old one, so it must have just been weakened over time or has a loose connection inside or who knows what.

Again - thanks everyone for the help and suggestions.

Jeff