Rubber in the fuel bowl.

Thu Aug 11, 2011 9:25 pm

I've been fighting a pesky contamination problem with my main mower (680 hydro) this year, and finally have it resolved.
(I thought I had it a couple of weeks go but it bit me again) The mower would run approx an hour, then start bogging down and lean out. (hot too) Wouldn't help much to choke or adjust the high end needle either. I got pretty proficient removing the carb after finding rubber in the bowl after about the 5th time. I decided that was enough, pulled the tank, cleaned it, replaced the fuel lines and inline filter. Guess what, happened again. Same thing, so I installed a second tiny inline filter between the fuel pump and carb. (not much room to play with) I thought maybe the pump diaphragm was separating. I thought it couldn't possibly happen now....wrong. More rubber! I had residual rubber in the inlet fitting above the float needle valve...Guess what! Don't anymore... And it hasn't quit on me the last two times I've mowed.
I can definitely tell when she's not right..the 680 has a K301 (12hp) and I have a 50" deck underneath. The term "maxxed out" is the phrase that best describes her. I even broke down and gave her a bath after all this...hehe
For what it's worth...


Re: Rubber in the fuel bowl.

Sat Aug 13, 2011 8:38 pm

You never told us what it was. My bet , it was non-alcohol resistant fuel line.

Re: Rubber in the fuel bowl.

Mon Aug 15, 2011 6:40 am

It had to be the fuel lines. Seems funny that these are not the original's and weren't that old. (I bought it from a neighbor's insurance company following a fire, and the tank, pump and carb were melted. 25hrs on the meter)
Here's today's lesson: If you lose the gas cap, do not stick a rag in it and park beside the gas water heater.

Re: Rubber in the fuel bowl.

Mon Aug 15, 2011 11:02 am

I did an insurance claim one time when the home owner pulled his lawnmower into the basement garage and was filling it up when he spilled some gas. Yep, you guessed it, gas hot water heater in the corner. Fumes hit the water heater and it caused major damage to the ceiling framing (1st floor joists). I think I wrote about a $100,000.00 estimate. Floor joists were brunt so bad they needed replacing and when a house is built the floor is build first and then everything else is built on the floor.

Re: Rubber in the fuel bowl.

Fri Apr 06, 2012 7:10 pm

After all this time, the contamination bit me again today. But, remembering all I've done to her previously, I went ahead and pulled the carb again. (pretty darn good at it now) The bowl was absolutely spotless. It starves for fuel, somehow. So, just for giggles, I unscrewed the elbow (inlet) again and found some sealer that had been used on the threads at some point. I hope that's the end of it...running nicely again.. While I had her apart, I changed the oil, sharpened the blades & greased the spindles on the deck. The grass discharged about 6' when I got into some heavy stuff so, that's about all you can expect...
Other than that...mowed the rest of the day without problems.. (& raked..aching back will testify) hehe
Gotta get this place in shape...DocFest approaching...

Re: Rubber in the fuel bowl.

Wed Apr 18, 2012 6:28 am

Say Subdurnal, you have earned some good running time with all that effort.

Re: Rubber in the fuel bowl.

Thu Apr 19, 2012 6:34 pm

........I thought maybe the pump diaphragm was separating..........

Unless someone added a fuel pump to the engine, I believe a 680 should have a gravity fuel system and not have a fuel pump. If so, the inline fuel filters you installed should be for a gravity flow system and not one for use with a fuel pump. If they are for use with a fuel pump, they WILL starve the carb/engine for fuel because they will not flow enough fuel when used on a gravity system.

Re: Rubber in the fuel bowl.

Thu Apr 19, 2012 7:57 pm

It's a quiet line series with a fuel pump. I got it with less than 25 hrs on it, so there's little chance It's been added.
(tractor was in a garage fire and got hot enough to melt the carb) I replaced all the plastic components, fuel tank, fuel pump, fuel lines, front tires, dash, wiring etc. (hour meter was damaged too, but due to the exorbitant cost with little function, I didn't replace it) I've been mowing with it for at least 20 years. Bored 20 over about 2 years ago due to oil consumption, & wear.
Really would like to replace the K301 with a twin of some sort due to vibration of the big single. (yes, I've replaced the drive shaft, pilot bearings, rag joints, and iso mounts many times) And, it's overtaxed with the current deck.
It's on it's 3rd deck, BTW.