saga of a lawn mower repair 7 years diaphragm

[rcrcomputing]

Lord what a learning experiance. I've got a 7 year old 5hp murry riding lawn mower that only has about 10 hours on it. Sat around for quite awhile. I got it to run. It wouldn't run fast and the throttle seemed to make little differance. I replaced the choke as it was frozen. After all this, I got new tires and put them on. Greased it, changed the oil etc..

I get on it for the test run. It starts, I push the pedal, it doesn't move!
I think to myself, "what changed". I changed the tires... So, I take the back tire off. And low and behold there is a groove on the shaft that something must fit in... Hmm, wonder where that part is.. Finally find it. Here I go now...

Anyhow, now I'm ready for the big time. I start it up to go for a test drive. I went about 40 feet, it dies and never starts again. I can poor gas in the carb and it runs. The fuel line is clear. The fuel filter is clear and gas runs cleanly thru the line. So, I take the front thing off the engine that looks like where a diaphragm would go and of course the spring and a thing that fits on it falls to the ground.

Soooo, my questions are now.
Which way does the little spring "cap" go. Towards the engine or not?
Secondly, ya think I'm on the right path with the diaphragm?

Symptoms are, when it ran, it smoked a tiny bit.
It ran a bit rough.
It wouldn't throttle up as high as I thought it should.
It died when testing and now won't start without pooring gas in the carb.

Side note: Buying a tractor made me think I was now a handy-man. Which I clearly am NOT... /forums/images/graemlins/smile.gif

 

[ronnie2005]

Your on the right track, the spring cap does go toward the engine.

If it will run with gas pored threw the carb there's not too much wrong with it. Pull the carb and clean all the ports. Carb cleaner in a spray can followed by compressed air should do the trick. Adjust the idle mixture to 1 turn open. That should be enough to start and run, and then adjust . You may also have a carb model that has an adjustable high side, if so, adjust that first with the throttle wide open. Adjust for the highest rpm and then screw in 1/8 turn. Then adjust the idle mixture screw for the highest idle and after doing all this advance the throttle and mack sure it doesn't bog down. If it does, adjust the high side 1/16 turn at a time until you can advance the trrottle with no hesitation.

Hope this all helps.

Ron

 

[rcrcomputing]

Well,, I finally got the pump kit that includes the diaphragm. I put it on. No differance. /forums/images/graemlins/frown.gif

So,, maybe some help on the dynamics would help me. It looks like gas comes thru this little pump, but I see no where that it actually enters the carburator. What's up with that? Does it just go back down the other black hose straight to the motor?

 

[rcrcomputing]

Yahoooooo, I seem to have made some headway! I can now start it and run it, even at high speeds, but only if the choke is like 80% closed. In other words, I seem to be getting to much air. The little screw with a spring on it seems to make no differance. I've tried screwing all the way in and 2 or 3 turns out to no avail.. Soooo, why am I getting to much air?

Shoo am glad you guys are here... I'm now a bonifide lawn mower mechanic.

 

[Kyle_in_Tex]

Your carb has some really tiny holes in it that get plugged with old gas. Take it apart, Put on some safety glasses, remove the adjustment screws and clean with carb cleaner in a can. Use the small straw supplied to get the tiny holes unplugged. Sometimes, you need a very small wire (like one off of a brass bristle brush) to poke thru and clean the holes.

When spraying carb claener thru the small straw, IT WILL TRY TO GET IN YOUR EYES, so be smart and wear some safety glasses.

 

[TractorLegend]

Your not getting too much air---just too little fuel.