Jiffy Model 30 Runs Bad

[IT Guy]

I have a Jiffy Model 30 about 10 years old. I was up on Upper Red yesterday punching holes and it ran really bad. I would start drilling and after 10 seconds it would bog down and die. One pull of the cord would restart it and the process would continue. After 3 holes I figured out that as soon as it started to bog down, if I hit the primer, it would keep running and cutting. Any ideas on what is causing this and how to fix it? Thanks!

[PierBridge]

Bad diaphram........

[IT Guy]

Can that be cleaned or is it a replace only item?

[kslipsinker]

Try replacing the plug before you go tearing into the carb.

[john.wells]

probably not the spark plug, but a new one won't hurt. The fact that when you prime it and it runs is a spot on indicator that the fuel isn't being pumped and 95% of the time it means a stiff/warped/cracked diaphragm, which pumps the fuel. There could be a loose or cracked vacuum line from the crankcase to the carb, or a loose or cracked carb, a leaking base gasket, or a couple other more obscure things, but history has proved that the diaphragm is usually the culprit.

[crappie todd]

True what John says as I have once upon a time owned model 30s. your problem is typical of them. But the plugs on them seem to take punishment as well. The best bet is to follow Johns advice and just a bit of mine.... add a new spark plug to help. And always carry a spare for a model 30.

[LMITOUT]

Mine was running somewhat similar this winter. I'd get to the bottom of the hole and it'd grab everytime as it didn't have enough oomph to bust through. Seemed like I had to pump the primer at least once on my way through the hole and it never "shifted" into the next gear like a 2-stroke should. Opened up the high-idle screw a tad and it runs like a cadillac again. It wasn't getting fuel on the top end and would bog down when under load. Now it'll zip up and go! Doing that might have been compensation for the diaphram and probably wouldn't hurt for the carb to be gone through at this age (about 7 yrs old).

[marine_man]

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Can that be cleaned or is it a replace only item?

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It's a replace only type of deal, but it's pretty cheap (less than 10 bucks) and easy to replace.

marine_man

[IT Guy]

I have tried the screw adjustment and it made of bit of difference. I kind of figured it was a fuel delivery problem since the primer trick worked. It's just hard to drill a hole with one hand and feather the primer with the other... The comment above about not "shifting" into high gear also happens. The thing is just to heavy to lug around if it's not going to work right. Thanks for the advice!!!

[PierBridge]

Diaphrams are available at any small engine shop for like 5 bucks.

[Gadgetman]

Had the exact same problem a couple weeks ago, dying under load, not shifting in to the higher range, drill a hole or two and quit. Brought it in and had a carb kit installed and it runs like a top now. May have been the diaphram, may have been the plug, may have been gummed carb, may have been badly adjusted hi or lo idle screw. Thing is after 10 years of trouble free service I figured it was time to spend some $ for a little tune up. $50 lateer I should be set for another 10 years.... Oh ya, they replaced the old fuel lines too.

[IT Guy]

I replaced the diaphram this weekend and she runs like a top. Thanks for all the advice.

[PierBridge]

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I replaced the diaphram this weekend and she runs like a top. Thanks for all the advice.

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Nice job....