My Mav started to run rough a few days ago. It feels like it wants to die when it is at a stop. I checked all the plugs, plug wires, cap rotor, and vac lines, and all look good, I also replaced the fuel filter, and added some gas treatment in case I had some bad gas, and drove it a few miles. No change. Anyone have any ideas? It is a 76 w/250. Thanks
could be the carb gasket. when its running in park spray some WD40 or the like around the base of the carb, not in it. it the rps change its because the wd40 is being sucked in under the carb aka bad gasket seal/vac leak. tighten down on the carb bolts and see if it improves good luck
I checked the carb gasket as described, and it seems to be good. I also noticed that I had some black smoke out the exhaust. Don't know what that means.
It's loading up. Edit: Black smoke is a sign of excessive fuel. More than the engine needs, running rich. Just thought I would clarify the term 'loading up'. There is something wrong in the carb. Your spark plugs are probably caked with soot and it is starting to miss at low rpm. Check your float level, clean your plugs, make sure your needle and seat don't have any junk in them holding them open. I don't know if that carb has a powervalve that can rupture... Make sure your choke isn't stuck, and check the air filter. For giggles, make sure your PCV and crank filter are good too.
try the wd40 test again, but spray it into the carb at idle. if it dies, too much fuel. check oil for gas smell also. be sure to change your oil after fixing the carb if that's the case.
as its running you might b able to giv it a few quick squirts into the carb to se it it helps any. sounds a little more complicated tho
On my Carter YFA the diaphram hardened up, could not be adjusted properly. $250 typical rebuild with installation and adjustment. Might just need to back off your fuel mix, but not likely. Play with it and see. If you can't get the mix right all the way thru the throttle range, rebuild it or have it rebuilt. Kits are cheap, and if the wife's not home, you can do it on the coffee table while you watch football.
I took the carb completely apart. There was a little bit of crud inside float bowl. The diaphram looked good, so I cleaned everything and put it all back together. Runs the same, but with more black smoke. Should I get a rebuild kit? The last time I tried to rebuild a carb was over 15 years ago, ended up having to take it to a mech. because I screwed up somewhere.
Hence my advice... if you're not confident, is it worth it to pay somebody? I can replace a transmission, but I wouldn't know where to begin when it comes to rebuilding them, know what I mean? Some things are best left to professionals, and spending the time and money on a rebuild kit, only to find out you didn't do it right, you'll kick yourself for spending the time and money. I usually punt. Heck, if I could get a water pump to not leak, or drywall tape to not bubble, or wire a panel box without killing myself, I'd be in another line of work.
I bought a rebuilt carb on ebay. Put it on, had to adjust the float, runs great. Thanks everyone for your help and advise.
