How much could I expect, rough estimate to have a carburator rebuilt for a 74 Mercury 20hp? Tried just cleaning it and it still runs high idle at times and starts missing. This has gone past my mechanical abilities (which is very minimal). Suggestions for a reasonable mechanic? I live in Hico but am willing to drive an hour/so if the price is right. The one I use for my Skeeter is $95/hour. Don't really want to spend alot of $ on this old motor if I can help it. Thanks

$35.00 Repair manuel

Sounds like you need to check the manual fuel pump. Double check all fuel line connections for leaks and make shure carb bowl vent is not plugged. Sounds like its leaning out. Check it good first because as you know its not cheap and a carb rebuild will run 120.00 at 50.00 per hour. Good Luck

I would start at the beginning. If everything is 35 years old I would start with a fuel tank/pick-up inspection and then move to the fuel line including any fuel line under the cowling. The mid 70's is when manufacturers began using ethanol resistant products. If the primer bulb/line is more than 5 years old or not oem, replace it. I have no reservation about using aftermarket parts but when it comes to the primer bulb, it is oem. Then replace all filters and rebuild the fuel pump. Check under the cowling for a small filter after the fule pump. SOme have them some don't.

Finally I would get a one gallon plastic fuel tank and 1 pint of SeaFoam. Dump the SeaFoam in the 1 gallon tank, add your pre-mix oil and top off the tank with enough gas to make 1 gallon. Warm up the engine to temp., shut it down, disconnect the fuel line from the tank and insert it in the 1 gallon tank. Restart, run at high idle for 20 minutes, let set for about ten, and then restart and repeat until it is gone. The motor will probably smoke like an assault vehicle storming the beach. What you're doing is getting rid of carbon in the cylinders but at the same time you're giving the carbs a good cleaning eliminating any varnish.

I don't recommend doing it on a garden hose because you may not have enough water.

That about covers everything to ensure your getting gas to the carbs. Taking it in and having a carb job done or doing it yourself won't improve performance if you're still have issues from the tank to the carb.

You're motor is old enough to gone through all our recent gas transitions from straight gas, to MTBE to ethanol and it is possible any original fuel lines are nothing but porous mush.