yamaha mechanic

[fshlbi]

i am new to boating in delaware (lewes, rehoboth, indian river area) and have an older yamaha. i have had some trouble with it lately and am looking for a good yamaha mechanic to look at it and tell me whether it is worth working on or am better off repowering. engine ran strong for a season, then the oil pump starting overfilling the remote tank and dumping oil all through the carburetor cover. that seems to be fixed now, but the biggest issue seems to be that it is just plain running like crap. sounds awful. misses, and it just sounds like the carberation is all fouled up.

i am hoping there is not a problem with a cylinder. all cylinders were okay with compression meter, but the bottom port one is a little weak. 120/119 on five. but 110 on that weak one.

anyway, i have poured enough money trying the diy method, and i am just looking for a good mechanic to take it to who will give me honest opinion as to whether i am chasing bad money with good.

 

[jbrinch88]

i am new to boating in delaware (lewes, rehoboth, indian river area) and have an older yamaha. i have had some trouble with it lately and am looking for a good yamaha mechanic to look at it and tell me whether it is worth working on or am better off repowering. engine ran strong for a season, then the oil pump starting overfilling the remote tank and dumping oil all through the carburetor cover. that seems to be fixed now, but the biggest issue seems to be that it is just plain running like crap. sounds awful. misses, and it just sounds like the carberation is all fouled up.

i am hoping there is not a problem with a cylinder. all cylinders were okay with compression meter, but the bottom port one is a little weak. 120/119 on five. but 110 on that weak one.

anyway, i have poured enough money trying the diy method, and i am just looking for a good mechanic to take it to who will give me honest opinion as to whether i am chasing bad money with good.

What did you do yourself? Carb engines are fairly easy to fix, I wouldn't give up just yet. That little difference in the one cylinder will not make it noticably "run like crap".

Make sure your fuel is clean (no water in the tank, no water in the seperator). Make sure each cylinder is firing. Run the engine (not in gear) at 1500-2000 rpm. Pull off each plug wire one by one with plug wire pliers. You should hear a big difference when you cut out one cylinder at a time. If you don't hear any difference on a certain cylinder, could be a bad pack, coil, wire, plug etc.

If that seems ok pull off the carb cover. Run the engine at 1500-2000 and stuff a rag into each carb one at a time or cover with your palm (essentially acting like a choke). If the engine starts running better than you describe you know you have a carb/fuel problem. You could also fill a spray bottle with gasoline, and mist it into each carb seperately and try and hear a difference. Either method works.

These are quick/basic tests to see if its electrical or fuel.

 

[fshlbi]

To fix the oil oveflowing, i have replaced the sending unit sensors/float switches in both the engine oil and remote tank. The engine oil did not overflow last time started. However, it is coughing and running extremely rough. the port side bank of three cylinders was running hot, but when thermostat removed ran cool again. so i guess i need to replace that (again). i backed it into boat ramp and it ran it which it ran okay at mid throttle. putting throttle back is essentially same as turning key off. it just dies right away. is sounds like it is fuel or oil mixture. it does have a fuel water separator so i will check that next time down. my father tried to adjust the mixture screws on the carbs (he knows much more than I do about this engine, though I am quickly becoming familiar with just about every part). it did not seem to run better or worse as the mixture screws were adjusted.

the plugs seemed to be workable condition. i was worried they were fouled, but we pulled them and looked at them. I sprayed combustion cleaner in the carbs thinking there might be carbon build up.

 

[jbrinch88]

To fix the oil oveflowing, i have replaced the sending unit sensors/float switches in both the engine oil and remote tank. The engine oil did not overflow last time started. However, it is coughing and running extremely rough. the port side bank of three cylinders was running hot, but when thermostat removed ran cool again. so i guess i need to replace that (again). i backed it into boat ramp and it ran it which it ran okay at mid throttle. putting throttle back is essentially same as turning key off. it just dies right away. is sounds like it is fuel or oil mixture. it does have a fuel water separator so i will check that next time down. my father tried to adjust the mixture screws on the carbs (he knows much more than I do about this engine, though I am quickly becoming familiar with just about every part). it did not seem to run better or worse as the mixture screws were adjusted.

the plugs seemed to be workable condition. i was worried they were fouled, but we pulled them and looked at them. I sprayed combustion cleaner in the carbs thinking there might be carbon build up.

Leave the screws alone, most likely not the issue. Sounds to be like you are either running rich or lean. Have you ever had the carbs done? Carb cleaner is a joke and does nothing, you have to pull the carbs and completely take them apart for them to work properly.

I'm thinking one of the low speed jets is gunked up (stalling at idle but not at high rpm). If you can get the motor to stay running at idle, you can confirm this by doing what i mentioned in my previous post and manually choking each carb seperately. That or if you have a push-in choke keyswitch, keep the key pushed in with the engine running and see if it will stay running or run better while doing so.

I would say it could be the float in one of the carbs, but if you are running ok at higher rpms and getting full rpms most likely not the issue. Unless at idle one is stuck open, causing you to run rich in one of the carbs and flooding the engine OR the opposite and stay shut, not allowing fuel and causing you to run too lean.

It usually never works, but try tapping on the bottom of each carb where the float is located (where the fuel lines are). You may get lucky and free it up. Best bet is to have them cleaned/rebuilt though IF you can narrow it down to a fuel issue. You can try draining each carb as well. Could be as simple as that.

 

[fshlbi]

is there a way to drain the carbs without taking them off?

 

[jbrinch88]

is there a way to drain the carbs without taking them off?

yes, theres usually a brass drain plug for a slotted screwdriver on the bottom of the float bowl. Would be located on the bottom most part of the Carb (if you're unfamiliar).

 

[Finatic]

I'm out of Ocean City, MD and I've had Shorts Marine in Millsboro, DE work on my Yamahas for the past several years. They have a mobile mechanic, Greg, who is great. He has been able to diagnose things quickly and get any issue addressed fast. Good luck.