[bittard]

Hi, I have a question about a merc carb that I rebuilt with a kit I got from you. The engine is running rich, excessive exhaust at idle and the engine surges in the mid-range RPM. Mid to top RPM it runs smooth. Under warm idle, I can see fuel dripping from the Venturi’s. More info. After the rebuild, I completely drained my fuel tank of ETOH-fuel and replaced the fuel-H20 filter before testing and using the carb post rebuild. Only using non ETOH fuel. Any ideas why the dripping at idle and surging in the mid range RPM. Thanks.

[RogerRabbit]

Yes, take a look at the trouble shooting page here, 4th section down https://www.carburetor-parts.com/Mercarb-Marine-Troubleshooting_ep_482.html Thanks

[Beelzebuddy]

Hi, i recently rebuilt a 2 barrel Mercarb with your kit. I changed the fuel filter and after the rebuild the motor purred like a kitten on muffs. I put the boat on the lake for the first time (probably 1 month later) and the carb appeared to be flooding. Took a while but I got it started and initially it ran and sounded good under load. As soon as the motor got up to temperature it choked out. In order to start it again throttle had to be to full. Bring it back to neutral it would choke out again. Any ideas what is going on? Thanks for your help. Matt more

[Cheater]

Re: Tohatsu MFS15C carb rebuild to 20HP [links]

[DevoJinx]

Yes, the motor ran smoother with less vibrations, a bit silenter and of course had a bit more "oomphh". An interesting side effect was that my Hardline tach/hour meter started to work properly and was able to show proper idle AND max rpm at the same setting?! (see this thread: http://forums.iboats.com/honda-tohatsu-nissan-outboards/rpms-hardline-tach-hour-tohatsu-mfs15c-yes-another-rpm-prop-question-kind-607923.html (actally I got another one since they thought mine was defective, which I also thought.. so now I got two of them?

[fleming.fletcheer]

By the way, how much is the needed carb (20hp one) in the US?

[MacRohard]

So I got a Tohatsu MFS15C and after studying the parts list, the only difference I can find between the 15 and 20 hp is swapping the following parts in the carb:

[puddinpop]

"main jet" to 3BJ-04421-0
"plug" to 3V2-03169-0
"slow jet" to 3BJ-04552-0
"main nozzle" to 3BJ-03141-0

[Barnabe]

Volvo Marine distributes Tohatsu in your area so they would be the one to contact. here

[DjeZAeL]

Briggs Engine 127802-0640-01 95091859
Carb has primer bulb
Toro Push Mower

[sherrymade356]

first guess: would have been float, needle and seat issue.
(but you changed carbs and still have same issue.) here

[firstgrip]

I replaced the flywheel key and retested. Fine mist of gas still came out of carb. more

[argos]

When key is turned off the spark should not get to the plugs so should not keep running, that is one of your problems you need to look into

[Timothy]

Looking for advice please. I have a Yamaha 85 aet pre mix power trim motor. I have found it has become very heavy on fuel. There is quite a bit of fuel mix ( the fuel that runs out is quite substantially oily) running out from the front of the carbs if I tilt the motor say when we get to a shallow area and switch off. The motor also runs on after switching off the ignition for around 5 to 10 seconds.
I am mixing oil fuel 50:1. shell nautilus

[bittersweet]

not sure what kind of boat you are running, but running at 2500 you probably get less than 2 MPG, and 4000 maybe around 4MPG but depends on the load you are pushing and how it is propped
Look at this site to see if you can find something close to what you have and see what kind of performance they got at different RPMs. 90HP will be close to your 85 is my guess
Performance Bulletins | Yamaha Outboards

[arturekert02]

Looking for advice please. I have a Yamaha 85 aet pre mix power trim motor. I have found it has become very heavy on fuel. There is quite a bit of fuel mix ( the fuel that runs out is quite substantially oily) running out from the front of the carbs if I tilt the motor say when we get to a shallow area and switch off. The motor also runs on after switching off the ignition for around 5 to 10 seconds.
I am mixing oil fuel 50:1. shell nautilus here

[brigitte2378sack]

For example we ran around 5km or so on the weekend . Some at 4000 rpm and some around 2500rpm from spot to spot fishing. We used around 10 to 12 litres of fuel.

[privacyshark]

For example we ran around 5km or so on the weekend . Some at 4000 rpm and some around 2500rpm from spot to spot fishing. We used around 10 to 12 litres of fuel. [links]