mid 80s 20 hp merc -wont throttle up

[jumpin johnny]

just picked up this unit at a g-sale,

it started right up and idles like a champ. thought i made a good deal for 100
bucks. But when i put it to test on the boat it dies when i throttle up.

i put the unit in a bucket to check it out and noticed a slight pop when idling
down (from the exhaust) and noticed a little tiny puff of smoke were the lower end bolts to the powerhead (?) I tightened the nuts but it did not make a diff.

any ideas ?

 

[Laddies]

Re: mid 80s 20 hp merc -wont throttle up

It sounds like the high speed is plugged you need to clean the carb.

 

[Yepblaze]

Re: mid 80s 20 hp merc -wont throttle up

If it were me, I'd have already been through the fuel pump, and carb.

 

[jumpin johnny]

Re: mid 80s 20 hp merc -wont throttle up

thanks for that, the carb is clean and i will fire it up weds am

 

[jumpin johnny]

Re: mid 80s 20 hp merc -wont throttle up

the engine fired up, ran good high and low, then it backfired while idling down (exhaust)

now it wont idle or throtle up? any ideas?

 

[CharlieB]

Re: mid 80s 20 hp merc -wont throttle up

Check the flywheel key. Sheared, would allow the flywheel to shift on the crank, timing would be off, run ok until it shifts too far then backfire and quit.