Same ol stuff...merc 120 bog no power

[retodd]

In my searches, I am back here to see if anyone has new ideas for this nagging problem. 1986 merc 120 on a Glasstream Tempest 152... This boat should fly!!! But still bogs and coughs... I am now wondering if I have a exhaust flapper jammed up somewhere in the exhaust path. Also I have developed a bit of oil around the carb. Looks to be coming from the line that comes up to the flame arrestor from the fuel pump. Could this be a failing fuel pump? Compression test and leakdown test were all good according to my mechanic.

 

[jeep8589]

Re: Same ol stuff...merc 120 bog no power

Have you tried cleaning the spark arrestor. They can get clogged with oil and limit air flow.

 

[crazyray]

Re: Same ol stuff...merc 120 bog no power

for your 120 to not bog out of hole needs to have proper spark both good points and condenser and properly timed....I had one that had worn bushing in distribor that caused a weak spark. Secondly you need an proper fuel mix if no accel pump then its major cause. with the aid of an helper hold choke plate open and watch in throat of carb as help advances throttle. should see an steady stream out of pump squirter.get back let us know which way these tests lead you. the oil in hose going to carb is caused by pump going bad

 

[retodd]

Re: Same ol stuff...merc 120 bog no power

Clean spark arrestor, freshly rebuilt carb with updated acc. pump New tuneup with plugs points condenser and cap...Runs great on muffs but in the water runs like a pig. I know my girlfriend aint that fat?!?

 

[I/O WALDO]

Re: Same ol stuff...merc 120 bog no power

fuel supply problem?(?line that comes up from the flame arrestor to the fuel pump?)

 

[retodd]

Re: Same ol stuff...merc 120 bog no power

could be, i have just been too leary to cut the hard line to hook a pressure tester to the pump. Although now that there is oil coming out of that tube, I will put money on the pump being shot...Also, just so I know, where on this drive is the exhaust flapper located?

 

[retodd]

Re: Same ol stuff...merc 120 bog no power

btt

 

[searay3]

Re: Same ol stuff...merc 120 bog no power

There is a clear line that goes from the pump to the carb in addition to the hard line. If there is oil making it to the flame arrestor, that is a crankcase vent and will be oily. If the diaphragm in the pump broke or tore, there will be fuel in the clear line. replace pump with a marine or get a rebuild kit. I have seen other posts where folks have located a kit. Have you run the boat with a small remote tank to eliminate fuel issues from the tank to the pump?

 

[searay3]

Re: Same ol stuff...merc 120 bog no power

Flapper is in the big exhaust pipe running down the back of the engine and makes it's way out the transom. If flapper is broke, you have to remove the drive to see and pull out the pieces.

 

[retodd]

Re: Same ol stuff...merc 120 bog no power

No I have not but I can do it