1985 Mercruiser 140 Bogging Issues

[Ithinkican]

Hi i am new to the forum so thanks ahead for any help..Heres what i have done then ill tell you the issue. New fuel pump and filters,new spark plugs,wires,cap,rotor,points,condensor,coil. The boat starts great and idles great but when i start accelerating it will not go past 2k rpm, if i try and give it more gas and it bogs down and starts slowing down but in neutral i can rev it up no problem, i have done the timming and it is spot on, i noticed when i take the flame arrestor off and start throttleing up a mist of gas starts comming out the carb... please help i replaced all i can think of any info is appreciated.

 

[thannah84]

Re: 1985 Mercruiser 140 Bogging Issues

Welcome to Iboats....Did you run this boat before making all these updates to the motor?

 

[P 0 P E Y E]

Re: 1985 Mercruiser 140 Bogging Issues

First off, revving an engine in neutral, with no load on it tells you nothing because it has no load to appose it.

Second, You replaced a bunch of parts, Were these parts replaced in an effort to fix a problem or are these parts causing a new problem?

If these parts did not fix the problem, then the problem is elsewhere in the engine.

Have you performed a compression test?

Is the firing order, distributor timing and condenser all to specs?

Do you have water on a spark plug, a milk shake?

Is the mechanical advance in the distributor advancing?

Are all cylinders fireing?

Is the carb dirty? how does the engine idle?

Lots of questions, sorry to hit you with them all at once

 

[Ithinkican]

Re: 1985 Mercruiser 140 Bogging Issues

Thank you for the quick reply. The original problem was it would bog a little while throttling up but after running for a while would just totaly be a dog until i let it cool..So this started the replacement of parts, mind you the problem has only got worse..The timming and condensor are to spec, spark plugs are clean, all cylinders fire, the boat idles great better then it ever has but when giving it throttle it is worse then it ever has been..as far as compression i have not check it with a tester. I took the distributer all the way apart and cleaner and greased it thinking the weights were sticking, still no change in performance.(I have msd blaster coil,ngk plugs,magstar wires,quicksilver cap rotor condensore and points.)

 

[thannah84]

Re: 1985 Mercruiser 140 Bogging Issues

I would do a compression check. Did you gap the plugs correctly? Set the dwell correctly?

 

[P 0 P E Y E]

Re: 1985 Mercruiser 140 Bogging Issues

Looks like you touched on all the ignition parts, now how about the carb?

You can get a kit from you local auto parts dealer if you take the number off the tag or mounting flange.

If you are confident that all the parts you replaced are right and adjusted to spec, I would check your carb for dirt and or water.

 

[dcastle01]

Re: 1985 Mercruiser 140 Bogging Issues

I am having the same problem, it seems to happen when the motor heats up to normal running temperature. If I hit the throttle from 800rpms it takes off no problem. If I gently ease it from 800-2500 then it bogs at 2500 if I back it below 2000 and gun it, it will take off quick. It idles fine though. Also sometimes will bog from neutral to reverse while coming into the dock. Look Ma NO BRAKES...HELP!

 

[Ithinkican]

Re: 1985 Mercruiser 140 Bogging Issues

just an update...i recently rebuilt the carb and it was definatly in need of it...but no change to my issue..so i pulled the head off and the head gasket between cylinders 2 and 3 was blown and the intake valve on cylinder 4 was sucked in, which my machine shop said is very common on marine valves.

 

[jseer891]

Re: 1985 Mercruiser 140 Bogging Issues

I am having the same issue with my motor. I have in line 6. Could you not tell the head gasket was blown without pulling the head?

 

[fat fanny]

Re: 1985 Mercruiser 140 Bogging Issues

When I had these same issues a few years ago the only thing besides pulling the head that told me the head gasket was blown was a compression test ont he cylinders except mine was between 3&4. Note to anyone that reads this mine was caused from trying to winterize my engine with sucking anti freeze up into the outdrive and block with muffs so that explains one of the reasons why you really need to get all the water out period!!!!!!!!!!!!!!!!!!!!!!!!!!! LUCKILY it only cost me a couple of hundred bucks and a few favors from a cusin.