middle cyl not creating power

[colin james]

Hey i need a little help i have a 60 horse mercury 84 ish 3 cyl 2 stroke top and bottom have power middle cyl wont burn fuel it has great spark plugs are good but is gutless if i can get it in gear then dies. even pulled middle plug out and started the same as before ran but guttless and a lot of nist came out of the spark plug hole is this cracket head gasget cause im stumpt . and the oil and fule comes out the prop exaust . eny thing will help thanks.

 

[Fuzzytbay]

Re: middle cyl not creating power

Running a motor with un even loading is a big no no. In other words, don't pull a plug out of a cylinder and run the motor, thats a good way to make a boat anchor. Now when you had that plug out, did you take a compression reading? If not, thats the place to start, find out compression on the three cylinders, and post back.

 

[colin james]

Re: middle cyl not creating power

ok ive done a compression test and cylinder one(top) is 105 psi . #2 (mid) is 110 psi and third (bottom) is 115 psi is this normal that there not the same and i did the test three times on each cyl just to be shure , now im thinking middle cyl timing might b off cause thats the last one that fires or the coil is week i need to get a non digital voltage meter. any thing helps thanks

 

[hkeiner]

Re: middle cyl not creating power

I think that the compression looks OK and would not be the cause of lost power. The next thing I would do in your situation is to check the ignition with a spark tester to confirm that the spark is OK on all cylinders. If you determine that the spark is OK, report back and more troubleshooting can be suggested.

 

[CharlieB]

Re: middle cyl not creating power

What he said. Test spark on each cyl.

You can rig a spark tester with a 2X4, a few nails, and some jumper wires.

Joe Reeves posted a thread some time ago describing a 'How-To' build your own tester by starting a few nails around a center nail that is jumpered to ground on the motor, bend and turn the out side nails such that the gap to the center ground nail is 7/16 inch.

Jumper each outside nail to a plug wire, crank the motor without the plugs to save the battery and starter.

Watch the spark quality on each, ALL should be hot bright blue healthy snap.

 

[colin james]

Re: middle cyl not creating power

All are giving a good blue snapng spark at 7/16 inch and i allso cleand the carbs out with carb cleaner im thinking the carbs are flooding that middle cyl is this possible, do i need to dial the carbs back this 3cyl has only 2 carbs same size do they both feed the middle. thanks

 

[hkeiner]

Re: middle cyl not creating power

i allso cleand the carbs out with carb cleaner

Sounds like you may have just sprayed some carb cleaner in to the throat of the carbs. This does not clean them. One has to remove and disassemble the carbs and soak the parts in parts cleaner to clear out the internal passage ways. http://forums.iboats.com/attachment.php?attachmentid=24015&d=1236380258

Checking if the spark plug on the center cylinder is wet or dry after running the motor a bit would tell a lot. Also, spraying some fuel mixture (50:1) into the throat of the carb in question to see if the motor responds would tell a lot too. Adjust the idle jets out 1 1/4 turns from seated (or whatever your manual says) should get them close enough so that incorrect idle jet settings would not be the problem.

 

[colin james]

Re: middle cyl not creating power

i did pull the carbs apart and cleand them very well but i dint let them soak for long and i will set the carb idle screw out a bit hopefully can have it working for the weekend.