97 40hp mercury/force series problems

B

Barefoot!

Cadet
Joined
Mar 28, 2010
Messages
15
so, i was going between reverse and forward the other day and all of the sudden i am running at half power/half rpm's. checked the prop to see if it was spun...it was not. replaced spark plugs with fingers crossed and no change. i have good spark to both wires. i find that if i remove the top plug wire and start the motor it idles but if i put it in gear it dies immediatley. however, if i unplug the bottom wire and start, it idles and i can run it in gear with just a hair less power than with both plugged in.

i know jack about boat motors and know not my next move. is there something else i can check?

any help is appreciated!
 
roscoe

roscoe

Supreme Mariner
Joined
Oct 30, 2002
Messages
21,750
Re: 97 40hp mercury/force series problems

Time to check compression on the cylinders.
Sounds like you lost the bottom cylinder.

Since you say it has spark, you may have blown a head gasket, of suffered a broken ring.

If compression is low on one or both cylinders, remove the head and visually inspect.
 
B

Barefoot!

Cadet
Joined
Mar 28, 2010
Messages
15
Re: 97 40hp mercury/force series problems

ok, compression is good! i have 130 on top and 125 on bottom. whew..... ;)

i also removed and blew through the fuel filter without resistance.

i removed the gas cap thinking maybe the vent was blocked and the tank air locked...no changes.

while running i can see gas spraying in the carburator and the butterfly valve opening up. they both appear fine but again...i am no boat mechanic AND i know jack squat about carburators in general ;)

it has been suggested that the stador or power pack could be shot. this makes some sense as it has had a high end miss for a while now. however, i am getting spark and it looks like good spark to me.

any other ideas or direction?

i guess i need to get a testor and learn how to test the stador and power packs. can anyone supply a linky for said marine electric tester/what i need or a name? i am to understand that a regular multimeter will not work....right?

any help appreciated!

ps, not sure why the moderators moved to here as this is a MERCURY force series for a tracker boat.
 
B

Barefoot!

Cadet
Joined
Mar 28, 2010
Messages
15
Re: 97 40hp mercury/force series problems

also, i am told there is a place i can put in my serial number and see a pic of my motor with parts broken down/labeled/diagramed?

can anyone supply link?
 
F

foodfisher

Captain
Joined
Feb 18, 2009
Messages
3,756
Re: 97 40hp mercury/force series problems

Chrysler,US Marine and Mercury ALL owned or made the "Force". A force is a force not to be confused with a Mercury.
 
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