85hp merc, no high rpm's

aaron-l

Recruit
Joined
Jun 3, 2009
Messages
3
I'm new to boating so not sure if I am gonna keep this goose chase up or not. I have a 1976 85hp merc, I have done alot of motor work myself but now I'm stuck. the engine idles fine and slowly builds up rpm but when I get closer to WOT it just chokes and dies then it's a pain to get started again but it will eventually get to running then same thing just chokes and dies, I really have no clue, I believe the timing is set close to correct, the plugs dont seem to be fouled up, i think the carbs are set correctly. I have been working on it for over a year and I still have yet to go fishing in it. I live in KS so if anyone knows of someone to look at it for me I would be willing to drive it to them, closest person I found was 60 miles away and hez not returning my calls anymore so????? I also would like to know what would cause your steering to be EXTREMEMLY tight, as in unable to turn with steering wheel, I took the lnk off the motor and the motors turns freely but steering wheel is still hard to turn. I have no manual on this boat or motor, any help is appreciated,
thanks,
Aaron
 

leserz

Petty Officer 3rd Class
Joined
Feb 2, 2003
Messages
81
Re: 85hp merc, no high rpm's

wish someone would reply to your post. like to know the answer my self
 

jbrown270

Cadet
Joined
Mar 25, 2009
Messages
21
Re: 85hp merc, no high rpm's

do a compression test. it should be over 100 psi.

if it idles good then it should have spark on all cylinders but it might be worth checking.

make sure all jets and passages in the carb are clean.

the needle valves could need adjusting, causing it to flood out. here is a link for that.
http://forums.iboats.com/showthread.php?t=318980

make sure that the vent on the fuel tank is open. that would cause it die at higher RPMs.

try pumping the priming bulb while accelerating. if that helps, you will need to rebuild the fuel pumps.

timing could be off or not advancing properly. here is a link for a link and sync.
http://forums.iboats.com/showthread.php?t=168855
 

CharlieB

Vice Admiral
Joined
Apr 10, 2007
Messages
5,617
Re: 85hp merc, no high rpm's

jbrown is heading you on the right track with his advise to squeeze the primer bulb as the motor begins to falter.

A restriction in the fuel supply caused by crude blocking the pickup tube in your tank to a poor sealing fitting leaking allowing air to be sucked into the fuel line to a weak fuel pump, any or all will cause the carb to run out of fuel at higher speeds and take LOTS of cranking to restart.

Pumping the primer bulb substitutes your hand for a weak fuel pump and also may seal a poorly sealing fitting on the fuel connector on the motor.
 
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