1990 120 evinrude looper unknown problem

leifer

Cadet
Joined
Jan 10, 2010
Messages
8
My 1990 120hp evinrude looper is on a 18 foot Javelin. I am having a problem about 50 percent of the time when trying to get it out of the hole. The motor runs good on top end, 56mph, idles great. but half the time when I give it the gas it like it bogs down and won't hardly get out of the hole and the ther half the time it jumps right up? I have a 22 pitch raker prop. I even tried some hydrofoils with same results. Any ideas?
 

diver_down

Seaman
Joined
Apr 19, 2009
Messages
64
Re: 1990 120 evinrude looper unknown problem

did you do any maintenance on it recently?
compression numbers?
 

71Windsor

Petty Officer 1st Class
Joined
Jun 25, 2008
Messages
286
Re: 1990 120 evinrude looper unknown problem

sounds to me like a fuel problem. when it bogs down have you checked your primer bulb? make sure its staying firm. i would start by changing any fuel water separator and primer ball. then move on to a carb cleaning if that hasnt been done in a while.
 

jonesg

Admiral
Joined
Feb 22, 2008
Messages
7,198
Re: 1990 120 evinrude looper unknown problem

My 1990 120hp evinrude looper is on a 18 foot Javelin. I am having a problem about 50 percent of the time when trying to get it out of the hole. The motor runs good on top end, 56mph, idles great. but half the time when I give it the gas it like it bogs down and won't hardly get out of the hole and the ther half the time it jumps right up? I have a 22 pitch raker prop. I even tried some hydrofoils with same results. Any ideas?

Hit the choke when it starts bogging, if it picks up the carbs are getting clogged. If not then I'd do a spark test, should jump 3/8th inch gap.
Got a water seperator, keep it clean?
 

Brew2

Chief Petty Officer
Joined
Jan 12, 2004
Messages
427
Re: 1990 120 evinrude looper unknown problem

Agree with Jonesg...fuel delivery. If the motor recovers immediately after bumping primer then start checking for clogged carb jets, air leaks in fuel system connections, kinks in fuel lines (particularly the small ones running to each carb), etc.

Something is preventing enough gas from getting to one or more cylinders.
 

wilde1j

Vice Admiral
Joined
Apr 15, 2002
Messages
5,964
Re: 1990 120 evinrude looper unknown problem

sounds to me like a fuel problem. when it bogs down have you checked your primer bulb? make sure its staying firm. i would start by changing any fuel water separator and primer ball. then move on to a carb cleaning if that hasnt been done in a while.

The primer ball does not "stay firm", it just should not collapse. It's only firm while squeezing.
 

ezeke

Supreme Mariner
Joined
Sep 19, 2003
Messages
12,532
Re: 1990 120 evinrude looper unknown problem

That's a lot of prop for the 120HP motor on most 18' Javelin boats, which are heavy.

What's your RPM at WOT?
 
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