Force 90 HP Intermittent Power

Ben Z.

Cadet
Joined
Jul 9, 2008
Messages
9
I have a Force Motor on a 18' Maxum boat that acts like it is losing fuel pressure - it will idle fine but periodically acts like it is running out of gas - It will rev up in neutral, but will barely run when in gear above idle - It did this twice this past weekend and will suddenly snap back to life and run just fine. I replaced the spark plugs which made no significant change. Any input will be appreciated.

Ben
 

GrindKore

Petty Officer 1st Class
Joined
Jun 20, 2008
Messages
211
Re: Force 90 HP Intermittent Power

Check your fuel intake filter, sometimes junk in the fuel tank get sucked in and partially blocks the fuel flow. Also, you may be getting air in to the fuel line. Air bubbles accumulate in the primer bulb and then travel up the line in to the motor effectively starving the motor and causing abrupt and random power loss.
 

Ben Z.

Cadet
Joined
Jul 9, 2008
Messages
9
Re: Force 90 HP Intermittent Power

Thanks for the suggestion - I plan to check it this weekend. Do you have any idea of what the fuel pressure and volume should be?

Thanks again for the reply!

Ben
 

Ben Z.

Cadet
Joined
Jul 9, 2008
Messages
9
Re: Force 90 HP Intermittent Power

Fuel filter was clean - Tank, hose free from leaks. Fuel clean
 

Ben Z.

Cadet
Joined
Jul 9, 2008
Messages
9
Re: Force 90 HP Intermittent Power

I checked the fuel hose and tank for leaks - OK.. The motor will slowly get up to about 1800 RPM while boating - if I move the throttle for more RPM it won't take it, and stalls. I pulled the carb bowls to check the main jets and everything was clean. After 2 days of trying to find the problem I noticed that if I run it up to 1800 RPM and choke it, it stalls. I then crank it as it is apparently flooded and when it starts it will run fine - I went through this routine at least 6 times when it would screw up, and it worked repeatedly - We skied and tubed as normal, in between the episodes when it would not go past 1800 RPM.
My patience is wearing thin - I am thinking about rerplacing the fuel pump.
Any comments will be appreciated
 

roscoe

Supreme Mariner
Joined
Oct 30, 2002
Messages
20,591
Re: Force 90 HP Intermittent Power

CHeck to see that the timing advance linkage is moving freely and not hanging up.

If it is hanging up and not advancing the spark, it will not take the extra fuel, and die.

What year is the motor?
 

199675hpforce

Petty Officer 1st Class
Joined
Feb 27, 2004
Messages
299
Re: Force 90 HP Intermittent Power

You must check fuel pump diaphram go ahead and order a replacement nowwww. crowleymarine.com $13bucks get to it
 

Ben Z.

Cadet
Joined
Jul 9, 2008
Messages
9
Re: Force 90 HP Intermittent Power

The motor is a 1992 - the advance seems to be working fine - the bakelite arm broke several years ago when the flywheel lost a magnet - (I replaced both at that time) I disconnected the fuel outlet hose from the pump and hooked up a fuel pressure gage a few weeks back - I was reading around 6PSI while cranking - the flow seemed questionable although I thought it OK as it will run at top RPM for long periods without starving. The ball in the tank line occasionally goes soft which is why I was leaning towards a kit for the pump, although I never heard of an intermittent fuel pump. The motor boat actually started this shortly after I purchased it in 1995 - I thought the underfloor tank was sucking air as it would run OK on a portable 6 gallon tank - thank you for your help - I hope I am not providing to much detail.
 

Ben Z.

Cadet
Joined
Jul 9, 2008
Messages
9
Re: Force 90 HP Intermittent Power

I replaced the fuel pump diaphram and one check valve - we went tubing for about and hour. It had a problem getting past 1800 RPM only once. Went to go tubing about an hour later and it would not start. No spark was present - Found one side of the stator open (red to blue). The stator itself is a black unit - The new stator is $135. and will take 6 to 10 days to arrive. Is this something that is prone to failure on the Force motor or should I be looking for the cause? I tend to think this is what has been causing the problem - Any comments appreciated..
 

Ben Z.

Cadet
Joined
Jul 9, 2008
Messages
9
Re: Force 90 HP Intermittent Power

I went to Crowley Marine to order the stator - they listed 2 different stators for my application -I called for clarification and was informed that my stator #398-8778 A16 (cost $134.95) has been superceded with #832075A7 (cost $580.83). Other then the fact that the replacement is "red", they could not provide any information as to the difference, or alternative. I have not had any success in contacting anyone at the Mercury Tech. line. Does anyone have any information to explain why the costly upgrade is needed? I would appreciate any info. provided.

Ben
 

chitownborn

Petty Officer 2nd Class
Joined
Jul 13, 2007
Messages
178
Re: Force 90 HP Intermittent Power

Try Standard magneto in Chicago Il they have new ones for about $125
 

walk-on

Petty Officer 2nd Class
Joined
Aug 16, 2006
Messages
112
Re: Force 90 HP Intermittent Power

Ben,
I bought my stator (95 Force 90HP) last year from Ebasic Power and it appears it is the same stator you are looking for.

CDI174-8778K1 Stator Kit, Mercury, 2, 3, 4 Cylinder

Current price is listed at $163
http://bpi.ebasicpower.com/mm5/merc...e_Code=eBasicPower&Product_Code=CDI174-8778K1

My new stator is the "red" stator that does not have the black cover on it. I just installed it this past weekend and it works fine. The instructions for installation are good.

I had a hard time removing the flywheel even with a puller. I also had a hard time torquing the flywheel until I bought a strap wrench at Sears along with the torque wrench. I believe I torqued mine to 90 ft-lbs.
 

Ben Z.

Cadet
Joined
Jul 9, 2008
Messages
9
Re: Force 90 HP Intermittent Power

Thanks for the info. - I will call tomorow

Ben

In reply to Walk-On - I spoke wth Mercruisers Tech line and was told that black was a 2 coil stator which had problems and was discontinued. I was further informed that if my motor had a voltage regulator it would require part #832075-A7 at $580.00 - it is now designed with one coil, and puts out 16 amps as opposed to the oem which was 9 amps. If the motor has no voltage regulator,the replacement is #832075-A5, at $250.00. It incudes a adapter kit & harness in addition to the stator - It seems odd it includes more parts at half the price. Needless to say, I need the $580. model and am trying to decide whether to buy it, or look for another motor. I am not happy with the Force - I have had to work on it more in the past 10 years then any other motor I've ever owned. Thanks for the help - I really appreciate it - I will let everyone know the outcome.

Ben
 
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