Force 125 - Is there anything left to try

aerofarm

Cadet
Joined
Apr 7, 2014
Messages
14
Force 125 still not making full power at WOT.

Checked compression - 125, 121, 123, 128
Emptied fuel tank
Brand new fuel line and bulb from tank to pump
Checked tank vent line - good
Checked tank pickup line - good
Added inline fuel filter after the pump
Checked spark - all four had great spark
Completely rebuilt and super cleaned carbs
Synced carbs and checked timing. - All good - RPM's on timing light match the tach
New fuel pump gasket and diaphram

The only thing I can see is there is sometimes a little air in the filter. Actually more at idle than when power is added. Runs great at idle. Purrs like a kitten. Just floods out or boggs down when you shove the throttle forward and can't seem to get over 4300 RPM with just me and 10 year old son.

Getting seriously frustrated with this thing!

Nate
 

Jiggz

Captain
Joined
Oct 23, 2009
Messages
3,817
How can you tell it is flooding? Is it spitting fuel from the carb? If yes then you might bad reeds. Do the carbs leak fuel from the vent hole on the sides? If yes, then the floats are not set correctly or the needle valve and/or seat are worn out. Are the fuel air mixture screw at 1 1/8 ~ 1 1/4 turn out from lightly seated? Are you sure you did not switch the low speed jets with the high speed jets on the carbs during rebuilt? A little air in the clear air filter is normal but it should fill all the way after some high speed runs. If not, there is possibility the fuel pump is sucking air upstream of the fuel system. Pics or video will be helpful.
 

aerofarm

Cadet
Joined
Apr 7, 2014
Messages
14
1987 Bayliner Cobra 19 ft.

I didn't change the jets. Just did a very thorough cleaning. Floats are set correct. There isn't any leaking from anywhere on the carbs. What I mean by flooding was that when you hit the throttle, it is slow to react, kind of bogged down. May not be flooding at all (sorry for incorrect terminology). I will check the needle settings. I think I set them both at 1 3/4 which was what they were when I took them apart.

I'm headed to the lake on Sunday. I will set the carbs to 1 1/8 and take some pics.

Thanks - I'll keep ya posted.
 

SkiDad

Lieutenant Commander
Joined
Jul 18, 2010
Messages
1,518
well the 4300 is probably the prop - if you have a 19p prop it's too high - try 17 or even 15. and yes your probably running too rich
 

Arawak

Chief Petty Officer
Joined
Aug 27, 2010
Messages
486
I had a similar problem on my FrankenChrysler 105hp+135hp+115hp that went away when I replaced the two inline fuel filters with a single new one. I suspect it was a fuel starvation problem.
 

aerofarm

Cadet
Joined
Apr 7, 2014
Messages
14
I rechecked the timing. It is at exactly 28 degrees at cranking speed. I set the carbs to 1 1/8 turn.

Forgot to mention, I have a stainless 15 pitch prop.

Thanks for the advice. I'll let you guys know how Sunday goes.

Nate
 

aerofarm

Cadet
Joined
Apr 7, 2014
Messages
14
The update

I took the boat out the last two Sunday's. It is a little better with the carbs but not perfect. The best response I can get is with both carbs set at 1 3/8 turns.

With me and one passenger, 350-400 lbs it with take off and go to 4500 rpms quickly. I can trim it out to 5000 at 40 mph.

As soon as I get someone behind it on a tube or skis it goes straight to 3000 rpms and then hangs there several seconds and then accelerates again. This is frustrating to skiers trying to get up. Doesn't seem to matter what setting I have carbs or trim.

I have a 15 pitch prop. Thinking bout trying 13 inch. Any other ideas.

I do have an inline filter before the bulb and another after the pump.
 

Jiggz

Captain
Joined
Oct 23, 2009
Messages
3,817
There is absolutely no need to have an inline filter before the pump since there is also a filter on top of the fuel pump. The filter after the pump is more for troubleshooting and because it is downstream of the pump it does not affect the pump performance unlike the one upstream or before the bulb. Try this solution first and repost back results.
 

aerofarm

Cadet
Joined
Apr 7, 2014
Messages
14
I will take out the pre-pump filter. I have another question. My main fuel line from the tank which includes the primer bulb is 3/8". The connection on the fuel pump seems to be 1/4." I currently have a reducer that takes my 3/8 line down to 1/4 inch about 1 foot before the pump. Could that be too restrictive on my fuel flow.

When I was setting the carbs, I noticed that I can turn the screw in till about 1/2 turn out before the motor sputters. I then have to turn it out over 4 turns before I get a response. I found I got the best response out of it at 1 3/8 turns.
 

Jiggz

Captain
Joined
Oct 23, 2009
Messages
3,817
I do not believe 1/4" is too restrictive although you do have the option of taking the reducer out and make the entire suction side hose to 3/8". One thing most people do not realize is that too many components connected on the suction side makes the fuel pump works harder to pump fuel from the fuel tank. Technically, there should only be a hose and a primer bulb between the fuel tank and the fuel pump. Some people take additional step to add in a water separator but that should be the most number of components on the suction side.
 

jerryjerry05

Supreme Mariner
Joined
May 7, 2008
Messages
17,923
Your motor came stock with 1/4 in hoses.
If your running a 175 or bigger I'd get a larger hose.
You sure the tach is working right?
Get a tiny tach and see if it matches.
You need 1 filter in the system someplace.
Usually between the pump and the carb.
Any inline connectors? Remove them and run straight hose.
 

aerofarm

Cadet
Joined
Apr 7, 2014
Messages
14
I will work on the fuel line. The tach on the boat matched perfectly with the tach on my timing light.
 

aerofarm

Cadet
Joined
Apr 7, 2014
Messages
14
Removed inline filter. Didn't really make much difference. Pulls kids fine, just not me.
 

Jiggz

Captain
Joined
Oct 23, 2009
Messages
3,817
The only thing I can think off that needs to be checked are the reeds. You may not have broken reeds but if the reeds are not properly closing anymore you will actually lose power to the motor because you will have less fuel oil mix getting into the cylinders. If you find the reeds not closing properly, try reversing the petals first and see if that will improve performance. if it does, then you have the option of replacing them for good. Just make sure you use loctite when reinstalling screws you removed from the v-blocks.
 
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