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125 force issues

Looking for some help. My 1988 force 125 is running rough. At low and wot. Shakes and is not smooth. B Have only owned for a year, figuring things out but have run into a wall. It ran great one time out until I ran out of gas, faulty gage. Refueled and has run rough since. Replaced fuel pump membrane, rebuilt carbs, compression 120-125-125-125, Sinked carbs. Tried other tank to eliminate gas issue and ran the same. Always starts. Max RPM has only been 3600 but not sure if gage is correct. Prop is manual recommended. Bought an inline spark tester to check for spark and am showing no spark on all. Am I doing it wrong? It works on the lawn mower. Can the motor run without spark? Sorry for babbling. Help!!!
 
Can't run without spark of course. Gotta try again to get a spark test. Compression is great. Is there any kind of screen or filter between tank and pump? If so, have you cleaned and/or replaced? Maybe something got stuck in the primer bulb/check valve?
 
Where is the air screw set at???
Needs to be about 1 1/2 turn out to start.
Then adjust from there.

Get a spark plug with a gap type electrode,
then remove each plug and test the spark.

At any time did it backfire?
Do the starting fluid test: start mootor, spray SF
around the intake side of the motor.
Any change, stutter, smooth out, miss?? Yes
then the motors sucking air somewhere.
 
Can't run without spark of course. Gotta try again to get a spark test. Compression is great. Is there any kind of screen or filter between tank and pump? If so, have you cleaned and/or replaced? Maybe something got stuck in the primer bulb/check valve?

Sorry forgot to post, new primer bulb and also a filter after the fuel pump.
 
Where is the air screw set at???
Needs to be about 1 1/2 turn out to start.
Then adjust from there.

Get a spark plug with a gap type electrode,
then remove each plug and test the spark.

At any time did it backfire?
Do the starting fluid test: start mootor, spray SF
around the intake side of the motor.
Any change, stutter, smooth out, miss?? Yes
then the motors sucking air somewhere.

Yes it has backfired. Will do the SF test and get back. I have removed each plug wire while running and did notice a change in the motor each time.
 
If it's a crankshaft seal, the top, or bottom cylinder will be running lean. You could detect that with spark plug color.
 
The chance the crank seal is bad is almost zero.
Now the port cover seals(4 of them) is much better.
The starting fluid test will show if they are leaking.
 
The chance the crank seal is bad is almost zero.
Now the port cover seals(4 of them) is much better.
The starting fluid test will show if they are leaking.

Ok, started the motor, sprayed SF around the port covers and nothing, sprayed into the covers and motor hesitated.
Checked anti syphon valve in tank, seemed ok. I noticed that I have air bubbles in the fuel filter. I have the filter after the fuel pump. Looks like a leak somewhere. Is there a special way to check for leaks? Or just replace the fuel line?
 
Ok, started the motor, sprayed SF around the port covers and nothing, sprayed into the covers and motor hesitated.
Checked anti syphon valve in tank, seemed ok. I noticed that I have air bubbles in the fuel filter. I have the filter after the fuel pump. Looks like a leak somewhere. Is there a special way to check for leaks? Or just replace the fuel line?

Moved the filter before the fuel pump, no bubbles but would not stay 3/4 full. Would almost empty then refill. Brand new membrane in fuel pump. Frustrated!!!
 
The squeezie: it's only job is to pump fuel to the carb.
When it's done it should get hard and then it just sets there.
If it doesn't get hard??? then there's a problem someplace??
A new squeezie can be bad???
It can be sucking air someplace (SF test) if the motor
changed when ding the test that shows a problem.

Bubbles in the filter not a problem.
 
The squeezie: it's only job is to pump fuel to the carb.
When it's done it should get hard and then it just sets there.
If it doesn't get hard??? then there's a problem someplace??
A new squeezie can be bad???
It can be sucking air someplace (SF test) if the motor
changed when ding the test that shows a problem.

Bubbles in the filter not a problem.


The Squeezie, which is new seems to working properly, gets hard and stays that way when running.

The engine did stumble when sprayed near the ports, what does this mean?

This motor ran great after a few times adjusting the idle, carbs, syncing the carbs, then after running out of fuel, it has not run good again. Don't understand.
 
The Squeezie, which is new seems to working properly, gets hard and stays that way when running.

The engine did stumble when sprayed near the ports, what does this mean?

This motor ran great after a few times adjusting the idle, carbs, syncing the carbs, then after running out of fuel, it has not run good again. Don't understand.

Also noticed that before this issue, I would notice a difference when adjusting the carb screws but now not noticing much of a difference, besides stalling when closing. I used to be able to hear in increase and decrease in the motor, now, not really.
 
Thats because the other air leak is the dominate leak.
You might have 2-3 air leaks???

I will replace the fuel lines this weekend. When I pump primer ball, should I hear anything from the gas tank? I hear air while pumping. Sorry have only owned a small boat in the past with a portable tank.
Thanks greatly for your help
 
You shouldn't hear any noise from the tank when you
squeeze the ball.
Then again: if there's an anti siphon valve installed you
might hear something???
There shouldn't be a valve installed as the pumps pressure
is so low that it can't draw the fuel through the valve.
Look at the fitting that comes from the tank.
Should be a small fitting.
A larger one might be an anti siphon valve?
 
You shouldn't hear any noise from the tank when you
squeeze the ball.
Then again: if there's an anti siphon valve installed you
might hear something???
There shouldn't be a valve installed as the pumps pressure
is so low that it can't draw the fuel through the valve.
Look at the fitting that comes from the tank.
Should be a small fitting.
A larger one might be an anti siphon valve?

I just removed the fitting and it is an anti-syphon valve, seemed to be working fine, the noise is coming from the bottom of the tank while pumping, not near the top and anti-syphon valve. Could it be the fuel pick-up tube?
 
That noise is the anti siphon valve.
Just seems to come from the tube.
Most tanks have a solid tube that extends to
about 1/2" from the bottom.
Some companies install a filter on the end of the tube,
not many but some do.
If it clogs it can cause problems.

I'm surprised the pump draws through the valve??
They are so low pressure.
 
Below are all the things that I have done with little to no improvement. Still idles and runs rough. Tried adjusting air/fuel mixture but I do not see a big difference while adjusting. Clockwise will eventually stall, Counter will run rough but do not get that sweet spot like I used to. Tried a portable tank thinking that maybe there was an issue with the internal tank and hoses but ran the same way. Should the fuel filter remain ¾ full while running? Mine does not, can see fuel going through but does not fill up. Starts with no problems but will occasionally backfire. Any more help would be appreciated. Thanks in advance.

Compression: 125-120-120-120
Cleaned Carbs-new needle valves, adjusted floats
New Plugs - Good spark
Tried portable fuel tank
New Fuel Pump Membrane & gasket
New Primer Bulb
Removed anti-siphon valve
New fuel filter
 
Have tried the starting fluid test, no change. And run with and without cowl, no difference. Can it be the timing? Not sure what else to check. Has never gone over 3500 rpm, according to the tac, if it is accurate.
 
Tried the starting fluid test again and did notice a slight difference where the bottom carb attaches to the motor. Also took the fuel pump apart again and all valves seamed to be working fine. Just an update. Watched a video on youtube and the same motor sounded the same as mine and it was his fuel pump. A slight pinging from the top when running. Some same timing, I am just baffled and want to go fishing. I wish I wouldn't have been lied to.
 
Busy day. cleaned recirc dog bone thing, filthy. Cleaned, adjusted and sinked carbs, new gaskets, new fuel lines, cleaned fuel filter. Visually checked reeds, looked good. Bottom carb looks to be leaking a little fuel from front opening.

Now it is surging at idle. 1000 jumps to 1200, then back, scared me!! Checked timing, right at 28. Seems to be a little smoother, after all this but with surging now. Might be throwing on Craigslist. I have learned a lot, just don't know where to go next.
 
Surging is probably the carbs not sync'd.
Undo the bar that connects the two carbs
together, sometimes being off 1/8th inch
can cause trouble.

When connecting, make sure the butterfly's
both move at the same time.
 
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