Force '89 125hp lacks power and top end speed

[Gearhard]

Have read through the whole thread now and first have you checked spark at all plugs with a timing light or with the plugs out and grounded?
Best is to check with a timing light and at the same time you check that it is firing at right time at each plug.
The timing light will work at 2 and 4 stroke but the tach if it has, shows wrong RPM if it is made for 4 strokers.
When checking spark with the plugs out and grounded you do not know if the spark is good enough to fire during compression.
If doing it with plugs out you have to check that it manage to jump spark at least 1/4 but 3/8 or up until 1/2 in would give sufficient results.
Imaging you have multiple issues, you have to verify spark at each plug under compression or in air it should jump spark 3/8 in.

The ignition system has two CDI modules and they can interfere with each other cause it is a blocking diod built in.
Also the rectifier can cause ignition issues.
Try with the rectifier disconnected.

Nordin, Thank you for the feedback.

I checked the spark on the motor and all of the cylinders tested out the same. I had good spark up to 9/16 +in. I have just recently replaced the rectifier with a voltage regulator as discussed in one of the sticky posts at the top of this forum. I will have to take boat out and see if the rectifier may have been affecting performance.

 

[The Force power]

As Puffitu already mentioned;

Verify if the fuel pumps are working/good condition check the fuel lines /vent in fuel tank
Inspect the re circulation hoses if plugged

 

[puffitu]

Check everything fuel related and the squeeze DOES go bad; mine crapped out partially. Anti syphon valve goes bad and the motor will starve for fuel at wot

 

[Gearhard]

Took the boat out yesterday. Not happy about results. Poor idle, kept stalling. Some coughing at WOT. New fuel pump diaphragm and new gas line. Checked timing at WOT, right on 30°. Tach got to 4800 rpms a couple of times, hit 33 mph GPS. Worked on carb adjustment from hole shot, improved slightly but was within 1/8 turn from starting point. Plus side is that 2000 to 4000 rpms ran pretty well. Idle speed may need to be adjusted at dock, in gear, but had already adjusted some at put in time. Not feeling good about tach as it starts at 800 before key Is turned. Is there a good way to connect a tach, and what type of tach? Thanks.

 

[Gearhard]

On a positive note...voltage showed approx 13.8v vs 16+v at Wot with new voltage regulator.

 

[The Force power]

What Tach. are you working with??
The Tach. in your boat should be a 20 pole tach. and the signal-terminal wire get wired to one of the yellow Stator wires & the positive terminal goes to a Pos. wire on the ignition-switch

 

[Gearhard]

Ok, I've upgraded my timing light to one with a functioning tach. Now I can see that the RPM drop on #1cyl is minimal, whereas the other 3 cyls all cause about 100 RPM loss on drop tests. Spark tested strong on all 4 cyls. Also the timing light seems to flicker a little faster on cyl #1. There seems to be an occasional, slight miss at idle. RPMs also seem to fluctuate about 50+/- RPMS at idle, not sure if that is normal. Not sure if I should be checking CD module or coil on cyl #1, or both? Is there anything else that might need to be checked? Thanks.

 

[Gearhard]

What Tach. are you working with??
The Tach. in your boat should be a 20 pole tach. and the signal-terminal wire get wired to one of the yellow Stator wires & the positive terminal goes to a Pos. wire on the ignition-switch

The tach I was talking about is the one that came with the boat, on the dash. It is old and doesn't seem consistent. The tach I'm going to be using for tuneup now is one on the timing light, since I replaced the timing light. Old timing light tach was reading 2000-3500 RPMs with induction pickup disconnected.

 

[The Force power]

Try this;
NO FIRE OR INTERMITTENT ON ONE CYLINDER:

1. Check stator and trigger resistance, trigger wire sets read approximately 50 ohms between the wire sets (DVA-4V or more), stator reads 680-800 ohms (factory) and 200- 300 (CDI/RAPAIR) DVA 180V or more from blue to yellow.
2. If readings are good, disconnect kill wire from one pack. If the dead cylinder starts firing, the problem is likely the blocking diode in the other pack.

You can also check for cracks/cuts in the spark-plug cables it can leak & short to ground; a good way to check for that is to run the engine in the dark (with the cowl off) and look for arcing

 

[Gearhard]

Try this;
NO FIRE OR INTERMITTENT ON ONE CYLINDER:

1. Check stator and trigger resistance, trigger wire sets read approximately 50 ohms between the wire sets (DVA-4V or more), stator reads 680-800 ohms (factory) and 200- 300 (CDI/RAPAIR) DVA 180V or more from blue to yellow.
2. If readings are good, disconnect kill wire from one pack. If the dead cylinder starts firing, the problem is likely the blocking diode in the other pack.

You can also check for cracks/cuts in the spark-plug cables it can leak & short to ground; a good way to check for that is to run the engine in the dark (with the cowl off) and look for arcing

Sorry for not understanding, but do you test each wire output individually with the DVA meter? Like red lead to blue wire and black lead to a ground? And resistance test from blue to yellow? I tried testing voltage output from blue to yellow and got something like 1.290v. It didn't make sense to me. and wires are disconnected from terminal block? Started motor in the dark and no arcing. Thanks.

 

[The Force power]

With the Stator wires disconnected and not running check the ohms reading between the two wires.
With the Trigger wires disconnected check the ohm reading between the two wires for that particular Cylinder
No DVA meter needed for these steps

 

[Gearhard]

Try this;
NO FIRE OR INTERMITTENT ON ONE CYLINDER:

1. Check stator and trigger resistance, trigger wire sets read approximately 50 ohms between the wire sets (DVA-4V or more), stator reads 680-800 ohms (factory) and 200- 300 (CDI/RAPAIR) DVA 180V or more from blue to yellow.

1. 
   
   CDI Stator resistance on both sets of blue & yellow wires is 303. Resistance on triggers #1&2 were 47.2 and for #3&4 were 48.4. Is that too low on #1&2 trigger?

 

[Ed_1976]

Change the diaphragms. I just pulled mine off on a 1981 Chrysler 140 and they were wrinkled and there was no gasket on it. I did that and my hole shot was a lot better and it reached top speed.

 

[The Force power]

CDI Stator resistance on both sets of blue & yellow wires is 303. Resistance on triggers #1&2 were 47.2 and for #3&4 were 48.4. Is that too low on #1&2 trigger?

I'd say they're good but electronics are funny at times
IF...you have a DVA-meter take the reading of the stator & trigger wire-sets.
Wires disconnected at cranking speed, make sure your battery/starter is good
refer to the link I send you.

As mentioned by me & two other members now; check the fuel-pumps/lines/tank-vent

 

[Gearhard]

I ran the boat yesterday and it seemed to run fairly well. I set the idle speed with the motor in F, at about 720 RPMs and that seemed good. But in Neutral the motor jumps up to about 1000 to 1100 RPMs. Is that normal for that large of a difference between in gear and out of gear? I actually got to 33 mph for a moment at about 4800 RPMs. I'm not sure of which model motor I have since I've never found anything to distinguish the model. So without a model number I can't be sure of how many RPMs I should be turning at WOT. I assume around 5000 should be a target, but would like to know for sure if anyone could give me a number? Using a 15P prop and still think that hole shot is slow and top end speed is low. Actually seemed to run a bit smoother at just less than full throttle, but I checked carbs and butterflies were horizontal at WOT. Electronics seem ok, fuel pump rebuilt and diaphragm replaced, new fuel lines, new plugs, fresh fuel, timing at 30° dynamic, roller set between marks on throttle control, and compression right at 150 on all cylinders. Wondering if it's just too much boat for this motor? Seem to recall getting a little better performance a couple of years ago and on a 17P prop.

 

[The Force power]

Both your idle RPM's settings are good & WOT should be 5000 + even with a boat slightly too big/heavy with a 15 P you should achieve the 5000 rpms

I don't remember if we covered the Re-circulation system and/or Spark-plugs ??

 

[puffitu]

Have you done the starting fluid test near/around recirc system/gaskets??? Spray under/around coils and modules to see if the motor is sucking air?? The thin gaskets turn solid; expand and sometimes let air in. I tore down and replaced all and it remedied poor running performance. There’s no perfect science and you may not get it to brand new running condition But ..get real close. I remember having to slightly mis-adjust bottom to top carb butterflies in order to remedy a slight idle sneeze and to calm it down-that significantly improved Hole shot-
not saying those are YOUR issues; all I’m saying is keep an open mind to the sometimes smallest detail or most over looked.

 

[Gearhard]

Both your idle RPM's settings are good & WOT should be 5000 + even with a boat slightly too big/heavy with a 15 P you should achieve the 5000 rpms

I don't remember if we covered the Re-circulation system and/or Spark-plugs ??

Force power, The plugs are new and the spark test showed a good spark at 9/16". The Re-circ system test is next. I assume that consists of just spraying carb cleaner around all components and mating surfaces on intake related parts? Also, is there a preferred motor speed for trying the Re-circ test? Thanks.

 

[Gearhard]

Have you done the starting fluid test near/around recirc system/gaskets??? Spray under/around coils and modules to see if the motor is sucking air?? The thin gaskets turn solid; expand and sometimes let air in. I tore down and replaced all and it remedied poor running performance. There’s no perfect science and you may not get it to brand new running condition But ..get real close. I remember having to slightly mis-adjust bottom to top carb butterflies in order to remedy a slight idle sneeze and to calm it down-that significantly improved Hole shot-
not saying those are YOUR issues; all I’m saying is keep an open mind to the sometimes smallest detail or most over looked.

puffitu, how did you mis-adjust your carbs? Not sure I can easily guess on the type of mis-adjustment you mean. I have adjusted slightly to take up slack in linkage, so both butterflies open simultaneously, but beyond that I'm not sure which way I would go. Thanks.

 

[puffitu]

There’s a set screw which screws into a metal clip which connects the two carbs; so they open simultaneously( in my case; my top carb butterfly needed to be ever so slightly adjusted forward of my bottom). I know it sounds crazy but it calmed the beast, hole shot and in forward idle gear are significantly much better. If that makes any sense