Force 125 Problem! WOT only 3200 RPMS top speed 8mph

[jvgilbert87]

I recently bought a 1998 bayliner trophy 1903 19' center console. It has a Force 125 two stroke motor which the previous owner claims works perfectly. I am only getting 3200 rpms at WOT and a top speed of 8mph. It is also burning fuel like crazy. I filled it up (50 gallons) in the other day took it 10 miles out and back for a little fishing and ran out of fuel. I have taken it out multiple times and have had 2 separate reputable mechanics working on it over the last month (ever since I bought it). The first mechanic to look at it was convinced it was a fuel pump and line issue so he replaced that. The problem still occurred so I had a second opinion from another reputable shop and he was convinced it was a bad prop and throttle cables were jacked so I had those replaced and still the same problem.

So far I have had the entire fuel system replaced, throttle cable/linkage replaced, new prop, spark plugs replaced, carb looked at and adjusted, compression tests showed perfect on all cylinders by both mechanics, fuel drained and replaced etc. Both mechanics have claimed they cant find anything wrong with the motor at all. No one seems to have any idea whats wrong with it. I am running out of ideas and options. There has to be something we are missing. If anyone has any ideas please share, thank you!

 

[jerryjerry05]

The prime system could be feeding excess fuel?

The 1998 boat and a 125 Force.
The 125 was stopped in 89 so someone has changed the motor,

What prop?
Compression?
Spark test on all cyl?


The 3200 sounds like a bad cyl.
OR: trigger, loose wire, they are famous for the wire breaking under the
shrink wrap.
Low comp on 1 or more cyl.
Reeds , does it spit back through the carb?

Does it still have the exhaust snout on the lower unit?

Pics of the motor and drive?

 

[Redbarron%%]

I would check the ignition by clamping an inductive timing light on each cylinder to see if each is firing all the time.
I had #3 on my 90 hp Sport jet not firing and the problem was a bad pickup in the trigger coil.
New trigger coil fixed that.
You could locate a bad cylinder by disconnecting the spark plugs one at a time to see if it stays the same or worse.
Be sure to ground the plug or install a spark plug tester on the disconnected lead because if not then the voltage from the coil may go high enough to damage it from over voltage breakdown of the internal insulation.

 

[legalfee]

I'd check your regulator / rectifier. For the fuel you might want to check the primer. It would help to know what year your motor is. Do you know the serial number?

 

[Redbarron%%]

A bad rev limiter might do that as well if it has one.

 

[jerryjerry05]

To my knowledge there is no rev limiters on the Force outboards.
The later Mercury ignitions might have something but ???

Pulling the plug wires one at a time but grounding them would be counter productive.
If you pull the plug wire it could cause damage to the pack, but not usually.

My last post, I said

The prime system could be feeding excess fuel?
That's if the motor isn't a 125
They used the choke until 1990 .​

 

[jvgilbert87]

Hey guys sorry for the late response I was trying to get additional info from the mechanic that is working on it. He is currently rebuilding the carb. He said the compression was consistently 140 on all cylinders. Spark plus were changed, prop was changed but I do not know what size. I will get serial number on motor, pictures, and prop size for you guys tonight when I head over there after work. Anything else I should be looking for that I havent already listed? Thanks!

 

[jvgilbert87]

He is also checking for excess fuel being fed, could there maybe be something with the choke? What size prop would you suggest? What should the normal RPM's be at WOT for this motor? What should normal operating RPM's be? Thanks again

 

[Nordin]

The RPM at WOT should be 5000-5500 for best performance, not sure about the exactly RPM, maybe Jerryjerry chime in.
I think a 19 pitch prop will do it, it depends the load.

If the boat is heavy maybe a 17 pitch or if it is lighter a 21 pitch.
Check with a tach.
Changing in 2 in pitch will low or raise with about 2-300 RPM, lower pitch raise RPM and vice versa.

 

[jerryjerry05]

Get pictures???

The pitch should be 17/19p aluminum.
Stainless would be 15/17p

That depends on the load and rpm's at wide open.​

If you send Bayliner your hull # they can tell you what motor, prop and equipment that came with the boat.

You say the fuel system is new? That include a rebuilt fuel pump?
You can rebuild the new style and have a bent reed and cause the problem.


What prop did you have?
Did you get the same when replaced?
Is it a Force prop? Pics of it mounted??

Pics of the motor, lower unit, choke and ignition system?

 

[jvgilbert87]

The entire fuel system supposedly was replaced including all hoses and fuel pump itself. I took the old prop off and went to West Marine to get a replacement. They told me they dont have a spec sheet for what I need and best thing to do is get the same prop as I took off. They gave me a 13X19 aluminum brand name is turning point hustler and has 4 blades. The old prop was also a 13x19 but had 3 blades. Not sure the difference. The mechanic put the new prop on and is currently looking at the carbs to see if the jets are either too big or too small, and then possibly rebuilding them if they dont look right. I am waiting to hear back on that, I wont be able to get pictures for a few more days because the boat isnt at my house. Thanks

 

[jerryjerry05]

I don't think they did you any favors by selling you a 4 blade prop??
The old prop can be rebuilt for about 50$
Any marine store or marina has access to a prop shop.

Rebuilding the carbs and check the jets?? Sounds like he really doesn't know
what he's doing and guessing is his way of diagnosing??
Your motor ran with the jets in there for a long time and now they might be too big or too small??
If you can't dazzle them with brilliance?? Baffle them with BS!!

It sounds like the fuel system needs attention.

I've asked for pics a couple of times??Some of the fuel system? Pump, carbs and primer/choke.
Pics of the lower unit?
They changed fuel systems and I need to know for sure what you have??

 

[Redbarron%%]

I don't think the prop is a problem, unless it is pretty mangled.
I think you have a fuel delivery problem and perhaps a mechanic problem

 

[jvgilbert87]

Ok so updates from the mechanic who has my carbs said that there doesn't seem to be any problem with them at all. To be honest I don't know exactly what I am looking at so I took several photos of the motor and parts. The carbs are not there because he still has them until tomorrow, also one of the spark plugs is out because those are getting changed still, i thought it was already changed out... The mechanic was convinced the problem must have been the carbs but is now saying he has no idea and will continue to look and brainstorm.... He is going back to the boat tomorrow to see what else he can find so if anyone has any other ideas on where I can direct him or someone else that would be helpful. Let me know what other info I can try and provide you. here is what I have for pictures thanks

 

[Redbarron%%]

I'd suspect the fuel pump, but at the same time there are two kinds of leaks, in and out.
I look at the tie wraps on the inlet to the pump and would make sure that that hose is tight on the barbs of the pump.
A connection may not leak fuel, but suck air and that will pull air and not fuel if it is leaking.
Verify that all connections are tight and leak free.
The pump is still a major suspect if the engine runs with your buddy pumping the bulb, but that does not rule out the possibility of a bad connection (but it does reduce it).
There is also a screen behind the outlet of this pump that needs to be checked for plugging.

 

[legalfee]

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[jvgilbert87]

Ok, Ill check all connections and hoses, Im just unsure that the fuel pump itself is a problem because the first mechanic I was using put a brand new one in for me as he was convinced that was the original problem as well. He did still leave that clear diagnostic hose in and forgot a few other things which is one of the reasons why we stopped using him, so its totally possible that the connections were no good and its still leaking. I do notice there are still some air bubbles in the clear tube when I am pumping the bulb.

 

[Redbarron%%]

Bubbles after priming indicate air is getting into the fuel stream.
Pumps will pump (or not pump anything) air in preference to fluid since it is so much thinner.
There could be some restriction in the fuel path as well.
These things could be quick connects, anti-siphon valves etc.

 

[jerryjerry05]

Legalfee, why the pic of the regulator?

The screen in the pump is behind the inlet not the outlet.

If your squeezing the ball and no fuel leaks from the pump?
Then its sealed right.
But the impulse hose and the hole behind the diaphragm might be feeding fuel
into the cylinders??

The clear plastic hose: it shouldn't be a problem unless it's so soft it collapses when the motor runs.
I've seen them used on outboards and snowmobiles, weed eaters etc..

A new pump doesn't mean it's a good pump.
The diaphragm in the pump could be 30 years old??? and dry rotted??

Take it apart and see if there are any cracks or holes.
One little backfire, cough or stutter can blow a hole in it.

The connector has rubber in it. It rots after time and sucks air.

 

[jerryjerry05]

[No message]