1987 force 125 misfire after warmed up

[msack]

I`m at the end of the line with this piece of sh**. The engine runs like a champ for about an hour. Then it will suddenly start to bog down over 2000 rpms. It will run all day below that, only at about 5 or 10 miles per hour. I`ve taken this boat out about 20 times. I think I`ve only had trouble free operations once. So after spending hours reading these forums, I`ve done the following: 1). Replaced the stator and trigger. Ran better and lasted longer before bogging at high rpms. 2). Replaced powerpacks. Ran it and the same thing. 3). Replaced coils and spark plugs. Ran it and same thing. Compression is good on all cylinders and I`m getting spark on all cylinders. Its kind of tricky. Because it seems like it only has problems after its warmed up. Then it won`t go beyond 2000 rpm with out stuttering And this is where I am at now. I really want to get rid of it. But I`d at least like have the thing running correctly. Its cost me over 600.00 in ignition parts so far. Please help. Mike

[maxum247]

My engine did simular to what yours is doing and it was trash in the fuel system!
What happens if you hold the throttle open?
Does the engine evently stall to an idle, does the squeeze ball go flat?
If so you may have trash in the fuel system.

As the engine's rpm's increase the suction on the gas tank pickup tube increases picking up the trash in the gas tank blocking the pickup tube causing the engine to die down, let off on the throttle and the suction on the pickup tube in the gas tank decreases and the trash falls away, Pump up the ball, accelerate to speed and it starts all over again!
Have you checked the fuel line and connectors for air leaks?
Is your inline fuel filter plugged and in need of a change?
When or has your fuel pump been rebuilt?
How old is the fuel your useing?
Water in your fuel?
Are your carb idle mixture screws adjusted correctly?
Is there trash and varnish in the fuel bowls?
Are the throttle and choke valves in the carburetors adjusted correctly?

That one trouble free day you had in the boat may have been like the one or two times mine didn't mess up out of 10 or so trips, the trash or water just didn't get to the pickup tube those times!
Hard to tell if this is your problem but maybe something here will help!

[CharlieB]

Use a test tank and a new fuel line assy to test, if all is well you can be sure where your problem is.

[john from md]

Can you keep it running by having someone pump the ball? If so, your checkvalves in the fuel pump are intermittant. I believe the older ones swell when they are used with gasahol. This causes them to stick intemittantly and drive you crazy. They cost $5 each and, if you are handy, are not hard to change.

I rebuilt my whole fuel system before finding that these were bad. Now my engine runs like a champ.

Hope this helps,

John

[CharlieB]

Try the test tank, if that works fine then start looking at the vent to your fuel tank. Sounds like it takes about an hour to suck enough fuel out of your tankk then the vacuum becomes tto great for the fuel pump to get much fuel any longer. Continuing to operate it like this is going to melt a set of pistons from a lean mixture.

Prove the problem with a test tank, then fix your vent.

[msack]

Thanks for all the replies guys. I don`t think it`s fuel related. Because I can run the boat fine for about an hour or so. She runs perfect. Then after about an hour, it will bog out when I try and give her some throttle. If I let the boat sit for an hour or two, she`ll run fine again for about an hour. I`ll try some of those great suggestions and post my results. I think I`m going to start with sucking all the fuel out and putting some fresh fuel in. I think I mixed to little oil with fuel in a few times. I`m thinking it`s possible that it could be causing the system run hotter without the proper oil mixture in there. Thanks.

[boatsmith]

I'm having a similar problem with my 89 Force 125 B model. Am in the process of pumping out all of the fuel through the water/sediment filter. Anybody know of a cheap way to check the amount of oil in fuel? My engine smokes like crazy when at low speed. The fuel I pumped out pre-filter is clean, I think it takes a fair amount of jostling to stir up the crud. I noticed that the bulb stayed flat when squeezed and engine was bogging. The filter seems OK, is there a screen on the end of the pickup tube in the tank? My tank is a 42 gallon plastic, under center console, very difficult to get to. Problem started last year. I had fuel pump changed and carbs cleaned, but still bogged. I put it up for several months. Last month I changed the vent hose and delivery hose and filter, still bogs. I heard one fellow say it turned out to be his fill hose disintegrating.

[maxum247]

With the boat setting level on the trailer and the fuel tank pretty near empty, useing one of the plastic kerosene squeeze pumps I removed as much of the fuel from the tank as possible without getting into the trash on the tank bottom, this way I didn't have but a couple of gallons or of gas to filter clean afterwards.
Then I jacked the bow of the boat up as high as I could get it on the trailer and used the plastic kerosene squeeze pump to get as much of the trash out of the fuel tank through the sending unit of the aluminum 30 gallon tank that I have on my boat as possible.
There is a filter screen on the end of the pickup tube in the tank, in my case the boat had set for years and I had to pull the pickup tube from the tank and change the screen. Good Luck! max!

[boatsmith]

thanks for the advice. What kind of weight did you put on the bottom of your pump pickup tube to keep it on the bottom of the tank? Were you able to pump up sediment and particles? I'm curious to hear the results of msack's testing.