1994 Force 120 dies while cruising

[dr.livingston]

I bought a used boat with a '94 Force 120. Due to serious illness of the previous owner it was actually used very little - perhaps under 100 hours total and not at all in the past 5 years. The owner's son-in-law revived the boat and I bought it. He did say that the engine died while he was checking it out. He attributed that to old gas in the tank, so he cleaned the tanks
out with massive amounts of carburetor cleaner and replaced with fresh gas.

I ran the boat for a couple of hours two days ago with no problem. Yesterday however, it died on me while running at near full throttle. It had been running that way for about 5 minutes when the RPM started to drop and then the engine just quit. After a couple of minutes checking the gas tank vent and fuel level, the engine started up again and we motored back to the marina at a slower speed with no more problems.

I'm thinking there is still some gunk in the carbs even though I added a half can of Sea Foam to the 6 gallon fuel tank. Any other ideas?

 

[kandil]

Re: 1994 Force 120 dies while cruising

how are your spark plugs? clean? and you may need to clean or replace the fuel filter and clean the carb good luck

 

[eurolarva]

Re: 1994 Force 120 dies while cruising

Sea foam will not clean the gas. It is a good de carb and possible a gas preservative but it will not do much good for varnish or gunk. I would replace the fuel pump diaphram first just cause it is cheap and is due. If problem persists try running on a 3 or 6 gallon plastic tank and see if the problem persists. If you dont know what you are doing or dont have the manual I would not take the carbs apart till you are sure that is where the problem lies.

 

[maxum247]

Re: 1994 Force 120 dies while cruising

I bought a used boat with a '94 Force 120. Due to serious illness of the previous owner it was actually used very little - perhaps under 100 hours total and not at all in the past 5 years. The owner's son-in-law revived the boat and I bought it. He did say that the engine died while he was checking it out. He attributed that to old gas in the tank, so he cleaned the tanks
out with massive amounts of carburetor cleaner and replaced with fresh gas.

I ran the boat for a couple of hours two days ago with no problem. Yesterday however, it died on me while running at near full throttle. It had been running that way for about 5 minutes when the RPM started to drop and then the engine just quit. After a couple of minutes checking the gas tank vent and fuel level, the engine started up again and we motored back to the marina at a slower speed with no more problems.

I'm thinking there is still some gunk in the carbs even though I added a half can of Sea Foam to the 6 gallon fuel tank. Any other ideas?

Remove the bowls from the carburetors one at a time and look for debree in the bottom of the bowls, if you find trash or a brown powdery looking substance in the carbs your problem is likely trash from the fuel tank that is breaking loose as the fuel sloshes around in the tank, in turn blocking the fuel pickup screen in the gas tank restricting the gas flow to the engine or the pickup screen in the tank may still be clogged and need replacing.

Check your fuel lines to be certain you have no air leaks in the fuel hose or quick connects, check the primer ball to be certain it is plyable and hasn't hardened looseing the ability to draw the gas properly.

It may be that the fuel pump is in need of a rebuild if non of the above prove to be the problem.

Or your carbs may need cleaning, if you decide to clean the carbs purchase a Clymer or factory manual for your motor first.

max!

 

[dr.livingston]

Re: 1994 Force 120 dies while cruising

The son-in-law of the previous owner told me that he experienced the same thing and it turned out to be the primer bulb collapsing while cruising. I didn't notice that when the engine stalled for me last week, but I didn't really look for that either. I did open the gas tank cap to check the fuel level and the engine started and ran fine after that.

Someone else advised me about the possibility of an air leak in the fuel line collapsing the bulb. He said that the original equipment hose clamps don't necessarily seal properly. That is possible I suppose but I noticed that one of my two gas tank vented caps seemed much harder to blow through than the other.

It will be easy enough to replace the original crimp-on hose clamps with the stainless steel screw type. I'll also investigate the restriction in that one vented cap.

 

[john from md]

Re: 1994 Force 120 dies while cruising

Start with one change at a time so you can isolate the problem. The easiest thing to start with is the starter bulb and line. It probably needs replacing anyway so start fresh and get a new one. Get 3/8 sized line when you buy it. I would also replace the fuel diaphram if you don't know when it was changed last.

Regards,

John

 

[dr.livingston]

Re: 1994 Force 120 dies while cruising

Turns out that the fuel line and bulb is brand new. Closer inspection of the gas tank vented cap showed no visible restriction greater than the other gas tank cap so I left it alone.

I did replace the original equipment crimp-on clamps on the fuel line with threaded screw-on kind. That did seem to make a big difference in the "feel" of the primer bulb. Before the clamp change the bulb was always a little mushy. After the clamp change it now gets pretty firm. I have not taken the boat out since the change but I'm hoping that was the problem after all.

 

[john from md]

Re: 1994 Force 120 dies while cruising

One last thing that it could be. If you are cruising and the engine quits, see if the bulb is soft. If so, it may be the check valves in the pump housing sticking. If this is the case, the engine usually will restart and will continue to run if you manually pump the ball. Manually pumping overrides the sticking check valves.

Regards,

John

 

[dr.livingston]

Re: 1994 Force 120 dies while cruising

Check valves in the pump? Makes sense. That would prevent the pump from losing prime if you stop the engine for a while and then restart it without pumping the bulb again. A friend of mine has an older Johnson 70 that I've also been working on recently. There were no check valves in his fuel pump so it didn't occur to me to look for one in this Force.

 

[john from md]

Re: 1994 Force 120 dies while cruising

If your engine has them, and I don't know if '94s do, they will be found in the fuel pump housing that you remove to change the fuel pump diaphram.

Replacing these stopped all of my stalling/shut down problems. My engine is so reliable now, I don't take my emergency kicker with me anymore.

The dead give away that these are the problem is that you can keep it running by pumping the ball. On more that one occasion, I would have to run back pump a few times and then grab the wheel to keep 'er straight. I finally installed a bungee cord to hold the wheel while I pumped.

It took me a good two months of troubleshooting and replacing parts to figure out it was the check valves all along.

I learned a hell of alot about my engine so it wasn't time wasted.

Good luck,

John

 

[dr.livingston]

Re: 1994 Force 120 dies while cruising

From where our boat is kept it is about a half hour at no-wake idle speed before we get to open water. Today I discovered a couple of things:

The resting battery voltage was down to 12.5 before I started the engine. Couple of days ago it was 12.7 before starting so the engine isn't charging the batery. After starting the engine today a careful voltage check with the engine revved up showed no charging. I removed the voltage regulator and did the static measurements shown in the Seloc manual. The regulator is dead dead dead. It fails every electrical test and is oozing a black substance.

Originally the boat had two batteries and a selector switch. Placard warns against switching batteries with the engine running. Previous owner may have done that and fried the voltage regulator.

As for the engine stalling, I didn't want to take a chance in open water with a nearly dead battery so I continued at idle speed and checked the primer bulb. It was rather soft. I gave it a gentle squeeze and the engine revved up. Time to rebuild the fuel pump I think.

Oh, and I checked for the presence of AC on the purple wire under the dash. None found there. Then I checked for the presence of AC on the short purple wire that comes out from under the flywheel but is attached to nothing. It read between 160 to 170 Hz at idle speed.

 

[john from md]

Re: 1994 Force 120 dies while cruising

Definitely sounds like the fuel pump check valves.

As far as the purple wire goes, that has to be the pulse for your tach. You need to find out where it is disconnected and reconnect it.

Hopefully all your problems will be solved before Christmas.

Happy Thanksgiving,

John

 

[dr.livingston]

Re: 1994 Force 120 dies while cruising

After reading the iboats catalog online I concluded I needed rebuilding kit for a 2-stage fuel pump based upon the serial number of my engine. Good thing I physically checked what I already have because it is definitely a single stage pump.

Another curious discovery. The son-in-law who got this boat ready for sale replaced the fuel lines inside the engine - and used plastic zip ties instead of steel hose clamps. Sheesh! Imagine what might happen if the plastic deteriorated at some future time and started spraying fuel around inside the motor.

 

[john from md]

Re: 1994 Force 120 dies while cruising

Tell him to keep his day job!!
Regards,

John

 

[dr.livingston]

Re: 1994 Force 120 dies while cruising

The fuel pump rebuild kit finally arrived. Through my own silly errors I managed to get the diaphragms and gaskets in the wrong sequence TWICE! The engine runs until the fuel I pumped in runs out. Then it stops. I finally relented and looked at the diagram in the book. Now it is right (I hope). I'll reinstall it tomorrow and try it again.

The old diaphragms I removed were all dimpled and distorted. Rebuilding the fuel pump was absolutely necessary.

 

[dr.livingston]

Re: 1994 Force 120 dies while cruising

Ahh, success. The properly assembled fuel pump works fine. The engine now idles 200 RPM higher than it did with the IMproperly assembled pump. I do notice that it is a bit rough at idle. Probably needs carb rebuild. Also, at WOT I would have expected something close to 5000 RPM. If I can believe the tach I'm not getting much over 3500.

 

[john from md]

Re: 1994 Force 120 dies while cruising

I suggest that you don't believe the tach. Most small boat tachs tend to get worse with age.

I bought a small hand held inductive tach from either Sears or the internet, memory is gone, and used it to check out my engine and the boat tach.

For WOT, I had my cousin sit at the back with the tach to tell me the readings at different speeds. My tach is ok at idle and below 2000 rpm, is not reliable from 2000 to 4000 and then is reliable again at WOT. Go figure.

I'm happy for you now that your fuel supply problem is fixed. A good carb cleaning and adjusting should smooth out the engine.

Happy holidays,

John