Force 120 fuel recirculation possible issue

[KenOverton]

2 weeks ago I took my boat out and had an issue where after extended idling in a no-wake area, the motor would not accelerate, it would bog-down as if it was flooding out. After multiple attempts, and after sitting shut off for about 2 hours while fishing, the motor initially bogged-down and then accelerated fine, but was very touchy on throttle placement. If retarded 2 far, it would start bogging down, and if advanced would not respond until almost 3/4 full throttle then would accelerate okay all the wa to full throttle.

Back in November I used a full can of sea foam to remove any built up carbon, spraying in the carbs while running until I had a decent smoke cloud started, then let sit for half hour or so and running until hot again.

I thought that maybe carbon had plugged up the fuel recirculation, and I think my guess was correct. The screens on the cylinder drain covers was blocked by carbon. I cleaned the screens but I am confused on the particular set-up that I have.

Looking at pgs. 232 thru 234 of my Clymer manual shows that my motor should be set up like pg. 233. It is, except I do not have any check valves or any hoses to them (no.11 and 12), and there are no ports to install any check valves. I also do not have the tees on the cylinder drain covers, and my drain covers only have screens. There are no reed petals or related parts and the drain covers do not separate, they are more or less solid with only the necessary drain passages. Attached are pics.

If any can clarify

 

[j_k_bisson]

Re: Force 120 fuel recirculation possible issue



I marked you photo of where they are. The hose is the recirc line and the bolted piece should be taken off, gasket normally able to be reused (only $2.5 if broken), and the screens need to be cleaned with brake cleaner or carb cleaner. The screens are in the bolted pices. I used a brass golf club brush to clean screen. If the are bad see about getting new ones. Check the valve by sucking and blowing into the hose when you have it off. If it is pluged, only use isopro to clean. Make sure you get all the liquid out. Carb cleaner might eat the hose. Don't know for sure.

Had the same thing with my force 120. Found out after cleaning the recirc it was a thrown ring. Might want to check compression before getting into this. Second piston from the top is the one that went on mine. Only showed 10psi difference when it started. Gradually got worse the more I drove it.

 

[foodfisher]

Re: Force 120 fuel recirculation possible issue

Extended idling fouls plugs.

 

[KenOverton]

Re: Force 120 fuel recirculation possible issue

View attachment 84904

I marked you photo of where they are. The hose is the recirc line and the bolted piece should be taken off, gasket normally able to be reused (only $2.5 if broken), and the screens need to be cleaned with brake cleaner or carb cleaner. The screens are in the bolted pices. I used a brass golf club brush to clean screen. If the are bad see about getting new ones. Check the valve by sucking and blowing into the hose when you have it off. If it is pluged, only use isopro to clean. Make sure you get all the liquid out. Carb cleaner might eat the hose. Don't know for sure.

Had the same thing with my force 120. Found out after cleaning the recirc it was a thrown ring. Might want to check compression before getting into this. Second piston from the top is the one that went on mine. Only showed 10psi difference when it started. Gradually got worse the more I drove it.

I cleaned the screens with some sea foam and a nylon brush, they are now clear. The part I am confused about is the 2 lines shown in the manual on page 233 of the Clymer manual, items 6, 10, 11, and 12. These are the not installed on my motor, and there is not a port to install the check valves 11 and 12. Items 4 and 9 are not tee fittings, they are regular hose fittings.
I'm just trying to get my head wrapped around the missing parts. At the end of the summer the motor was running great. I'll check the compression again, though I don't suspect a problem there. As far as extended idling fouling plugs, the time was roughly 5 minutes, and I have idled it for longer with no issues so I can't see that being an issue, in November the plugs were good after doing the de-carb.

By the way, my motor is model 1208F91C serial no 022xxx

Any help is appreciated.
Ken

My motor is a

 

[Frank Acampora]

Re: Force 120 fuel recirculation possible issue

Your engine's fuel recirculation system is set up correctly. There are no check reeds and there are no tees in the lines. Clymers is not always correct and it is also written for generalities--they may show later or earlier engines in the illustrations.

later model engines did have tees in the recirc lines and the extra hoses went to the center and upper crank bearings, not back into the cylinders.

On the older models like yours, I never liked the arrangement since one cylinder gets the excess oil/fuel from both of the set (of upper or lower two cylinders) and this is injected directly into the bypass port. Personally, I drill and tap the manifolds 1/16 NPT and insert the nipples into them so the long tube is centered inside the manifold just above the reed plate. Then I connect the hose from the bottom two cylinders to the top manifold and the upper cylinders to the bottom manifold.

Since the manifolds are always under some vacuum, the puddled fuel/oil will always run into them, and be mixed with the incoming fresh charge. To my way of thinking, this puts much less mixture into each cylinder, puddling is eliminated or reduced, and idle is improved.

 

[j_k_bisson]

Re: Force 120 fuel recirculation possible issue

Again don't worry about what you don't have, "Tee's and fitting's", the clymers is not the best book for working on this system. Hel I had a wrough time figuring out the factory manual. Just check them when you have them apart for flow. If they do not have check valves in them don't worry about it. If they do great. You just want to make sure that the fuel can flow throu them.

Like I said before double check the compression. It is you fist step of diagnosis every time. The next is spark, then fuel. Keep posting until you figure it out.

Hell I have seen one bad plug cause this also. How often do you change plugs?

 

[puddle jumper]

Re: Force 120 fuel recirculation possible issue

Since the manifolds are always under some vacuum, the puddled fuel/oil will always run into them, and be mixed with the incoming fresh charge. To my way of thinking, this puts much less mixture into each cylinder, puddling is eliminated or reduced, and idle is improved.

I was thinking along the same lines with my 50hp but running the lines back to the fuel tank. Not trying to hijack the thread but would this lean the engine out? I have the exact problem with my engine.

 

[Frank Acampora]

Re: Force 120 fuel recirculation possible issue

No, it won't lean the engine because the puddle system only squirts fuel/oil mix into the one cylinder at idle. During high speed operation, fuel stays vaporized and does not puddle. Oil droplets or mist will be slung through the engine too. This system is in place solely to improve the idle of the engine. In engines that idle a lot, oil will tend to accumulate and settle into the crankcase and bypass passages. Eventually, it will become enough to enter the cylinders as a slug and of course, the plug can not fire it.

SO: It may seem counterintuitive to pump oil into only one cylinder but, the puddle system moves this puddled oil and burns it BEFORE it becomes such a large amount that when inducted into the cylinder, it causes a misfire.

 

[KenOverton]

Re: Force 120 fuel recirculation possible issue

Again don't worry about what you don't have, "Tee's and fitting's", the clymers is not the best book for working on this system. Hel I had a wrough time figuring out the factory manual. Just check them when you have them apart for flow. If they do not have check valves in them don't worry about it. If they do great. You just want to make sure that the fuel can flow throu them.

Like I said before double check the compression. It is you fist step of diagnosis every time. The next is spark, then fuel. Keep posting until you figure it out.

Hell I have seen one bad plug cause this also. How often do you change plugs?

Thanks everyone, I just wanted to be sure someone had not done something odd with the fuel recirc as I keep finding on everything else I have an issue with. As far as the plugs, they were installed last summer and when I did the sea foam thing they were checked and looked great. What first made me look at the fuel recirc was when I started it prior to taking it out, the engine did not want to idle at all, and every time it would cough it would almost blow the upper hose off at the lower fitting. Hose was very soft, so I changed it and then the idle was fine. As of now all the hoses have been changed, and when my water pump pieces arrive, I will check the compression and the plugs. Having to change the water pump upper body and the impeller housing because when I had it out 2 weeks ago, it began not pumping water at idle, but above idle was good. Took it apart and found the impeller housing had been installed incorrectly and it would spin with the impeller. That's what I mean when I say I keep finding things done wrong.

Thanks again.
Ken

 

[Bustedknuckle84]

Re: Force 120 fuel recirculation possible issue

i have the same issue with the no water at idle, so is that true? I had a 130 thermostat on mine then a 110 and stil lthe same issue as yours described. but im lost on what is installed incorrectly?

 

[foodfisher]

Re: Force 120 fuel recirculation possible issue

When my recirc. system was clogged, heavy smoke was the symptom. Hadn't put it on the water yet.

 

[KenOverton]

Re: Force 120 fuel recirculation possible issue

i have the same issue with the no water at idle, so is that true? I had a 130 thermostat on mine then a 110 and stil lthe same issue as yours described. but im lost on what is installed incorrectly?

If you have the same set-up, the cup that the impeller sits in has a tab to prevent it from spinning with the impeller. Mine had been installed previously with the tab out of place, so that at idle it would spin with the impeller, so no pressure would build. When I went to straighten out the tab, it broke, of course, since stainless steel is not very forgiving when it is bent more than once. Not sure what the differences is between a '99 and a '90.

Hope this helps.
Ken

 

[KenOverton]

Re: Force 120 fuel recirculation possible issue

Again don't worry about what you don't have, "Tee's and fitting's", the clymers is not the best book for working on this system. Hel I had a wrough time figuring out the factory manual. Just check them when you have them apart for flow. If they do not have check valves in them don't worry about it. If they do great. You just want to make sure that the fuel can flow throu them.

Like I said before double check the compression. It is you fist step of diagnosis every time. The next is spark, then fuel. Keep posting until you figure it out.

Hell I have seen one bad plug cause this also. How often do you change plugs?

Had a little free time so I checked compression and plugs, all are good. Compression #s are 160, 165, 160, 160. As soon as my parts arrive I will get it running and take it out and see if my problem is fixed. I'll let ya' know.

Ken