1987 force 50 no fuel to one cylinder

Robmorgan357

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I have a 87 force 50. So a couple weeks ago my motor starting running rough so I did a good seafoam clean. I took it out and it started great idled great took off and ran full throttle great for about 5 min then boom started running like it was misfiring. It felt like she wanted to go full power but hesitated wanted to go but hesitated continuesly Shut it down came home and started testing. The plugs were brand new but pulled them out to check them and one was burning white and the other was normal fuel oil mix.. so fuel isn't getting to one of my cylinders. I checked fuel to the carb it was flowing good through the filter and pump I checKed compression both were at 130.
 

Nordin

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Check spark for both plugs.
Clean the carb and then check the reeds.
 

Robmorgan357

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They both do but What does spark have to do with no fuel getting In to a cylinder? I ordered a carb kit so that comes Tuesday I have no idea about reeds or what they do.
 

jerryjerry05

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IMPOSSIBLE for the fuel to only get to one carb.
​Unless someone's stuck a rag in the reeds.
The carb kit's a good thing to have if the old carb is corroded and full of crud.


It sounds more like a missing spark problem.
The 87 depending on serial/model # has 2 ignition systems.
One has points the other a CDI ignition system.

You have a blue cdi and 2 blue coils?
Or 2 black coils and no CDI??

It might be a simple trigger lead broken under the shrink wrap or the points dirty??

Tell us what you have and we can direct you further.
 

Robmorgan357

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I only have 1 carb. I state fuel is only getting to one cylinder I have no issues with spark.. no offense but did you read the question or am I not clear when I say I'm only getting fuel to one cylinder I do not have spark issue both are firing fine.
 

Nordin

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Robmorgan357 check for spark is the first thing to do when you got problems, thats why we suggest for that first.

In your case you have checked for spark and that is okey.
Next step is check the reeds as your engine only have one carb and it feeds both cylinders.

The reeds is behind the carb.
Loose the carb with the manifold. There you have to sets of v-reeds (8 pedals for each cylinder).
They are working like checkvalvs to lead fuel/air mixture into each cylinder.
If one or more are broken or there is a gap more then 010, they might not seal and mixture is not reaching the cylinder.
 

Jiggz

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I only have 1 carb. I state fuel is only getting to one cylinder I have no issues with spark.. no offense but did you read the question or am I not clear when I say I'm only getting fuel to one cylinder I do not have spark issue both are firing fine.



Actually you were very clear in saying, "You're only getting fuel to one cylinder . . ." Which is why Jerry said it is IMPOSSIBLE considering there is only one carb that feeds both cylinders. If one cylinder gets fuel and there is only on carb feeding both, then the other cylinder surely gets fuel also. UNLESS, you have broken reed on one of the cylinders you said is not thing any fuel.

Reeds are like check valves between the carb and the crankcase cavity/plenum. During piston's upstroke, it creates a low pressure at the crankcase cavity hence forcing the reeds to open (it only opens to the crankcase side) allowing air and fuel mix from the carb into the crankcase cavity. At the piston's TDC position, cavity pressure equalizes with atmospheric pressure and the reeds closes.

During the piston's downstroke, with the reeds closed, this creates positive pressure on crankcase forcing the air and fuel mixture into the cylinder thru the intake port. As soon as the piston clears the intake port, the fresh air and fuel mix rushes to the top of the cylinder and at the same time forcing the exhaust to the exhaust port. The piston crown is specifically designed with a deflector to help in this process.

Now if the reeds are not faulty, then it could be that a seal in the crankcase is leaking air. To double check you are not getting fuel into the suspected cylinder. do the simple paper test. Remove the spark plug, get a white sheet of paper and place it about 2~4 inches away from the plug hole. Crank the motor over for about 3-4 revolutions. Do you see fuel spray on the paper? For comparison, do the same with the other cylinder. Is the fuel spray pattern almost the same?
 

jerryjerry05

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I read it.
​And gave my opinion on what I thought the problem was.
Without being able to work on it myself??????????

You said it was running normal and then boom it dropped a cylinder.
That sounds more like an electrical problem.
You said. ​the plug was burning white and the other normal oil.??


You have a points system or CDI??
Depending on the system: the cdi the pack could be dropping a cyl.
The stator can drop a cylinder.
The trigger can drop a cylinder.
Points system: condenser can drop. the points can the coil can.

I have twin 85's on my boat.
The port motor would miss at an idle.
Then once it got past the lower rpm's it ran great.
Then one day the miss didn't go away.

The trigger lead for that cylinder, under the shrink wrap was broken.

Like I said I read it,
Just posting from my experience.

There isn't a seal between the cylinders
 

Robmorgan357

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Ok so I did a compression test both were at 130. I had the carb rebuilt I rebuilt the fuel pump and a put new hose on also put all new gaskets on intake carb an pump. I can spray around with carb cleaner an don't affect idle at all so don't think their is a leak. It starts and runs fine for hours at a idle no miss or jump smooth as can be. I took it on the water it started great ran for about 6-7 minutes full power then slowly kicked down and shut off. Tried to start it back up it wouldn't start unless I was giving g it throttle as soon as I put it in gear it would die unless I gave it full throttle the it only ran half speed at full throttle but didn't feel any kind of miss. Got back home hooked it to the muffs it started fine just normal ran at idle no problem for an hour. Tested the coils their putting out 12 amps. Would they drop amps at a higher rpm? Thermostat issue? I have plenty of water coming out of it.
 

jerryjerry05

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From the description, 1: you have a restriction in the fuel system.
Check the hoses and the check valve in the squeezie.
​Check the vent on the tank.
Any inline connectors? They can suck air and cause this.

2:eek:verheating pull the thermo and replace the impeller.
 

Robmorgan357

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OK so I'm sorry it's been a few weeks had a injury. So I am still having a issue. At full throttle it only goes about 10 mph. It starts and idles great. I can troll all day without a issue. I have had the carb rebuilt. I had the fuel pump and filter replaced, I put on a new hose and have a new tank, compression are both at 130, their is spark. Coils reading 12 just sitting at idle, replaced thermostat, impeller is good pushing plenty of water. now the problem is when I give it throttle it feels like it has power but won't go over about 9-10 mph. A few people say spark but the coils are testing at 12 amp and plugs are firing. Now could their be a stator issue?? Like a high side or something like that. Is it testable out the water? I'm so lost I don't know what else to do
 

Robmorgan357

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Oh I also had the reeds out cleaned them they moved and open easily I put on new intake gaskets as well
 

Robmorgan357

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It sucks I called 4-5 shops and none of them would even look at it cuz it's to old or try don't work on force motors.
 

jerryjerry05

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If it sounds like its running but not going anywhere???
​Then the hub in the prop might be spun?
Remove the prop, scribe a line across the hub, reinstall and go for a ride.
Then if it does it again?? Pull the prop and see if the scribed line has moved.
Where you located?
 

Robmorgan357

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And how is that gonna work if I can low speed troll and get up to 10mph the prop is spinning to move the boat
 

Nordin

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The prop hub has rubber in it, no share pin.
The rubber will hold it at low rpm but will slip at higher rpms.

The symptomes is that at higher rpms the engine will rev up, but no speed increase
 

Robmorgan357

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Def not the prop the shaft it sits on is not smooth it's kinda like a sprocket it has groves it slides onto..
 
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