Force 85hp Fuel Issue..#3 cylinder spark plug dry..Motor losing power at WOT..Carb

[dngbt5]

Ok I took the boat back out today and was very happy for a couple trips around the lake. After starting and stopping a three times I took off again, the boat planed out I slowed to a crawl for an on coming fisherman and took off again. She once again planed out again but after a few moments the motor began to pulsate and lose power. I stopped, removed the spark plugs and the third cylinder looked dry compared to the other two. I took off again a couple times with the same results. It definitely seems to be a carb/fuel issue.

What could be causing this problem? It definitely seems like a fuel delivery problem to me?

Seems that this float/needle is sticking Closed to me? How could this be happening?

I have replaced the fuel pump diaphram. Is there anything else I could do with the Fuel pump? Jets to clean/replace inside the fuel pump?


What I have:
1988 Force 85 hp On a Bayliner Capri 1700 (856X8A)

What I have done:
-Checked compression 125 on all cylinders when cold
-checked all ground and ignition wires for solid connections
-replaced Trigger
-replaced all fuel lines and bulb
-checked for spark - have good spark on all cylinders
-replaced fuel pump diaphram
-removed and cleaned all carbs
-checked and adjusted timing.

 

[foodfisher]

Re: Force 85hp Fuel Issue..#3 cylinder spark plug dry..Motor losing power at WOT..Car

You could have run the fuel level down to where it is now picking up some debris in the tank.

 

[jerryjerry05]

Re: Force 85hp Fuel Issue..#3 cylinder spark plug dry..Motor losing power at WOT..Car

Good comp/spark and fuel?? You should be running great!!
Clean the carbs again.When you take the affected carb apart,look at it and see if the needle is stuck in the seat.
They should fall out when taken apart.
A tiny piece of dirt will make it stick.
Install a filter between the pump and carb.
Wally World G12 or G2 depending on hose size.
You have a water/fuel seperating filter?
Install one and check every month.
Any water on the plug?

 

[dngbt5]

Re: Force 85hp Fuel Issue..#3 cylinder spark plug dry..Motor losing power at WOT..Car

I removed the carbs, cleaned them, and check to make sure all needles and floats were working correctly. Everything looked good. I also checked out the linc and sync thread from Frank A and followed his instructions to the T. Also I adjusted the timing and have it set to the single mark at idle. There is a triple III mark also but it didn't seem that I could even adjust it to that point. Is the single I mark correct at idle? I took the boat again yesterday after working on it again and it ran great. However, I was by myself and there was no load on the boat. Today I took it out again and had three friends in the boat and it ran good also, It was a little slow on the whole shot but I probably had about 800 pounds in the boat at the time. I was really proud of the boat and then another buddy showed up and he weighs about 230 himself. After he got in the boat I took of and it took a little bit but the boat planed out, but soon after maybe 20 seconds the boat once again began to bog and lose power. If I stopped for a few seconds and took another whole shot it would once again plane out and then bog. Seemed to be losing one cylinder. I checked all the plugs and they all looked the same (pretty dark wet and dirty, but they always have been) none were dry as the number three had been previously. I am thinking I am running the carbs a bit rich, and under the heavy load I am fouling a plug. I have the turned the jets to about 1 to 1&1/4. I am a little worried that the guy who worked on this boat before I owned it over tightened the screws and may have damaged the seats as they were all the way closed when I got the boat and it still ran. I am scared to closed them any further as Frank A says not to close past 3/4 and most people have said 1 to 1&1/4 works good.

I have replaced the screws themselves and they seem to be a little loose ( they turn very easily and am worried they may vibrate open or closed) Could this be my problem. It sure seems to be a fuel issue to me.

 

[dngbt5]

Re: Force 85hp Fuel Issue..#3 cylinder spark plug dry..Motor losing power at WOT..Car

Had the boat out a couple times since I was last on here. I took it out the first time and it ran horrible. After messing with the air screws on the carbs I realized that I could close them completely and the motor still ran. From what I know this should not happen. I am guessing that the guy who worked on it before I bought it drilled the seats out because he couldnt get it running or was trying to get more horsepower?. So what I did was close the top two carb screws and open the bottom one about 1 1/2 turns out.
It ran awesome immediately after that for about six trips around the lake until I went in. I checked the plugs and the top two look nice and wet with fuel and the bottom one was too but not as fuel soaked as the top two. I took it back out on Sunday and it ran awesome again I even went wake boarding for a while and then all the sudden she lost power again.
I did notice that the bulb was all the sudden ca lapsing, when I would squeeze it it did run better. I was about at half a tank at that point. I did check the fuel pump diaphram and the filter before it and it looked good.
I know I have a problem with the seats, but she seems to be starving for fuel. I have been told there is not a filter in the tank, but I am wondering about it now?
Do I need to buy new carbs? I dont think there is anyway to fix the seats? Are there screws that I could find to actually make a good Seat and therefore be able to adjust them?

Please Help

 

[bentle]

Re: Force 85hp Fuel Issue..#3 cylinder spark plug dry..Motor losing power at WOT..Car

A flat primmer bulb is a sign of either a plugged pre screen on the fuel pickup tube in tank or a plugged fuel vent. Also check the quick connects for any blockage. Never run carb screws closed for long periods of time or major motor damage will result.