I've got a Force 85 HP, Model 856X7A, Serial 1331. I installed it on my 1961 Crestliner Chieftain two months ago, after running it on a test stand.
Y'all helped me get this motor running this summer, and it was going great in a tub of water in the driveway. I let it sit two months while I fixed up the boat itself, electrical system, and mounted the engine on the boat. I ran it several times installed on the boat in a tub of water and saw no problems.
I put fresh fuel in the portable tank and I took it out on the lake today: it barely ran!
Here's the one thing that I changed on the engine: My old fuel line and bulb was beat. I replaced the bulb and line, only the fuel line on there was such a small inner diameter that it barely fit over the nipple on the fuel supply filter at the engine. I bought a 3/8" inner diameter line for fuel supply, new generic SeaSense bulb at Walmart and hooked it all up.
Today the engine ran super-rich, apparently. I could only idle it with the throttle cocked to 3/4 open. It missed repeatedly at all power settings, and would stall out below half-throttle. I couldn't go into reverse without stalling, I got it to go forward, barely, and then took it off the dock. I thought if I ran it hard it might clear it out. It ran great for about 5 minutes, except for the occasional miss. Then it bogged down and would only give me about 20%power on the way back to the dock, even with the throttle at 3/4. Full throttle would stall it out.
Checked the plugs when I got home, and they're all very dirty. The bottom plug was pitch black and greasy/ sooty. So I fouled the plugs during the endeavor. Over-rich, I assume.
Where do I start?
Is the inner diameter of the fuel line a factor? If so, what I/D is required for this engine? I have the Clymer manual, but I can't find that spelled out anywhere.
Also, I haven't taken y'all's advice yet about changing the water pump either. I've read the manual and I'm not sure I'm up to the task. I was going to run it around the lake and put it through it's strides before I dug into that project.
So at this point, would you recommend taking this to a shop, getting the water pump done and asking them to tune this thing up? Should I replace this fuel line and tackle the tune up myself?
Does anyone have any clue what's a fair price estimate on a water pump install for this engine, and also a tune up?
Don't know where to start, or what to do. Little discouraged at this point. I was so close! Any ideas?