I have a 1999 15hp 4 stroke Bigfoot with electric start ,power tilt and controls at console as a kicker that will not run well passed 1/2 throttle. Boat is a new to me 18.5 Lund aluminum ( main motor is a 4.3 merccruiser mefi3 that also runs very rich and backfires but I'll start a separate post for that) 15hp idles well but It shakes and has no power as I accelerate. When running on muffs there is carbon buildup/soot from exhaust. Running rich.
what I've tried so far is:
-changed oil and filter
-new gas( ethanol free) blew out lines, inline filter.
-changed plugs, old ones were black and carboned up. No change
-went over the wiring as per service manual, a few wires weren't terminated correctly. Now matches the electric print. The motor seemed to run as it should on muffs after this. But no change under load in water. Once back home symptoms are the same on muffs
-my father in law pulled apart the carb and cleaned it. originally the float was stuck and fuel spilled everywhere while pumping the bulb. So the carb was torn apart twice and cleaned once before any troubleshooting and at this point. No change.
followed manual trouble shooting for motor not revving above 2000rpm
-took off oil press switch, tested ok. contact changes state at 2.5-3 psi.
-resistance readings are within spec except for primary on the ignition coil. Spec is0.14- 0.24 ohms. (From memory, I don't have the manual with me right now). I am getting 0.6 ohms. Went to buy new coil, Measured the new coil before buying and the primary gave me the same 0.6 ohm reading. I decided not to drop 172$ for a new coil that matches my readings.
I think is about sums it upfront memory, my notes with resistance values and serial number for motor are not with me at the moment I will post them shortly once I get back to the shop.
i have a DVA on order arriving in two days.
Any ideas with a path forward would be appreciated. Thanks in advance.
Dan
what I've tried so far is:
-changed oil and filter
-new gas( ethanol free) blew out lines, inline filter.
-changed plugs, old ones were black and carboned up. No change
-went over the wiring as per service manual, a few wires weren't terminated correctly. Now matches the electric print. The motor seemed to run as it should on muffs after this. But no change under load in water. Once back home symptoms are the same on muffs
-my father in law pulled apart the carb and cleaned it. originally the float was stuck and fuel spilled everywhere while pumping the bulb. So the carb was torn apart twice and cleaned once before any troubleshooting and at this point. No change.
followed manual trouble shooting for motor not revving above 2000rpm
-took off oil press switch, tested ok. contact changes state at 2.5-3 psi.
-resistance readings are within spec except for primary on the ignition coil. Spec is0.14- 0.24 ohms. (From memory, I don't have the manual with me right now). I am getting 0.6 ohms. Went to buy new coil, Measured the new coil before buying and the primary gave me the same 0.6 ohm reading. I decided not to drop 172$ for a new coil that matches my readings.
I think is about sums it upfront memory, my notes with resistance values and serial number for motor are not with me at the moment I will post them shortly once I get back to the shop.
i have a DVA on order arriving in two days.
Any ideas with a path forward would be appreciated. Thanks in advance.
Dan