I have a 1998 75HP Force on a 25ft Crest Pontoon. It was running around 4600 rpms with a intermitant miss at high speeds. (sounds like machine gun) Eight weeks ago the high speed miss increased and also a loss of rpms which is now at 3000. (all readings from tach on dash) Also a drop in mph 19 to 14. I have worked on this and currently starts and runs but at 3000 WOT with a miss. I can improve the miss and increase rpms 50 or so by pulling the throttle back from fully fwd about 1/8" but still misses and 3000 rpms. Also in last couple weeks dash tach was working intermittently but now quit all together. What I have done in the past months with no improvement:
- New Plugs
- Rebuilt fuel system.
- started running non ethenol 100% fuel 89 octane
- Inspected pick up tube and verified vent is clear
- performed link and sync. (best improvement, smooth)
- set timing to 28 tdc as per video not running but full throttle in gear (2900 RPM test run)
- re set timing to 30 tdc running full throttle in water. (Runs more rough than the 28 setting but picked up 200 rpm 3100 now)
- Swapped all 3 CDM's with known good ones from friends motor.
- Replaced 3 recirc check valves (valves missing the checks)
- Pulled carb apart verified needle and float ok. All ports cleaned again.
- 20 amp fuse was melted bad, not blown? Replaced
- Yellow wires on regulator looked like they had been really hot/black melted connector shields. Ordered all new connectors to replace all.
- Compression on all 3 cylinders around 125
- Stator resistance W/G to G/W = 470 ohms ( out of spec low. 500-700 is spec?)
I need to order the DVA adapter for my meter I think.
I'm looking for any suggestion for going forward and if Im on the right tack with troubleshooting.
- New Plugs
- Rebuilt fuel system.
- started running non ethenol 100% fuel 89 octane
- Inspected pick up tube and verified vent is clear
- performed link and sync. (best improvement, smooth)
- set timing to 28 tdc as per video not running but full throttle in gear (2900 RPM test run)
- re set timing to 30 tdc running full throttle in water. (Runs more rough than the 28 setting but picked up 200 rpm 3100 now)
- Swapped all 3 CDM's with known good ones from friends motor.
- Replaced 3 recirc check valves (valves missing the checks)
- Pulled carb apart verified needle and float ok. All ports cleaned again.
- 20 amp fuse was melted bad, not blown? Replaced
- Yellow wires on regulator looked like they had been really hot/black melted connector shields. Ordered all new connectors to replace all.
- Compression on all 3 cylinders around 125
- Stator resistance W/G to G/W = 470 ohms ( out of spec low. 500-700 is spec?)
I need to order the DVA adapter for my meter I think.
I'm looking for any suggestion for going forward and if Im on the right tack with troubleshooting.
Last edited: