posted 03-13-2009 08:29 PM ET (US)        

I have just completed a Powerhead Rebuild on a 1999 135 Optimax. Everything seems fine, engine starts immediately and pumps plenty of water. I have checked Temperatures with an external thermometer and they seem fine. Alternator is charging. Pressure differential is OK as well 10 PSI (80 - 90). The only issue I have is that if I try to accelerate the engine does not respond. It idles fine but it will not increase RPM past idle.

Unfortunately although I have a DDT I only have the Smatcraft v1.3 Cartridge and I do not have the Outboard v 5 Cartridge needed to check this engine. Because of this I have not been able to troubleshoot this issue.

Can anyone point me in the right direction and tell me why this engine would not increase RPM? Could it be that a Guardian mode has kicked in? If so what should I be looking for without a DDT?

posted 03-13-2009 09:29 PM ET (US)            

Thanks for your comment. I think you are right!

The Manual points to a TPS (Throttle Position Sensor) error. This engine has 2 TPS and apparently if they both fail the engine can only idle. I will investigate this further and bring an Update by Monday.

posted 03-15-2009 06:28 AM ET (US)            

I can confirm that I had swapped the connectors of the 2 TPSs and this had caused this issue. Following the wiring diagrams I connected the correct color cables to the inner and outer TPS and the RPM is now working correctly!