2002 Response w/Hammerhead running rich

[Gary Pelletier]

Crew - love the forum and appreciate the information/feedback. I have a 2002 Response Barefooter with Hammerhead. Starts, idles, runs great at all speeds, great power - only complaint is that at idle there is a overpowering "unburnt" gas smell from the exhaust (not present when engine is off). Seems the engine is running rich. It's recently been through a PM (cap, rotor, plugs, oil, filter, etc) and has 725hrs. All the plugs looked good during swapout - don't think I have a fouled plug, etc. Pretty sure the condition was present before the maintenance and haven't paid much attention as the boat runs great. Several skiers, barefooters have mentioned that gas smell when circling around to pick them up - so I figured it's time to poll the experts! Thoughts?

[electricjohn]

A fauly or failed ECT (engine coolant temperature) sensor would cause the ECM to run the engine rich, making it think it is always cold. But this also causes hard starting of a warmed up engine. If it starts normal once warmed up, look elsewhere.

[Gary Pelletier]

A fauly or failed ECT (engine coolant temperature) sensor would cause the ECM to run the engine rich, making it think it is always cold. But this also causes hard starting of a warmed up engine. If it starts normal once warmed up, look elsewhere.

Electric - great pickup! I do notice it takes a couple of extra "cranks" to fire up when warm (unlike the immediate start when cold). I'll try replacing the ECT....

[electricjohn]

The sensor can be tested with a multi-meter. Any auto part store would have the part. It is a basic GM part.

Edited July 18, 2010 by electricjohn

[Gary Pelletier]

The sensor can be tested with a multi-meter. Any auto part store would have the part. It is a basic GM part.

Swapped out the part this afternoon - boat starts great when warm and the gas smell when idling has all but disappeared. Thanks!

[electricjohn]

No problem, it is nice when you can solve a problem with only 1 or 2 reply's.

[SURFRAY]

A fauly or failed ECT (engine coolant temperature) sensor would cause the ECM to run the engine rich, making it think it is always cold. But this also causes hard starting of a warmed up engine. If it starts normal once warmed up, look elsewhere.

I have a similar problem with a rich smell when running and idle. Also collects some black soot on the transom every time I ride. Mine is a 2006 Hammerhead with 520 hours. It doesn't start hard when warm, I've changed the ECT and the water thermostat because it took so long to reach maximum engine temp. I did change the fuel filter and checked the pump strainer about 200 hours ago but there was no change in the rich smell or soot. Otherwise performs good, just really annoying. Any thoughts? Thanks so much!!