merc 170 starts on land but not in water

[Tom Sherwood]

I have a 1985 sea ray seville, with a 170 merc. and alpha one drive. I can start this baby with half a second turn on the key on land. but in water it will not start. I have started a couple of times while in the water but it seemed to really take a drain on the batteries. I can run around all day and have no issue with the engine running or stalling. But I turn the key off........try to start it and I can run the battery dead trying to start it. It has to be back pressure on the engine. Is there a back pressure switch or is the starter going bad, maybe not enough cranking power to blow out the exhaust when in the water?

Thanks, and Cheers,
Tom Sherwood

 

[Tom Sherwood]

Re: merc 170 starts on land but not in water

After viewing the parts list I found a exhaust flapper in the exhaust the old one was gone. must of ran hot one time or another. I will see if this could have cause the problem

 

[Maclin]

Re: merc 170 starts on land but not in water

I have heard of a blocked exhaust causing this, but it was on an engine that had been modified with a large cam. The blockage kept the idle relief ports from working as well and in the water was hard starting. Maybe the shutter did get hot and melt off the hinge and lodge somewhere "downstream". Just an idea, not sure how to test for that easily.