Engine or Electrical Problem?

S

SEAHorse38

New Member
Dec 29, 2008
5
I own a 2006 38 Sundancer with twin 8.1 S HO Mercruisers. The engines start fine but shortly after starting one or both engines quickly zero out on the tach and come back on. I hear the ignition beep each time this happens and usually the engines surge a bit before going back to the original rpm. So far my mechanic has replaced everything and I have spent well over $2,000 trying to solve this issue. I trust my mechanic but he says he is stumped. We also tried replacing a PCM Module (another $1900) which also did not help. He suggested replacing the other PCM but at a cost of $1900 each I told him to wait. This has been going on now for a year! has anyone had this problem and, if so, what was the fix. Thanks.

Steve
 
SEAHorse38 said:
I own a 2006 38 Sundancer with twin 8.1 S HO Mercruisers. The engines start fine but shortly after starting one or both engines quickly zero out on the tach and come back on. I hear the ignition beep each time this happens and usually the engines surge a bit before going back to the original rpm. So far my mechanic has replaced everything and I have spent well over $2,000 trying to solve this issue. I trust my mechanic but he says he is stumped. We also tried replacing a PCM Module (another $1900) which also did not help. He suggested replacing the other PCM but at a cost of $1900 each I told him to wait. This has been going on now for a year! has anyone had this problem and, if so, what was the fix. Thanks.

Steve
Click to expand...
My 5.7s 2000 310 does that sometimes on the stbd engine. I know it is my start switch.I plan on replacing it soon.
 
SEAHorse38 said:
I own a 2006 38 Sundancer with twin 8.1 S HO Mercruisers. The engines start fine but shortly after starting one or both engines quickly zero out on the tach and come back on. I hear the ignition beep each time this happens and usually the engines surge a bit before going back to the original rpm. So far my mechanic has replaced everything and I have spent well over $2,000 trying to solve this issue. I trust my mechanic but he says he is stumped. We also tried replacing a PCM Module (another $1900) which also did not help. He suggested replacing the other PCM but at a cost of $1900 each I told him to wait. This has been going on now for a year! has anyone had this problem and, if so, what was the fix. Thanks.

Steve
Click to expand...
I can't solve your problem, but I'd find a new mechanic who doesn't just throw parts at it hoping it will work. Get some one that knows what he's doing.
 
Did your mechanic check your cool fuel modules?
My boat had the same symptoms and I had to change both modules and injectors.
its a known issue and parts are still under warranty by mercruiser ( not the labor though).
 
Did you ever solve this problem? I am experiencing the same problem. I assumed the issue is a ground but I am not sure. It is only for a split second then everything is normal the rest of the day.
 
pog mo thon said:
Did your mechanic check your cool fuel modules?
My boat had the same symptoms and I had to change both modules and injectors.
its a known issue and parts are still under warranty by mercruiser ( not the labor though).
Click to expand...
Hi pog mo thon. How did you get mercruiser to pay for the parts? I have a 2005 and I had to replace both modules last year. Paid out of pocket. Be great to get reimbursed.
 
I was going through the same symptoms as the OP. After changing plugs, wires and rotor caps with no success resolving the issue.
MM decided to check the fuel system and that’s when they realize the flaking paint in the module. They had to fill up a formal warranty request with the manufacturer before we approve for the repair.
My engines are from 2007 and I believe the tech told me it’s a known issue since 2006 but I can’t be sure.
FYI labor is on you and will set you back $600 per engine.
 
I had simular issues. turned out i need a new crank shaft sensor. took days and hours to figure it out. just swapped sensors from one engine to the other until the gremilin followed to the other engine. mystery solved!
 
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