Engine won't do ANYTHING when hot.

[WFMTWaker]

I have a 2003 tige 22V with merc mag 350 serial # OM391368. I bought the boat used as 2nd owner with what I thought was 135 hours on it. Old guy owned it and kept it in a boat house and used when his grandchildren visited. So about the second time out on the water I turned the boat off. When I tried to restart it, nothing, like the kill switch was hit, but I don't have a kill switch. When i put the key in all instruments light up everything comes on, test alarm sounds but when I turn to start the engine nothing, not even an attempt to try to start. So after about an hour when the engine cooled off enough, boom boat fires back up. Weird thing is, the engine hours reset to 0. So this past weekend, before diagnosing said problem, I went out and just have not been turning the boat off, I was waiting for my son to suit up to surf, and I inadvertently turned the engine off, same thing waited almost 2 hours and nothing, flagged down a boat to tow me in and about half way back, boom boat fires back up. Again engine hours go back to 0. Next day I had friends in another boat and said if you see me dead in the water, come see what is happening, about an hour in I loose all oil pressure, turn the boat off, check the dip stick, and have proper oil level. Thinking that I am now not going to start, engine fires right back up. I decided to play it safe and just hang in the lake, every time I started the boat to putt away from shore, boat fired back up no problem. I just took the oil sending unit out and tested it and although the ohms were good on 241, when I blew air into it nothing happened, replaced, fired it back up and oil pressure is reading fine. kept it on the fake a lake until engine temp came back up. Fired back up no problem. Anyone have an idea what might cause the engine to do nothing when it is hot and ran awhile, and why my engine hours would go back to 0? I believe in not to long a time I will be out on the lake and not able to get the boat started again. Sorry for the long read, but i thought more information was better.

Thanks in advance to any answers.

[boatwakes]

Your intermittent start issue can be a few things. Try holding the key in the start position and moving the shifter between neutral and fwd/rvrse. If the engine tries to start, it's just your neutral safety switch. However, from your description, we have seen several problems with the 10 pin round connector on boats of that age. The connector brings power and continuity to the dash, gauge readings and start signal. It's located at the back of the motor and usually has a hose clamp around it. In certain cases we replace the connector but it's not always necessary. Instead, we will disconnect the round plug, check terminals in both male and female side (some may round out or corrode over time), reconnect and before tightening the hose clamp, will twist the male side and hold it while the hose clamp is tightened. If this resolves your issue, replace both sides of the connector.

Here's what it looks like and where to buy it:

Engine side: https://bpi.ebasicpower.com/shop/mer...volvo-crusader

Boat side: https://bpi.ebasicpower.com/shop/mer...oot-mercruiser

[WFMTWaker]

I tried the jiggle and start many times thinking that the neutral safety switch was the issue, but that does not ever happen when the engine is cold, so don't think that is the issue The weird thing to me is why the engine hours go back to zero. Does this cable interact with the ECM? I will inspect it tonight when I get home and see what the connection looks like and add some dielectric grease to it.

[boatwakes]

The dash digital hour meter is completely independent from the ECM so even though the dash gauge has failed, the correct hours are stored in the ECM and cannot be erased. Careful with the dielectric grease, you can actually block signal if the pins are sloppy in the connector. We've also bypassed the connector and hard wired those connections so for reference, the yellow with red stripe is the start signal wire.

[WakeWes]

WFMTWaker did the issue end up being with the cable boatwakes suggested? I've had a similar problem where the boat ( 2001 2100v) wouldn't start back up and had to get a tow back to dock. Took lunch and she fired back up. Ran the next two days with no issues. But I'm also afraid to kill the engine away from the dock now.