'99 Mercury 175 not starting......then started

[kylelp]

Hey folks,

On Friday I was on the water and made several runs. My last run was 3-4 miles to a rocky island. I fished there maybe an hour. Motor would not start when I was ready to leave. Seemed to turn over but would never "catch". The battery gauge seemed show a good charge but it sounded like (from previous experience) when my car battery just didn't have quite enough juice to start my car. When I got home, I checked the voltage which read 12.8 and she started up just fine. On the water, I flicked the kill switch back and forth, wiggled some wires going to the motor and made sure the fuel bulb was full with no luck. At home the only thing I did was check the voltage. My FIL thinks there could be a loose wire(or short) where the road vibrations made it connect back. Went out Sunday and had no problems. Any one have any thoughts or what I should do? I just got it serviced and everything was fine.

[JOE54]

EFI ??????? no ser number , check all connections, did fuel pump run at key on ,possible loose driver in ecu

[kylelp]

I’m sorry, yes it’s an EFI. I will update with the S/N. Does the fuel pump make a noise when you turn it part way on?

[EuropeanAM]

If you would, please take a few moments to review the Announcements at the top of the Forum, and be sure to provide the REQUIRED info each time you post. Thanks!

As suggested, listen for the electric fuel pump when or if it fails to start. If it's failing to start, either lack one of the basics (Compression, Spark or Fuel) or one of them is substantially out of balance.

[Pokesgrad]

My ‘99 merc 175 efi is doing the same thing. I haven’t had a chance to get back on the water and continue to trouble shoot but noticed the problem shows up when the engine gets hot. If you allow the engine to cool off it will fire back up and run like a top again. Your could be different but if you make a long run and it won’t start I bet you are experiencing the same headache.

[JOE54]

possibly

[kylelp]

Sorry I haven’t responded I got distracted with other things. I went out another day and made some runs and everything did well. I asked the marine guy I took it too and he was in the same mind set of me to make sure all the connections are good and don’t worry about it. I think it is hard to diagnose if it doesn’t happen again