Mercury 200 EFI Starting problem

I own a 1996 Astro with a Mercury 200 EFI. I have inermitent starting problems. Had boat in water Wednesday for several hours with no cranking problems. Friday several hours- no problems. Saturday cranked for 10 seconds in driveway, trailered to launch and started, no problems. Then when speeding up- shut off and would not restart. Would spin but did not seem to fire. Checked spark at house, present. Put on charger for 5 hours- cranked. Should mention 1) was on a trickle charger overnight,2) recently had both voltage regulators changed 3) new battery 750 MCA deep cycle that was load tested at two different places Saturday, 4) new contoller with new kill switch checked and was on RUN. This same type scene has happened prviously. Boating shouldn't be this hard!

Re: Mercury 200 EFI Starting problem

This may not be your issue but the EFI engines require a lot of MCA, I think generally 1,000MCA is recommended. They need to spin a certain RPM strongly to start correctly.

Re: Mercury 200 EFI Starting problem

Agree, these big engines need all the battery power they can get. Start by ensuring all battery/starting cables are clean and BRIGHT, posts are clean and connectors are sufficient size.

Re: Mercury 200 EFI Starting problem

check your fuel pressure while cranking. You'll need a fuel pressure gauge.

Re: Mercury 200 EFI Starting problem

Thanks for input. Been thinking might be battery. Going there first then to fuel (seems easier routing)