Optimax won't start after being warmed up

[slyck68]

Hi all,

I have a Ranger Bass Boat with a 2001 Mercury Optimax 200 hp, Ser. #0T322497. The engine will fire up and purr on the first turn of the key every time. Idle and throttling are normal and smooth. However, once I turn it off I cannot get it to start again until several minutes have passed, sometimes as much as 45 minutes to an hour. Then, it will fire up first crank again.

In the interim where it won't start, the engine sounds as if it is cranking normally but it doesn't even sputter -- imagine cranking with the kill-switch pulled out. Some additional info that may help the diagnosis:

• The battery is a group 31 blue top Optima, fully charged. Battery is 5 years old, but I had it load tested at two different shops yesterday and both said it was in good condition.
• The alternator appears to be working fine. Battery voltage increases with engine running (tested on multi-meter).
• The bulb was going flat immediately and the fuel tanks were fairly low. I topped off the fuel tanks today and added Don's recommended cocktail, per usual. Issue still persists with brand new fuel, primer bulb still gets soft after starting. This makes me think I may have air in the lines. (My next course of action is to replace all fuel lines and bulb).
• I serviced the boat this spring, including replacing plugs with NGK IZFR5G at 0.032" gap. This is the only plug I've ever run in this boat and change annually.
• I have run the boat on the garden hose but have not lake tested.

I've owned this boat for several years now. It gave me plenty of trouble at first, but we've gotten along great the last 3 or 4 years. I've never had this type of an issue before. Hopefully someone can point me in the right direction!

Thank you all,

-Josh

[lpugh]

The battery is marginal at best for a optimax on a bass boat for starters, at five years old it very well may not be enough to meet minimum requirements, at least fully recharge it and have it tested first thing
You need to narrow it down some, test for proper spark during the no start condition

[slyck68]

The battery is marginal at best for a optimax on a bass boat for starters, at five years old it very well may not be enough to meet minimum requirements, at least fully recharge it and have it tested first thing
You need to narrow it down some, test for proper spark during the no start condition

Thank you, Leon. The more I dive into this issue, the more I'm leaning towards the battery, too. Even though it tested ok, I'm not impressed with the voltage reading I just got after cranking the motor over a few times. It fires when fully charged, but afterwards the voltage may be too low for the engine to start. I tend to recall the Optimax requires a minimum voltage before it will send the signal to fire...or something like that.

I will try a new battery tomorrow and report back. Fingers crossed!

[lpugh]

At or around 9.5 volts the master power relay may not function, no spark or fuel

[EuropeanAM]

Batteries post was updated just today- see the FAQ Section (also pinned at the top of the Forum).

Would be nice to check and see what the Air/Fuel pressures are, and whether you have spark (when it's failing to start). Have to have the "basics" to make the magic happen.

[slyck68]

Thank you to all who replied. I wanted to close this thread out with the solution for anyone facing a similar issue. I replaced the battery with the Batteries Plus AGM recommended in the updated Batteries Post in the FAQ Section. So far I have been able to start and stop the engine at will with no signs of the old problem.

I will hopefully get the boat on the water to confirm in the next few days, but for now everything looks promising. Lesson learned: even though the battery tested ok (twice), obviously it was lacking.

Don, I still plan on ordering new fuel lines/bulb/pulse pump rebuild kit from you to be on the safe side. Sounds like cheap insurance against a future issue to me.