1994 Mercury Black Max EFI 200HP No power under load

Hello all new to the forum
i have a 200HP Black Max EFI and over the weekend took it out and it ran like a champ for about 20 minutes then all of a sudden lost power and engine struggled above idle and bogged terribly

when I put it in neutral full idle was strong and no issues but under load it was a dog. Wondering if this is a stator problem?
if it is a stator problem I should be able to confirm by easily measuring the voltage,correct?
Will I see the voltage problem running on the trailer or do I need to load the engine ?

safe to assume +/- 13.5 VDC?

Do I need a social tool to remove stator?

any ideas or thoughts greatly appreciated



thx all

You are going to need a good service manual to figure the ignition out. It is well worth the money and they have excellent instructions on how to diagnose each part correctly. You can waste a lot of money throwing stators, coils, and switchboxes at motors. The test of 13.5 volts only test one of three parts of a stator. You have the charging part which is the 13.5 volts, the low speed ignition part and the high speed ignition part. Based on your symptoms I would not necessarily say it was a stator.

Try using this sequence to narrow down your problem:

Start with a compression test to make sure the engine is in good condition. All cylinders should be within 10% of each other. Next do a spark test with a spark gap tester to make sure you have strong spark. If both of these check out you are down to fuel and timing. If this is a new development then it probably isn't timing but a fuel issue. Start at the tank, make sure it is vented correctly and the fuel line connections are tight and not sucking air or leaking fuel. Make sure the ball pumps up good and solid without any fuel leaks anywhere (very common problem) Check the fuel filters to make sure they are clean and not clogged. If everything checks out to this point then you can try re-setting the idle mixture by following the procedures in the service manual. If this doesn't work, you probably need to work in the carbs. I personally follow this order and if I find anything along the way I fix it and keep going on this sequence until it runs correctly. Don't forget to replace your impeller and change the lower unit oil if you haven't done it recently as well.