2001 200 efi Hard to explain issue.

[fledderw]

Mercury 2001 200 EFI

Serial #OT334140. Rebuilt in 2015 with Mercury remanufactured power head. At that time they also rebuilt the pulse fuel pump and cleaned and calibrated the injectors.

It has run perfectly since the 2015 rebuild until Friday morning Sept 2. On that morning, when I tried to plane out it went into like a "guardian mode", only reving to 1800 RPM. It did not shut down. After about a minute of this it returned to normal and planed the boat.

Ever since this it keeps happening again and again at random. When I can get it to full throttle it runs normally at 5800+ RPMS at 67 mph.

It still always starts up as normal. At crusing RPMs (3500 to 4500), it will sometimes act like it is cutting out for a second and then returns to normal. However when I slow way down at times it then goes into this "guardian mode", for a while. The warning buzzer does NOT sound.

I checked the spark plugs and they look OK. No evidence of fuel or oil leaks or insulation cracks on wires. No kinks in fuel hose.

I know this is either a fuel or ignition issue. I am leaning towards ignition/ECU.

I am working with a dealer and using the service manual. I don't have the tools or skills to do many of the tests suggested in the manual.

The engine has the old ECU #824003A30, renamed 8M0068753 which is no longer available. It does not save any codes and is not Smart Craft compatible. From reading various posts, I conclude this ECU has a reputation.

I am not sure but I don't think this engine is designed to go into a guardian mode.

I plan to change the spark plugs and the fuel filter water separator and then retest. Also will check the fuel pump pressure.

I welcome any ideas or comments.

[JOE54]

fuel psi when problem occurs , right no guardian , reputation for sure , explained very well

[fledderw]

Update - Put new spark plugs and water separator / fuel filter as advised by dealer and it still does the same thing.

[JOE54]

horn still sounds at take off ?????

[fledderw]

No, the horn does not sound at all while running.

It does sound when I first turn the key to on as it is supposed to, indicating it is working.

[JOE54]

correct no guardian on it , if fuel psi test passes find another ECU for a test or isolate which cyls are dropping out , would bet 5 and 6

[fledderw]

If I swap ECU's for testing, is a full "sync and Link" required?

[JOE54]

no sir

[fledderw]

Update - I have noticed a pattern when the engine sits unused for a while it runs perfect at first, but after I slow down to an idle and try to plane the same issue happens - max 1800 Rpms. When in tis mode it idles at a slower 600 RPMs and runs rough. Normally idles 650 Rpms.

I winterized the engine and put it away for the winter. I will take it to a dealer next spring (April). All Mercury service center in my area are too busy to look at my motor anytime soon. I dont want my rig to sit outside in winter.

I winterized it by the service manual, removed all 6 sparkplugs and spraying in storage protection "gunk" as well as premium plus oil into each cylinder. I removed the plastic flywheel cover and attempted to turn the flywheel by hand to distribute the "gunk" and oil. However, the flywheel was stuck and would not turn by hand. I then turned the ignition on to distribute the gunk and oil mix (all spark plugs removed).

Thank you for all your ideas and help. I have seen several other posts on Mercury EFI engines that have the same problem as mine. That is intermittently going into a mode where it will not go over 1800 RPMs.

Does not being able to turn the flywheel by hand indicate an issue with the stator or trigger?

[fledderw]

Question: When I winterized my engine, I removed the plastic cover over the flywheel and attempted to turn it by hand after spraying oil into each cylinder (spark plugs removed). It was stuck and would not turn by hand. Is this a sign of a possible stuck trigger?

I then inserted the key and turned it to ignition and this turned the flywheel just fine to distribute the oil. This is what I have been doing in the past years.

Thank you for all your help and advice.

[leonreno]

When you say turned by hand do you literally mean by hand? Or did you use a ratchet/breaker bar with a socket on the crankshaft nut in the center of the flywheel?

[fledderw]

I attempted to turn by hand without any tools.

[leonreno]

That would be difficult, put a socket on the nut at the top with a long ratchet or breaker bar and then turn it.

[EuropeanAM]

Sounds like you're dropping two cylinders. Need to determine if it's spark or fuel (timing light, clipped to each of the 6 plug wires while watching for a flashing pattern is a simple on-the-water test you can do when it's acting up).

Very likely a loose driver on the board in the ECU. Simon Performance Technologies (BBC Sponsor) can test and repair them.

[fledderw]

Thank you Don.