What could be some of the things that could cause a loss of power on my Merc Pro Max 200 Ser# OG367943. I am having trouble getting on plane and not as much speed on top end but still turning the same RPM. I have tried different props changed plugs, fuel filters and checked the coils. All looks ok. I have NGK BU8Hin it and someone was saying I may need BUZ8H. Something about it not interfering with the ECU? Thanks in advance for any info.
Last edited by thaydel; 02-18-2018 at 07:10 PM.
Have you checked out the stator?
Fuel drivers in ecu can cause what your describing. I had it years ago, started intermittently and became progrsssivly worse
No, I hadn't checked the stator yet. It was replaced a year or so ago. That doesn't mean is didn't go bad again tho. Do you need a special type of gauge to check fuel system pressure? I would like to check that just to see where its at.
compression first,spark on all 6 second= timming light, report back
.................................................. ...the scariest thing in life is the unknown ...................................
The compression on all 6 is around 122, I checked the spark and all cylinders have a good blue spark and timing light flashes on all 6 cyl.
Last edited by thaydel; 02-19-2018 at 10:14 AM.
Check the sticky at the top the FAQ by Don and make sure you did the compression check correctly.
got access to a known good ecu off 200 for test,need sensors tested [air] specialy ,map ,temp ,possible injector or drivers in ecu,Does it seem like its missing sometimes hard to tell???
.................................................. ...the scariest thing in life is the unknown ...................................
It idles fine and runs ok once on plane just missing some power. With no water in live well it will get on plane but slower than normal. If I fill one live well and 2 people in the boat it will not get on plane without the other person sitting on the front deck then it will roll over. It will still turns the same RPM on top end just less speed. No missing or rough running at all, just lacks power.
Well I finally got some time to work on it again. I replaced the fuel hose from the tank to the motor, primer bulb, fuel filters and the diaphragm pump. Went test on the water and still will not get on plane. Gets to about 2300 RPM and will not get any higher. Fuel pressure while trying to get on plane is about 37-38 psi, about 35-36 at idle and holds 35 for a few minutes after engine is shut down. Drops to about 32 psi after about 5 minutes. Put a spark tester on all cylinders and all have good fire. Could it be bad or fouled injectors? This problem also progressively got worse. Didn’t happen all at once.
Last edited by thaydel; 03-28-2018 at 08:26 PM.
yes it could be injector,gonna HAVE to isolate which cyls not not working, if its 2 cyls one on each side likely inj driver bad,one cyl possible bad injector
.................................................. ...the scariest thing in life is the unknown ...................................
Just a suggestion- drop the gearcase and check to make sure the TUNER is securely fastened to the bottom of the adapter plate. Reach right up in there with a big, long screwdriver and see if you can move it around (it should NOT move at all).
Dual Mercury Master Technician- for Mercury Outboards, Mercruiser and Mercury Racing at European Marine in Greenville, SC.
Still consider myself a "Marine Apprentice" after 47 years (learn something new every day).
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Update. I had my injectors tested and 2 of them were not spraying properly. After cleaning and re-testing they were spraying properly. I re-installed them and ran the boat yesterday and problem fixed. Runs great. Thanks everyone.
lucky you didnt stick a slug, glad you got it in timeOriginally Posted by thaydel
real lucky,
.................................................. ...the scariest thing in life is the unknown ...................................
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