2001 Mercury 200hp efi not running well

[2001trophy]

Hello everyone,

Im a new memeber to the forum as you my suspect Im having some engine problems on my Mercury outboard.

Little back ground, 2001 Mercury 200hp efi serial #OT305995

Boat sat for 10 years as per seller, marina tech did check up changed, lower gear oil, water pump, eletric fuel pump, cleaned out VST. When I looked at the boat started up ran nice, I did a compression test 115 on all 6 cly on the dot.

Got the boat home, put the muffs on again ran it ran great started right up.. 2 days later put the boat in the water startes up ran rough low idle and would die.. restarted it up drove it to my slip ran rough shaking.. would bearly restart.. if you give it few pumps with the accelerator handel while off, then crank it would start but run rough.


Today changed out the water seperator, new rebuild kit on the primery fuel pump the one w diaphragms, still ran like crap.

Drained all the fuel from water selerator and fuel pump holding tank..(where eletric fuel pump is) and hooked up a external tank to eliminate bad fuel..ran ok at idle but it was to windy to take it out for test..

Fast foward 5'-6 hrs later...went back tried to start it.. would start and die..low idle and die out.. i took out the spark plugs they looked wet.. dried them w a rag put them back in boat started up and idled ok.. (little rough) let it idle for 15min.. then took it out you can feel it chocking up shaking really bad wot feels like it wants to open up then bogs down..

Voltage at bettery 12.5 boat off.... idle 12.5 but idle is low then as it warms up pumps out 13.10V

I checked the resistance on stator.. the green wires going for spark I got 395 ohms.. the 2 sets of 2 yellow wires going to volt regulator I got 1-2 omhs..

Sorry for long post just trying to provide a whole picture , exuse the typos typing on cell phone. Thanks

[JOE54]

welcome , need to check fuel psi and for over flowing vst / stuck inlet needle/bad float pull small hose that got to injector housing from vst pump bulb look for fuel leaking, pumping handle does not induce fuel to mtr only opens air valves , may have to test sensors also

[EuropeanAM]

Above all: Don't continue trying to run it until the problem has been located and addressed. IF you have a FUEL delivery problem, you also have an oil delivery problem. Continuing to try to make the engine run without appropriate lubrication can have catastrophic results.

The stator tests you did may be questionable... but likely due to a setting on your meter. 1-2 ohms would be a dead-short.

[2001trophy]

Joe54 and EuropeanAM thank you for reply.

I spent some time working on the boat trouble shooting it without much success.

I checked the fuel pressure its 34-35psi at idle and also in gear.. it remains 34psi even when dying out in gear. In gear is when it dies out turns off and hard to restart. Once its idling it runs but not smooth as it should.

Things I done.

Got another 2001 efi motor for spare parts and testing purposes.
150hp but many items are the same I believe.

1.Replaced the voltage regulators and now im getting 14.5 volts at idle vs 12.5v -13 volts before. At least that is fixed.

2. Open up open up VST verified the float works, needle not stuck, checked flow while lifting float up and down by hand. Cleaned out vst. No change. Swapped out vst from other motor no change..

2. Took out whole injector assembly, cleaned fuel rail no debris or dirt, took injectors out inspected the mesh strainers which looked clean. Checked for any stuck open injectors all seemed ok. Sprayed crab cleaner while powering up the injectors all 6 had nice steady wide spay pattern . All 6 were consistent. And no gunk came out. Pressure tested fuel rail (from pump hose to vst return inlet) held solid pressure.

3. Looked into the reed valve section with flash flight (reed plates still on motor) all looked intact no broken reeds.

When i pulled the spark plug wires off while motor running you hear the arc zapping but no real change in idle when wires pulled on cly 1,4,5 the rest 3,5,2 the motor changes sound.

4. Got new plugs gapped them to .040 no change.

5. Took the ignition control module from other motor swap it.. no change.

6. Took whole cdm plate with all coils wires whole thing swapped it over no change..

Did a compression test this time with motor warmer and throttle wide open.. all 6 cly 120psi

Loosing my mind, but at same time getting very familiar with these components and their locations lol

Things that I did not check and don't really know how to

air temp sensor, tps sensor and its position, temp sensor on head.

Things I didnt change is trigger under flywheel and the stator.. not sure if they would mess with spark timing.

Thanks in advance guys

[JOE54]

trigger most deff will that is the timer , ive had 2 in the last year both would ohm test good and had spark on all 6 but were indeed bad both on cdm mtrs like yours

[2001trophy]

So little update

Took the trigger out it had cracks in the silicone area. Installed trigger from spare motor. It idles better smoother.. was able to take it out the slip but still shakes and has no power. Definitely runs smoother.

So to be extra sure I tried a brand new trigger CDI trigger, and stator and no change.

I have a youtube link how its running now. In the video we giving it throttle even full throttle and just chocks up.. if you keep giving it throttle it wants to die... you have to put it back in neutral idle to recuperate .

[EuropeanAM]

Did you perform a Complete Sync-n-Link procedure after replacing the trigger? You MUST.

What is the fuel pressure when attempting to accelerate under load (such as the above video)?

Why did you use aftermarket electronics?

WHAT Spark Plugs (and what gap) do you have in the engine currently?

[2001trophy]

I did not do a Sync-n-Link procedure I didnt really know I had too. But I will look at the service manual how to...

I will double check fuel pressure, i know at idle and in gear it was 34 psi but did not check with that much load.

Aftermarket electronics is what i had laying around friends new parts.. i put oem stuff back. This was just for testing purposes

Plugs are BPZ8HS10 and gapped .040 as per manual.

[JOE54]

sure sounds pressure related to me ,lean lean

[2001trophy]

Joe and europeanam thank you guys for response..

Soo it seems like you guys are are 100% right w fueling issue.. i sprayed some starter fluid. Just a little since there isnt any lubrication.. the boat took off opened up and wanted to rip.. immediately i backed off.

My fuel gauge fitting for shrader is not fitting good and im not sure im getting a 100% accurate reading. When i press the bleed valve on pressure gauge definitely dosnt seem like 34psi eventho the guage is reading 34psi..

My next question.. if fuel pressure is really 34psi and not dropping under acceleration what items control the fuel deliver.. or in what order..

Ex. Tps, map, air temp.. just trying to think ahead if i need tonorder any tools or adapters etc

Just want to say thank you and really appreciate your time

[EuropeanAM]

ECM controls the fuel delivery, plain and simple. It uses inputs from the MAP, TPS, IAT, and Coolant Temp sensor to process the correct injector pulsewidth and RPM.

[2001trophy]

Ok So I have another questions guys..

I have a ecm from a 150hp same year etc.. how different are they between 150vs200hp could it be used for a test to rule out the ecm. Like partial throttle.

Thanks guys

[lpugh]

150 ECM would run extremely lean, dont try that

[JOE54]

yea needs to be 200

[2001trophy]

Just to update everyone .. sending the computer to Simmons motorsports for testing and repair if needed.

Checked the temp sensors, and tps and in spec at .245 amd fill throttle 7.60 I think the injector drivers might be the problem..

Did notice something while checking the tps voltage.. while pressing down the throttle wot some where around 3v the fuel pump would run for a 1 or 2 sec.. wont do it everytime but was able to replicate it. Idk if thats normal or not.

[JOE54]

that does not sound normal at all

[EuropeanAM]

that does not sound normal at all

^^^^^ DEFINITELY agree.

[2001trophy]

Ok guys.. so wanted to came back and update so if anyone runs across a similar issue.

I got call from Simmon the ecm had a bad map sensor and loose 5&6 injector driver.. he got that repaired and being shipped out.

Meanwhile I ordered a spare ecm . That ecm arrived yesterday. This morning installed it checked tps volts..
And she rocks! Took of nice and smooth. Runs really nice.

So turnes map sensor was bad and loose injector driver. I will test repaired ecm from simmon once it arrived.

[EuropeanAM]

Glad Eric got you taken care of.

Just remember: We don’t support the “bay”, or items purchased there in the forums.

[2001trophy]

Fixed!