MR1 engine not running more than 6,000 RPM at times

[Konnie]

Removed the ECU today for the engine having problem.
Found water in the case. Will send the ECU to Camron Electronics for diagnostics.
Assume the water comes in from the top but does not drain from the bottom.
Any suggestions for how to seal the top and or add drain hole at the bottom?

 

[dgfreeze]

The general consensus is that it’s from water splashing up onto the swim platform, then making its way through the hinge side of the engine hatch, and down onto the ECU. I’m sure there are some cases of flooding also, but the water would have to get pretty high to reach the ECU. Most people add a strip of duct tape across the top, covering the seam of the ECU. Should be a simple and effective way to keep moisture out if that’s how it’s getting in. Hopefully others weigh in if they have found other possibilities. I’ve had both of my ECU’s apart to replace the starter relays, and they were both bone dry. I suspect the water intrusion might be compounded from some people adding ballast for watersports.

 

[dadofral]

In my experience it is spark plugs or something like weeds, in the intakes wrapped in the impeller shafts.

 

[Konnie]

So I removed the ECU of the port engine, the one that has been giving me trouble, it had a fair amount of water in the ECU enclosure.
I left it out for a few weeks. I then swapped the port and the starboard ECUs. The starboard side ECU enclosure was bone dry.
Took the boat for a test ride yesterday, The star board engine ran fine with the suspected port side ECU (the one exposed to water) at all RPMs. The port side ran fine up the 8K RPM, but would only go above 8K RPM for a few seconds and then drop down to 8K RPM, repeatedly. It did go up and down between 4 and 4.4K RPMs for a few instances as well.
Thoughts on this issue? Seams like the port side ECU isn’t the problem.

 

[84rzv500r]

one other suggestion if you get a temp sensor that is bad or detects an over temp (usually in the exhaust) it will limit engine to 6000 rpm exactly.. can you check the YDS fault code LOG ?

as said before these engines are very sensitive to spark plugs and I have had a new coil fail... Even with YDS they can be a bit tricky to diagnose..

 

[Konnie]

So got the YDS app and scanned both engines.
The engine with the issue show an error code 54, Bypass valve motor.
So the issue appears to be related to the engine not getting enough fuel, I think...
I inspected the connections to the bypass valve motor and could not see any issues.
I cleared the error code then ran the engine on a hose and the error code 54 did not reappear while on the hose.
My understanding is that I could operate the bypass vale motor with help of the YDS app but not sure what that would do or what to expect as I do not have a good understanding of the function of the bypass valve motor.
Any help / suggestions are greatly appreciated.

 

[Beachbummer]

I thought that was for no wake mode. Wet ECU= injector driver probably shot. But it worked fine on the other engine so that should not be it.. I see your already swapped them.

Are you in salt water? Hows the oil look?

 

[84rzv500r]

Low fuel pressure will limit MR-1 max RPM... the symptoms is they go lean and feel like they loose power... if pulling back on the throttles feel like the power comes back its a good indication... they lean out...

I have fuel pressure gauges in my opinion they are mandatory for understanding engines... MR1s like 47-52 PSI... if you dont run alot of WOT you can get by at the book setting of 47PSI.... I run 50-52 PSI which fattens the mixture a tad

low fuel pressure will also let you know if a fuel filler is in need of changed will also give you the first (if not too late) indication of running out of fuel

 

[84rzv500r]

So got the YDS app and scanned both engines.
The engine with the issue show an error code 54, Bypass valve motor.
So the issue appears to be related to the engine not getting enough fuel, I think...
I inspected the connections to the bypass valve motor and could not see any issues.
I cleared the error code then ran the engine on a hose and the error code 54 did not reappear while on the hose.
My understanding is that I could operate the bypass vale motor with help of the YDS app but not sure what that would do or what to expect as I do not have a good understanding of the function of the bypass valve motor.
Any help / suggestions are greatly appreciated.

look in my repower thread or search here as we've had couple discussions on what the bypass servo motor does.... i didn't look yet to see if its a servo with feed back or just a stepper motor...

 

[Konnie]

I thought that was for no wake mode. Wet ECU= injector driver probably shot. But it worked fine on the other engine so that should not be it.. I see your already swapped them.

Are you in salt water? Hows the oil look?

In salt water, Florida East Coast, Oil look good.

 

[Konnie]

Low fuel pressure will limit MR-1 max RPM... the symptoms is they go lean and feel like they loose power... if pulling back on the throttles feel like the power comes back its a good indication... they lean out...

I have fuel pressure gauges in my opinion they are mandatory for understanding engines... MR1s like 47-52 PSI... if you dont run alot of WOT you can get by at the book setting of 47PSI.... I run 50-52 PSI which fattens the mixture a tad

low fuel pressure will also let you know if a fuel filler is in need of changed will also give you the first (if not too late) indication of running out of fuel

Have you installed fuel pressure gauges on a MR1? Any suggestions for how to install them?

 

[Konnie]

look in my repower thread or search here as we've had couple discussions on what the bypass servo motor does.... i didn't look yet to see if its a servo with feed back or just a stepper motor...

Thanks for you help. Will look up your threads. I suspect it is a stepper motor as the YDS app indicated “step” for the bypass valve motor When analyzing while running the engine.

 

[Konnie]

So I swapped the ECU and the issue(s) persisted on the port side engine (now and then not rev above 6K RPM and at times not starting at all). At the moment it isn’t starting at all. Start board side engine starts and run just fine.
I disconnected the fuel lines at the top of the fuel pumps and the pumps appears to be pumping fuel just fine. Then reconnected them.
Scanned both engines with YDS and not fault codes other then overheating many hours ago which I expected as seaweed get sucked in at times..
I got a spark tester and no spark on the port side when cranking the engine, it cranks just fine but does not start nor fire at all. Star board side has a good spark and runs just fine.
Any thoughts on what is causing the no spark on the port side engine?

 

[84rzv500r]

well i'd check the primary and secondary coil resistance, also the TPS sensor voltage must be in the correct range ~0.747V at otherwise the ecu thinks the throttle is open and wont light the spark

 

[Konnie]

well i'd check the primary and secondary coil resistance, also the TPS sensor voltage must be in the correct range ~0.747V at otherwise the ecu thinks the throttle is open and wont light the spark

Wouldn’t incorrect sensor voltage to the TPS prevent the engine from turning over all together?

 

[84rzv500r]

no that's after the variable resistor if the sensor is out of range the ECU will gladly fire the injectors but will not fire the ignition in my experience

 

[Konnie]

So checked primary and secondary coils. All measured with in specified tolerances.
Will look into the TPS tomorrow,
If connecting the YDS I should be able to see the TPS voltage readings on the YDS application as I move the throttle from idle to wot, correct?

 

[84rzv500r]

yes and check the range in the service manual off the top of my head its like 0.747V +- something like 0.016V check me on this,,, and this should be with the throttle at idle. its a bitch to get to the screws to adjust in my boat but yours might be easier and if you cant adjust it in range the TPS sensor is bad...

 

[Konnie]

So checked the TPS and got the following values

PS
Idle .796 / Throttle valve opening 2.4
Wot 3.896 / Throttle valve opening 79.9
SS
Idle .757 / Throttle valve opening 2.4
Wot 3.877 / Throttle valve opening 79.4

These values appears to be within range.

BUT
I did realize while using YDS that the “Engine stop lanyard switch“ was ON on the port side engine, the one the won’t start.
It is “OFF” on the start board side engine, the one the will start.

Based on reading other threads within this forum I suspect that the issue is related to the kill switches located under the clean out hatch.
There are two kill switches under the hatch.
Opening the hatch and manually pressing down the left switch the starboard side engine can be started and run. When allowing the switch do come up the starboard side engine is killed.

The port side engine does not start when pressing down the right switch. Suspect something is wrong with this , right, switch or the wiring related to this.

 

[84rzv500r]

very likely my dead man/lanyard switch rolled Tango Uniform when i did the engine swap... had to replace and all was well..