Brand New Mercury Reman 300XS (just out of break-in) Surging/Skipping on the Top End

[Savage]

Added more info to post #39.

[lpugh]

Ran a lot of tests today @WOT, with my Son running the lap top, and saving and addressing files.

The Map sensor made no difference. The only sensor I could find locally to test was GM #12614970. I'm hoping it was compatible.
Ran the boat on a 6 gallon fuel tank, made no difference.
Did a coil swap dance. Put a brand new coil on cylinder #1, then put coil #1 on cylinder #2, then put coil #2 on cylinder #3, then put coil #3 on cylinder #4, then put coil #4 on cylinder #5, then put coil #5 on cylinder #6........No change.
Had my Son pumping the primer bulb @ WOT in case the pulse pump was weak.....No change.

Did a cylinder drop test beginning @ WOT (5600 RPM) and ending @ WOT. Results are below.

Cylinder #1 RPM dropped to 5100 and came back up to 5600
Cylinder #2 RPM dropped to 5090 and came back up to 5600
Cylinder #3 RPM dropped to 4800 and came back up to 5600

The above tests were on the small 6 gallon tank. The below tests are on the boat tank because we ran out of fuel in the 6 gallon tank.

Cylinder #4 RPM dropped to 5090 and came back up to 5600
Cylinder #5 RPM dropped to 5060 and came back up to 5600
Cylinder #6 RPM dropped to 5010 and came back up to 5600

I have 13 Rinda Diacom files, with the problem occurring on EVERY file.

Don and Joe can you guys review some of the files for me? If so PM me the email address that you would like the files sent to. Hopefully you can view the data, without having the Diacom software.

I reviewed 385 packets of data at a play speed of 1000 MS, while the motor was at 5400- 5600 RPM, and the problem was active.
The TPS stayed at 4.48-4.53 the entire time that the motor was at WOT.
The MAP stayed at 13.99-1425 the entire time that the motor was at WOT.
The battery voltage stayed at 13.79-14.16 volts the entire time the motor was @ WOT.
The block pressure stayed at 25.26-26.44 PSI the entire time the motor was @WOT.
The RPM's fluctuated between 5657-5327 the entire time the motor was @WOT
The engine load percentage fluctuated between 81.55-86.58.
The charge Temperature, which I believe is the MAT fluctuated between 86.00-93.20 *F.
Both the starboard and port cylinder temps stayed between 118.40-120.20 *F.
Motor stayed IN Gear.
Demand 100%
Available Power 100%
Throttle Percent 100
Power limit Set Point 100%
Sensor Power 5.02-5.03 VDC
Sensor Power Two 4.97-4.98 VDC
Fuel Flow Rate fluctuated between 24.85-26.30 GPH
Air compressor temp 104-107.60 *F


I borrowed a bore scope from work, but I'm saving that test as a last resort. I'm really not sure if its even possible to get a good look at the ports any way.

Running out of Ideas though!

The two in red peak my interest, I would not expect quite that much variation, was the cowling on during this test?
Was the ambient air temp about 80 degrees or maybe a bit more
I think the load numbers in the 80 range is result of operating at less than ideal RPM for max load, variation could have been because of rpm change
Sorry you have go thru this but problems like these intrigue me and a desire to learn more

Any chance you have another VST you could install for testing
Maybe a high pressure leak inside the VST causing foaming
I seem to remember Don mentioning something about a deflector that could cause fuel foaming a while back if installed wrong or missing

[EuropeanAM]

Leon- that Deflector is pretty easy to check for, and I'll be Savage will be taking a look this evening. Good idea.

MAP or Load variation may simply be due to changes in water/trim/wind. The IAT temp fluctuation is a bit odd, usually remains pretty steady at WOT for a given run unless there is a major change in weather occurring.

Savage- you can get a view of the ports (limited to the resolution of your camera) through the Spark Plug or the Direct Injector openings. Doesn't matter much which port you're viewing, as a rotated sleeve would overlap on one side or the other of any port.

[Savage]

Cowling was removed during testing due to data cable and 6 gallon fuel tank connections.

I checked the plastic deflector early on when I had the VST opened up.

I'll be testing direct injectors and checking sleeves on Sunday.

Stay tuned.

[Savage]

Don head thickness from the block deck to under the head bolt flange is around .875 on both heads.

I borescoped all 6 cylinders and I don't see any big misalignment. I'm posting the best picture of each cylinder port match below.

*****Update***** These borescope pictures are of ONE edge, with the assumption that if one edge was good then all the other port edges are good, this assumption is not true as I found out later in this thread, when I removed the heads.

Some of the port edges were manipulated with a die grinder to make the sleeve appear to be in alignment.


#1
132524-1 Cylinder #1.JPG

#3
142003-1 Cylinder #3.JPG

#5
134823-1 Cylinder #5.JPG

#2
131737-1 Cylinder #2.JPG

#4
125501-1 Cylinder #4.JPG

#6
143236-1 Cylinder #6.JPG


Testing Direct injectors tonight after I get the boat back in the shop, where it is quiet.

[EuropeanAM]

[Savage]

Performed numerous "Direct Injector Activation" tests and there is no doubt that my untrained, tinnitus ringing ears, hears something "flaky" on the #6 direct injector. The number #6 direct injector sounds different than all the rest, and I experimented with different piston stroke locations to perform all the tests and settled on TDC for best results.

[rvaha]

Since this is a new RE-manufactured motor doesn’t it have a warranty that a dealer should take care of?

[mercuryproxs77]

I had a 2014 225 pro xs we had in our shop one time doing almost the same exact thing and we chased this problem to the moon and back. We suspected injectors but had no real accurate way to test the flow at high rpms. Customer bit the bullet and we took the direct injectors out and sent them to Rich at Brucato and he found all them scored from a previous compressor failure. Mercury then replaced all the direct injectors under warranty and solved the problem.

[Savage]

Since this is a new RE-manufactured motor doesn’t it have a warranty that a dealer should take care of?

No, this is the third motor that I have had problems with, and I don't want to get into the details because it serves no purpose. The warranty is ONE year from the date of purchase on the FIRST motor, it doesn't matter how many defective motors you get.

[Savage]

I had a 2014 225 pro xs we had in our shop one time doing almost the same exact thing and we chased this problem to the moon and back. We suspected injectors but had no real accurate way to test the flow at high rpms. Customer bit the bullet and we took the direct injectors out and sent them to Rich at Brucato and he found all them scored from a previous compressor failure. Mercury then replaced all the direct injectors under warranty and solved the problem.

Good to hear that we might be on the right track.

[slim110]

I’ve got 2018 250 proXs that I’ve been fighting the exact same thing for a year now. It is super frustrating. I or a number of techs have been unable to find the culprit. It only runs to about 5600 then dumps to 53-5400 and jumps right back. Almost like a false rev limiter. I’ll be following this closely.

[Savage]

I’ve got 2018 250 proXs that I’ve been fighting the exact same thing for a year now. It is super frustrating. I or a number of techs have been unable to find the culprit. It only runs to about 5600 then dumps to 53-5400 and jumps right back. Almost like a false rev limiter. I’ll be following this closely.

Agree that your issue sounds EXACTLY like mine. "False rev limiter" is what it feels like.

I might have the answer for you.....Stay tuned. Ill be testing a replacement direct injector (thank you Don Weed!!!!) Friday, or Saturday.

[lpugh]

Savage do you have a digital storage scope and a low current probe that you can configure to view the current ramping on the injector. Current ramping tests are quite valuable tools for actuators like injectors. If a pintle is hanging, stalling or bouncing it can be seen on the current ramp on the scope, no specs on this as to what is normal, just comparison to the other units as to what is.
The reason I ask this is it would be very good information to have a before and after visual comparison should this be the problem, possibly adding a way to spot problem regarding injectors on these motors
Take look at this video on scope testing injectors, I have identified bad one this way that seemed to be working ok, were not
https://www.snapon.com/Diagnostics/US/KB/Fuel-Injector-Voltage-and-Current-Tests.htm
I use a digital pulse simulator to cycle the injectors at a high rpm rate to duplicate very high demand, many times they only fail at very high cycle rates

[slim110]

I can't wait to see if you can get it fixed. It's driving me nuts. Thank you for all the info and work you're doing! I've been on the verge of selling the boat because of this.

[EuropeanAM]

Savage do you have a digital storage scope and a low current probe that you can configure to view the current ramping on the injector. Current ramping tests are quite valuable tools for actuators like injectors. If a pintle is hanging, stalling or bouncing it can be seen on the current ramp on the scope, no specs on this as to what is normal, just comparison to the other units as to what is.
The reason I ask this is it would be very good information to have a before and after visual comparison should this be the problem, possibly adding a way to spot problem regarding injectors on these motors
Take look at this video on scope testing injectors, I have identified bad one this way that seemed to be working ok, were not
https://www.snapon.com/Diagnostics/US/KB/Fuel-Injector-Voltage-and-Current-Tests.htm
I use a digital pulse simulator to cycle the injectors at a high rpm rate to duplicate very high demand, many times they only fail at very high cycle rates

Leon- that's a great idea, but unfortunately there are very very few devices out there capable of testing and driving these low impedance injectors that fire at TWICE the rate of 4-stroke or Automotive injectors. Due to the configuration of the drivers in the PCM, one malfunctioning injector can actually affect others.

[Savage]

Savage do you have a digital storage scope and a low current probe that you can configure to view the current ramping on the injector. Current ramping tests are quite valuable tools for actuators like injectors. If a pintle is hanging, stalling or bouncing it can be seen on the current ramp on the scope, no specs on this as to what is normal, just comparison to the other units as to what is.
The reason I ask this is it would be very good information to have a before and after visual comparison should this be the problem, possibly adding a way to spot problem regarding injectors on these motors
Take look at this video on scope testing injectors, I have identified bad one this way that seemed to be working ok, were not
https://www.snapon.com/Diagnostics/US/KB/Fuel-Injector-Voltage-and-Current-Tests.htm
I use a digital pulse simulator to cycle the injectors at a high rpm rate to duplicate very high demand, many times they only fail at very high cycle rates

I don't have the tools to do this. I'll have Don Weed @ Integrity Injection verify my findings, to see if I picked the right bad Direct Injector.

[Savage]

I tested a "loaner" direct injector in cylinder #6 and noticed NO CHANGE. The max RPM was 5400 RPM.

[slim110]

Dang it! There was a glimmer of hope. That was one of the few things we hadn’t tried in mine. Please keep us updated.

[Savage]

Dang it! There was a glimmer of hope. That was one of the few things we hadn’t tried in mine. Please keep us updated.

Well I suppose I just could have picked the wrong direct injector to swap out. Don said a bad direct injector can cause the other good direct injectors to not function at 100%. Still have FIVE more chances at finding a bad one.