2008 250 Pro XS Loss of Power After Compressor Replacement

[MidniteTA]

Motor:
2008 3L 250 Pro XS
S/N: 1B550534
Currently at 513 hours

Boat:
2008 Triton TR21XHP


Motor has been running great all season. 2 weekends ago (sunday 9/10), I had an air compressor failure. Was running normal, about 15 seconds after coming off plane for a no wake zone, I heard the dreaded sound of a failed air compressor. Motor was immediately shutdown and not restarted. I drifted with the current to the next boat launch, got a ride back to my truck, then loaded boat on trailer with trolling motor/getting in the water.

I got a new compressor, had the fuel rail, all fuel lines, fuel injectors, and air injectors cleaned and flow matched. I installed new plugs and wires at the same time as it was a no brainer with the fuel rail off. I took it to the local dealer last friday (9/22) for oil pump prime and diagnostic check. All came back well and was told I was good to go.

The following day (saturday 9/23), I took the boat out for a test run. Took it easy, letting it get up to temp on the vessel view, then ran ~10 mins at 3000-3200rpm (just on plane), followed by 10 mins at 4000rpm, and 10 mins at 4500rpm. Motor ran fantastic . I loaded it back on trailer and got ready for my sunday tournament (9/24).

Let the motor get to temp before running to 1st spot, but kept it to 4500rpm max since I had some fears still. Motor was smooth as silk running flawlessly. The 1st run was ~15 mins. About an hour later, I went to run to the next spot. The drive started out great (partner even commented on how the new plugs/wires/fuel system cleaning must have done something since it felt smoother than usual). Again, I kept it to ~4500rpm. At about 20 mins into this run, the engine started loosing speed at constant throttle, and would not pick back up. I came to a stop, shut down, pulled cowl and checked to make sure nothing came loose. I didnt notice anything, so i started the motor back up with the cowl off. It idled smooth (certainly no signs of misfire) and didnt make any odd noises (I have a Corvette performance shop so I am pretty in-tune with the normal engine sounds and anything that sounds slightly odd). But when putting it into gear, it would run rough as if missing on a cylinder. Back to neutral and smooth again. It was probably unwise, but i tried to give a little throttle to see if it would clean up, but quickly realized that wasnt happening. I did not give it much, but just enough to see if it would clear up.

I know its possible to have hurt the engine when the compressor failed (should have compression checked then, but am absolutely doing it in the next day or so). Seems odd though that it would run so good for an hour + then quit if it got hurt when compressor failed.

One of my thoughts is that an air injector seal got damaged during installation. To the point it didnt get totally trashed and can seal enougj with the low cylinder pressure at idle (hence normal idle), yet once there is load and cylinder pressure increases, combustion gas is leaking through the seal.

Anyone seen anything like this or have any ideas where to look?

Thanks much,
Dan

[lpugh]

air/fuel pressure test are in order
Suspicious of contaminates were missed and have found ther way into the direct injectors

[EuropeanAM]

Who did the rails and injectors, if I might ask? Every inch of hose must be cleaned at the same time (starting at the compressor, all the way through the system and into the air dump hose). ANY missed metal can and will damage direct injectors.

Flow test report may be helpful as to see if they were indeed "run through their paces" and tested in a scientific manner, or simply time-buzzed at low RPM parameters in a common rail.

[MidniteTA]

Don,

The injector cleaning and flow testing along with the cleaning of the fuel rails, all fuel lines, and the air lines from the compressor was done by Doctor Injector (at the location in Federal Way, Washington).

http://docinjector.com/

They were recommended to me by my local Mercury dealer/service center (listed as a Premier dealer by Merc). This was Tanglewood Marine in St. Charles, IL. The owner of the dealer told me that Doctor Injector in the Federal Way, WA location is who they use for every engine that suffers a compressor failure, and have been using them for taking care of the Optimax air and fuel systems for over 10 years without issue. This is also the same dealer where I had the oil pump prime and diagnostic checks performed after installing the new compressor and cleaned fuel system. They said everything looks great and to go out and have some worry-free fun.

https://tanglewoodmarine.com/

I have attached images of what was sent to Doctor Injector, as well as the before/after flow test results. The injectors and rails were not shipped out just laying in the box as the picture shows. I took a picture for my documentation and as a reference image to send to Doctor Injector to make sure I had everything he wanted me to send. Everything was properly bubble wrapped prior to shipping.


20230912_193305.jpg20230921_073720.jpg20230921_073851.jpg20230921_073902.jpg

Thanks,
Dan

[lpugh]

I am having some concerns about those reports, lets hope Don comments on them.

[JOE54]

as well as compression verified

[MidniteTA]

I will be doing a compression test likely this evening after work or tomorrow

Had a question on one of the steps... I keep seeing that plug wires should be connected to an enclosed spark tester or grounded to the block. Alternatively, is there any reason the coils just cant be unplugged from the harness?

[lpugh]

Pull the kill switch and disconnect the fuel pump connector near VST.

[MidniteTA]

I will be doing a compression test likely this evening after work or tomorrow

Had a question on one of the steps... I keep seeing that plug wires should be connected to an enclosed spark tester or grounded to the block. Alternatively, is there any reason the coils just cant be unplugged from the harness?

No concerns about oiling/lubricating cylinders with fuel pump disconnected? Or does unplugging the fuel pump not impact the oil injection? Or does it not matter for the short amount of cranking required for a compression test?

Appreciate the help here. Thanks!

[lpugh]

non concerns.

[MidniteTA]

Just finished up compression test. All came back great.

#1 - 120
#2 - 120
#3 - 122
#4 - 122
#5 - 120
#6 - 122

[JOE54]

proceed with spark test and injector operation testing or cyl drop test to locate non working cyl

[EuropeanAM]

I am having some concerns about those reports, lets hope Don comments on them.

I would concur. If I'm reading that correctly, those injectors were tested at only one setting (which isn't listed or shown)- but given the 10-second comment, it's going to be at or below IDLE parameters.

"Rinsed"... hmmmm