EFI vs oil injection failure diagnosis

[brownfish]

I'm rebuiding a 2001, 200 EFI Merc. As I make the rounds looking for parts, I can't help but notice a large number of engine failures similar to mine; a single cylinder melts down and/or seizes sometimes pulling the wristpin out and beating the cylinder up. Almost invariably, the oil injection system is blamed. Can the Mercury oil injection system fail on a single cylinder or is this problem not indicative of a fuel injector failure?

 

[alousteau]

Re: EFI vs oil injection failure diagnosis

I don't know, but I can tell you this. We have a carb 175 that we just had rebuilt b/c the oil injection failed and ate up a piston. Had the block bored all new pistons, and to make a long story short the first trip out we had a top pistion cease up and pull the pin. The rebuilder had to get us another block, crankshaft, pistons and two rods. Kind of odd to have this happen twice!

 

[Silvertip]

Re: EFI vs oil injection failure diagnosis

Some contend oiling problems are not "cylinder-specific" therefore It is highly unlikely that an oiling system failure would seize just one cylinder. On the other hand, an oiling system failure probably would not seize "all" cylinders at exactly the same time so its hard to say whether or not that was the issue in your case. Generally speaking however, lean conditions on the failed cylinder is the root cause. That may be due to air leaks, fuel injector problem (or carb on carbed engines), or overheating. Checking the plug condition on all cylinders might provide some clues. Teardown may show evidence of bearing and bearing journal problems, or the beginning of seizure/scoring on other cylinders if oiling was the culprit. As with any failure of this type, careful inspection and analysis is required at teardown. Simply rebuilding without fixing the root cause will ensure you will be doing the job again.

 

[BIGALF]

Re: EFI vs oil injection failure diagnosis

I'm rebuiding a 2001, 200 EFI Merc. As I make the rounds looking for parts, I can't help but notice a large number of engine failures similar to mine; a single cylinder melts down and/or seizes sometimes pulling the wristpin out and beating the cylinder up. Almost invariably, the oil injection system is blamed. Can the Mercury oil injection system fail on a single cylinder or is this problem not indicative of a fuel injector failure?

 

[BIGALF]

Re: EFI vs oil injection failure diagnosis

:'( My 1997 Sea Ray is now in the shop with a engine that just lost one piston that burned up with the new spark plugs that were just put in and only 1 completely burned out on the inside.
First they said it was caused by the fuel pressure regulator but now they still don't know why. The new engine is on it's way. It cost just as much to buy a rebuilt then to try to rebuild he existing engine. This way at least I get a 1 year warranty as long as no water get's into the block.:''''(

 

[Silvertip]

Re: EFI vs oil injection failure diagnosis

Is your SeaRay an outboard or I/O? While the logic about replacing the engine with a rebuilt sounds reasonable, that new engine generally includes just the rebuilt block. It will use all the original fuel system and other external parts. If those are the problem your new/rebuilt engine won't be new very long. Diagnose and then repair!!!! Don't just throw parts (or a new block in your case) at a problem.

 

[heeba597]

Re: EFI vs oil injection failure diagnosis

Very good question, last year I noticed my 225 EFI outboard was sputtering, backfiring and would not get on plane. I noticed one of the ECM plugs was showing the blue portion of the weather proofing on the plug. It was not long after this discovery that I also noticed the oil reserviour had a hole burnt into it. Very soon after that I lost all the oil in a very short period of time.
From what I can conclude, the cylinder that had the ECM unplugged was not firing and when it stroked to open the exhaust port combustion would begin. This blew out and burnt the oil injection tubing and with further operation eventually burnt a hole in the oil injection reserviour. Hot gasses from retarded combustion made their way out of the oil injection port and caused the damage to the reserviour.

Other than that there are small check valves in each cylinders injection line which may become clogged if debris enters the oil system.

I hope this helps, I can only speak of my experience as I only know about my motor. Good luck finding your answer and solution.