This is why we remove that stuff. Thats the plastic gear that drives it all.

What make model and year is it?

most of the time what causes the gear to melt is running the engine overheated for a long time taking the oil injection off of a late model merc or yammi carb or efi will take a big hit on the resale of those motors .

I'm doing a 99 model 135 V-6 right now that the bolts that hold that worm gear together came loose. I also just found out that the motor had been rebuilt a year ago by a "self proclaimed mechanic" in his backyard shop. He failed to put red loctite on those bolts as well as the rod cap bolts. So end result, engine failure......Looks exactly like your pic.

This is an 1989 XR4 that I'm working on to replace my 2 liter. I think the same gear is used in most of the Mercs and Mariners up to the 2.5 liters right?

Yep, same gear (2 piece)

I wish I had known about this design deficiency on my 1990 XR4 when it was new. It caused me grief and heartburn becuase it didn't die suddenly. First, the pump would slip a little bit, and the horn would sound off. It took me a long time to get educated on this system, and finally bit the bullet and converted to "mix my own".
I wasn't about to work that hard to replace the gear, or come up with the cash to get it done. It was a great decision for me because the reliability factor when sky high, compared to what it had been. It had taken the fun out of going out on the water.

I never did understand how any one in their right mind would think that a plastic driver gear would last, driving a steel gear that looks like a buch of knife blades.

so does a 93 mariner 90 with oil resevoir on side of engine, have this same type oil gear drive? if so how do u disable the oil injection/alarm to go to premix? ive worried about this since ive had the motor. so i premix and fill the oil tank, so i foul alot of plugs.
doc

spark plugs are much cheaper than block repair.

I guess I am the lucky one here. I have had 3 ProMax motors and now a 300XS and never had one problem.

Guess so! You and several thousand more.......Neglect, overheat (more than just once), turnin' 'em to high are tha usual culprits. Some DO just fail but so do a lot of other parts on tha motors. Your not gonna hear about all tha ones still kickin'.

Wouldn't be a very interesting thread!

Texas Machine Work did the same to my motor took of the oil injection now its just pre-mix its a mercury 150 powerhead but a marinar motor

didnt they make some with metal drive gears, ??