View Full Version : Mercury 250 M2 Optimax - No Power

10-02-09, 06:02 PM
2 months ago bought a 2005 Seadoo Islandia boat. Has the mercury m2 250 optimax in it. Boat originally came from Florida and now I have it here in Albuquerque, NM. Elevation at the lakes are about 4500'. Anyway, took it out and did not have any power...felt like I was dragging an achor. Engine RPMS topped out around 5500 rpms - looked like I was pushing a ton of water out the back. Took a long time to plane out and build up speed. Tried to pull my 12 year old son behind with a water ski and couldn't hardly get him out of the water. Im very upset, dont know what the next move is or really where to take it? The Seadoo dealership here in Albuquerque no longer work on Merc. engines and then the local certified Merc. repair shops here say they don't work on jet's. Looking for some leads, advise, help and words of wisdom!

10-02-09, 09:13 PM
Sounds like the engine is reving up nicely just not accelerating, correct? If so you need to check the jet pump. Could be as simple as some trash up in there or too much clearance beteen impeller and wear ring. Service manual will show you how to check and fix. Pretty simple job.

My boat with same setup takes off great and will pull skiers, tubes and wake boards without hesitation. Great hole shot as they say.

Unfortunately the wear ring and impellers on these M2 jets are on the expensive side unlike on the seadoo jets.

Can't edit my post but wanted to add that crowleymarine.com is a good place to order parts.

10-02-09, 11:06 PM
I have a 240EFI M2 Mercury and it had a problem with a worn wear ring. I got high revs but no acceleration. You can buy a new wear ring for $450 or repair the old one with JB Weld. Click on my name on the left to see my other posts. I have photos of the ring before and after. It works great now after the fix.

10-03-09, 10:06 AM
well ask the mercury dealer how much to pull the codes. also because its all computerized I doubt the altitude will have much of an effect.

i found a thread a few days ago about the air injectors going bad you'll loose a cylinder.

also check the impeller for anything goofy

you still have to worry about wear rings on these mercury jets

5500 rpm sounds right if you're not getting any beeps from the controls seriously look at the pump/intake grate ect ect

this is a large ass boat what was your top speed?



10-03-09, 11:07 AM

The max RPM for the 250 is 5375 + or - 250, so you are dead on there. Either your wear ring/impeller are worn, or you have some trash stuck in the pump. Have a good look in both ends of the pump for trash and damage. If everything looks good measure the clearance between the impeller and the wear ring. It should be 0.038 - 0.058 in. (0.96 - 1.47 mm).

With the pump working properly, your Islandia will have no problem pulling your son up on a ski.


10-05-09, 09:44 AM
I do know for a fact that the intake grate/impeller is clear of debris. Im wondering if Mercury makes a OEM 18 degree impeller for this jet drive?
After a long time of full throttle, problably 20 seconds, it finally reached top speed. Not sure if the speedometer is working correctly, but it said 42 MPH. That 20 seconds felt like I was dragging a boat anchor though.

10-05-09, 09:56 AM
The previous owner had a new impeller put in since he sucked up a rock. Damaged the OEM impeller and wear ring. I have both of these damaged parts. I looked up into the intake gratem the new impeller looks nothing like the factory one. It has rounded blades instead of sharp pointed edges like the the factory installed. The clearances look tight.

Also I know that there is not any debris/trash up in there. It's clear. Im wondering if this aftermarket impeller is the wrong pitch degree? Wondering what degree pitch comes for the factory one?

10-05-09, 10:17 PM
Just to clarify, how quickly does the engine get up to max RPM, is it really quick and nothing happens, or does it take forever for the engine to reach 5000 RPM?

There are a couple of part numbers in this thread http://www.seadooforum.com/showthread.php?t=10926 for different aftermarket impellers designed to give you better hole shot. Google them and compare the pictures to the one you have.


10-06-09, 09:48 AM
The RPM's shot up quickly. Like I had described before, felt like the engine was reving max, felt like trying to make a quick hole shot, but tied down to a anchor. Also since the engine was reving so high - saw white smoke coming out the back.

10-06-09, 08:58 PM
Definitely sounds like a pump problem. Either the impeller is wrong or there is some damage that you can't see. Try and get a couple of pictures in both ends of the pump, and measure the clearance with a feeler gauge.