2001 Seadoo RX cranks but will not fire.

[JaredMorgan]

I have a 2001 Seadoo RX with a new engine (951), new carbs, new mag. It cranks but will not fire but will eventually have a huge backfire. The flywheel timing is correct (I checked it a second time to make sure. It was doing this before I replaced the engine but it had kind of low compression and had previously flooded the engine so I put the new engine in before tackling this issue. Any ideas?

 

[mikidymac]

Are the carbs adjusted correctly? Correct jets, needle and seat, spring?

 

[JaredMorgan]

Are the carbs adjusted correctly? Correct jets, needle and seat, spring?

It is a brand new carb, I didn't touch any setting on it.

 

[DaddyLoafin]

you need to pull the carbs and check the jets, pop off, and what the high and low speed screws are set to.

 

[mikidymac]

you need to pull the carbs and check the jets, pop off, and what the high and low speed screws are set to.

Exactly!

 

[JaredMorgan]

you need to pull the carbs and check the jets, pop off, and what the high and low speed screws are set to.

Ok, thanks I'll check the carb out

 

[NCGator25]

Ensure that you have the spark plugs hooked up correctly. If you have them backwards, the timing will be off, and can result in the backfire you describe. Same thing happened to me when I was troubleshooting my coils.

 

[NCGator25]

 

[DaddyLoafin]

Ok, thanks I'll check the carb out

Compare that to what the manual says and make whatever adjustments needed

 

[NCGator25]

If the carbs are brand new, you shouldn't need to open them up. The only thing I could think that would be wrong with them is the low and high speed needles were adjusted for a different engine. The high speed should be all the way in, the low speed should be 1.5 turns out for the 951.

 

[DaddyLoafin]

If the carbs are brand new, you shouldn't need to open them up. The only thing I could think that would be wrong with them is the low and high speed needles were adjusted for a different engine. The high speed should be all the way in, the low speed should be 1.5 turns out for the 951.

View attachment 65854

How else are you going to confirm that it came set for a seadoo 951 and not some other engine or just having a standard factory setting from Mikuni?

 

[NCGator25]

How else are you going to confirm that it came set for a seadoo 951 and not some other engine or just having a standard factory setting from Mikuni?

I don't disagree that he may have to take them off to check them, but based on his issue (backfiring), I'd check the spark plugs first to ensure they are set up correctly. If they check out, then I'd check the low speed settings with the carbs on the engine. They don't need to be removed to check the low speed settings. If they're not 1.5 turns out, which is what the 951 should be set to to start, that would probably lead me to pull the carbs off to check them further. Just my thoughts on how I'd approach the problem based on what I've experienced in the past with my 951 carb.