Not getting top RPM on GTX Di

[nhmort]

So last year I put a new top end on the ski. At 180 hours.

Could only get about 5800rpm. Runs at times with a bit of hesitation when varying the rpm. When I go full throttle it bogs down a bit.

Current compression is 135. Still getting 5800rpm.

Have replaced the rectifier with OEM after maintenance light had been on. Along with a new AGM battery.

Bought new fuel injectors from South Bay.

Replaced fuel pump with a High Flow pump. It tests at 27psi with key on. And 107psi when started, all the way through the various rpms.

Put in new fuel filters in gas tank. Last season put in a new inline fuel filter.

Hooked up CanDoo and no codes.

What the heck is wrong. I’m banging my head with this.

Maybe I should hook up the CanDoo and check again. But what should I look for that I may be missing?

Would the wear ring be a problem if worn?

I realize that this ski can be a pain. The usual problematic issues are rectifier it fuel pump.

@jhjesse for some answers or anyone who has extensive knowledge on the Di.

Nhmort

 

[Rossterman]

Verify you have the proper impeller as it could be over-propped. Also verify rave valve solenoid is working and the hoses to the rave valves are good. Finally, pull apart and clean the rave valves in case they are gummed up.

 

[nhmort]

Rave is clean and the hoses are not leaking.

I can hear them cycling on shut down and I can tell when they “kick” in if you will.

I should check the impeller. Since I bought this used several years ago.

 

[nhmort]

Update, if I go past half throttle, the rpms start to bog down.

Would a bad throttle position sensor cause this?

 

[etemplet]

Not that familiar with the DI 947/951 but it's still just and engine and a SeaDoo System. Did you check your water control valve for leakage? Check you wear ring and impeller area. The Wear ring may be coming apart. I'm working on engines for 2 DI's at the moment.

 

[mikidymac]

You have to check fuel pressure. That's about it for now.

 

[nhmort]

Fuel pressure is great.

The water control valve is good too.

I’ll check the wear ring this weekend when I go up to the cabin.

 

[bdesim2]

It’s not your wear ring if your rpms are topping at 5800.

Is your fuel pressure 107 under load when the issue happens ? Or on the trailer just idling.

Have you cleaned the raves just to be sure?

You said the maint light is on? No codes? Have you looked at the air injectors or tested the air compressor psi?

If no maint light it’s either air or fuel. Those are not monitored by the mpem.

 

[nhmort]

I have a fuel pressure gauge set up attached in line on the fuel system. I’ve tested the ski on the water, at idle as well as all the way up to the 5800rpm.

Raves have been cleaned to eliminate the problem during trouble shooting.

I haven’t looked at the air injectors. What do I look for in a bad injector?

No maintenance light.

Can the compressor be bad if I still get 107psi on the fuel tests?
I was under the impression that wouldn’t be the case. 80 psi from air and 27psi fuel pump.

I will do some more tests tomorrow. I’ll let you know the results.

 

[etemplet]

This shiznit is gonna be interesting for me as I now have 3 DI's to work on. I just pulled an engine to send out for rebuild, the first one ever. Lotta extra parts on the DIs for sure. I gotta go to the parts list to find out where the parts are you guys are talking about. LOL

As for the injectors, I haven't pulled any yet but I'll be sending mine out for rebuild. I always do that. Cheap enough and better safe than sorry.

 

[nhmort]

Keep in mind, it has fuel injectors and air injectors (direct injectors).

As stated above, the B.U.D.S or Can Doo doesn’t detect any faults in the fuel system. So this is where this thing becomes a real bitch.

I’ve been chasing this gremlin down for awhile. Mind you, it lives at my cabin, so between my kids driving it and going home. It’s taking me a length of time to try to figure this out.

 

[nhmort]

So I’m still having the same problem. Doesn’t go above 5800rpms at half throttle, then bogs down to 5000rpms with additional throttle.

Hooked up the CanDoo Pro to read the codes. Nothing.
Cleared the codes, rode the ski for a half a day and no new codes.

So it has to be either a fuel problem or the impeller issue. It’s tough to read the damn writing on it. I think I’m going to have to pull the damn pump.

Any thoughts besides this?

 

[mikidymac]

If it won't build RPM it isn't and impeller issue.

 

[jimmyluke]

So I’m still having the same problem. Doesn’t go above 5800rpms at half throttle, then bogs down to 5000rpms with additional throttle.

Hooked up the CanDoo Pro to read the codes. Nothing.
Cleared the codes, rode the ski for a half a day and no new codes.

So it has to be either a fuel problem or the impeller issue. It’s tough to read the damn writing on it. I think I’m going to have to pull the damn pump.

Any thoughts besides this?

Have you tried resetting the TPS?

 

[nhmort]

TPS has been reset.

 

[Sportster-2001-951C-Stock]

Restriction in exhaust maybe? If one of the hoses is delaminating internally?

 

[nickmo12]

I have had a fuel pump related problem and ordered a fuel pump from High Flow. After 3 returns because of defective pumps out of the box, I bought a used unit on Ebay. Problem solved. High Flow has excellent customer service as they were very responsive and sent me new pumps, but none of them produced the required fuel pressure. Not saying it's your problem, but I'd take a look.

 

[nhmort]

This most likely is my problem.

I’m just going to bite the bullet and get a seadoo fuel pump.

Thanks for the help guys.

 

[mikidymac]

You would be better off actually testing fuel pressure instead of throwing money at it.

 

[Sportster-2001-951C-Stock]

I vote yes on measuring fuel pressure.although replacement electric fuel pumps are highly questionable.

 

[nhmort]

I have a fuel pressure gauge installed inline like the Seadoo manual states.

I’ll give it another test run to see if I get less than 107 after the 5800 rpms when it bogs down to 5000 rpms past about half throttle.