Rear cylinder running rough 2002 gtx di

[cd24747]

2002 GTX DI 951
The ski will only go about 28-29 mph on the water and it takes a little while to get up to that speed. The RPMs will only go as high as 4700. When I put it in reverse (while in the water) it will sometimes rev over 6000RPMs. It runs very strong on the front cylinder and not very well (if at all) on the rear cylinder. I removed and cleaned the carb and the compression is good. Any ideas? I really don't want to take it to get serviced. I would like to do it myself. PLEASE HELP!!!

Update: I just played around with the ski while it is sitting on the trailer in the driveway. I started it with only the rear plug on the wire and it will start but stall when I give it gas. I then started it again with only the front wire on the plug and it revs when I give it gas. The thing that confuses me is that the rear plug is still clean LIKE NEW!!! but it will run on just the rear cylinder.

 

[LouDoo]

I'm not that familiar with 951's I've never worked on one and never owned one. I think we need to determine if its a fuel or an ignition problem. Since Rotax engines both spark plugs fire at the same time simple switch spark plug cables. If the problem follows the cables you have an ignition problem, if not it's fuel.

BTW does your ski still have grey tempo fuel lines?

Lou

 

[cd24747]

I think they're black.

 

[cd24747]

I put the front wire on the rear cylinder and it wouldn't even start at all. When I did this I did NOT have the rear wire on the front spark plug. It won't reach.

 

[SabrToothSqrl]

Lou, that information is not correct for the DI or RFI. Only the carb skis, and only the ones before 99 I believe fire both at the same time.

on the DI and RFI, YOU CAN NOT SWAP SPARK PLUG WIRES. IT WILL NOT WORK. Also, a DI will not have tempo lines. It will have high pressure fuel lines. This is why it's so important to identify the ski / engine.

As far as the reverse RPM: You are greatly reducing the load on the engine. These engines will hit RPM limiter at 1/4 throttle with no load. It tells you nothing.

The clean rear plug makes me think it's not getting fuel, if it was getting fuel, even with a weak or no spark, I'd expect to see something other than a brand new looking rear plug.

Have you removed and examined the fuel rail / injectors?

Since the front one appears to be working, you could try swapping the fuel injectors. There is also a fuel filter in the fuel rail.

I'm best with the 951 carb engines, but I've been reading up on the DI and RFIs.

"I started it with only the rear plug on the wire and it will start but stall when I give it gas. "

Also makes me think fuel injector issue. Your not getting any gas... so it can idle with the gas it's getting, but not actually run.

 

[cd24747]

OK. I'm gonna admit something here. I'm pretty clueless. Did I already say that? This is a carboerated engine. Sorry that I'm so confused and don't know my ski like I should. Here is the carb when I had it apart.

 

[LouDoo]

Sqrl,

I'm gonna back out on this one, the poster PM'd me and asked me to look at this thread. I know very little about 951's and nothing about DI's, so see if you can help him out, because I'm in over my head. From the picture it does appear to the carbed and it does have grey fuel lines, I dunno. I'll know better next time. Thanks.

Lou

 

[SabrToothSqrl]

Not your fault, I know very little about anything outside the 951. That's the only engine I work on.

Yea, that's a funny looking DI part.

I plead the 5th on this thread.

 

[cd24747]

Should have thought of just looking at the sticker first. Sorry. Here it is.

 

[cd24747]

Based on the sticker can anyone tell me if mine is a di or rfi or ???

 

[SabrToothSqrl]

It's a 951 CARB ski.

Make a new thread, however my guess is clogged fuel line going to that carb. or clogged fuel filter in the carb.

replace the grey fuel lines with new black automotive* ones, and clean out the carbs/filters and under hood fuel filter.

*fuel lines are not coast guard approved

 

[cd24747]

Do you know which fuel line goes to the rear carb? It looks like there are 3 lines that go into the carb. Top, bottom and one on the end (front of ski).

 

[cd24747]

I replaced the lines that go to the top and bottom of the carb. I couldn't figure out the route of the one that goes on the front of the carb as it goes under the motor. Still no good. Any ideas?

 

[cd24747]

I know it's improper to bump my own thread but I'm desperate so "bump"

 

[Strizzo]

did you change out the fuel lines when you had the carb off? did you have the carb cleaned and rebuilt at that time as well? the lines in that picture are the grey tempo lines that break down and clog up the filters in the carbs. if you don't want to do the carbs yourself, Dr. Honda does them for a reasonable cost and does great work. he recently did the carbs for my 95 GTX and all I had to do was install them and set the idle, and that ski had been sitting for 5 years, and the carbs were so clogged up that the needle/seat wouldn't even pop off.

 

[cd24747]

I did replace the lines. I also had a guy that I know that does carb work take the carb apart and clean it up but I did not have him rebuild it. He said that there was a lot of junk built up inside the carb but he completely cleaned it out. That really did not seem to change anything. Could it still be the carb? Maybe I need to rebuild it with a kit. Any thoughts?

 

[Strizzo]

I did replace the lines. I also had a guy that I know that does carb work take the carb apart and clean it up but I did not have him rebuild it. He said that there was a lot of junk built up inside the carb but he completely cleaned it out. That really did not seem to change anything. Could it still be the carb? Maybe I need to rebuild it with a kit. Any thoughts?

there are some tests that need to be performed to ensure that the carb is working correctly and is adjusted where it needs to be. the fuel pump diaphragm in the mag carb also needs to be checked, and over time the diaphragms in each of the carbs can get hard a make things not work correctly as well. there are also little filters inside the carbs that can get clogged that should have been cleaned/replaced when your buddy went through them. the needle and seat can also get worn and leak when it should be closed, causing inconsistent fuel mix at idle-low rpm, and cause the engine to flood when you shut it off for a few minutes, causing hard restarting as well.

i would recommend you either go through the carbs completely or send them to someone who knows what they're doing to get them set up correctly. if you keep riding the ski with a fuel supply issue, you can burn a piston, costing much more than a carb cleaning.

 

[cd24747]

Just ordered a carb from a guy on eBay. Hope this works.


Gun control is not about guns, it's about control.

 

[cd24747]

I installed the carb and its doing the same thing. Any other thoughts???


Gun control is not about guns, it's about control.