Another GTX Di

[G&J]

I'll check the fuel pressure when reving tomorrow I think it went up a little but not sure. No have not retested air pressure yet.

Regarding my musings running on the water I was wondering if consistently higher revs would lead to an increase in voltage as the rectifier output as measured across the battery seems to slowly increase with revs.

Edit: slightly higher voltages with new regulator

 

[G&J]

Fuel pressure test; idle and rev. When revved maint and red light come on.
[video]https://m.youtube.com/watch?v=6O-0xyPxubw[/video]
Misses occasionally when revving with resultant spike, down, in fuel pressure. Tested on trailer.

 

[G&J]

Air compressor test
[video]https://m.youtube.com/watch?v=CA8CgRA-Fy4[/video]
Over 100 PSI good!

 

[68ragtop]

Air pressure looks great. There is still something going on tho. That miss is going to be very pronounced on the water. Not sure if your air pump is causing the fuel drop from the RPM decrease at the time of the miss, or if there is something going on with your fuel pump that is creating the drop & miss.

This is where shop compressed air would be a great test. if you could supply 90 PSI to the rail from shop air, the needle on the fuel gage would be steady as a rock & no needle bounce. If the needle still dropped with the hesitation I would suspect something is up with the fuel pump. I am at at a bit of a loss at the moment to tell you what to try next with out knowing for sure the fuel pump is ok. It looked a little like the fuel pressure dropped under revs, but maybe that was just the miss making it hard to see?

Normally what happens under revs:

the fuel pump being electric is alway providing a consistent volume & capable of 150psi

The air pump being mechanical will increase volume with RPM increases.

the extra air volume will be released by the regular, but it will still rise a little in the rail
this is the normal pressure rise you should see on the gage when revved up.

Seeing your pump is 100psi at 500 RPMS, we know your pump will produce the extra volume

If you fuel pump is just borderline, it might struggle to keep the pressure above the air at this time. This would show on the fuel pressure gage as a drop because its having a hard time keeping the pressure 27 psi above the the air & the fuel injector are increasing their demand for the fuel at the same time.

So, Now the question is, is the fuel pump pressure causing the miss, or is the miss causing the air pump pressure to drop. Hhmmmmmmm.

 

[G&J]

Hi Guy's

Haven't given up, been tied up with work. Hopefully get some time this long weekend to do some more testing

Maybe even pick up and hand air compressor....

 

[G&J]

Work is still crazy... I will fix this machine! ☺

 

[Mickirig1]

I known what you mean about work! Been trying to do the service on my two GTI's to get them ready. I have 8 days straight of 12 on / 12 off on an ambulance.

 

[G&J]

Hi All

Finally got a day with good weather and time off

So took the GTX Di for a quick run on the water...

Start-up idles good now, slight revs OK.

No warning message or red light.

Apply throttle revs start to increase and unit .... misses... if I hold revs at around 3500 unit gets up and planes with miss every half a second or so...

Warning and red light come on and off and occasionally audible warning also went off. Bring back to idle and everything settles down.

Took the seat off to have a look at the fuel pressure, needle seems to be vibrating too much and when the unit "misses" pressure drops momentarily.

Next stop I think will be in for dealer to hook up to diagnostic unit to read fault codes to narrow down problem as I am at a loss as to what to do next.

 

[G&J]

UPDATE

Contacted local dealer his morning... Their response...

Our only BRP trained guy is away for a week and last time we looked at an old 2 stroke machine BUD's did not recognise the model. Call back next week and we will see what we can do...

Seem's I am getting no where :-(

I was avoiding buying a air-compressor to follow-up on 68ragtops suggestions (which are great) as I couldn't source a suitable second hand unit and the cost of a new one was comparable to a new fuel pump.

Now I am undecided if I should bite the bullet and buy a air-compressor or new fuel pump.

Thoughts?

 

[G&J]

Had another look at the ski this afternoon and with the tools, knowledge etc I have I can't go any further...

Therefore I think my best option if I want to fix this beast is to select the most likely faulty parts and replace. The lucky first part, or should I say next, is the fuel pump. I'll let you know how I go I expect it will take a couple of weeks at least for the pump to get here from the USA.

 

[Coastiejoe]

Had another look at the ski this afternoon and with the tools, knowledge etc I have I can't go any further...

Therefore I think my best option if I want to fix this beast is to select the most likely faulty parts and replace. The lucky first part, or should I say next, is the fuel pump. I'll let you know how I go I expect it will take a couple of weeks at least for the pump to get here from the USA.

Don't buy a low end aftermarket pump, they just don't hold up. Sadly a good one is pretty expensive.

If it were me, I'd do a fuel pressure test.

 

[68ragtop]

Don't buy a low end aftermarket pump, they just don't add up. Sadly a good one is pretty expensive.

If it were me, I'd do a fuel pressure test.

He has done the pressure test, but nothing rock solid since he found the rave solenoid was plumbed backwards. It looked to me in the last video like the fuel pressure dropped a little under higher revs & that would indicate a fuel pump problem. The pressure must rise from 104 under revs, if it doesn't, or it drops, there are issues.

like I mentioned earlier in this thread, everything must be correct for these skis to run correctly.

 

[Coastiejoe]

He has done the pressure test, but nothing rock solid since he found the rave solenoid was plumbed backwards. It looked to me in the last video like the fuel pressure dropped a little under higher revs & that would indicate a fuel pump problem. The pressure must rise from 104 under revs, if it doesn't, or it drops, there are issues.

like I mentioned earlier in this thread, everything must be correct for these skis to run correctly.

I didn't go back and re-read it all. Based on your post I would agree. The DI is a sensitive system for sure,,,

 

[G&J]

Hi All

I'm back...

The replacement fuel pump finally arrived... that's a story for another time.

OK removed the fuel pump, again, from the outside looks clean and tidy outside filter OK. Note: this is as far as I got with a visual check long time ago when I first started playing with the beast.

Knowing more that I did then, ha, I broke the pump down to its component parts to fit replacement unit.

1. Old pump is a non OEM pump with no spring fitted to maintain downward pressure on pump to correctly seat bottom filter. If not fitted perfectly it could flop around in the aluminum cylinder.

2. Bottom internal filter is filthy. This may have been the problem all along?

I will endeavour to fit new pump anyway, just gotta work out what bits I have to modify to fit and what I am missing like the spring.

Wish me luck

 

[Mickirig1]

Go for it ! Report back results.

 

[G&J]

OK managed to find all the bits and pieces I needed... minor miracle!

It all went together very nicely, refitted the pump, connected battery and.... zip... battery 5V? Weird...I am surprised as battery is only 5 months old and has been excellent to date.

Recharging battery now.

Old filter

Old vs new pump

 

[G&J]

Hi

Battery not charging correctly - on charger showing only 11.6 V, must have dropped a cell, disappointing only 5 months old - will check warranty.

OK

Swapped out battery from the Yamaha. GTX Di started immediately, no fuel leaks Woo hoo!

Runs exactly the same as with the old fuel pump :-( Boo hoo!
There does seem to be less fuel pressure needle bounce at idle...

Video link [video]https://youtu.be/2h3TqLAM30w[/video]

Suggestions? All I can think of is fuel injectors?

 

[Mickirig1]

Fuel injection pumps need the correct voltage to function correctly. I have read about disconnecting the rectifier and seeing if that makes a difference. Some Ski's the rectifier is built into the Mpem. Make sure all your connections are clean and protected with dielectric tune up grease. ( Where you can use it.) Do not fill plug in connections with it.

 

[G&J]

Hi

I have cleaned every electrical connector I can there were a couple that had some corrosion that had to be treated to ensure conductivity. I'm sorta stuck now not having a diagnostic unit. I have read where my problem could simply be an adjustment of the throttle position sensors... which requires the candoo or buds system.

Anyone got a used candoo they want to sell? With the current exchange rate a new unit would cost me nearly $900 AUD.

Edit: or am I looking at the wrong unit? And it's more like $650 AUD?

 

[G&J]

Hi All

I have been reviewing the tests I have undertaken, parts replaced and current situation and have come to the following conclusions or should I say assumptions?

1. Parts replaced
Rectifier / regulator
Complete 'electrical box' including both coils, leads etc
Spark plugs
Fuel pump

2. Fault probably not due to fuel injectors as unit idles smoothly?!
3. Fuel and air pressure OK
4. Spark OK

Q. Can low 'current/voltage' output from rectifier / regulator cause missing at revs above idle?

Any other suggestions?

If low current/voltage could not cause the missing problem I'll have to look at purchasing a Candoo as the local Seadoo agent isn't interested in looking at old 2 stroke units...

 

[nhmort]

I had these problems. I'm on my third rectifier. I had one that didn't work a few weeks later. I determined that it was the battery and then got the AGM. The battery tested fine though. It just would cause all kinds of problems with the rectifier. I finally bought an AGM oversized battery, a 20 instead of a 16.

I also put a disconnect on the battery or you can just pull off the negative. I don't use it frequently since its at our lake home. It may get a weekend of use every couple of weeks or so.

My ski was displaying all kinds of "bad" behavior too. The plugs were even fouled. It's hard to believe. My plugs are burning perfectly now.

My ski works great now. I need to rebuild the top end this winter. I have 180 hours. I don't want to fry the Pistons and get all kind of damage.

I looked all over the site and I finally found that I need the AGM battery. Design flaw in the electrical system and the regulator.

Another idea, the guys that really know this ski are already helping you out. So make sure you take their advice. 68ragtop, jhjesse, tktavelis and Doowacka. Among others.

 

[snsbuck]

Hi, I have an '02 GTX DI. Mine ran great until one day I started it on the trailer in preparation to go riding. It was difficult to start but when it did, it would idle pretty good for the most part. When I would try to accelerate, it would die most of the time, but if i feathered the throttle I could get it to rev up some. Once it reached roughly 4k rpm's it would run very poorly, the "maint" message would flash in the display & a red light would flash. We found the PTO injector was rusted badly & not working. My understanding is the engine runs on the mag cylinder only at idle & then the PTO cylinder begins working off idle & that would explain why mine would idle OK but not run right once I would accelerate. I replaced both fuel injector with reconditioned used ones & it runs great again.
Thought I would share as it may help.
Steve.

 

[G&J]

Thanks - after a brand new battery going flat on me I will recheck all of the electrics. Specifically battery voltage at start and try and measure if there is any change in V or A as the load changes. Think I'll remove the fuel injectors also and find a local mob to test and clean them properly.

 

[G&J]

UPDATE....

The old Seadoo dealer agreed to have a look and hooked up the beast for me. Error - crankshaft position sensor. Now I have something to go on, first check resistance and connectivity

 

[Sportster-2001-951C-Stock]

On the RFI there are several codes for CPS, depending on details of the problem detected. Not sure that's true for DI