Seadoo GTX RFI 787 after top end rebuild

[lmarkie74]

After months of trouble shooting, I finally figure out what was wrong with my jet ski. I would run for a while just fine and then not be able to go over 2,000-3,000 RPM.

I replaced the:
1) TPS and reset with my CandooPro software.
2) Replaced the aftermarket Rectifier/Regulator with a genuine Seadoo part. ($165)
3) Cleaned all the water cooling lines out.
4) Cleaned RAVE valves.
5) Cleaned Injectors.
6) Replaced fuel pump and filters (59psi).

Turned out to be the Stator. Stator static test showed good specification results (.1Ω to 1Ω). Dynamic test didn't do so good. At the 3 yellow wires coming out of the stator, 1 -2 measured (20VAC @idle), 1-3 (2VAC @idle), 2-3 (2VAC @idle). Specifications call for 25 to 70 VAC @3500 RPM. Bad stator. I replaced the stator with an aftermarket JetUnit stator from Amazon even though I had read that you need to go back to the original Seadoo OEM stator.

Ran great for 4-5 hours total time that I had taken it out at different times. The last time I took it out, it died and wouldn't start. Long story short the MAG side cylinder piston bottom ring broke (85 psi compression). I rebuilt the top end with fresh honed jugs, new pistons, new rings.

Went out to test and break it 787 motor in. Ran for about 20 minutes perfect. After that it wouldn't run worth a s##t. Idled badly, couldn't get RPMs up, stalled, and hard starting. Took it to the house and rechecked compression. 125 psi on the MAG side, 130 psi PTO side since it hasn't been broke in yet. Thought I'd check out the Stator again last night. 1 -2 measured (11.5VAC @idle), 1-3 (11.5VAC @idle), 2-3 (11.5VAC @idle). Specifications call for 25 to 70 VAC @3500 RPM. I tested wiring at 3500 RPM and got worse.....1 -2 measured (8.5VAC @idle), 1-3 (8.5VAC @idle), 2-3 (8.5VAC @idle). The higher the RPM the worse the AC voltage got.

Am I over looking something after the Top End rebuild, or is this one of those Chinese stators that coincidentally went bad?

 

[etemplet]

I'm chasing electricl issues on a 2004 GTI RFI. I checked everything twice. LOL I have not replaced the stator but I did purchase a used wiring harness. Mine doesn't run long enough to check the stator output but I am getting a varied spark (testor gets dim) using my testor and it coincides with a loss of RPM.

I'd suggest buying 2 spark testors that plug into the lines and you can visually verify the spark. This instrument has helped me 2 times determining the problem. Plugs will fire and you'll assume you have fire constantly but that is not always the case.

Sounds like you could have a coil issue but from what I understand they don't go bad very often. Good Luck !!

 

[lmarkie74]

I'm chasing electricl issues on a 2004 GTI RFI. I checked everything twice. LOL I have not replaced the stator but I did purchase a used wiring harness. Mine doesn't run long enough to check the stator output but I am getting a varied spark (testor gets dim) using my testor and it coincides with a loss of RPM.

I'd suggest buying 2 spark testors that plug into the lines and you can visually verify the spark. This instrument has helped me 2 times determining the problem. Plugs will fire and you'll assume you have fire constantly but that is not always the case.

Sounds like you could have a coil issue but from what I understand they don't go bad very often. Good Luck !!

I do have 2 inline testers. I'll try it. I did read in another post that a guy went through the same thing. I checked all the wiring from the MPEM with a diagram. Turned out to be a pin wire on the 3 pin connector at the coil. He pulled the pin out and replaced it. Don't know which one it was. Worked! Don't you just love theses RFI's? Lol!

 

[etemplet]

I do have 2 inline testers. I'll try it. I did read in another post that a guy went through the same thing. I checked all the wiring from the MPEM with a diagram. Turned out to be a pin wire on the 3 pin connector at the coil. He pulled the pin out and replaced it. Don't know which one it was. Worked! Don't you just love theses RFI's? Lol!

My plan was to next look at the pins on the coil connection. I was thinking it might be a bad ground so I was going to add another ground from the battery. A wire can give you a positive continuity test but break down under load. That makes the problem difficult to find. I've swapped every part you can swap except the mag coil with absolutey no change. To be conservative I have at least 16hours hard work troubleshooting this ski but it's probably 20 hours. At some point even a blind squirrel finds a nut.

My cousin has a automotive mechanic shop and we talk about such things. The more you know the more difficult the problem will be to solve. Wouldn't it be nice to have a guru with great information... "Oh yea check that plug it's pretty common for the connections to go bad." You bringing that up may help me solve the problem. Thanks for sharing !! Good Luck

 

[etemplet]

Here is a video of the RFI trying to run at 1/2 throttle. Watch the spark plug testors grow dim and bright as the engine RPM changes. Weird stuff. This is why I recommend spark testors. They solved another weird issue I was having with my 1996 XP and weird it was. The spark testors work better at night as you can more easily see changes in spark.

This is the link to the video
2004 RFI Spark Problem

 

[lmarkie74]

Here is a video of the RFI trying to run at 1/2 throttle. Watch the spark plug testors grow dim and bright as the engine RPM changes. Weird stuff. This is why I recommend spark testors. They solved another weird issue I was having with my 1996 XP and weird it was. The spark testors work better at night as you can more easily see changes in spark.

This is the link to the video
2004 RFI Spark Problem

Damn....looks like the 4th of July. So you haven't figured this out yet?

This morning, I started my 2000 GTX RFI and it was hitting perfect. Came back later that afternoon and the SOB wouldn't start.

 

[etemplet]

Nah I havent messed with this ski in over a month. I restore skis so I have a long list of stuff to do.

 

[etemplet]

Damn....looks like the 4th of July. So you haven't figured this out yet?

This morning, I started my 2000 GTX RFI and it was hitting perfect. Came back later that afternoon and the SOB wouldn't start.

Was it getting fire? You have have a DESS post or switch problem. I had dirty contact on the computer once and the ski was tempermental. It wasn't seeing the power. one of the wide blades on the computer had some corrosion. Just be gentle cleaning them. You may have a key issue. Check the simple stuff.