96 GTI Trying to Resusitate - need help

[fishingfund]

Working through some issues with my inherited 1996 GTI and have spent many hours troubleshooting based on information in this forum. But I’m stuck. I’ve nibbled away at some of the issues but it still runs bad.

Here are symptoms.

• Starts and idles fine. Sluggish on any further throttle and will only reach about 15mph full throttle. If I back off the throttle a bit it will periodically surge like it’s getting little spurts of gas and then once in awhile go full speed. But not often.
• Cavitation. Wear ring was original. No longer an issue.
• Oddly enough, it will die when I flip to res tank.

What I’ve done:

• Replaced wear and carbon ring. Impeller fit like a glove in a testfit so I didn’t replace it. It feels much better coming off idle and the few times I got the ski up to speed it was fast out of the hole. One a rough day last week it would kick in after going over a wave when the impeller
• Not a huge telltale out back hole but there is water coming out exhaust so something is cooling.
• Replaced gray lines.
• Replace fuel selector. It’s an aluminum one. Not sure if this is my reason why it dies when I flip to res.
• Blew out vent lines. There was actually some oil in the one with the pressure valve.
• Bypassed fuel filter direct to tank. No luck.
• Pulled tank and cleaned baffle screen. There were some black chunks inside there. Almost looked like paint chips.
• Checked all line connections again to make sure they were all right and tight.
• Speaking of paint chips, the first time I cleaned the carbs I noticed paint chips on the flame arrestor. Pretty sure these chips were from outside the carbs where they were sprayed with carb cleaner. Not sure if that’s what I saw inside the baffle.
• Rebuilt both carbs (38i) with OEM kits. Replaced needle and seats (1.2) with OEM. Seats were a tight fit. Did not replace springs and used what was in there. Couldn’t tell you what color they were. Pop-off at 32/30. Not ideal and I didn’t mess with it further to boost it up to the 36-60 range per specs since I had no other springs to use and everything else seemed fine. Low speed at 1.25, high at 0. Forgot to pressure test carbs and didn’t mess with pulse line. I also did not soak the carb bodies but I made sure I was getting a good stream of cleaner out of the small orifices
• Compression around 155 in both. A little oil coming out of PTO side plug hole but both plugs looked ok.
• No water leaks or exhaust leaks I can see. I did not change the manifold gaskets but do have a new set coming for my next tear down.
• Replaced rectifier cause it was cheap. It wasn’t OEM. Have not tried the “remove red line” thing yet.

At my limits here. I plan to go back through carbs and get some 80g springs to see if I can raise pop-off. Also plan to do the pressure test. Maybe even put back in original needles and seats.

Any other recommendations?

Thanks - FF

 

[fishingfund]

Quick update. Pull carbs. Pulse line is fine. Opened up PTO side. Replaced seat with original but with new gasket and used new needle with original spring. Was popping at 30 now popping off at 52. Tight fit in new seat and the gasket that came with kit must have leaked under pressure. Will try Mag later.

 

[POPPS]

What do you mean,,,a little oil coming outside pto plug hole???

 

[fishingfund]

Seems like some staining around spark plug hole that runs down side of top end. It’s not bad. Not even sure it’s oil. Could be carbon? Dunno but figured I’d call it out if others have seen similar.

Managed to get to Mag side carb and put back original seat. Popoff at 52 just like PTO. Soooooo … Popoff is in the range per specs. Curious if this was my problem.

Just realized the needles and seats that I got from Titan 757 were OEM quality aftermarkets.

 

[mikidymac]

There’s no such thing as OEM quality aftermarket.

You need to replace all internal carb parts with only new Genuine Mikuni parts and follow the carb rebuild sticky exactly.

OSD Seadoo has complete back to OEM kits if you want one stop shopping of genuine parts.

If you don’t do this you are just going to keep going in circles.