951 Carb stuck at 6K wot? Well... here's why for me... TPS.

[SabrToothSqrl]

So, after over a year of troubleshooting between RAVEs, whole engines, Water Regulators, spark plugs, and even replacing the carbs and reeds... I figured out why my XP would sometimes hit 6K at 90% throttle, and pushing it to 100% would still hold... 6K... then some days it would hit 6,800 WOT (Solas concord w/plastic pump means I can't hit 7K WOT). (will hit 7K with stock prop). (solas is faster). (so, on/off issue of no difference between 85%-100% throttle).

Anyway, some days it would hit 6800 WOT every time, then 1/2 way through the day or 5 min later or some jumps later... it would be STUCK AT 6K where I didn't DO anything! I swear I've tossed at least 20 plugs at this thing, even going as far as buying BRAND NEW CARBS and having the engine rebuilt a few times! I've pulled engines from this ski at LEAST 6 times.

So, I won't bore you with the full history, but at one point the oil pump pull cable collapsed in on the end with the 10mm nuts.

So, I had to replace the whole throttle cable assembly. That was fall 2011. I never did get back on the water in 2011...

So, I, Logically thought the adjustment at the top of the cable (near the steering system) was to remove slack in the line, so I adjusted the carb end, oil end, and left that on it's 'loosest' setting. Throttle plates pulled full open, and everything seemed legit.

Here we are in August, and last Saturday I finally decide to hook my multimeter to the TPS and give it a go before I send the ski over the dam and collect the insurance... (even tried a 2001 MPEM).

I removed it (TPS) from the ski's connection, tested the plugs on ski side, 12v Black = Ground, Purple = 12v, white = signal wire.

So, I used some wire and wired up the sensor right to the battery. Never could get it work right.

Plugged sensor back into ski, and was able to remove the small rear clip from the plug, sensor side. (opens, not removed). so, with the TPS still connected to the ski, I used a + on the white wire, jammed in the back, and grounded to anywhere metal. (push start on ski (KEY OFF) for 30 seconds of testing).

The Throttle Position Sensor on the CARB 951s is actually a throttle position SWITCH, it's a dumb switch on/off. It' doesn't report position. 0-80% throttle pull is 5v on the white line (mine read 5.4 or so.) 81% - 100% is ZERO (mine read 0.03).

(why 5v and not 12 is beyond me)... why go to this hassle just to report 2 throttle positions, vs. all?

So, even though I discovered this issue, and adjusted the cable end near the steering, the cable didn't have enough slack to actually PULL enough cable to trip the switch. Sometimes I'd get 5v at WOT, sometimes 0v...

So, I pulled the oil tank aside, removed air horns and air box, let out some slack on the carb side, re-adjusted the oil pump side (line the lines up). then spun the top side out, making sure the throttle plates were still resting on the idle set screw, and not being opened by the throttle cable! No one likes a run away ski at 3K in the water idle.

After all this, I once again fired up the multi meter. I got 0v every time at approx (from what I can tell) 85% - 100% throttle. every time.

I reassembled everything, and am hitting 6700-6800 WOT every time. Only time will tell if this keeps up, but I figured it out, eventually...

So, to anyone who's replaced their carb TPS assembly... CHECK IT W/A MULTIMETER TODAY if your RPMs are not realized.

But, in other news, I now have a full spare carb set for my backup engine, making it even more drop in ready... right?

 

[Dr Honda]

First... congrats on finding it. I didn't think about the cable since you said you replaced yours already. I guess this will be like the "Regulator" issue where it needs checked regardless of what you think it's doing.


Second (just for an FYI)... the 5v - 0v thing is TTL logic level. Basically... that's the voltage the data is at, inside the MPEM. So... "YES" or logic high is 5v. And "NO" or Logic low is 0v. Add a timer, and you can turn that into TTL serial data. In contrast to RS232 serial that's at -5v(logic low) +5v(logic high). (the old com port on a computer) USB serial is TTL level.

 

[brock1]

first... Congrats on finding it. I didn't think about the cable since you said you replaced yours already. I guess this will be like the "regulator" issue where it needs checked regardless of what you think it's doing.


Second (just for an fyi)... The 5v - 0v thing is ttl logic level. Basically... That's the voltage the data is at, inside the mpem. So... "yes" or logic high is 5v. And "no" or logic low is 0v. Add a timer, and you can turn that into ttl serial data. In contrast to rs232 serial that's at -5v(logic low) +5v(logic high). (the old com port on a computer) usb serial is ttl level

what language is that ??????lol

 

[SabrToothSqrl]

http://en.wikipedia.org/wiki/Logic_level

I just thought it would have been simpler to have an actual switch. You have 12v at the switch, so on/off, would be simpler as 12v. unless that might damage the MPEM. If your going to step down the v and have a switch, why not just a potentiometer?

I might play with it a bit more to see if I can get better acceleration out of it, but I'm kinda afraid to mess w/it now...

I would have thought it was adjusted from the factory to the 80% 0v thing, but guess not...

You could interrupt the wiring, and put a switch on the dash... lol cheap learners key, tops out at 50 vs 65...

You guys have NO idea the stress, time, and money this issue has caused me. Many people would be happy to hit 50 on a 10 year old ski... but unless It's running 100% perfect, it eats at me... and who wants to get passed on the water

NOW the issue for me is... the ski came to me w/a shaved head (unknown to me)... and would hit and hold 7,200 WOT (with the solas). regardless of what I was doing on it (hard turns, under water, etc)... my buddy who's been fixing these for 10+ years now said it was the fastest 951 he'd ever been on. But I didn't know about the modified parts... and ran 87 in it (maybe 89)? and within a few runs (a month ish)... the engine blew. When I found the modified part I was so pissed I tossed it because I wanted RELIABILITY... my last 951 went 300 hrs for me, this ski had less than 70 when I bought it.

So, here I am with a stock engine and thinking...

I need some more pep lol!

Apparently the first thing in the 99 racing manual is.. Shave the head... but I don't really want to do that... the head my ski came with also had 2 additional cooling outlets on the top, tied into the factory line... I think Group K or something? I read their site, and my guess is that's who shaved the original head...

The ski does seem to run a LOT better in cold water (march / april) where I ride the water is pushing 85 degrees right now! Can I put a bigger cooling 'elbow' on the head? that's where the water IN is at right? so if I go up in size, it should allow more water through the block, keeping things cooler?

Has anyone installed an engine temp gauge?

Ohh, and with the shaved head it would regularly blow past 70 on the speedo (which is 1-2 off vs. my Garmin GPS).

 

[SabrToothSqrl]

Well, good news. I've officially given up on this ski. It's going to be parted out and destroyed as soon as I locate a replacement 02 XP.


Ever since the first engine blew it's been nothing but trouble with inconsistent performance and things breaking. Engines, Stators, Bildge pumps, I've replaced more parts than are left on the ski. Everything is new TWICE. and I STILL get stuck at 6K WOT or 6500 if I'm lucky. My other factory 951 hits 7K WOT (ok, 6950). EVERY DAMN TIME of EVERY DAY of EVERY RUN. 60 hours on it.

I'm SICK of throwing money, time, and stress at this thing. I'm DONE. The best decision I made 2 years ago was selling my 99 GTX that didn't perform up to spec and buying a 02 GTX with 20 hours on it. BEST thing I've ever done. I'm tired of fixing, tired of working, this has been THREE YEARS of this shit. and... I AM DONE. I AM FREE.

I am actively looking for a low hours original engine 02 XP, I know it's rare, but I have CASH in hand, want to water test it, and I will buy yours if it's in mint condition. I plan to keep my XP for parts / sell off parts as well. I have a title to mine and hull.

I'm just done. I quit this ski.

 

[brock1]

Well, good news. I've officially given up on this ski. It's going to be parted out and destroyed as soon as I locate a replacement 02 XP.


Ever since the first engine blew it's been nothing but trouble with inconsistent performance and things breaking. Engines, Stators, Bildge pumps, I've replaced more parts than are left on the ski. Everything is new TWICE. and I STILL get stuck at 6K WOT or 6500 if I'm lucky. My other factory 951 hits 7K WOT (ok, 6950). EVERY DAMN TIME of EVERY DAY of EVERY RUN. 60 hours on it.

I'm SICK of throwing money, time, and stress at this thing. I'm DONE. The best decision I made 2 years ago was selling my 99 GTX that didn't perform up to spec and buying a 02 GTX with 20 hours on it. BEST thing I've ever done. I'm tired of fixing, tired of working, this has been THREE YEARS of this shit. and... I AM DONE. I AM FREE.

I am actively looking for a low hours original engine 02 XP, I know it's rare, but I have CASH in hand, want to water test it, and I will buy yours if it's in mint condition. I plan to keep my XP for parts / sell off parts as well. I have a title to mine and hull.

I'm just done. I quit this ski.

wait what?????? i thought u had it fixed

 

[SabrToothSqrl]

Yea, I thought I did. went out last night... first 10 min can hit 6500 but has no kick in the arms PULL like my 02 GTX does. Same engine, same pump, same prop.

Then within maybe 1/4 tank of riding or less, nothing fancy, no submarines, no water ingestion... can't break 6K. I checked the TPS again at home. 80% is 0v. 100% is 0v. 0-79% is 5v. works correctly.

I didn't change a damn thing and some days it runs 6700 WOT sometimes 6k. when it runs 6K there is no difference between the throttle it takes to run 6k and full throttle. The only thing I can think of now is that I put brand new carbs on it, ordered from WSM, $500 or $600 and I don't know if they are correct for this engine / ski. It says 'you may have to adjust to your whatever'. I have my old carbs, which I believe are right. I guess it's worth a swap to find out if they give me more punch, then I thought about asking Doc. Honda to look over my brand new ones and make sure they are setup right for a 02 XP.

Could it be not getting enough fuel WOT? I'd love to test with parts from my 02 GTX, but that runs so well I'll be damned to touch any part of it. 60 hours on it now, and it runs amazing.

I know I've spent

Engines: $2,200 (2 of them!)
Engine Rebuilds including a hot rod crank: $1,200
Carbs: $500
Stator: $200
body parts: $200
bilge pump $50

HOURS, HOURS, AND HOURS of time / stress / pissed off at everyone and everything... I value at at least $4,000.00

There comes a point when you have to say F' It. and I'm there. This could be an easy fix, but I've looked at EVERYTHING 20x over.

I'm at my wits end. I just want a 02 XP that... WORKS.

 

[brock1]

your not too far away ill trade you a 96 xp with a new motor and pretty much evrrything else...for yours i want an 951 xp SOOOOOO BAD LOL

 

[SabrToothSqrl]

You don't want this one... stuck at 6K is no fun. It doesn't pull like it should.

 

[brock1]

ill take my chances...i like the look of it

 

[brock1]

what ya think......since its such a headache to ya...ill even drive down

 

[SabrToothSqrl]

I'm testing using my old carbs this week, and want to secure my replacement for it first, but after that I will let u know.

 

[bhatch21]

Sabr, sorry to hear it. I've been following your saga with interest b/c my GSX only hits 6350rpm. It pulls hard though and will hold 66mph on the speedo. I can't remember, have you replaced the water regulator? I've read where too much water in the pipe and muffler will keep the motor from reaching max rpm.

 

[SabrToothSqrl]

Yes, the water reg has been inspected and even replaced.

3 years I've had this ski. It made me happy... a few times, but not enough. I found a few 02XPs all at least 5-8 hr drives...


I love the model, just plan to replace this ski. I'm putting on another set of carbs and new plugs this week, and if it doesn't go perfect every run, I'll be putting some $ up for another.

 

[Strizzo]

not for nothing, but have you replaced this TPS switch? it sounds like your raves aren't opening like they should. given that on the 951 you turn the caps all the way in and they're controlled by a solenoid rather than the exhaust, logic seems to be that the TPS activates by way of the MPEM, the RAVE solenoid. have you tried new/known good ones of both of these?

just an idea but seems a heckuva lot cheaper than buying a whole new ski

EDIT: sorry, forgot to mention reasoning behind replacing TPS and/or RAVE solenoid. in college i worked at autozone, where i saw all kinds of unexpected modes of failure. i had a ford probe gt turbo that had a bad distributor, but drive it to warm up, stop for gas for 10 minutes, then drive some more and it would start working again. more importantly, i had a guy bring a chevy ignition module in to test, saying it would cut out after driving for a while. we hooked it up, it tested fine. the guy helping the guy said, "it tests good, must be something else" i say, no, keep testing. so he keeps pushing the button to test, it starts getting warm, and starts dropping tests.

with these little electronic sensors, heat does some strange things sometimes. maybe swap the TPS and rave solenoid from your GTX to see it that helps things.

 

[SabrToothSqrl]

the RAVES are opening approx 3,200 RPM, where it jumps to 4,200 RPM.

TPS was new last fall. and yes, it reads correctly. Also tested w/it unplugged, no change.

 

[JJinSC]

I'm leaning towards where Strizzo is at. This sounds like a RAVE issue. RAVES are more sensitive than most people think. I think that is the biggest reason they are adjustable. For instance, My ski was running fine with the red caps turned all the way in. This was after replacing, springs, bellows, o-rings and caps. However, I still had oil leaking at the RAVEs. So, I replaced the housing and guillotines. They were worn and this did fix my leak. However, in order to get max RPMs after replacing the housing and guillotines, I had to keep adjusting the red caps out until they are one complete turn past level with the black cover. This is further out than I have ever had to turn them, but it took adjusting and trying, adjusting and trying. I would look at the RAVEs and related components closer. Make sure there is no plugged vacuum lines too. Doesn't the 951 have a vacuum line that assists with the RAVES on that model?

EDIT: Oh yeah, I forgot to mention that once I had a RAVE not opening simple because the plastic cap that screws on the top was screwed down too tight. Don't asked me why this caused it. I still cannot figure it out, but it was a noticeable problem even when testing the up and down movement by hand.

 

[SabrToothSqrl]

Yep. I even have 2 complete sets of RAVES. Plus the air line and 1 way valve are also all new....