05 RXT strange problem...

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Duane72

Duane72

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I posted in a nother thread the overall issue with the machine not starting. TO save a lot of not-needed reading I'll say this is where I am at. New plugs, coils are fine, fuel is fresh, fuel pump operates, cleaned all ground connections on the block and battery. No codes and brand new battery.

That being said the engine turns over fine when you try to start it. I get some ignition but not a full start up. I pulled the throttle body and cleaned it good, including soaking and cleaning out the passages to (and hopefully the sensor itself) the Idle Control Valve. Put it back on and the engine REALLY wants to start. It fires just enough to the point of over-running the starter (when you would normally let go of the start button because it's running). When the starter disengages the engine stops. It won't keep running on it's own.

Pull the plugs and they are a carmel color, but not thick with it. Some brake clean sprayed on them and they are clean as new and it starts all over. What could cause the engine to be so rich right at start up like that? Is there a choke of some sort on these machines? It's not a manual one I know that.

It's a 2005 RXT Supercharged.

I'm right on the brink here of getting it running!! PLEASE, any advice is welcome!!

Duane
 
What was it like last time it ran? When was it running last?

Bad jelled fuel in the fuel lines? Possibly low compression on the cylinders? If the cylinders don't have enough compression the engine will try to start but won't run either as you describe. How many hours are on this machine?

These engines are fuel injected they don't need a choke.

- Michael
 
I wasn't on it last time it ran I don't think (it's a friends I have worked on for him), but I did ride it shortly before it went down for the winter. I put a new wear ring and impeller in it early summer. it was running like a new machine. Excellent power and torque. Hit top RPM and speed every time out. The DESS post went out on it (stuck and kept beeping even when key removed... stuck reed) so it never came to me to be winterized. I was able to get the DESS switched out with a used one from an RXP and it works fine. It was in saltwater it's last trip I am fairly certain.

I've replaced all the fuel, even to the point of disconnecting the line to the injector raila nd operating the pump to get the last of it out. Filled with fresh high-test. I've tried to start it enough I can't imagine there being any old fuel left in the rail.

I knew injected doesn't need a choke, but there must be sensors fo some sort that tell it when it's cold or warm to adjust the fuel appropriately right? This thing is driving me crazy.

Oh, I havent check the compression on it... what is considered "low" compression on these motors??

Thanks Michael.
 
And all 3 cylinders aught to be pretty close to one another on the compression numbers... no outlyers!

I only suggested checking the cylinder compression because I recently had a small model helicopter engine that would try and try to start but wouldn't actually run on it's own (much like you're description, but on a much smaller scale)... turning it's start shaft by hand I realized there was almost no compression. The ring had become stuck on the piston, it wasn't sealing against the cylinder walls robbing the engine of compression as a result. I had to replace the ring to get the compression back (the stuck ring wouldn't come loose I had to break it out of the groove with an o-ring pick). This makes me wonder if your engine has lost compression on 1 or more cylinders... they'll start to fire, but won't run like that.

Everybody says to get the Craftsman compression tester from Sears... I bought one from O'Reilly's Auto Parts but it doesn't appear to be calibrated correctly EVERYTHING I tried it on showed low compression even engines that ran just fine so... my RXT had faulty spark plugs it turned out. :-\

- Michael
 
You are describing a ski that has low fuel pressure or dirty injectors. I say this assuming the compression is good. I would remove the fuel rail and injectors from the intake plenum as a assembly, crank the engine (coils unplugged), and see if they spray fuel.
 
Oooh! Just re-read your posting... it was last run in saltwater, and then not winterized. That sounds bad, really bad! I wonder if the person on that last ride even bothered to rinse it off or flush it out? :puke:

Talk about watercraft abuse.... there aught to be a law! :mad:

- Michael
 
Dennis said:
You are describing a ski that has low fuel pressure or dirty injectors. I say this assuming the compression is good. I would remove the fuel rail and injectors from the intake plenum as a assembly, crank the engine (coils unplugged), and see if they spray fuel.
Click to expand...

Did that in the beginning cause I had the same thought. They spray solid and even.
 
UPDATE: The RXT went to the shop this morning. They are backlogged up to two weeks so it will be at least a week probably before we hear from them. I hope it's nothing major, but it will be good to know finally. I've tried all I know.
 
UPDATE: Got a call from the dealer today. They hooked it up to the computer. No codes that would cause a non-start issue. Checked through everything and did a compression test. 60psi in all 3 cylinders!!!

Holy CRAP! So I have a theory but I wanted to see what you all thought of first. What can cause that low of compression on a machine that ran perfect the last time it was shut down? No clunk bang stall die problem (read initial post above).

By the way, the dealer says I am $200 into it now and anything once they tear into the motor to investigate further will most likely run me at least $1500. Can pretty much tell you what I think of that!! Should have spent the $200 towards the software to check it myself, but it's not my money so...
 
I find that suspicious, that all 3 cylinders would be at 60psi... if only 1 was low on compression I'd say something was mechanically wrong with that 1 cylinder, but for all 3 to be low and at the same psi that's just not right.

How many hours are on this machine? I re-read your posts but never saw the hours posted anywhere.

Also did you try a brand NEW set of spark plugs in it? Even good clean spark plugs will crap-out on these 4TEC engines, I've experienced it myself and it made me believe something was wrong with my engine's cyclinder compression also... a compression guage I purchased from O'Reilly's Auto Parts read low compression on all 3 of my cyclinders, but guess what: I tried the compression guage on my pickup truck engine (454 big block) and my John Deere riding mower and it showed them as having low compression also (in spite of the fact that they ran just fine). Finally realized that though my spark plugs looked brand new they weren't, my new spark plugs were still stored in the spare plugs caddy under the seat! (Oooops! Thought I'd changed them the previous Fall). I put the new spark plugs in, the 4TEC engine runs just fine.... I suspect as some others on this forum were telling me last year that the compression guage I bought is miscalibrated. :-(

So ask them to check the compression again, with a different compression guage this time! If both guages give the same readings then perhaps it's true (in which case there must be a problem with the head gasket or the timing gear... I've read some people adjust their timing gear to change their compression readings on their engines)... but if the 2nd guage's readings are different then their guages like mine are miscalibrated and misleading you, try new spark plugs before going any further!!!

ps. No matter what, if you didn't try it with brand new spark plugs DO SO before spending any more time or money on this engine! Spark plugs can look clean with no electrode wear and even spark if hooked up to the coils and a ground wire lying on top of the engine (I did this in fact!), but once in the cylinders under compression they won't spark or will only spark intermittantly!

- Michael
 
Hey Michael. I know where you're at with the spark plugs. I'm of the same mindset... that's why they were brand new from the store. Two sets in fact because I wanted to be sure.

It has 102 hours on it. My first thought was s/c but that wouldn't cause compression issues or no start unless it let go completely. I haven't pulled the hose and checked the spin on it, but from the last ride it didn't fail like that. The motor ran fine when it was last shut down.

Would the idle air control valve or TOPS valve affect compression at all? Are there any valves that allow compression to escape on these things?

My theory is that the last ride being in saltwater with no follow up on fogging or rinse down left the salt air/moisture in the engine. The plugs were covered with white corrosion on them when I pulled the original ones. Wish I had taken a picture. But if that same corrosion built up on any of the valves enough to keep them from closing all the way... ?? Seems like a long stretch but I don't know.

My thinking is I am at the point of tearing the head off minimum.
 
It makes sense that low compression is keeping it from starting. From your decription ( all 3 cylinders are low) it makes sense that possible rusty rings, cylinder walls and valves are the reason. I would try pouring a few tablespoons of Marvel Mystery oil or automatic tramission fluid down each spark plug hole, crank the engine alittle bit and then let it sit overnite. The object is to get the compression high enough for the engine to start. Repeat as necessary. If it eventually starts just let it idle (no reving), warm up and then shut it down. Add a little more oil, crank engine and let it sit again. You might get lucky. :cheers:
 
Get it back from the Dealership before they charge you an arm-n-leg... then try what *Dennis* said.

Also I was told that Craftsman makes a very good high quality compression tester (I bought from O'Reilly, not so good evidentally). You might want to try getting a Craftsman compression tester and check the cylinder compression readings yourself.

You didn't say before that the old spark plugs were eaten up with corrosion... probably the rings and cyclinder walls look about the same. Stuck rings will also kill cylinder compression, and if the thing sat up like that over the winter then yeah I kinda bet the piston rings are frozen on the pistons and not sealing them to the cylinder walls.... that would make sense to me, better sense than any TOPS valve issues.

Try what Dennis said, and get a good engine compression tester by Craftsman from Sears and see if the numbers don't come up and it starts running finally. Otherwise you're going to have to pull the head off and split the engine open to get the pistons out, cause I bet the rings are corroded and frozen on each and every piston if the spark plugs were that nasty looking! The dealership will charge you more than the cost of a good used low hours never-used-in-saltwater PWC would cost! Eeek!

- Michael
 
Duane72 said:
Would the idle air control valve or TOPS valve affect compression at all? Are there any valves that allow compression to escape on these things?
Click to expand...

Nope. The TOPS valve just shuts off the engine crankcase vent and turns off the ignition if the watercraft turns over, I don't think there's any provision in the head to close all 3 exhaust valves at the same time...

The idle air control valve has nothing to do with the exhaust valves as far as I can tell, either. When the intake and exhaust valves on a cylinder close shut, that's it the cylinder will build up as much compression as it can as the piston comes up on the compression stroke before firing... but if the rings had corrosion on them (and sounds like they almost surely do!), then they would squeeze into their grooves on the 1st upstroke and stick... then not expand back out on the downstroke anymore, so next upstroke the rings are already fully compressed and allow air/fuel mixture past them resulting in loss of compression because it's losing air/fuel vapor past the rings from then on.

This is what happened to my model helicopter engine (but because there is high oil content in my model's fuel, and I left the engine in the fully compressed state for a few months without realizing the piston was at top of cylinder), the ring had become stuck in the groove and would not expand outwards to maintain the cylinder seal resulting in loss of compression... I bet the same has happened to this PWC now. The symptoms match perfectly I swear that's exactly what my model's engine was doing it would try to run while on the starter but then die as soon as the starter was removed and it was far too easy to turn the engine over!

- Michael
 
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Man, never even thought of the Marvel Mystery Oil!! And I've done/heard of it before on engines that have sat for long periods of time. Mower engines that are "seized" can often be losened that way. That's an awesome idea! Thanks guys. I can pull the injector rail and drip some oil down onto the intakes as well.
 
Hey Michael... I did mention the plugs being nasty but it was in the original thread so it was a while ago and burried. Sorry I didn't refresh that in the new post. Yeah, it makes sense. I didn't think of the piston rings holding corrosion, just the valves. I should have thought of that, but that why I put it out there for thoughts. Thanks! And thanks Dennis!
 
You would have to program a new DESS post to the original key, that I know. My RXP had similar symptoms, was running perfectly then stopped, fault code was that the pick up sensor was faulty, I did extensive investigation and narrowed it down to the ECU, cost me 900 pounds, now the machine has ran perfect for 2 seasons now, hope this helps mate.
 
Actually, the DESS post is just a switch, but the DESS lanyard has to be programmed to the ECU.

All 3 cyl at 60 psi leads me to believe the timing is off, like it jumped a tooth or two due to a loose chain or bad tensioner while at running speed and now won't turn fast enough to skip anymore. Way too big of a coincidence that all 3 are exactly low the same. check the timing, and the timing chain tension, simple 10 minute check.
 
I never got back to this... maybe because I wanted to block it from my memory. I filled the pistons with marvel mystery oil and let it soak a few days. went back and turned it over to blow out the oil good, then installed new plugs. Same problem. It didn't cure the compression. So I gave the owner the bad news and backed off. He doesn't want to dump any more money into fixing everyone else in the family's misuse and I don't blame him. I think he is ready to just sell both the 05 RXT and 04 RXP at this point. The GTX I think he'll keep since it runs and can be used.
 
did you ever check the timing? you don't have to take the head off and it really only will take 10 minutes. these have known timing chain issues as well as the timing gear can easily slip. if the valves are opening too soon, you will get exactly the same low compression on all 3 cylinders, sound familiar?
 
I didn't actually. I'm not sure I would know how to be honest. I looked in the manual and it seemed like a lot more involved process than 10 minutes?
 
Take the valve cover off, bring #1 cyl to tdc and see if the marks on the timing gear are lined up. Done.
 
ski-d00 said:
Take the valve cover off, bring #1 cyl to tdc and see if the marks on the timing gear are lined up. Done.
Click to expand...

Sounds easy enough. I'll check that next. I have to go over and get the only one that starts back in the water for them so I'll check the timing when I'm there.
 
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