760 Pump problem?

[dhud64]

Hey everyone-
I've been trying to figure out a rough idle at low rpm's. During the posting when I stated my top end rpm's, 99gp mentioned I may have a pump problem. Thought I should start a new thread?

Here's more background of problem: I have been experiencing rough running on my 760 between the rpm range of idle, which is now about 2,500 rpm and about 4,000. After 4,000 it breaks loose and runs pretty good. My top end rpm's are about 6,900 to 7,000, and shows 51mph.
Can ya'll explain more? I know nothing about ski's, obviously [img]smile.gif[/img]

[Technical Support]

Try unscrewing the spark plug boots and snipping the cables back 1/4", then screwing the boots back on.

[99gp1200]

Those 6900 to 7000 rpm numbers seem high to me.
Was that in smooth water while it was hooked up?
760's in my experiece turn 6400 - 6500. Something in the pump or an impeller problem could result in those high rpm's. Then again I could be wrong. Tech??

[Technical Support]

Yes that's high, but I bet he's just not remembering correctly. I bet he's in the mid 6000's.

[dhud64]

Yes that was in smooth water. I assume by hook-up you mean....good traction, no cavitation? Then yes! BTW, thanks for lookin out for me, reading between the lines of my problems etc... As I said, I'm new to all of this and it's appreciated!!!

I'm sure I was pushin' 7,000 rpm, with out a doubt. Unless the gage is wrong?

[Technical Support]

I'd say 99's right then. The stock tachs are pretty accurate. Read the pump inspection article, you have some pump damage causing low-end problems and slip at high speed, you are several hundred RPM above your normal max.

[dhud64]

Thanks guys, I'll start looking tonight.

[dhud64]

Ok, here's the scoop.

Impeller -OK
Clearance-.25
Vanes-OK, could use bluprinting! Is it worth it? Are there seals or O-rings I'll need to replace? If so, I'll do that later.
Nozzle-OK I see one nozzle. There are three hoses, but one nozzle. Is that correct? The hose with a nozzle is towards the rear of the cone, and the other two hoses are stagered further in but no nozzles protrude.
Everything looks good to this untrained eye!

Do I use Locktite on the intake grate bolts? What kind?
Any special sealer on the intake grate itself? It had kind of like a silicone on it to seal it to the hull mounting bracket....

Think I'll skin this idea for now and shorten the plug wires to correct the roughness @ low rpm's. Will advise.

Thanks!!!

[99gp1200]

Blue printing is not worth the cost for rec use.
Blue loctite on the bolts
I don't think you need sealant on the OEM grate
It comes with rubber pads to fill in the gaps.
Check those rpm's the next time your out.

[dhud64]

Thanks 99 I will.
I will also check them riding normally! I was way back on the ski with the nose up and I 'thought' I was getting good hook up? It was recorded that way at 51 mph, the fastest I've seen it go.

Thanks again.

[dhud64]

Trying to trim spark plug wires but boots are frozen to the wire after removing the zip tie. I gently pryed around the wire with an eyeglass sized screwdriver, and put a little dish soap between wire and boot but is still stuck?
#$%^&*#$%^&*!!!

[ June 23, 2004, 04:45 PM: Message edited by: dhud64 ]

[Technical Support]

You know they unscrew, they don't pull off - right?

[dhud64]

I saw unscrew in your earlier post but those things are really stuck!

You are talking about disconnecting the boot at the spark plug end of the wire correct? (I don't see where the other end of the wires go anyway, other than into a black box).

I feel real ignorant now!!!

[dhud64]

Re: 760 Pump problem?

OK I finally got the spark plug wires trimed(?). That seemed to have solved the rough running between idle and 4,000 rpm. THANKS!!!

As far as top end rpm's it it turning 6,800-6,900 at WOT. I've checked the pump etc... as stated in the tech article and all seemed well. What else could cause too high rpm?

[99gp1200]

Re: 760 Pump problem?

If it running good I would not worry about it. Your tach could be wrong.