What is wrong with my Challenger?

[Mazdarx]

I had it out at the lake for the first time yesterday, it's a 96 Challenger with the 787, and I had a couple issues with it. It was experiencing some sort of cavitation or power loss at low speed, like I would throttle and it would rev up but not take off that fast. Once it got going it was pretty good and I was still able to hit 45 mph (indicated on speedo that is). From some reading I have done, this sounds like it may be a drive shaft seal? Or should I be looking at the impeller/wear ring? I thought that was less likely as it still worked well once up to speed. My other issue is with the throttle, I can't go full throttle on the lever or it starts to bog out and the revs drop. It will hit 7000 rpm but it won't go any more than that. Aren't these supposed to hit 7200 rpm? I am really not sure what is wrong there. I am thinking I will clean out the rave valves just since it probably needs to be done, but the posts I was reading usually describe other problems to do with the rave valves so I don't think that's the issue but I could be wrong. That is why I came here to ask the experts.

 

[Chico]

im watching this thread to homie, trying to learn as much as i can about my challeneger

 

[cheappc]

.............

 

[mlebauer]

Mine is a 2001 with twin 717s, so a bit different beast. But I had similar problems until recently. I just replaced my wear rings and cleaned up the impellers, also used a ring seal on the pump to shoe contact point (previously used silicone sealant that was falling apart). I was worried that my carbon ring may be the reason. But those things made a huge difference.

On the stalling, that's definitely another problem related to fuel delivery. I've seen such things from old spark plugs, and a leaking carb gasket on mine. I don't have rave valves so can't comment there.

Good luck! The pump work should yield dividends, unless your wear ring is already fairly new.

 

[scski]

The cavitation can be the carbon seal, pump wear ring or both. (could also be the ride plate/shoe but less likely)

The 96 Challenger revs to 7000 rpm.

 

[Mazdarx]

I saw on here a bit of a write up and pictures on greasing that seal to see if that is the issue, as well as being able to move a clip or something to make it fit tighter, but I can't find that now. Ok so 7000 rpm is normal then, that's good to know. Could my issue be a cable adjustment? It revs up to 7000 nicely but the last 3/4-1" of travel on the lever it doesn't like.

 

[scski]

You can push the stainless ring back and see if there is another groove to move the clip up, which may help if the problem is just a weak bellows. You can also try putting tie wraps on the bellows grooves to stiffen it up.

It doesn't take long to pull the pump and just check it all out though. Then you can use a feeler gauge to see what kind of wear your ring has, and you can check the driveshaft to make sure it's straight.

 

[Mazdarx]

Ok well bear in mind I am new to jets in general although not to boats, so I don't really know what's involved in doing that. Is there a write up somewhere on pulling the pump?

 

[Mazdarx]

Oh and after a little reading, I found that these are supposed to idle at 1500 rpm? Well mine was idling at 2000. So my thoughts are the cable needs adjustment, that is it pulls too far at WOT and not far enough back to allow a normal idle. What do the experts think?

 

[scski]

Be sure to check the idle in the water, not out as there is no load on the pump. (It should be close to 3k out of the water.)

The idle stop won't affect full throttle.

Take a look at a shop manual download to see the pump parts. It's pretty straight forward. Disconnect the water inlet hose inside the hull first. You may have trouble breaking the rtv loose on the final bit. You can rig a chain bolted to the pump and pry it off with a 2x4 against the rub rail if you need to.

 

[craigy]

Raves drool some,just make sure they`re tight at base gasket and i put small zip ties on bottom of bellows. Check the carrier to carbon seal alignment with hand. My 97 787[single] once in awhile gets out of true alignment[stationary carbon seal to spinning carrier seal] from me jacking around in the engine compartment. Also what I have noticed, if you have the accordian boot up against the fiberglass it will throw it off and cause cavitation. Just loosen the radiator clamp and pull it forward a[1/4 inch] little. The shaft runs at an angle[[same as thru-hull] and the fiberglass is a straight up and down plane.

 

[Mazdarx]

Well I spent some time working on the boat last night, last chance I will have to do so this week due to my work schedule. Anyway I got the raves out and cleaned up, somebody had already put zip ties on the bottom of the bellows. Where the bellows attached to the plastic cap with the spring wrapped around it was coming off on one side on both of them. Not sure how serious that is. So I cleaned them all up and put everything back together properly. The caps are also cranked all the way in, next time out on the lake I'm going to play with the adjustments on those. The whole engine compartment is covered in some kind of pond scum, you can see it in the picture I attached of the raves, like this boat was sunk or I don't know what. The air filter screen was full of that scum and whatever else, so I cleaned that out too. Then I started working on the drive shaft to see if I can sort that out. I pulled the rubber bellows back and moved the stainless cup back, then I moved the O ring into the rearmost notch on the shaft. I also hooked up my grease gun to the fitting on the shaft and pumped it full of water insoluble grease. I am hoping that these changes will help the performance of the boat, I won't know until Monday when I can take it out again though.

 

[scski]

I had a similar looking scummy still on my hull and engine parts. I think it was just mildew, the PO had it on a lift over the water for some time so it never dried out. Pretty easy to clean up, just sprayed purple power on everything and let it soak before hosing it down. Almost all of it came off pretty easily. (This was in the foot locker area too, and also in the spark arrestor like yours.)

The bellows spring is no biggie, as long as you put back together correctly and it's not leaking.

Careful when grease the pto flywheel - you can burst the boot. Usually just takes one or two pumps - when you see the shaft or boot move (or swell a bit), that's enough.

 

[Mazdarx]

Yes it is in the ski locker as well. This boat was abandoned outside and was covered in tarps for the winter so maybe that's it. Oh and I definitely put more than one or two pumps into it. I stopped when I saw that the boot closest to the fitting was starting to swell. The person who had this boat had zero idea how to look after or maintain this boat so who knows when this was last done.

 

[Mazdarx]

Well now that I have had a chance to get it out on the lake I can update this. Went out on the lake, had 3 people in the boat and it seemed pretty good, definitely an improvement over the last time out. I was able to get it all the way to full throttle, and the cavitation seemed decreased, or at least at first. It started getting worse through the day, with 3 people on board it wouldn't rev up past 6000 rpm, or come up on plane easily. It would get up to about 15mph and stay there for a while and eventually come up on plane, once on plane I could still hit about 45 mph. At one point it was really choppy and with 3 of us on there I couldn't get any more than 35 mph not sure if that was related. With just me or with 2 of us on board it ran good, planed faster and launched harder. So with greasing the drive shaft and moving the O ring to tighten up the bellows having helped, I think what I need to do is replace the carbon ring and the bellows. Does this sound like I'm on the right track? And is there anything else I should replace while I'm in there?

 

[Chips]

Replace the rubber o-ring with a metal c-clip if you can.

 

[Mazdarx]

What is the advantage of doing that?

 

[Chips]

The stainless ring can press past the rubber o-ring...or the rubber o-ring can fail but the metal c-clip will never fail and the stainless ring will never slip past it.

 

[craigy]

Yes, your on the right track. Its a hobby,Man.