97 Challenger problems as well!!!

[spyderman824]

Right engine fine going great peaks out at 7500 rpm. Left engine cavitated between 7000 down to 5000 finally to rev limit at 4500. Last night though I couldnt get it to go past 3000 rpm. Here is what I've done:
Carbs were pulled and cleaned and checked
Spark plugs and fuel filters replaced
Voltage rectifiers changed

Any thoughts?

 

[kustomkarl]

I don't understand your problem...it will cavitate between 5000 to 7000 rpm's...with other engine running at full power...Is the jet pump shaft working freely on the bad engine? Pull the spark plugs and spin the engine by hand at the jet pump shaft at the rear of the engine. Rotate it counter clockwise to see how free the shaft turns. Compare it to the other engine. It sounds like te bearings might be bad in the jet pump. Visually check the jet pump for any obstructions.

Karl

 

[pincusa]

Check your carbon seals as they could be putting air into the stream. Easy way to test is to move the bellows up a little and see if that helps. But that will only be a temp fix

 

[spyderman824]

Jet pump is unobstucted, spins freely. Right now drivers side engine runs great at 7000 rpm passenger engine wont go above 3500 rpm. Before this it would cavitate between 5000 and 7000 rpm while the other engine was at full power. I have had suggestions that this could be electrical, any one dealt with something like that before?

 

[timmyboy76]

yup...in my challenger 1800. If i brought starboard motor to 6500rpm, the port motor, then, would turn 7k, if starboard was WOT, then I couldnt get port motor to run, kept fluctuating from 7-5-4-7-4..rpm'z. Went thru entire fuel system, replaced the filters, tightened all clamps..etc, EVERYTHINGA, and dont know what caused it, but one/all those things fixed the problem.

 

[break9009]

spyderman824,

We've had the same issue with our '97 1800 challenger..

initial symptoms:

With the throttle for both engines at the same place(about 75% full), one engine will sit around 5000RPM and the 2nd revs right up to 7000+ without delivering power to the boat. if you pull back on the throttle and and very slowly moved it up, it would make it to 7000RPM and deliver full power and work fine. It's done this for the last 4-5 years. sparks,fuel system have all been replaced, no blockages exist, nothing seemed to fix it.

Now when the "bad" engine reaches 7000RPM it drops immediately to 4500RPM and stays there. ... no matter how slowly you increase the throttle.

I've read about the MPEM (multipupose electronic module) PCB acting up and we are going to replace it to see if it is the cause. $1300

i'll update then.

 

[spyderman824]

So i took and swapped from the good engine the:
Jet Pump and impellor assembly
Electrical Boxes

Replaced:
Fuel Filters
Spark Plugs
Voltage Rectifiers

Repaired/ Cleaned:
Carbs
Fuel Lines
Air Cleaner

Added:
New 4 guage ground to block of engine
New Grounds at Electrical Boxes

Noticed today when changing the spark plugs (again) that one of the plugs looked brand new while the other looked like normal wear, didn't look like there was any combustion going on. But the electrical boxes were swapped (including spark plug wires) and no issue with the other engine. So I took off the air cleaner and gas is getting sprayed into the carb, but it didn't look like any combustion is happening in that cylinder at all. Could the MPEM cause this or is this mechanical failure somewhere?

 

[spyderman824]

Break9009,

This is so frustrating, let me know if the MPEM cures your problem, I'm getting to the point where I don't think there is anything left to do but the MPEM.

Hopefully that works for yours, Thanks.

 

[break9009]

It has arrived and wil be installed in the next couple of days... I'll let you know.

 

[break9009]

Apologize for the delay in getting back to everyone, i've been out of town for a while.


MPEM did NOT work... $1300 down the drain, no better off and no leads to follow. Our dealer is trying to get a hold of Bombardier directly for more information.

The fun continues!

 

[phough5757]

May I suggest?

A compression test.

 

[pincusa]

Break and Spyder -
As I mentioned before, both of you should check your carbon seals. I suspect that you both have major air leaks from them and that's the cause of your problems. With air in the water stream, the impeller has bite and the engine has no load. So the engine will just rev up without pushing the boat.

Or just keep buying parts and eventually you'll get to the carbon seals... :rofl:

 

[break9009]

Finally

hey guys,

carbon seals were checked as well and they were fine.

the problem has been solved for us. i dont have the full technical details yet but it was a problem with the exhaust system. a crack on an inner pipe inside of the exhaust system that regulates water intake for cooling. the entire exhaust system was dissassembled(only once-overed the last time).


the boat would rev up to 7k and drop 4.5k to protect the engine from over heating. the crack caused a leak that prevented proper water flow and cooling through the system.

i'll try to get more details.

hope this helps someone.