I have a 98 challenger 1800 that has been giving me problems and has been driving me crazy. My portside motor when i full throttle it will only go to 5K rpm and it sounds like its hitting a rev limiter while the other motor shoots to about 7K rpm. but if i back off the throttle of the port side motor and hammer it once and while it will then go to 6K rpm. once i back of the throttle it will only go up to 5K again. It was at the shop and they checked the coil, fuel lines, carbs, compression good at 125 for both motors, and the rave valves all looked good. i picked it from the shop since they didnt have time to work on my boat anymore and dropped it off at another shop. Anybody ever have this problem? Any ideas on what else could cause this.
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98 challenger 1800 rpm problems
- Thread starter chargedz
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timmyboy76
New Member
you said, they "shop" LOOKED at the carbs. You know when, the carbs were last serviced?
Open up the elect box, and disconnect the red wires from the rectifier, then give a shot, if works, replace them.
Open up the elect box, and disconnect the red wires from the rectifier, then give a shot, if works, replace them.
i bought the boat last october from a marina near my house. they told me they rebuilt both motors and eveything was good. so i dont know when the carbs were serviced last. But my seadoo mechanic went through them and he said they looked fine. i will remove the red wire from the rectifier and see what happens. shakedown are you having a similar prob as me?
shakedown
New Member
Yes I am!!!!! I have a 95 speedster, problem started with rpms @ 6800 then would cut down to 5500, back and forth back and forth. if I didnt go over 4500-5500 rpms it would not cut out. but now it has gotten worse, it wont go over4000-4500 rpms at all. my other engine runs perfect. my compression is 145-148. having 2 engines I have switched alot of parts from one engine to the other.
switched carbs
switched fuel lines (and selector valves) also new inline filters and fuel lines
switched coils
switched rectifiers
new plugs
cut plug wires back
switched (ECM)
water flow is good with no restrictions
no exhaust restrictions or leaks
pulled the flywheel off looks all good nothing loose no metal shavings
I am going to do a leak down test as soon as I can fabricate the parts for it
switched carbs
switched fuel lines (and selector valves) also new inline filters and fuel lines
switched coils
switched rectifiers
new plugs
cut plug wires back
switched (ECM)
water flow is good with no restrictions
no exhaust restrictions or leaks
pulled the flywheel off looks all good nothing loose no metal shavings
I am going to do a leak down test as soon as I can fabricate the parts for it
well after another 3 weeks of being in another shop and still the boat isnt performing the way it should. Again this mechanic went through everything with no luck or exact cause. but at least its getting better. the port side motor now goes up to about 6500/6700 rpm and hits 53 mph but the other motor still kicks harder. The mechanic changed the jets in the problematic motor by going down one size. i have almost given up why my boat wont perform the way it should and why i had to drop the jet size. i believe the only other thing causing this might be the computer/rev limiter. is there anyway to check if this is the problem before dishing out $1300?
shakedown
New Member
if you can switch engines on the computer, that means switching the wires on the stator/mag @ the plug-in outside of the housing, and the coil wires(the wire going to the coil from the mpem, one wire on each coil, then the wires also get switched on the rectifiers, befor you do this disconnect ground on both batteries.
To bypass rev-limiter
isconnect the wire between the mpem and coil leaving the coil connected to the stator and see what happens. If that clears it up you have a mpem problem. Also remember if you do that you have to choke it to kill the engine since the kill circuit will be bypassed. in the computer box find the black and green wire, there will be one for each engine, now follow where the wire plugs into the coil, the same black and green wire has a junction connector in it that will allow you to unplug the mpem, but still keep the engine plugged into the coil.
To bypass rev-limiter
isconnect the wire between the mpem and coil leaving the coil connected to the stator and see what happens. If that clears it up you have a mpem problem. Also remember if you do that you have to choke it to kill the engine since the kill circuit will be bypassed. in the computer box find the black and green wire, there will be one for each engine, now follow where the wire plugs into the coil, the same black and green wire has a junction connector in it that will allow you to unplug the mpem, but still keep the engine plugged into the coil.thanks shakedown now i got the boat in my hands so i can mess around with it. i took it out today for the 1st time since i got it back from the shop and the motor only goes to 6K rpm not 6700 like the shop said. and also when i hit it the motor jumps to 5K and takes a few seconds to get up to 6K. funny thing is that the motor sounds the same at 5k and at 6K. IM GOIN CRAZY!!
I should have been posting here as well...
I dont know anything about boats but my dad is having the same problem.. The boat has been with a good 30-year boat mechanic for 3 weeks and he's completely stumped.
From what i've gathered, the symptoms seem the same for everyone..
SYMPTOMS:
---------------
one engine is not getting full power. As you push it up to 7K it either runs smoothly for a short time and drops or immediately drops to around 4K-5K, The second engine seems fine. Also playing with the throttle apppears to partially correct the problem sometimes.
I've been compiling a list of what we've done and read being tried. If you see something you haven't done, see if it helps or you can assume that it won't because it been tried.
Add to the list and see if someone can figure this out.
TROUBLESHOOTING
--------------------------------
SWAPPED:
Jet Pump and impellor assembly
Electrically jumped wires from left to right engineattempting to recreate problem on 2nd engine.. (in my case it wouldn't even start)
REPLACED:
Fuel Filters
Spark Plugs
Coils
Voltage Rectifiers
Multi Purpose Electronic Module ($1300 wasted)..
switched (ECM) ..(is it the same as the MPEM?)
REPAIRED and CLEANED:
Carbs
Fuel Lines
switched fuel lines (and selector valves) also new inline filters and fuel lines
Air Cleaner
Fuel Ports
verified proper water flow
no exhaust restrictions or leaks
ADDED:
New 4 guage ground to block of engine
New Grounds at Electrical Boxes
Good luck.
I dont know anything about boats but my dad is having the same problem.. The boat has been with a good 30-year boat mechanic for 3 weeks and he's completely stumped.
From what i've gathered, the symptoms seem the same for everyone..
SYMPTOMS:
---------------
one engine is not getting full power. As you push it up to 7K it either runs smoothly for a short time and drops or immediately drops to around 4K-5K, The second engine seems fine. Also playing with the throttle apppears to partially correct the problem sometimes.
I've been compiling a list of what we've done and read being tried. If you see something you haven't done, see if it helps or you can assume that it won't because it been tried.
Add to the list and see if someone can figure this out.
TROUBLESHOOTING
--------------------------------
SWAPPED:
Jet Pump and impellor assembly
Electrically jumped wires from left to right engineattempting to recreate problem on 2nd engine.. (in my case it wouldn't even start)
REPLACED:
Fuel Filters
Spark Plugs
Coils
Voltage Rectifiers
Multi Purpose Electronic Module ($1300 wasted)..
switched (ECM) ..(is it the same as the MPEM?)
REPAIRED and CLEANED:
Carbs
Fuel Lines
switched fuel lines (and selector valves) also new inline filters and fuel lines
Air Cleaner
Fuel Ports
verified proper water flow
no exhaust restrictions or leaks
ADDED:
New 4 guage ground to block of engine
New Grounds at Electrical Boxes
Good luck.
hey.
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.
hope this helps.
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.
hope this helps.
PROBLEM SOLVED!!!!!!!!!!!!! After the entire summer of a problematic boat the issue is finally resolved just in time for fall 
. After checking everything minus the internals and swapping everything from one motor to the other with no changes the shop went to seadoo for some ideas. The first one worked! The shop i bought the boat from rebuilt the motors prior to me buying the boat. they forgot to torque the crankshaft gear which in turn messed up the timing and made one motor all out of wack. But the good news is the boat is running like a champ and hopefully get out on the water 1 or 2 more times before good old winter. thanks all the help and ideas everyone :hurray:
. After checking everything minus the internals and swapping everything from one motor to the other with no changes the shop went to seadoo for some ideas. The first one worked! The shop i bought the boat from rebuilt the motors prior to me buying the boat. they forgot to torque the crankshaft gear which in turn messed up the timing and made one motor all out of wack. But the good news is the boat is running like a champ and hopefully get out on the water 1 or 2 more times before good old winter. thanks all the help and ideas everyone :hurray:- Status
