98 GTX limited idles fine won’t rev out

[Idiotwita elec prob]

I have been working on this 98 gtx limited since Christmas I had to replace the motor as it was seized and no hope of repairing it. Got the new motor in got a battery and wouldn’t turn on turns out just a fuse. Replaced fuse tried to start it turns over stops turns over stops all holding the button firm replaced solenoid and did the same thing checked wires all fine checked starter all fine checked start stop button all fine tested wires for power drops or just 12v’s wire to the button is 10 11v wire to the solenoid bounces all over so no idea. But that’s not the major thing I can get it started and keep it running and idles fine but on the dash it says it idles at 3k rpm but it’s definitely not and took it out to the lake today and went to give it some throttle and it won’t go past 10 15 mph and wont get on plane and it also thinks it’s at 8k rpm when it’s 100% not at that high of rpm and it sounds like it’s rev limiting but not really. First thought is plugs or clean carbs but I find that hard to believe it would cause it to think it’s at 3k rpm on idle.

 

[mikidymac]

Most engines are ruined by fuel system and carbs on these. If you installed a new engine on the old fuel system/carbs that is 99.9% of the time your issue and can cost you another engine.

 

[Idiotwita elec prob]

I would say that but it runs fine at low rpm sound like it should it doesn’t make sense to me. Just a proposal do you think a bad computer could be the cause of it thinking it’s at 3k idle which it’s not and 8k on half throttle which it’s definitely not and causing it to run weird at medium range rpm and not letting it get to rev out as it should. Reason for me thinking I have a bad computer is the starting problem as theirs nothing left in the system but the computer.

 

[mikidymac]

A bad voltage regulator can make them do very strange things too.

 

[Idiotwita elec prob]

Sounds like a sound question but where is that located.

 

[mikidymac]

Some are integrated into the MPEM but OSD makes an external conversion kit.
To check test the battery voltage with the ski at idle and at 5,000 rpm. Should be above 12V at idle and about 13.5-14V at 5,000 rpm. It should never go over 14V or bounce around.

 

[Idiotwita elec prob]

It is hard to know exactly what rpm it’s at but I don’t think it jumps around like that.