1995 spx won’t stay cranking.

[Tgspxer]

I recently picked up a 95 spx for a cheap deal as it wouldn’t start. previous owner had it out the season before but was having trouble this year after a new plug and battery. The start button will only crank the engine a few times but would cut out before it would turn over with or without plug. I sanded all the battery connections and starter leads cleaned all the grounds and connections to the solenoid and still couldn’t get it to keep cranking.
Battery is new and I have also tested with a larger marine battery with higher CCa with no luck.

The starter will only stay engaged if I jump the solenoid terminals.

I’m starting to think either bad sol. trigger from Mpem or a DESS issue ( no beeps when lanyard is attached didn’t think DESS was equipped on the 95 but I can press the start/stop button 5 times and get the diagnostic beeps)

Any suggestions would be helpful.

 

[mikidymac]

1995 SPX doesn't have DESS so that isn't your issue.

 

[Tgspxer]

1995 SPX doesn't have DESS so that isn't your issue.

Then why does 5 button presses with no lanyard give short beep long beep indicating diagnostics then after attaching the lanyard either two short indicating bad key or the engine cranks?

 

[mikidymac]

Are you sure it’s a 1995 SPX?

The SPX didn’t get DESS until 1997.

Is your kill switch a push button or a post with a metal ring and a metal button in the middle?

 

[Tgspxer]

Plastic/rubber push button start/stop

 

[Tgspxer]

Are you sure it’s a 1995 SPX?

The SPX didn’t get DESS until 1997.

Is your kill switch a push button or a post with a metal ring and a metal button in the middle?

It’s not the DESS post style but the diagnostics can still be run for some reason

 

[Tgspxer]

Update: did some more testing on the starter circuit today start/stop button is good. lanyard post is good. Checked the trigger wire coming from the Mpem and have 0.4v when the starter button isn’t pressed and when I press the start button the voltage spikes to 12 then drops back down almost instantly. Is this a bad Mpem? Pretty sure this is the reason the starter cuts out after beginning to crank.