502 mag lack of power
 

motors are late 97's with cool fuel in my 97 Baja 322 85hours on a rebuild
my port engine runs rough and is lacking power when rev'n at idle it has a slight hesitation. while running the port engine throttle has to be way more to make the sync gauge match it also doesn't do much if I open it up whereas the other engine if I open it up(while crusing around 40) it will take off like crazy. its a heavy boat and I don't push it to get on a plane but it does struggle. I just installed EMI thunder exhaust over the winter it ran fine last year. Ive checked it theres no codes. while running around 3k it sometimes pops like a back fire but with both engines running its hard to tell what it is. I pulled the plugs on the easy side and they all look good(all I could do on the water things were hot) I also tried pulling off one plug wire at a time to see if it was one cylinder that was acting up but the computer doesn't seem to like that cause it alarms and shuts off instantly. im going to give it a tune up in the next few days but im doubting it will change anything.

any ideas? fuel pressure regulator? I have a heat exchanger on the front and I believe the shrader valve is hidden behind it.

thanks

Neil

Star with the basics.
Plugs, cap, rotor and water sep fuel filter.

Youmwont believe how bad the inside of your distributor looks..

Ok so now I'm pulling my hair out I changed plugs wires cap rotor fuel filters same thing but now I can't even get it to stay running I had it running then it started sputtering and quit. Now just fires seems like no fuel so I started the other motor which ran like a top it started ran smooth but now alarms and shows code 33 I swapped map sensors with my spare and same thing.... Is it possible since I've put on the new exhaust I'm running lean??

Found a loose cap wire now it won't stall is was shorting on the intake not sure why this computer is setup to shut off instead of just missing

Other Motor has only 25psi while cranking with the occasional pop looks like regulator time

Changed the fuel pump and regulator has 40+psi cranking still will only pop and the odd time start for a few seconds.

Turns out the msd coil was weak swapped it with the other engine and it fired right up