525 issue. Boat was not used for a year or so. Starboard didn't start, turns out a simple slave solenoid. Replaced, started right up. I took out all the plugs, lubed the cylinders, etc. sounds good in idle. Took it for a test ride. Around 1800-2000 rpm, sounds rough, like dieseling sort of. (I think that's what called, when it sounds like wroom wroom wroom, instead of nice even wrooooooooom sound) Plus randomly makes a loud snap, clink sound. I think it's backfiring. Didn't go past 2500, the higher the RPM's the worse it sounds. Idle seems ok. Suggestions? What should I look for or test.?
THX
P

Check fuel pressure on the rails with guage...we had a similar issue and it was the fuel pressure regulator.

also check cap and spark wires...

put fresh fuel in it

If you have a rinda, I’d also do a cylinder cut out test. I had one acting up last year and swapped out one banks coil pack to cure it. Did the other side as preventative measure.

Also, the PCM 555 controller is voltage sensitive so going over connections and hounds might be worthwhile. Ask me how I know...

What's a "rinda".. I'm bad, but ?

Rinda is a scantool

X 2 : check fuel psi

you could have fouled a plug or 2 or 8 :wink when you sprayed ‘lube’ in the cylinders. Replace plugs and make sure their connectors click on.

Start there.

I don't have the scanning tool, but I have the Smartcraft screen. There are some codes I will have to track down what they are. I turned over the motor before I put the plugs back, pushing anything out, so I doubt the plugs are bad. Gaps were good and I cleaned them, but I will check them further. Fuel pressure regulator makes sense. Or even one of the fuel pumps.
THX
P

Well, update: And I need some help.
I hoped I just swapped a plug wire, but no. Wires are all on the right plugs, so it has to be the fuel pressure regulator. It's under the block, near the electric fuel pump, but I can't even see it. How on earth do I get to it and change it.???
Any suggestions? THX

So, you checked the psi ? What was it ?

What where the codes you got on the Smartcraft ?