Engine rough and backfiring

[Seevee]

All,

I have a 4.3 Mercrusiser, 2003 model, injected. It's been a bit hard to start and is slow to power up... sometimes a few minutes or more.

Power is down and the boat isn't performing like it has.

When in neutral, and running it up I can here it missing and backfiring.

When under power, slow to accelerate. (have two of them and the good one runs fine).

I know I'll check timing and plugs.

Other ideas where to trouble shoot?

 

[eweise]

Check the distributor cap/rotor.

 

[hottoddie]

If the cap and rotor are 5 or more years old replace them along with the ignition wires. Make sure the flame arrestor is clean as well.