Logo
FULL SITE MENU

2004 8.1L running rough

M

Mike305

Member
Hi need help with my 2004 8.1 L Crusader engine. I have done the following to try to resolve the issue but the engine is still running rough, especially at higher rpms. If I accelerate in neutral from 0 to 3000 rpms it seems fine, but if it goes over, the engine starts running rough and back fires, tach goes up and down. Also, I ran the boat today and as long as I was below 3100 rpm it seem fine, over 3100 rpms the tach was going up and down.

- changed spark plugs
- clean fuel injectors
- new fuel filter

any suggestions?
 
Backfiring sounds like the engine is running lean.

Tach going up and down sounds like it being an electrical problem, as in the ignition intermittently shutting off and coming back on.

Combining the two events could result in a sudden firing of an overly rich mixture when the ignition comes back on, but also could be a distributor problem as well.

One way of checking for a bad ignition/firing is to use a Timing Light, and see if there is any change in the light at the higher revs.

Is the engine a fuel-injected one, or Carby?

Bruce.
 
It is always a good idea to post as much information as possible.-------------Is this a problem that showed up suddenly at full throttle operation?-------Is it something that showed up after a long lay-up ?-------How many hours on this engine ?--------Any recent work done on the engine ?
 
Back
Top