2000 Volvo 5.0GL periodic misfire??

[firebird1158]

Hey guys.... I have had this periodic misfire over the last couple of years that i have not been able to find the cause of. It is almost like a little backfire with a kind of popping noise usually at beginning of the day at load getting on plane but sometimes what sounds like a little miss at wot.

people don't usually pick up on the wot miss.. but of course I do! Anyway it comes and goes for weeks at a time .

I have put new plugs and wires, water separator, and coil, sprayed some carb cleaner... checked timing and distributor cap and button... all seems fine and I am stumped? It seems to do it more when boat is being used less or sitting for a week without use...

Anybody have any suggestions where else to be looking??

any help much appreciated... thanks in advance

 

[Wroxbury]

Re: 2000 Volvo 5.0GL periodic misfire??

backfires occur either when the intake valve is not closed completely or when the exahaust fumes ignite.

so either it is a timing issue (intake) or exhaust when your air fuel mixture is lean or your timing is too advanced. if you have already done timing it is probably time to look at the carb and do a rebuild.

 

[dubs283]

Re: 2000 Volvo 5.0GL periodic misfire??

could also be a lack of fuel when the engine really needs it

the popping noise could be a lean pop due to insufficeint fuel delivery when demand is high

would be a good idea to test fuel pressure at all rpm ranges under load