Lack of power with problematic Volvo Penta GXI-J....now backfiring at 3000rpm

[saltymoff]

Yes my friend checked that all clear...I'm convinced it's the pump or injectors...had it out yesterday and only getting 4200rpm..getting worse.
Was going to put the test gauge on the fuel rail but the weather was pretty choppy and I couldn't ride fast for long....when testing the fuel rail I need to run the engine under load?? Correct?? At WOT range to see what the pressure is at 4200rpm...?
Cheers

 

[ericga]

Yes test your fuel pressure at all operating RPM. Since the problem is progressively getting worse I would check the following:

Fuel tank vent
Pick-up tube (is boat running better after a fill up?)
Exhaust restriction (clogged manifolds?)
fuel lines (bending or collapsing under load)

old petrol = send your injectors for professional cleaning and flow testing.

 

[saltymoff]

Ok so I went out yesterday and hooked up a gauge to the HP rail...atarted engine and 30psi was the reading on the gauge, took the boat out put it up on the plane and it wouldn't go passed 30 psi. Called my local marina who fitted and tested the "new" pump to let them know..

Anyway today I'm ​taking the boat back through the canal which has a 5mph to its pontoon, I arrive at my pontoon and then go to disconnect the test guage only to see it reading 50-60psi....??????
Tried it again a few times and the HP side was reading as it should at 50-60psi??....I could not take the boat and put it under load as I was now in a restricted speed zone but this is starting to get very confusing??

Any advice??? got to be a faulty pump causing my problems?? ...the connections on the pump are all ok..

 

[Tail_Gunner]

A lean condition in general could cause a engine to back fire... cleaning your injectors cleared that up to some extent and now your fuel pressure is fluctuating. If this is mpi off the cuff im quite sure you need to be at 45lbs steady... lower than that would cause a lean burn situation and also more than probably cause some detonation which in return the ecu would retard the timing and again loss of power or performance...

http://www.volvopentastore.com/Fuel...on_id.469248303--store_id.366--view_id.772077

Fuel pressure regulator would be the first suspect then as mentioned earlier.. timing... spark issues.

 

[saltymoff]

Thanks TG sir....I'm steering towards the pressure reg now...
I have read the FPR Are OEM Bosch and you can buy them direct from Bosch on Amazon for fraction of the price that Volvo offer....I have the part number, seems to good to be true though...anyone used one??

Cheers