Hey guys, I have a quick question. I've got a little problem on my mpi 502 volvo penta in my boat. The last few times I've taken it out, it doesn't seem to want to get up to speed, and backfires under heavy acceleration. I've replaced the fuel filters, cleaned out the 2 pumps(low/high pressure), lines, fuel cooler cell/float. Everything but injectors but I really think its a fuel pressure issue. Oh and I've changed all ignition components also over the past few months as maintenance. I was planning to take it out Wednesday but not if the problem persists. I started it up in the driveway today and it starts and idles fine, revs up fine, but not under very heavy acceleration(not under any load either). When I rev it hard, it hesitates and backfires through the intake once, then revs up fine. I just wanted to get an opinion before I go out and get a nice set of fuel pressure gauges, which I kind of always wanted anyway. Thanks guys.