Logo
FULL SITE MENU

volvo 350 knocking and backfiring after around an hour of running

M

mproske

New member
my boat seems to working fine but after an hour it starts knocking and backfiring and seems like its miss firing. i thought it was fuel related as I just installed a fuel flow sensor but i've since bypassed the new sensor and filter and still the same problem. now i'm thinking it is ignition related. coil? timing?
 
its running rough at an idle, start revving it up and it starts knocking, starts popping and backfiring at around 1900 2000. the weird thing is that it runs like a top at cruising speed for an hour or so. the first time it did it i made it to the fishing grounds and trolled on the kicker for four hours then it was hard to start and had the problem right away. the second time it did it i was on the way to the same spot and noticed a loss of power just as i was arriving, fished for a couple hours and it was running rough when i went to start. it seems something is getting hot (coil, ignition?) because it starts great in the morning after everything cools down. the engine has been in its regular temp range 165 to 175. i have put some new electronics and pulled some wire through the boat, changed the alt belt, and changed the oil recently but all that seems unrelated to this problem
 
Maybe the anti-siphon valve at the fuel tank slowly gets clogged while you are running, and unclogs itself after the engine is shut off? It happened to a co-worker of mine.
 
Back
Top