BigJoeB
Member
- Jul 25, 2012
- 177
- Boat Info
- 1992 Sea Ray Amberjack 310 with Tuna Tower Mod. Great Boat
- Engines
- Twin 7.4 Mercs.. Thirsty Girls
I have a 7.4 Merc Inboard closed cooled with about 625hrs.
After we splashed for this season we took her out for a run and when she hit 2000 rpm start backfiring out of carb.this never happened last year. So, I changed fuel filters again, rotor,cap,wires and plugs, adjusted carb had the timing adjusted and had the valve cover taken off to check rocker arms and adjusted them or valve adjustment done, Fuel was good, this is on port motor, starboard fine. The motor starts fine, idles fine, runs at 1900 rpm like nothing is wrong. Hit 2000 rpm and back fire out of car.. I had a compression test done by marina mechanic a few weeks ago. found all cylinders at 145psi except #4 was 90#psi.
I didnt make them go further yet, I am gonna pull rocker covers off soon and check rocker arms and give a look. thinking valve problem thats the obvious.
lets here some thoughts and worst case
Thanks
Joe
After we splashed for this season we took her out for a run and when she hit 2000 rpm start backfiring out of carb.this never happened last year. So, I changed fuel filters again, rotor,cap,wires and plugs, adjusted carb had the timing adjusted and had the valve cover taken off to check rocker arms and adjusted them or valve adjustment done, Fuel was good, this is on port motor, starboard fine. The motor starts fine, idles fine, runs at 1900 rpm like nothing is wrong. Hit 2000 rpm and back fire out of car.. I had a compression test done by marina mechanic a few weeks ago. found all cylinders at 145psi except #4 was 90#psi.
I didnt make them go further yet, I am gonna pull rocker covers off soon and check rocker arms and give a look. thinking valve problem thats the obvious.
lets here some thoughts and worst case
Thanks
Joe