77 omc 190

[pete s]

Just purchased a 1977 cruisers with an omc 190hp. Ran perfect first time out earlier in the week. Today different story... Under load has a backfire through the carb and boat almost shuts off not like only one cylinder is missing. Points condenser cap rotor plugs wires and fuel filter are all new. Firing order is correct points set to .017. Idles great will rev up no problem out of gear and in water but under load above 1500 rpm will start to backfire. Thinking ignition related but not sure where to start. Also thinking (hoping) if it was valve train issue ie cam lobe burnt valve ect I would have issue load or no load. Any ideas would be great!!

 

[Howard Sterndrive]

sounds like it is running out of fuel under load. That backfire will happen as the mixture goes lean. Maybe check that the fuel filter was installed right. Could be fuel pump or anti-siphon valve (if equipped) or otherwise restricted fuel flow.

 

[pete s]

Thanks for the help! It's hard sometimes to remember the basics! Did some checks on fuel system Sunday and fund hose from the tank to the pump to be collapsed causing it to starve for fuel. One new hose later ran like a dream all day.