backfiring at WOT

[redmansmb]

i was wondering if anybody had some info on why my 1984 mercruiser 470 will backfire at WOT?i replaced carb from rochester to mercarb put elec fuel pump on and water/fuel seperator on.i also checked dwell and timing and they are allright.i was thinking of getting a conversion kit for the distributor cause i think thats about all i can replace thats left.any info would be great,thanks

 

[jeff13601]

Re: backfiring at WOT

you set the dwell but did you replace the points cond and rotor? The points could be glazed over or pitted. After that I would prob look at the plugs and wires

 

[Don S]

Re: backfiring at WOT

Instead of just throwing parts at it and hoping you hit on the problem, try some troubleshooting first. You checked the timing, but did you check the advance timing, have you done a compression test, a vacuum test, have you done a tuneup.

 

[redmansmb]

Re: backfiring at WOT

thanks guys for the info.my father n law and i looked at the engine and found that my advance in the distributor was all gummed up.after freeing up the CENTRIFUGAL ADVANCE i went thru all the timing again and seems to run alright even when i gun the throttle with no miss.question, finding this problem would that cause the backfire at WOT?<br />thanks again guys

 

[redmansmb]

Re: backfiring at WOT

well folks i got to put my boat in yesterday and all seemed to be real good then the engine at wot started to bog down.tried to adjust the mixing screw on the carb but no dice.the funny thing is that the longer i was out on the water the worse the boat got as far as just keeping it running.no backfiring anymore just trying to get it to stay running under a load,wait for a sec then started and then just putting it in gear to idle back to shore it would still die in just about a min.is it time to rebuild the carb or may it be elec?thanks folks for your help.

 

[Haut Medoc]

Re: backfiring at WOT

Have you checked the water separator?

 

[Don S]

Re: backfiring at WOT

The mixture screws are for idle adjustment, not WOT.<br />Did you look at the plugs for evidence of problems? (water). Did you do a tuneup (points, condenser, plugs, cap, rotor)?<br />Check the fuel filter for water?

 

[Striper Blues]

Re: backfiring at WOT

How about the vent line, does it do it with the gas cap off?

 

[jeff13601]

Re: backfiring at WOT

Did you check the carb and see if it was starving for fuel?