mercruiser 7.4L popping through carb

[FreeBeeTony]

Re: mercruiser 7.4L popping through carb

Another issue could be water in the fuel............

 

[7228sedan]

Re: mercruiser 7.4L popping through carb

Update: I got the carb off & torn apart again. The float was set too low, I reset it to .25 with the air horn gasket in place. Also, the tension spring on the primary metering rods had come off. The rods were in place, but they were not being held together. I also noticed that the gaskets were a little moist with fuel. I'm wondering if there was a leak at the seams of the carb? I plan on reassembling everything tonight & re installing the carb tomorrow. I'll post an update then. Thanks again all!

 

[bomar76]

Re: mercruiser 7.4L popping through carb

I hope you are using new gaskets....

 

[xltier]

Re: mercruiser 7.4L popping through carb

COIL. Had the same problem. Redid the carb twice and I've done a ton of them. New wires and plugs. Not the problem. The coil has broken down. Put a new one in. they're only $20.

i took a 21 footer with a 305 chev out for a sea trial for a marina that replaced the carb.cost the guy a small fortune cause they did carb-pluhgs -wires cap-rotor-.it would start popping after it warmed up under acceleration and high speed.it was the coil.seen many times.

 

[6meter]

Re: mercruiser 7.4L popping through carb

Popping through the carb is the gas exploding with an intake valve open. Ignition timing, rotate the distributer; valve/cam timing, timing chain jumped...$$$; valves not seating, need a valve job, BIG $$$. Put a coil in it. I did all of this on my Dads boat, it was 20 yrs old. What fixed it was a coil. 10 years later I didn't learn. On my boat I only rebuilt the carb, plugs and wires. Plugs were original and some wires were arcing. The boat wasn't used much in 10 years so I really doubted the valves. The coil fixed it.

 

[7228sedan]

Re: mercruiser 7.4L popping through carb

To all who said it was the coil, I think you win. I replaced the coil after resetting the float 3 times. I have not yet taken her out & tried to plane off yet. With the new coil & the timing corrected the motor revs clean with no poppoing. It was probably the coil the whole time, the float is pretty much where it was when I started. I'll be going out this weekend to give it a good run, I'll post an update then. Everyone have a great Memorial Day!