1962 fd-23 surging at wot...fuel pump?

my 62 fd started surging yesterday at wot...stayed running but would run up and down every few seconds. i don't have any way to measure rpms, but i also don't think the high rpms it hit still didn't feel like it was running full out. primer bulb felt firm the whole time. did it on the way out to my spot, but on the way back it was fine. it ran right back up and got the boat right on plane. today, on 3 passes across the lake it was fine but on the last pass back towards the ramp it started surging again. it seems to be idling smooth. new coils were put in a few days ago, but this feels like fuel issue to me. the fuel pump is original...someone told me you can replace them with a newer 9.9 pump? is this true? what else should i check. motor has good compression...my only other concern is that i know there might be some ethanol in the tank. its nearly impossible to find non ethanol fuel in iowa

Re: 1962 fd-23 surging at wot...fuel pump?

also should mention that po claims to have put a new carb on last year

Re: 1962 fd-23 surging at wot...fuel pump?

I would do a spark test on it. It sounds like you have a coil dropping in and out. Did they trim and make new connections on the spark plug leads? Often times if people replace the coils and use the old wires, they don't trim off the ends of the wire to creat a new connection. Trim off 3/8" on the coil end a 1/4" on the spark plug end.

Re: 1962 fd-23 surging at wot...fuel pump?

coils were new as of a few weeks ago...i should check spark too just to verify that they are ok

Re: 1962 fd-23 surging at wot...fuel pump?

yes, I would do a spark test.

Re: 1962 fd-23 surging at wot...fuel pump?

ditto on the spark test, but I would check the carb too, just to be safe. it's a cheap easy, DIY job. You can get a rebuild kit right here at ibots too, for about $25. here are some handy links that can walk you though an entire rebuild/tune up of your motor.


http://forums.iboats.com/showthread.php?t=158086
http://www.duckworksmagazine.com/07/columns/max/index1.htm
http://forums.iboats.com/showthread.php?t=167352

Re: 1962 fd-23 surging at wot...fuel pump?

Definitely do an external spark test. One of the problems you are going to face is that the fact that it surges indicates that a cylinder that was not working is all of a sudden kicking in and working, giving your motor more power, hence the surge. What this means is that your problem is the annoying of all annoying problems, called the intermittent problem.

In other words, check the spark and you may very well find that one cylinder is not firing or is weak. But you may also find that it is fine when you test it and then not fine later. The luck of the intermittant problem.

In any event, it would seem to me your problem is ignition related and since new coils were just added and now you have this problem, I would be skeptical of those. I would look very closely at them and the wires and connectors, etc.