1988 2pg Acceleration and backfiring problem

[nr2bohica]

Good morning all, I have been working on a 1988 2pg for a while. I got it running but have always had a acceleration problem. While it runs fairly well at low throttle it will die when I go to half throttle or full throttle. I have changed carb twice, same results. I changed all fuel lines and filter and new pump. It has now developed a backfire when holding the throttle steady. I have the spring on the carb throttle, have checked that micro switch is engaged before throttle opens. I removed gas line from carb and cranked engine, pump worked fine when throttle barely opened, when I went to mid throttle or wot gas flow really dropped. Is this a crankshaft seal problem or something else? Thanks

[cart around]

On my first read, I was thinking ignition problem. After reading several more times, I'm not sure about the fuel flow dropping off. Maybe it's a natural thing with so much more air flow, and no fuel, or maybe it's an indication of bad seals. I couldn't say with absolute confidence.

To me, a backfire is caused by unburned fuel igniting at the wrong time. If it was running low on fuel, there would just be intermittent dead spots. So now I have talked myself back into an ignition problem. I would try a new plug first.

https://buggiesgonewild.com/showthre...=105501&page=3
In case you don't have it, the 88 manual is in post #22.

[nr2bohica]

Thanks Cart around, I haven't changed the plug but did have a good spark when tested. I will change and see what happens. A few times lately I have driven it and it runs fine, park it and get in 10 minutes later and runs badly. The backfiring has just started, I checked muffler for leaks and found none. Doesn't make any sense. Thanks

[nr2bohica]

Just an update on problem. After pretty much changing everything I found a oem carburetor and installed. Runs very well now, was expensive but solved the problem the cheap chinese junk couldn't. Thanks for the help.