Need some help, Backfires when given gas.

[geezer101]

Is there a black wire with a white stripe on the side of the carb that is/isn't hooked up? It's for the fuel cut solenoid. This bad boy needs to be hooked up or it'll shut off the internal air metering in the carb and do things like randomly kill the engine (or perhaps in this case mess up fuel delivery enough to cause it to run badly) It is powered by the ignition circuit - no power, no fuel.

[geezer101]

Make sure that accelerator pump in the carb is working. This is a symptom that it's not getting the little extra boost of fuel off the mark. But even if you go hard open on the throttle, the carb won't be able to keep up with the sudden increase in vacuum. The Mikuni is a slug and you have to 'feel' your way into the power curve. Give my tune method a try (I know you are subject to Cali EPA crap) but you can always re-set it when it comes to inspection time. If you can get the ignition to follow a similar curve to the throttle butterflies opening, you'll unearth some useful midrange power and improve your highway cruising top speed.

Well done to you for persevering. It sucks when you keep hitting a wall and can't get around it. The biggest issue you had was the coil wiring and the distributor being out a tooth. It didn't help that a workshop couldn't even hook up the fuel lines properly and took a short cut just so it would run.

[FenstermakerWJ]

Thank you!

I have been reading your advice and by luck I found this guys thread as well http://www.mightyram50.net/vbulletin...-for-smog-Help.

I think my choke needs to be adjusted a tad, it's closed up tight when sitting and has some tension on it that a "light tap" can't easily open it when cold.

I'll see what I can do to it tomorrow.

Thanks again for your help!

[geezer101]

The accelerator enrichment pump is the square block on the side of the carb with a fuel line in and out. Top barb is from the fuel pump, bottom barb goes to the return line. The primary and secondary fuel feed lines (from the pump) are different diameters (primary/fuel bowl line is obviously the bigger diameter hose). It wn't kill the carb but the engine won't run right if they're swapped.