weird electrical glitch when accelerating

I've got some known (and unknown) electrical issues in my 84 B250. I can inspect and replace the wires that are obviously frayed but I got a weird one that I need help on where to begin looking...

When accelerating above 1500 rpm the radio speakers will stop. The radio maintains power and the sound kicks back in after rpm's drop down. It happened today after first time starting but didn't happen after the second time starting. When it was happening it always happened, when it didn't then it didn't do it during that drive. Also, the A/C switches to vent (default position for vacuum) when accelerating, not sure if its related or not.

I'm willing to entertain any and all ideas on what might be the cause. I know I have a wire that lost insulation between oil pressure switch and electronic choke and I will replace but I don't think its related to acceleration issue.

If no one know about this specific issue then please share any general electrical diagnostic tips.

First try checking the ground straps from the engine and tranny to the body. For an older vehicle, these usually tend to dissolve away or fall apart/off fast. Restoring the ground wires could remove the issue since the spark runs higher at higher rpms. Just my 2 cents.

also check your battery, age , strength, & connections. i think you have seperate issues goin on. heater/ac issue is vacumn related. radio problem is most likely internal, especially if its factory. would just replace with aftermarket, imho., peace, larry

The wire that goes electronic choke also connects to the charging system on my '78. This could be the problem.

Originally Posted by B-300

The wire that goes electronic choke also connects to the charging system on my '78. This could be the problem.

Battery is less than one year old. Head unit is also new.

My Electronic choke is definitely an issue so I hope its just that. As you can see, my original wasn't doing too good. Driveability has been rough until engine warms up but I didn't think the two were connected until you mentioned it. I rewired the blue one and will install tomorrow and see how it does.