RaWarrior
Well-Known Member
Since you have an '85, you have the old analog ignition. They're not known for being super reliable, and on their way out they can cause all sorts of wacky problems.
I suspect the heat rising from the engine(since you mentioned it happens while idling) warms up the box(it sits right above the front head) and aggravates the problem. I suspect the pop/miss is from intermittent/weak spark.
Unfortunately, it's not the easiest fix. Even if you got your hands on a good analog box, it's a PITA to change....buried in front of the carbs. Someone here would repair the analog boxes, but I don't remember who or if they still are. It's possible to swap in the '90 and up digital box(which tend to be very reliable), but you'd also need a '90up wiring harness since the connectors are different.
I think your problem is weak spark, which can be caused by bad wires, crappy plugs, and most likely, a corroded connection at the coil. Unscrew the plastic cap and pull the wire out. Cut like 1/4" of wire off to expose fresh conductor and put it back in, or better yet if they're the original wires, replace them.
I highly doubt the fuel pump is the problem, if it was the problem would emerge at WOT or high RPMs, not idle. If it was a tank vent issue, revving it up wouldn't really make a difference since the fuel pump is electric and it's "pump strength" isn't dependent on RPM.
Good luck.
I suspect the heat rising from the engine(since you mentioned it happens while idling) warms up the box(it sits right above the front head) and aggravates the problem. I suspect the pop/miss is from intermittent/weak spark.
Unfortunately, it's not the easiest fix. Even if you got your hands on a good analog box, it's a PITA to change....buried in front of the carbs. Someone here would repair the analog boxes, but I don't remember who or if they still are. It's possible to swap in the '90 and up digital box(which tend to be very reliable), but you'd also need a '90up wiring harness since the connectors are different.
I think your problem is weak spark, which can be caused by bad wires, crappy plugs, and most likely, a corroded connection at the coil. Unscrew the plastic cap and pull the wire out. Cut like 1/4" of wire off to expose fresh conductor and put it back in, or better yet if they're the original wires, replace them.
I highly doubt the fuel pump is the problem, if it was the problem would emerge at WOT or high RPMs, not idle. If it was a tank vent issue, revving it up wouldn't really make a difference since the fuel pump is electric and it's "pump strength" isn't dependent on RPM.
Good luck.