How to find the misfire on my truck, and what to do about it!

[Joseph C]

This forum has GREAT help. Ok, so, there is no way around it.. truck IS misfiring. Took it to a shop yesterday, for the muffler and cat, and they straight up told me: “Fix the misfire first.”

1994 Chevy 4.3L L35 Vortec VIN W – yeah, with the spiders.

So, this truck doesn’t have fuel injectors I can listen to.. would the first thing to check be maybe fuel pressure?

Also. When you do a “power balance..” Do you pull them AT THE PLUG, or AT THE DIZZY?

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[Richard Kirshy]

This should get you started:

As to the spider injection:

[Joseph C]

[quote=”nightflyr” post=161114]This should get you started:

As to the spider injection:

https://www.youtube.com/watch?v=O8At2P3XEVc%5B/quote%5D
The post got messed up, I can’t see the link ..

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[Richard Kirshy]

Must be on your end..
What you posted back shows up fine here.

[none]

Start with the basics and check your spark plugs, wires, cap, & rotor…especially if you don’t know the history on the tune up parts. Read the plugs for any inconsistencies between one plug to the next and measure out the plug gaps. Your spec is .035″. Look at the plug wires to see if any of them have been misrouted and/or got burnt on an exhaust manifold.

If you find you have to go after a power balance test anyway, pull the wires at the distributor. Plug wires, especially old wires, are tough to pull off the plugs and there’s better potential you’d tear a wire out of the boot at that end AND you’re going to burn yourself a lot trying to finagle wires off the plugs. I own a 4.3 S10 myself. It’s a bad place to work down at the plugs. Do make yourself a jumper wire that can absorb the spark coming off the terminals at the cap. Take a screwdriver and wrap a wire around the shaft. Then clamp the other end of the wire to a known good block ground. Keep that screwdriver tip close to the terminals as you’re pulling the wires and the spark will jump to the screwdriver. You get your power balance test without getting zapped and the spark has a way to discharge itself.

I found you a Scanner Danner video to show you how to test for injector balance. That spider injector is a little pricey so it’s better that you can replace it knowing it’s the right part to replace.

[Greg]

Another thing worth mentioning, this engine has a tendency to wear out the distributor gear that can develop enough slop to cause some misfiring issues as well. It is easy enough check by pulling the distributor and looking at the gear.

[Author]

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