Violent Hesitation

[Oriley]

89 K1500
350
140k Miles

Drive 6 miles to neighboring town, leaving town for home push the gas a
bit to speed up and it was just like you turn the key off an on
quick like. I wanna say a bang but... I don't know, it's gettin gas.

While back I let it get to operating temp and did the same in the
garage. Accelerate slowly it's fine, do it quick and you feel a
hesitation, thud and revs up, almost like a accelerator pump in the old days
but violent. Hard to explain.

Owned it 20 years, starts an idles fine, just this so I'm afraid to drive it.

Thanks for any suggestions, I've never seen this.

 

[Scooterwrench]

Check your secondary ignition(plugs,wires,cap,rotor)and fuel filter. When you remove the fuel filter try to not let all the fuel spill out. Hold you fingers over the ports and shake the crap out of the filter then drain it from the inlet end into a container and check for metal. If any metal or big chucks replace the fuel pump.

 

[Schurkey]

Check your secondary ignition(plugs,wires,cap,rotor)

Use a spark tester calibrated for HEI. Do not use a "spark tester" that has a friggin' light-bulb inside. You need one with an actual spark gap. The spark must CONSISTENTLY jump the gap.

"Rule of thumb" that's not 100% accurate: VIOLENT misfires like you're experiencing are usually ignition-related, not fuel related.

and fuel filter. When you remove the fuel filter try to not let all the fuel spill out. Hold you fingers over the ports and shake the crap out of the filter then drain it from the inlet end into a container and check for metal. If any metal or big chucks replace the fuel pump.

Even if the filter shows clean fuel rather than rusty/dirty/chunky fuel, when the filter has been drained of fuel, try to blow into the inlet. If it's hard--or impossible--to blow through it, replace filter.

I'd add a proper fuel pressure test as well. Pain in the asp as TBIs don't have a service port, you'll have to use an adapter to connect the gauge to.

 

[Drunkcanuk]

Had something similar years back....was a broken spark plug wire. Amazing how "violent" it was, scared the bejebus out of me.

 

[Scooterwrench]

A good spark tester is a new spark plug with the ground electrode cut off. Ground the valance(shell)of the plug against any good engine surface. A good HEI system will jump the gap with no problem with a fat,blue spark.

DO NOT! hold the plug in your hand unless you like pi$$ing on yourself.

 

[Schurkey]

A good spark tester is a new spark plug with the ground electrode cut off. Ground the valance(shell)of the plug against any good engine surface. A good HEI system will jump the gap with no problem with a fat,blue spark.

That "works" but does not have a huge enough gap to properly test an HEI ignition. Works OK for ignition systems that use a ballast resistor in-line with the ignition coil.

While your at it, weld/solder an alligator clip to the side, so it'll support itself on whatever ground you clamp it to.

Two spark testers, one for HEI (recessed center electrode to make for a larger spark gap) and one for "conventional" ignition systems (including early Chrysler electronic style which had no more voltage than their points-controlled ignition) with a visible center electrode.

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Or just buy one suitable for HEI from Amazon or your local parts-store.
www.amazon.com/dp/B003WZXAWK/?coliid=I3S98D7T1J0RLJ&colid=2VLYZKC3HBBDO&psc=1&ref_=list_c_wl_lv_ov_lig_dp_it

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DO NOT! hold the plug in your hand unless you like pi$$ing on yourself.

DO NOT! be leaning over the steel fender of the vehicle, so that the spark grounds through your pants-zipper, either.

 

[Scooterwrench]

Hmm,that sounds like experience talking.

Yeah those old Chrysler electronic ignitions were pretty weak. My cousin had a 76 gold Duster with a 225 super six in it. He would pull a plug wire out of the cap with the engine running,stick his finger in the hole and stand there and grin.

 

[Oriley]

Okay, thanks guys.

First time this happened driving back home with the violent
deal I let off and slowly accelerated to 55 for the few miles
home and it was fine. That is why I didn't think of fuel filter.

Went under today, sprayed the filter connections and will change it tomorrow.

Thanks again.

 

[Scooterwrench]

Normally a clogged fuel filter will cause the engine to just lay over under demand but yours may be stopped up to the point where it just flows enough fuel to only feed 20% throttle.
This fuel they're distilling nowadays is pure garbage. Pretty bad when black mold grows around the gas cap.

 

[Oriley]

Sorry so late but it was the fuel filter, NEVER would have thought of that.
Bear to change, definitely recommend flare fitting wrenches.
Finally took it out and no problems. I can tromp it down and away we go.

Now the smoke. Late last fall it would smoke like crazy for a block or two then quit, same thing the other day. Valve stem seals I think.
Found a video - I can do that. ?? Talked to BIL, he said with hydraulic lifters with 140k miles it might work or not unless you know what
you're doing. Okay, I'll take it to my nephew's shop for that. $$$

Thanks again guys, I love my Family Truckster

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