4.3L TBI Distributor question.

[DeCaff2007]

So, I've decided to dig in and find out why my 89 4.3L falls flat on it's face during WOT. I went through all the usual things, then took off the distributor cap. Not sure what to make of this:

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What I mean is, what's the rusted thing under the rotor? I'm used to seeing springs, weights, and a vacuum advance. Is it fixable or do I need to get a whole new distributor?

Thanks.

 

[Schurkey]

what's the rusted thing under the rotor? I'm used to seeing springs, weights, and a vacuum advance. Is it fixable or do I need to get a whole new distributor?

No springs, no weights, no vacuum advance since...1981 for most GM cars, maybe '85-ish for pickups/suburbans.

All spark advance is controlled by the computer with input from the pickup coil/ignition module, knock sensor, EST module.

Remove the scuzz, you'll find internal and external "teeth" that go in and out of alignment as the distributor shaft spins. There's a disc magnet that's often faulty. And a pickup coil hidden inside; with only a couple of visible wires as evidence.

V8 parts:

Cracked magnet near "Copyright" symbol--extending through rivet to outside of magnet.

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New replacement mainshaft, not installed in distributor housing yet.

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[Schurkey]

I've decided to dig in and find out why my 89 4.3L falls flat on it's face during WOT.

What is the fuel pressure?
How old are the plugs, plug wires, cap 'n' rotor?
Will the ignition coil fire a spark-tester calibrated for HEI ignitions?
Does the electronic spark advance actually work?

Connect a scan tool, look for issues in the data stream--TPS, MAP, O2 and all the rest of the sensors.

 

[DeCaff2007]

What is the fuel pressure?
How old are the plugs, plug wires, cap 'n' rotor?
Will the ignition coil fire a spark-tester calibrated for HEI ignitions?
Does the electronic spark advance actually work?

Connect a scan tool, look for issues in the data stream--TPS, MAP, O2 and all the rest of the sensors.

Wow thanks for the info!

Fuel Pressure: Dunno. Didn't get that far. It's on my list.
Plugs are brand spanking new as of yesterday. Plug wires are burned spaghetti (having trouble sourcing new ones in a timely manner). Cap 'n' rotor are not great. Have to get new ones. Their age? Don't know. I wasn't going to give this heap a second look when I saw that it's a regular cab, but then I saw 3 pedals and that was it. SOLD!

I usually use a timing light to check for spark. Quite effective if used properly.

Electronic spark advance... from what I've read and how corroded everything else is under the hood, I guess I've got some work to do. So the answer to that is "I don't know if it actually works".

A scan tool. Sorry, I don't have have one.

Again, I appreciate the info. I'll be out there some more today looking into things.


EDIT: Found a new distributor and wires on amazon. Cheaper than Rock Auto and will be here faster. RA is going to run themselves out of business if they don't get their act together with their ridiculous shipping times/prices.

 

[Schurkey]

I usually use a timing light to check for spark. Quite effective if used properly.

Depends. The inductive pickup on the timing light can verify the presence of a voltage pulse--spark--but not the ultimate voltage potential in the coil.

A coil can be defective--weak--and still fire the plug under light load--while crapping it's pants under heavy load.

Determining ultimate voltage in the ignition coil takes expensive equipment...but...a simple spark tester calibrated for HEI gives you 95% of the real answer at low cost and easy set-up.

www.amazon.com/dp/B003WZXAWK/?coliid=I3S98D7T1J0RLJ&colid=2VLYZKC3HBBDO&psc=1&ref_=lv_ov_lig_dp_it

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Electronic spark advance... from what I've read and how corroded everything else is under the hood, I guess I've got some work to do. So the answer to that is "I don't know if it actually works".

Connect your timing light, start engine with the EST connector unhooked. "Should" be at base timing--0 degrees. Shut off engine, connect EST wire. Start engine. Timing should be advanced, perhaps 12-ish degrees. Rev engine. Timing should advance more.

This doesn't tell you that it's working perfectly, but it tells you that there's at least some electronic advance.

A scan tool. Sorry, I don't have have one.

Put it on your wish-list. Dicking with computer-controlled vehicles without one is like walking around in the dark, wearing welding goggles. Yeah, you may stumble onto things now and then, but it's more a matter of getting lucky than any science or skill.

EDIT: Found a new distributor and wires on amazon. Cheaper than Rock Auto and will be here faster. RA is going to run themselves out of business if they don't get their act together with their ridiculous shipping times/prices.

Keep in mind that "new" distributors are almost always Communist Chinese knockoffs.

"I" would rather have a used-but-usable OEM distributor than brand-new Chinese crap.

 

[evilunclegrimace]

Wow thanks for the info!

Fuel Pressure: Dunno. Didn't get that far. It's on my list.
Plugs are brand spanking new as of yesterday. Plug wires are burned spaghetti (having trouble sourcing new ones in a timely manner). Cap 'n' rotor are not great. Have to get new ones. Their age? Don't know. I wasn't going to give this heap a second look when I saw that it's a regular cab, but then I saw 3 pedals and that was it. SOLD!

I usually use a timing light to check for spark. Quite effective if used properly.

Electronic spark advance... from what I've read and how corroded everything else is under the hood, I guess I've got some work to do. So the answer to that is "I don't know if it actually works".

A scan tool. Sorry, I don't have have one.

Again, I appreciate the info. I'll be out there some more today looking into things.


EDIT: Found a new distributor and wires on amazon. Cheaper than Rock Auto and will be here faster. RA is going to run themselves out of business if they don't get their act together with their ridiculous shipping times/prices.

Go to rock auto and order a Tri Pack from United Motor Products PN 3680. Includes a cap ,rotor and wires. I would also recommend a distributor from UMP but they show out of stock at this time.
I have been using UMP products in my trucks for years and recommend them with out reservation.

 

[Erik the Awful]

Go to rock auto and order a Tri Pack from United Motor Products PN 3680.

Wow! I hadn't realized UMP sold a set like that. I looked it up, but they don't list a UMP 3680. I drilled down under a '92 truck and found the following kits:

V6
www.rockauto.com/en/moreinfo.php?pk=1144894&cc=1031263&pt=684&jsn=928&jsn=928

5.7 V8

More Information for UNITED MOTOR PRODUCTS 3880

7.4 V8

More Information for UNITED MOTOR PRODUCTS 18855

Good stuff!

 

[HeavyAsAChevy]

Just did cap rotor and wires last night. But had to work this morning and since I work out of my house and ride with my brother I haven’t had the chance to drive it test. When it comes to parts I usually just go to O’Reilly’s and get whatever has a warranty. Between me and my two brothers they opened a business account. Lol. It’s pretty nice.

 

[DeCaff2007]

@ Schurkey: I saw that exact tool (the HEI spark detector) at Autozone one day and thought it was a gimmick. I might just give that a try.

Oh and gents, I know that the cheapo, get-here-faster knockoff distributor is probably chinese garbage. When my brain sees "gets here FASTER for free" - I'll admit that my impatience falls victim to that. That's why I went with the Amazon distributor. I haven't had a chance to dig back into anything just yet with respect to ignition parts. I've been busy putting the radiator support and bumper back together. Long story.

 

[evilunclegrimace]

Wow! I hadn't realized UMP sold a set like that. I looked it up, but they don't list a UMP 3680. I drilled down under a '92 truck and found the following kits:

V6
www.rockauto.com/en/moreinfo.php?pk=1144894&cc=1031263&pt=684&jsn=928&jsn=928

5.7 V8

More Information for UNITED MOTOR PRODUCTS 3880

7.4 V8

More Information for UNITED MOTOR PRODUCTS 18855

Good stuff!

PN 3860 is listed under tune up kit. I just checked.