Engine Died On Increased Throttle, Can Only Crank-No-Start In ‘99 Suburban 5.7L

carnerd3000 said:

Over the week I took a look at the ignition system, and so far I went through the spark plugs, wires, and the distributor cap and rotor. I replaced the spark plugs, since they were worn anyway, and I did a resistance test on each of the wires, with all of them being within 9-11 ohms on the long ones and 6-8 on the short ones. The wire to cylinder 3 had a sticky coating at the end connected to the spark plug, but nothing seemed broken or burnt, at least on the outside.

When I checked the distributor cap and rotor, this is what I got:

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They do not look good at all, and I will replace them. The outer terminals on the cap are chalky-looking, but I don't know if they are any shorter than normal, and then the middle terminal is chalky, but it also has brown spots on it too. As for the rotor, you can see a burn mark towards the middle, as if the spark was arcing through the rotor itself.

So now here's my question: is this distributor still usable at all, or is it absolutely dead and possibly even the cause of my crank-no-start condition? Also, should I be worried that there is a burn mark on my rotor?

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Definately need a new rotor and I would also suggest a new cap. I have not had good luck with any other cap and rotor than a MSD on these. My United Motor aluminum body distributor had one of their cap and rotors on it. Ran for less than 2 years before giving up.

carnerd3000 said:

My thought was to just get the regular AC Delco cap and rotor, probably from Rock Auto, but if a cap with brass terminals is actually better than the AC Delco, then I will do that. I saw other threads about having no spark, and I saw people say either go with the AC Delco or a cap with brass terminals, so I just wanted further clarification.

And just to double-check: based on my pictures, are both my cap and rotor completely dead?

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I have had the absolute worst luck with the Delco caps and rotors. Even after venting my distributor with positive ventilation like an opti spark it would still ionize and corrode very quickly.

I need to do a writeup on venting the distributor properly.

carnerd3000 said:

My thought was to just get the regular AC Delco cap and rotor, probably from Rock Auto, but if a cap with brass terminals is actually better than the AC Delco, then I will do that. I saw other threads about having no spark, and I saw people say either go with the AC Delco or a cap with brass terminals, so I just wanted further clarification.

And just to double-check: based on my pictures, are both my cap and rotor completely dead?

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That rotor is toast! Cap is not so great either, best when they are really bad to replace both.
I grew up in a family owned independent auto parts store, in the 70s and 80s, and have seen a whole bunch of these GM HEI setups. The original style coil in cap, would eat rotors and eventually modules and other internal distributor parts,if the rotor was burnt like this. Extreme heat is a big reason why GM moved the coil and module away from the distributor. That helped parts longevity, but a rotor that's burnt like this is still an indicator of other problems. Coils do go bad, so does wiring. Look at them closely.

I ordered the United Motors premium cap and rotor from Rock Auto last night, so I'll let you guys know what happens when I install it. Thanks again for your help!

carnerd3000 said:

I ordered the United Motors premium cap and rotor from Rock Auto last night, so I'll let you guys know what happens when I install it. Thanks again for your help!

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I've got the vented version, but haven't installed it yet. I look forward to hearing what you think of it. Next week, I might be starting work that will see it installed soon.

454cid said:

I've got the vented version, but haven't installed it yet. I look forward to hearing what you think of it. Next week, I might be starting work that will see it installed soon.

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So basically with the vented model, should be able to get a vacuum tee, a vacuum check valve and small engine style fuel filter. T into the vacuum line that goes to the HVAC vacuum check valve on the engine side of it, then place your check valve to prevent fuel from entering the distributor while the engine is off, then your filter goes in line to keep anything from the inside of the distributor from entering the engine, I then cut a 1" length of 1/8" od copper tubing with a 0.01 wall thickness. This reduced the 1/8" hose to a 0.105" metered hole. I then removed the vent mushroom and stuck an 1/8" vacuum hose on the nipple. Engine vacuum will continuously purge the distributor body of moisture and ionized air. I did the setup described on the 305 in my 99 Tahoe. In the 3 years it ran with the 305, never had a cap and rotor issue. On my first setup on the van, I plumbed two lines and vented the distributor body to the air intake between the maf and throttle body. Later I found that it realistically made no difference to fuel trims whether it was pulling vent air from the stock distributor vent or through the MAF because the volume of air was so small. For $20 I positively vented the distributor. Since I run a non vented MSD cap on the van, I drilled and tapped my distributor base for two 90° 1/8" barb fittings. My van still has the vent hose from the distributor body to the air intake and the OEM vents are gone. I seal the distributor cap to the housing with a narrow bead of RTV to keep moisture out.

Alright, so I got the distributor cap and rotor, but I forgot to charge the battery again, so I couldn't start it properly anyway. However, I may have messed up something else; I just wanted to check battery voltage from the harness connectors that go to the coil and the ICM. I checked them, and got a reading of 11.73 volts, so at least I saw voltage. But then I tried to plug the connector for the coil back in, forgetting that I had the vehicle in the "key on" position. Then when I tried to double-check the voltage again, I was getting a reading below 1 volt, like 0.7 I want to say. Did I screw something up, maybe with that specific harness connector?

Continuing off my previous post, I did another check on the connectors to both the coil and the ICM. I was getting a reading of 0.192 volts from the pink wire on the 4-way connector to the ICM with "key on". Then I did a check of the positive terminal of the battery itself to the ground on the connector, and I got 12 volts. So I'm even more convinced now I screwed something up regarding the connector to the ICM and coil. My next guess is to just check the pink wire. Should I check the computer, or is there no need to?

carnerd3000 said:

Continuing off my previous post, I did another check on the connectors to both the coil and the ICM. I was getting a reading of 0.192 volts from the pink wire on the 4-way connector to the ICM with "key on". Then I did a check of the positive terminal of the battery itself to the ground on the connector, and I got 12 volts. So I'm even more convinced now I screwed something up regarding the connector to the ICM and coil. My next guess is to just check the pink wire. Should I check the computer, or is there no need to?

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What is it that you're trying to test? What voltages are you expecting?

454cid said:

What is it that you're trying to test? What voltages are you expecting?

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I just wanted to check the ignition coil and ICM, and the corresponding connectors, just to rule them out. And I figured that the same, or similar, reading as the battery voltage would be what to look for. Now I have a near-zero voltage, as I mentioned yesterday.