Cranks but won't start.

[DeCaff2007]

This is a better choice.

1989 GMC K1500 Davis Unified Ignition 12620BK Davis Unified Ignition GM Computer-Controlled Distributors | Summit Racing

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Thanks for that. I dunno where you all find this stuff but I agree that that is a better choice.

I still, however, need just that ONE plug wire for cylinder #6.

Hmmm, where I can scob just one plug wire lol.

 

[sntrym]

I haven't even thought of such a thing. I mean that shouldn't be necessary, but I can take a look at it.

To be honest, I'd rather a higher quality distributor.

This seems to get "ok" reviews.... thoughts, anyone?

Summit Racing SUM-850200 Summit Racing™ Computer-Controlled Billet Distributors | Summit Racing

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I run this one. Haven't had any issues in 6 years. I clean the contacts on the underside periodically with a small wire attachment on a rotary tool.

 

[PlayingWithTBI]

What about your CTS wire, is it still disconnected? When troubleshooting, whatever you find, FIX IT BEFORE MOVING ON,,,

 

[DeCaff2007]

What about your CTS wire, is it still disconnected? When troubleshooting, whatever you find, FIX IT BEFORE MOVING ON,,,

You mean that brown, one wire connector on the firewall behind the glovebox? Yes, it' still disconnected. Is that not a step in setting base timing?

 

[PlayingWithTBI]

I did notice that the coolant temperature sensor wire had somehow made contact with the header on the driver side and it burned RIGHT THROUGH the insulation, letting the wire make contact with the header. That sensor, if I've read correctly, is the one that sends the signal to the ECM, not the gauge on the dash.

I did fix the wire, but that has had no effect on the no start issue.

You mean that brown, one wire connector on the firewall behind the glovebox? Yes, it' still disconnected. Is that not a step in setting base timing?

No, I was talking about your CTS wire, are you getting the correct feedback to your ECM?

BTW the CTS sensor on the head between cylinders 1 & 3 DOES feed the gauge not the ECM?

 

[Nad_Yvalhosert]

3 years ago my '88 1500 (4.3L swap to 5.7L) had the same symptoms as yours. Cold start was easy, and would idle fine, albeit high ~1800 rpms. Once it reached operating temperature (and I assume closed loop) the moment I tapped the go pedal, it would stumble, die, and not restart until it cooled down a bit. If I never touched the throttle it would continue to run and fast idle...
With a scan tool, I observed the data stream. And lo & behold, the CTS (coolant temp sensor) showed -40°. A $12 temp sensor located right at the water outlet fixed the running AND idle back to normal.
Oh, there are 2 sensors: the 2-wire goes to the computer, the 1-wire feeds info to the gauges.

Ignore the 1-wire, focus on the 2-wire.

Get a scanner and look for erroneous data. My issue did not set a code, but I knew what I was looking at. If you're not fluent with a scan data, find a friendly mechanic to come by, throw a case of barley pops in his truck and see what comes up.

 

[Nad_Yvalhosert]

If you're having issues dropping in the distributor, have you aligned the oil pump drive shaft prior to installing the distributor?
You need to, with a long flathead screw driver, spin the shaft so it slips right in. Remember, the distributor will slip in and twist along the curved teeth of the gear, so it will advance. You'll need to start a little behind "pointing at #1"

DO NOT REMOVE THE ROLL PIN AND MOVE THE GEAR ON THE DISTRIBUTOR.

 

[DeCaff2007]

No, I was talking about your CTS wire, are you getting the correct feedback to your ECM?

BTW the CTS sensor on the head between cylinders 1 & 3 DOES feed the gauge not the ECM?

Both the 1 wire sensor and the 2 wire sensor are both connected. Temperature gauge actually works-ish. The gauge will climb to about 210° and then drop to just below 200°. It does this consistently at both idle and WOT. I don't see it as a problem.

@Nad_Yvalhosert: I hear ya with the CTS issues. Both are brand new and wired correctly. I do not have a scan gauge although I have someone I can ask. I'll get back to you all on that.

Now for the latest in progress. STILL will not start when hot. Ice cold, fires RIGHT up. I replaced the #6 cyl wire with a known good one from my Trans Am. Twisted the key and VVRRROOOOMMMMM!!!!!!!

I let it sit there at idle and got my timing light out. The base timing (with advance connector unplugged) was over 20° retarded!! I'm surprised it started. Sooooo, I twisted the dizzy CCW until the timing mark lined up with 0°, and the idle shot up from 700 rpm to about 1150 rpm. Then, I went ahead and plugged in the timing advance. The timing mark settled pretty close to the 0° mark and idle stayed @ 800-ish. I'm ok with that.

Granted, this was on a cold engine.

Now, I let it warm up to operating temp (while still trying to complete the break-in) and I got no backfires nor stuttering at all

HOWEVER, after a few minutes, even with the garage door wide open and a fan on high speed, something smelled like burned fireworks, only worse, and my eyes started to sting. Then, I noticed that the cab was starting to fill with smoke - coming from the glovebox.

No fires, just nasty stuff burning off of the engine and there's clearly some places in the firewall that are not sealed. I'll have to fix that lol.

I have a carbon monoxide detector set up in my garage. It's been very reliable. Can't get the thing to shut up when the Wife's Buick is in there, sitting at idle. Never once went off with my truck in there. Ok so that just means the exhaust is doing it's job... but then where is that sickening smell coming from?

But, my original problem is STILL NOT SOLVED. I can't get this beast to start when it's hot.

Oh, and btw, I don't like how far CCW I had to rotate the dizzy to get the base timing to 0°

Right now, it seems that symptoms and suggestions point to a CTS and a new ICM in the distributor. Yes?

 

[Nad_Yvalhosert]

I let it sit there at idle and got my timing light out. The base timing (with advance connector unplugged) was over 20° retarded!!

Your distributor is still off 1 tooth. 13 teeth on the gear ÷ 360° is ~28°
Your starting at -20 something? Move it 1 tooth and you're in the single digit positive degrees which is easier to time than where you are...

Right now, it seems that symptoms and suggestions point to a CTS and a new ICM in the distributor. Yes?

Gauge display is from the 1 wire sensor. The ECM uses the 2 wire. Figure out that PID from the scanner before "supposing" any other parts are defective.

 

[Nad_Yvalhosert]

Both the 1 wire sensor and the 2 wire sensor are both connected. Temperature gauge actually works-ish. The gauge will climb to about 210° and then drop to just below 200°.

Temp gauge fluctuation is normal, especially on cold start. The engine heats up hot until the t-stat opens, then is cools down ~20° or so.
But temp gauge is not a diagnostic tool. It's merely for general observation by the driver. Scan data is still your best bet.

T-stat will be fully open 23° above the listed temp. Starts opening at 195°, fully open at 218°. That'll means all other times is partially opening and closing to regulate temp "around" that 200° mark.