1993 K1500 runs terrible when hot

[rhandwor]

Originally Posted by palhegyi

I am the idiot in this Topic.

I worked on one of these trucks with an after market EGR valve and these used to come with washers and the engine would shake on hills. I had some used washers and found one that worked to correct the problem.

[ASJT3]

Did you ever check the ICM like j_cat said? The ignition control module (ICM) is in the distributor underneath the rotor, it's a brake pad-shaped plastic computer card held down by two screws underneath inside the dist cap (wires running to it). Maybe pick one (or two) up from the junkyard when you go to test out.

When the ICM in my '93 went the truck just died, but I've heard that it can cause erratic behavior as it starts to fail (electronics sensitive to heat).

[Thor1993]

Hi Guys,
I am in Germany at the moment on a business trip so I apologize for not respnding sooner. I did replace the ignition control module a few weeks ago. I thought it was the issue because the distributor cap never really fit good and when I put the new ICM in I had to leave it loose and then fit the cap and then remove cap, tighten ICM. After that the distributor cap fit perfect. I thought I had found the problem but noooo... it did not make any improvement.

Please keep the ideas and suggestions coming!!
Greg

[rhandwor]

Originally Posted by Thor1993

Hi Guys,
I am in Germany at the moment on a business trip so I apologize for not respnding sooner. I did replace the ignition control module a few weeks ago. I thought it was the issue because the distributor cap never really fit good and when I put the new ICM in I had to leave it loose and then fit the cap and then remove cap, tighten ICM. After that the distributor cap fit perfect. I thought I had found the problem but noooo... it did not make any improvement.

Please keep the ideas and suggestions coming!!
Greg

http://www.rockauto.com/ Search distributor pick up coil these will definitely make your engine run bad.

[Thor1993]

rhandwor
I saw that distributor pick up coil in the service manual. I will add that to the list of parts to order. It looks fairly cheap so maybe I should just do it to eliminate it. looks like distributor must come out to change it on the bench.
Thanks, Greg

[rhandwor]

Originally Posted by Thor1993

rhandwor
I saw that distributor pick up coil in the service manual. I will add that to the list of parts to order. It looks fairly cheap so maybe I should just do it to eliminate it. looks like distributor must come out to change it on the bench.
Thanks, Greg

Pull the distributor and on the bench vise drive the pin in the gear. I have a specialty puller for this purpose. I think the Ford distributors especially needed this tool.
Most Chevy's I didn't need it. Ask Auto Zone or Advanced auto for a loaner.

[Thor1993]

Hi Guys,

Well I made it back from Germany despite all the cancelled flights. In Germany, I had a Black Audi A4 with a 6 speed that was fun to drive but to be honest I am just more comfortable driving my Chevy W/T pick up. Speaking of the W/T.... I had a few minutes today to check the fuel pressure as rhandwor suugested. I put a T in the line right after the fuel filter. I then went for a ride. The pressure was 12-13psi when the truck was running good, when the truck was running bad, at idle, at WOT and at cruising speed. So I think we can eliminate the fuel pump as the problem. Still could be a fuel pressure problem in the TBI but at least we know the pump is good.

Tommorow I hope to do the distributor coil pick up or the intake gasket.

Thanks for all your suggestions guys,

Greg

[Thor1993]

News flash!!!

Hi Guys (and gals if there are any)

We may have had a break through tonight. We decided to replace the distributor pick up coil tonight. We picked one up at AutoZone until we get an AC Delco one. When we took the cap and rotor off we noticed the rotor is contacting the cap. See the dark spots in the photo. That is where it rubs on the cap. I do not understand this, there is no play in the shaft??




Then when we took the distributor apart the magnate came out in 2 pieces.



Next the old pick up coil had the pin filed off. See where the punch is pointing to. The new pick up would not fit unless we removed the pin. We decided not to use it.


In the distributor there was no hole for the pin in the pick up coil to engage. Also there was a roll pin sticking up that did not engage into the pick up coil. You could see in the old pick up coil that it had been smashed into the plastic.



So clearly there are some issues with the distributor!?!? Even when we tighten the cap, it rocks a little on the distributor. I am thinking to order a rebuilt AC Delco on line. I don't know if this is the final solution but now that I know it is all messed up I gotta replace it.

Any suggestions or ideas?

Greg

[Thor1993]

Schurkey- Here are photos of the fuel pressure gage set up. A simple plastic T in the line after the fuel filter with enough hose to put gage where I could see it when I was driving.

[j cAT]

if the distributor shaft wobbles even a little get a new one.

[rhandwor]

I would order the rebuilt A C Delco distributor on line. I'm glad you found the problem.

[Thor1993]

Rebuilt AC Delco is ordered. It would be great if this were the problem!!!

Rock Auto said it is at an outlaying warehouse and may take several days to get it. I put the truck back together with the old parts so it runs and I can plow if necessary.

Greg

[j cAT]

Originally Posted by Thor1993

Rebuilt AC Delco is ordered. It would be great if this were the problem!!!

Rock Auto said it is at an outlaying warehouse and may take several days to get it. I put the truck back together with the old parts so it runs and I can plow if necessary.

Greg

the distributor bearing worn is a problem that will cause these issues. timing is off and poor engine performance then no performance.

[Schurkey]

Originally Posted by Thor1993

my truck runs like a new truck for 3-4 miles (open loop maybe) then runs terrible after 3 miles (closed loop maybe) After 20 miles on freeway the pass side exhaust manifold is red hot.

Broken magnet in the pickup coil = problem
Wiped-out distributor mainshaft bushings = problem

I don't see either one of these causing a degradation of power/performance after 3-4 miles. They should be a consistent problem, not a heat- or time-related issue.

I don't see either one of these causing ONE manifold to glow, either.

Yes, you need distributor repairs/replacement; but I wouldn't count on the distributor fix taking care of the entire driveability problem. (We can hope...)






I can't figure out how you can attach that fuel pressure gauge to your fuel system. Isn't your fuel plumbing steel tubing and steel-braided hose? Where is the rubber hose that attaches to your "tee"? Has someone installed section(s) of rubber hose under the vehicle?

[Thor1993]

Schurkey -There is a rubber line at the bottom of the firewall it connects the steel line from the TBI to the steel line that runs to the tank. I am not sure if the rubber line is factory or not. When the main fuel line rusted out a few years ago I went to GM and got all new replacement lines to the firewall. I don't remember cutting a steel line and putting a rubber line in. I usually don't cheat on fuel pressure stuff. Isn't rubber line Ok on a 13 psi fuel system?? Anyways, I sure hope you didn't think I was being a smart ass by posting the picture....but that is actually what I used.
Greg