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Username Post: Truck just quits running        (Topic#364731)
drice0517 
Newbie
Posts: 20

Reg: 01-21-21
03-27-21 03:49 PM - Post#2816944    

I have a 1985 GMC C1500, 305, 350 automatic, stock everything, no modifications. It's been hard to start the last week or so. Yesterday, it started and idled ok after pumping accelerator 10-12 times, idled for about a minute, then just shut off...no sputter, no rough idle, just quit running. I added fuel even though I didn't think it needed it, poured a little in the carb, and tried to start it agin...no luck...this morning it started and idled smoothly for about a minute, then just as suddenly, shut off. It turns over fine, just doesn't start and run....any ideas or info would sure be appreciated...!

1985 GMC Sierra Classic, C1500
305 CID, 4 bbl Quad
Stock Configuration


Edited by drice0517 on 03-27-21 04:14 PM. Reason for edit: No reason given.

 
55 Shaker 
Member
Posts: 1596

Age: 71
Loc: north central IL.
Reg: 03-13-06
03-27-21 04:37 PM - Post#2816945    
    In response to drice0517

Ignition module, would be my guess. Take it out have have Auto Zone or somebody like that test it.
If it tests bad, when you replace it with a new one don't forget to put heat sink paste on the bottom of it.

The older I get, the more dangerous, I am !!!!


 
gchemist 
Member #271 Senior Chevytalk Moderator
Posts: 25409
gchemist
Loc: Austin, TX 78748
Reg: 05-09-00
03-28-21 03:09 AM - Post#2816969    
    In response to drice0517

You probably have a bad fuel pump. How old is it? If starts with fuel poured down the carb, ignition should be okay. Does it have spark when it's cranked and won't start?
Harbor Freight or a parts have a handy tool to test spark.


'83 Silverardo XST - ZZ4 powered
'95 Jimmy SLT (Bought @131,814)
'96 GMC Jimmy LS Ret. @236651 miles
'08 GMC Acadia 3.6L SLE


 
drice0517 
Newbie
Posts: 20

Reg: 01-21-21
03-28-21 04:53 AM - Post#2816975    
    In response to gchemist

Thanks for the replies...I'll have the ignition module tested and replace it if it's bad 55Chevy...any tips or advice if I need to replace it..? Kinda new to this stuff, is it hard to replace..? I read about the paste, any other advice...?
gchemist...I tried pouring a little fuel into the carb, and checked around the fuel pump and lines for leaks, etc. Dirty and grimy from some earlier oil leaks around the valve covers, may be original to the '85 truck, I'm not sure. I was thinkingI if it was a fuel problem, it might spit and sputter a little before it died, or at least want to crank when I added fuel directly into the carb.

1985 GMC Sierra Classic, C1500
305 CID, 4 bbl Quad
Stock Configuration


Edited by drice0517 on 03-28-21 04:56 AM. Reason for edit: No reason given.

 
gchemist 
Member #271 Senior Chevytalk Moderator
Posts: 25409
gchemist
Loc: Austin, TX 78748
Reg: 05-09-00
03-28-21 07:06 AM - Post#2816980    
    In response to drice0517

A new fuel pump would be good maintenance. Plus a new carb filter. Does it have dual tanks? Is the problem with both tanks? I had a similar problem once. Turned out the tank switching valve was not going over to the other tank. However, it would indicate the level on the full tank.

Your truck has electronic spark control (ESC). Rare but the ESC can go bad. Read about it here:
http://www.73-87.com/7387garage/drivetrain /escrepl...



'83 Silverardo XST - ZZ4 powered
'95 Jimmy SLT (Bought @131,814)
'96 GMC Jimmy LS Ret. @236651 miles
'08 GMC Acadia 3.6L SLE


 
drice0517 
Newbie
Posts: 20

Reg: 01-21-21
03-28-21 07:41 AM - Post#2816985    
    In response to gchemist

Update...truck started and idled fine this morning for about ten minutes..shut it off, waited about ten minutes and re-started it. Idled for about another ten minutes just fine. Shut it off, waited a few minutes, re-started and it's been idling fine for about 20 minutes now. WEIRD...!! I'll drive it a while later this morning and see if runs ok at driving speeds...
gchemist...just doesn't seem to be a fuel supply issue. It has a single tank, and doesn't cough or sputter when quitting...I'll read up on the electronic control, thanks..!
I'll post again with more info later today...!

1985 GMC Sierra Classic, C1500
305 CID, 4 bbl Quad
Stock Configuration


Edited by drice0517 on 03-28-21 01:26 PM. Reason for edit: No reason given.

 
bobb 
Super Senior Member
Posts: 5776

Loc: paradise
Reg: 09-05-03
03-28-21 09:06 AM - Post#2816990    
    In response to drice0517

i would guess ignition module.

70 L camino, grampa engine, g-force 5 spd, road rage suspension. Pray first before all else fails.


 
gchemist 
Member #271 Senior Chevytalk Moderator
Posts: 25409
gchemist
Loc: Austin, TX 78748
Reg: 05-09-00
03-28-21 09:50 AM - Post#2816994    
    In response to bobb

I second bobb! The ignition module may be acting up after it gets hot.

'83 Silverardo XST - ZZ4 powered
'95 Jimmy SLT (Bought @131,814)
'96 GMC Jimmy LS Ret. @236651 miles
'08 GMC Acadia 3.6L SLE


 
drice0517 
Newbie
Posts: 20

Reg: 01-21-21
03-28-21 01:28 PM - Post#2817004    
    In response to gchemist

I'll have it tested and keep ya'll posted...thanks for the help..!

1985 GMC Sierra Classic, C1500
305 CID, 4 bbl Quad
Stock Configuration


 
55 Shaker 
Member
Posts: 1596

Age: 71
Loc: north central IL.
Reg: 03-13-06
03-28-21 03:20 PM - Post#2817009    
    In response to drice0517

When you test it, have them do it multiple times, so it warms up. To see if it fails when it's under that condition.

The older I get, the more dangerous, I am !!!!


 
drice0517 
Newbie
Posts: 20

Reg: 01-21-21
03-29-21 03:40 AM - Post#2817031    
    In response to 55 Shaker

Will do 55...thanks..!

1985 GMC Sierra Classic, C1500
305 CID, 4 bbl Quad
Stock Configuration


Edited by drice0517 on 03-29-21 03:40 AM. Reason for edit: No reason given.

 
drice0517 
Newbie
Posts: 20

Reg: 01-21-21
04-04-21 06:01 AM - Post#2817422    
    In response to drice0517

Another update...I've started my truck 5-6 times this week and let the truck idle for up to 30 minutes and it starts and idles just fine...drove it now and then for a few miles and it seems to run fine now...is the ignition module something that can go bad all at once or can it be good for awhile, then not work occasionally...? I'm thinking about putting a complete distributor in with the new coil and ignition module..I already have new plugs and plug wires. Is there is anything else I might need to replace that could cause this problem while I'm at it..?

1985 GMC Sierra Classic, C1500
305 CID, 4 bbl Quad
Stock Configuration


Edited by drice0517 on 04-04-21 06:02 AM. Reason for edit: No reason given.

 
gchemist 
Member #271 Senior Chevytalk Moderator
Posts: 25409
gchemist
Loc: Austin, TX 78748
Reg: 05-09-00
04-04-21 07:10 AM - Post#2817424    
    In response to drice0517

The pick up coil underneath cap can go bad. Usually it's the wire connections that corrode over time. An ohm check will tell you if it's bad. Sorry, I can't remember the OHM values. On TBI trucks, I swap the entire distributor. Check the pick up coil connections. If they are bad, a new distributor will solve ignition issues.

'83 Silverardo XST - ZZ4 powered
'95 Jimmy SLT (Bought @131,814)
'96 GMC Jimmy LS Ret. @236651 miles
'08 GMC Acadia 3.6L SLE


 
drice0517 
Newbie
Posts: 20

Reg: 01-21-21
04-08-21 10:13 AM - Post#2817704    
    In response to gchemist

Update...and thanks for everyone's input...! Based on local advice and some thinking, I went ahead and had the complete distributor replaced. When I spoke with the local mechanic I use sometimes, he said no problems with putting it in, but he couldn't set the timing with his light because he couldn't visibly see or access the timing mark area because of the way the water pump housing and other stuff blocked his light from shining on the timing marks area. He said he had marked the position of the original distributor and set the new one back in the same place, and he told me he set the timing "old school" style by turning the distributor until it started and ran ok. I Asked him if he tried removing the #1 plug, finding TDC, and setting the rotor to the 1 position, but he said that marking before removing it essentially did the same thing. Well, when I picked it up yesterday morning I know it wasn't right from the git-go. It made noises so bad I thought the distributor shaft was too long and hitting something..! I've never heard a motor spark knock this bad..! I even had to put it in gear to get the engine to shut off...needless to say, I went straight back and asked him to work on the timing someway somehow...he fooled with it all afternoon and now it's much better but still has a few hiccups. He suggested I start using 93 octane, but I can't find any reference saying my 305 needs any 93 octane to run good...any thoughts on that..? And, to top all this off, my transmission shift point seems to have changed a little (wants to downshift at low speeds more than it used to), and my idle is really low in drive, and almost won't idle smoothly in park. Any thoughts on how timing is affecting the idle and shifting..? Sorry for the long post, but I wanted to try to give an update with a few details. Headed to a Rod Run Thursday and would like to drive it there with some confidence I'll make it back home, lol...! Appreciate any advice and help...!

1985 GMC Sierra Classic, C1500
305 CID, 4 bbl Quad
Stock Configuration


 
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