Truck won`t start sometimes!!!!! - The 1947 - Present Chevrolet & GMC Truck Message Board Network

Scott Johnson · 11-12-2003, 01:05 AM

Wondering if anyone has any ideas. Every now and then my truck won`t start. I take the dist. cap off and move around the wires inside the dist., put the cap back on and it starts up. I have checked the wires in the dist. and they seem to be good with no kinks or exposed wire. The truck is a 71c10 with a 350, electronic ignition. This doesn`t happen very often, it may go 1 month or 6 months before it happens, and I have no idea what is causing the problem. Any ideas would be greatly appreciated.

Scott

jhow66 · 11-12-2003, 01:36 AM

Check where the green and white wires off the pickup where they plug into the module. The wires in the plug sometimes slide back when pushed on the module blades. Found out the hard way on wifes car --replaced 4 or 5 modules before finding this. Hope this helps. ( It is HEI-right?)

krue · 11-12-2003, 01:36 AM

I'm no mechanic, but is there any pattern. Like cold start, cold weather, firing but not starting, not firing or even trying to start. Any info you can think of would help someone diagnose your problem.

doughby82 · 11-12-2003, 02:10 AM

it could be the cap itself.could have a hairline crack.

1969 GMC · 11-12-2003, 02:19 AM

while you are looking for the problem, you might as well change the battery cables. Cheap insurance, and hey, it might even be the problem.

Scott Johnson · 11-12-2003, 10:48 PM

The truck is HEI and the problem has no pattern, it just happens. It may crank up with no problems for 2 months straight, or it may happen in a week. I think I will try replacing the cap and see if that does it.

walker · 11-12-2003, 11:12 PM

You say it doesn't start, does it crank and not start or does it not crank? If it cranks check your input voltage, need 12v for the HEI. Also check the internal ground strap as well as the carbon tower, rubber gasket(also that it has dielectric grease on it), and the little springy thingy.

Scott Johnson · 11-13-2003, 12:56 AM

Motor turns over, but doesn`t start. Haven`t checked under the coil for grease, but that may be an idea.

dinnut · 11-13-2003, 01:00 AM

i have hei and when i put a new cap, wires, plugs, and rotor i couldnt turn the truck off anymore. id turn the key off and the truck would keep running. it still does it. i have to pull the power off of the hei to turn it off.

shuttermutt · 11-13-2003, 01:31 AM

You are taking 12-volts from a crank and run circuit, right dinnut? Sounds to me like you're feeding it juice full time.

jorgensensc · 11-13-2003, 03:26 AM

Dinnut, Check to make sure you are getting power from the fuse block to your Distributor and it is coming from a source that torns off with the key in the off position. There should be one in the middle of the fuse block.

Class of 69 · 11-13-2003, 11:35 AM

Look VERY carefully at the two small wires that come out of the pickup coil. They are notorious for braking at that place, due to the movement of the coil from timing advancement. It is hard to tell if one is broken, especially if they are held together with a small zip strap, so push and pull on them, a bit with a blunt object. The plastic insulator may be holding it together, but watch for unusual bending of the plastic, indicating the wire is broken internally.

Old Dave · 11-13-2003, 12:44 PM

Class of 69 had a good idea about checking the wires on the pickup coil. The enameled wire that the coil is made of that the green and yellow wires attach to are very small (#30 or smaller) and they will break inside of the coil itself. You can check the pickup coil with an ohmmeter by disconnecting the pickup wires from the module and attaching your meter. Normal resitance is about 140-160 ohms. With the meter attached here, wiggle the wires around and see if you have an intermittent connection. If you leave the meter connected and turn the motor over you should see a spike (more resistance in the meter reading) as the 8 magnetic points of the coil interrupt the current flow in the ohmmeter. This is more obvious with an analog meter than a digital. Since you can get it to start by removing the cap and moving wires around sounds like it's a distributor problem of some sort. It could even be in your coil since it's in the top of the distributor cap.

Good luck...Dave

Scott Johnson · 11-14-2003, 12:48 AM

Thanks Old Dave and Class of 69, That sounds like it could possibly be my problem area. I`ll give it a shot this weekend. Would be nice if that`s what it is. I`ll post back if I find the problem.

Scott

bluec10 · 11-17-2003, 10:34 PM

I like doughby82's idea of a hairline crack. I had a hairline crack in a coil once and it drove me crazy because I couldn't figure out what was wrong. I finally saw a tiny blue arc when I opened the hood at night on a humid evening.

Huck · 11-18-2003, 11:05 AM

CAN WE SAY ''''CONDENSER'''-----IT WILL FAIL IRATICALLY AND DRIVE YOU NUTS. AFFECTED BY HEAT, MOISTURE, ETC. It is simple and cheap to swap out.

*redbowtie* · 11-18-2003, 11:56 AM

HEI, no condenser...

WRMZ71 · 11-22-2003, 11:55 PM

I'd have the ignition module tested, make sure you got a good keyed hot and if you have a tach wire hooked up to it make sure it doesn't touch the hot one. I have that problem a lot and the truck will just die!!!

71GMC_3/4T · 11-23-2003, 12:55 AM

I'd guess a loose connection at the "BATT" contact on the cap. Either that, or you're still running the resistive wire, like I was. Hey, it worked *most* of the time, up until the time it just decided to start working occasionally! Had me chasing ghosts for a while... God, I hate intermittants!! New wire from "IGN-UNFUSED" on the fuse block solved it.

Check your ignition feed wire. If it's yellow and comes out of the factory harness, it's WRONG for HEI! Trust me, go check.

**smitty62** · 11-23-2003, 01:04 AM

Dollar to a donut that Old Dave has the answer!!!

11-12-2003, 01:05 AM	#1
Scott Johnson Junior Member Join Date: Feb 2003 Location: Louisiana Posts: 281	Truck won`t start sometimes!!!!! Wondering if anyone has any ideas. Every now and then my truck won`t start. I take the dist. cap off and move around the wires inside the dist., put the cap back on and it starts up. I have checked the wires in the dist. and they seem to be good with no kinks or exposed wire. The truck is a 71c10 with a 350, electronic ignition. This doesn`t happen very often, it may go 1 month or 6 months before it happens, and I have no idea what is causing the problem. Any ideas would be greatly appreciated. Scott __________________ 71 C10 Step Daily Driver 72 K10 Suburban Work in Progress www.louisianaclassictruckclub.com

11-12-2003, 01:36 AM	#2
jhow66 Registered User Join Date: Jun 2002 Location: Knoxville Tenn. Posts: 3,058	Check where the green and white wires off the pickup where they plug into the module. The wires in the plug sometimes slide back when pushed on the module blades. Found out the hard way on wifes car --replaced 4 or 5 modules before finding this. Hope this helps. ( It is HEI-right?) __________________ 56 Chevy Bel-Air 2dr. HT (purchased new) 71 Chevy Cheyenne SWB PU (502HO) 65 GMC short bed step--work in progress and my gofer

11-12-2003, 02:10 AM	#4
doughby82 Registered User Join Date: Mar 2001 Location: springfield ill Posts: 836	it could be the cap itself.could have a hairline crack. __________________ springfield illinois 2003 custom (harley)built from scratch 68 swb

11-12-2003, 02:19 AM	#5
1969 GMC Registered User Join Date: Feb 2003 Location: The Rubber City Posts: 5,498	while you are looking for the problem, you might as well change the battery cables. Cheap insurance, and hey, it might even be the problem. __________________ 1969 GMC K2500 1996 Honda Accord 2007 Kawasaki KLR 650

11-12-2003, 10:48 PM	#6
Scott Johnson Junior Member Join Date: Feb 2003 Location: Louisiana Posts: 281	The truck is HEI and the problem has no pattern, it just happens. It may crank up with no problems for 2 months straight, or it may happen in a week. I think I will try replacing the cap and see if that does it. __________________ 71 C10 Step Daily Driver 72 K10 Suburban Work in Progress www.louisianaclassictruckclub.com

11-12-2003, 01:36 AM	#3
krue Designated A-hole! Join Date: Mar 2003 Location: South Mississippi Posts: 36,450	I'm no mechanic, but is there any pattern. Like cold start, cold weather, firing but not starting, not firing or even trying to start. Any info you can think of would help someone diagnose your problem. __________________ "If it ain't broke, fix it 'til it is!" Being stupid ain't illegal. We're Still Debt Free Except for the House!!! www.daveramsey.com 70 GMC SWB Stepside project "Green Booger" soon to be 6.0l/4l80e 93 S-10 "Poppaw's Truck"

11-12-2003, 11:12 PM	#7
walker Registered User Join Date: Jul 2003 Location: north of Phx AZ about 30 miles Posts: 698	You say it doesn't start, does it crank and not start or does it not crank? If it cranks check your input voltage, need 12v for the HEI. Also check the internal ground strap as well as the carbon tower, rubber gasket(also that it has dielectric grease on it), and the little springy thingy. __________________ Andy,Phx AZ '67 C-10 (Ahhh, done at last. Well there is that disk front end I want to put in and...) "23 C-Cab-sold '48 Ford 8N tractor(still working) '67 Scout(Now on the road) '70 MG B.-sold

11-13-2003, 12:56 AM	#8
Scott Johnson Junior Member Join Date: Feb 2003 Location: Louisiana Posts: 281	Motor turns over, but doesn`t start. Haven`t checked under the coil for grease, but that may be an idea. __________________ 71 C10 Step Daily Driver 72 K10 Suburban Work in Progress www.louisianaclassictruckclub.com

11-13-2003, 01:00 AM	#9
dinnut Registered User Join Date: Apr 2003 Location: missouri city, tx Posts: 4,486	i have hei and when i put a new cap, wires, plugs, and rotor i couldnt turn the truck off anymore. id turn the key off and the truck would keep running. it still does it. i have to pull the power off of the hei to turn it off. __________________ 70 longbed 496/th400/Ford 9"

11-13-2003, 01:31 AM	#10
shuttermutt Don't say "Oops!", Doctor Join Date: Nov 2003 Location: Houston, TX Posts: 677	You are taking 12-volts from a crank and run circuit, right dinnut? Sounds to me like you're feeding it juice full time. __________________ 'Mutt 1968 CST LWB: R.I.P. 1967 Chevelle: TPI 454 beast 1967 C10 SWB: Claimed when Bumpster didn't put it on his list

11-13-2003, 03:26 AM	#11
jorgensensc Registered User Join Date: Jul 2003 Location: Cypress, Tx Posts: 4,005	Dinnut, Check to make sure you are getting power from the fuse block to your Distributor and it is coming from a source that torns off with the key in the off position. There should be one in the middle of the fuse block. __________________ 1972 C20 Suburban- Big Blue Betty '56 Chevy Bel Air Sedan- Frame up Restoration -What would you attempt to achieve if you knew you could not fail?- -I Refuse To Tiptoe Through Life, Only To Arrive Safely At Death's Door- R.I.P. EAST SIDE LOW LIFE

11-13-2003, 11:35 AM	#12
Class of 69 Registered User Join Date: Mar 2003 Location: Stillwater MN Posts: 1,166	Look VERY carefully at the two small wires that come out of the pickup coil. They are notorious for braking at that place, due to the movement of the coil from timing advancement. It is hard to tell if one is broken, especially if they are held together with a small zip strap, so push and pull on them, a bit with a blunt object. The plastic insulator may be holding it together, but watch for unusual bending of the plastic, indicating the wire is broken internally. __________________ 69 GMC K10 ..some restoration required....still..

11-13-2003, 12:44 PM	#13
Old Dave Is a bullfrog waterproof? Join Date: Nov 2000 Location: OLATHE, KANSAS Posts: 1,130	Class of 69 had a good idea about checking the wires on the pickup coil. The enameled wire that the coil is made of that the green and yellow wires attach to are very small (#30 or smaller) and they will break inside of the coil itself. You can check the pickup coil with an ohmmeter by disconnecting the pickup wires from the module and attaching your meter. Normal resitance is about 140-160 ohms. With the meter attached here, wiggle the wires around and see if you have an intermittent connection. If you leave the meter connected and turn the motor over you should see a spike (more resistance in the meter reading) as the 8 magnetic points of the coil interrupt the current flow in the ohmmeter. This is more obvious with an analog meter than a digital. Since you can get it to start by removing the cap and moving wires around sounds like it's a distributor problem of some sort. It could even be in your coil since it's in the top of the distributor cap. Good luck...Dave __________________ "It is better to remain silent and be thought a fool, than to open one's mouth and remove all doubt." Ben Franklin __________________ 1970 Chevy shortbed 2002 Harley Custom Chopper (Long sucker) 1998 K2500 5.7L 5-speed Longbed 1st two are My son's toys...they just live in my garage! 1997 GMC K1500 Suburban 1993 S-10 Blazer 4D (youngest son's daily driver) 2000 Dodge Ram 4WD Ext. Cab (5.9L) Wife is a late year 1951

11-14-2003, 12:48 AM	#14
Scott Johnson Junior Member Join Date: Feb 2003 Location: Louisiana Posts: 281	Thanks Old Dave and Class of 69, That sounds like it could possibly be my problem area. I`ll give it a shot this weekend. Would be nice if that`s what it is. I`ll post back if I find the problem. Scott __________________ 71 C10 Step Daily Driver 72 K10 Suburban Work in Progress www.louisianaclassictruckclub.com

11-17-2003, 10:34 PM	#15
bluec10 Registered User Join Date: Apr 2002 Location: Manitoba, Canada Posts: 663	I like doughby82's idea of a hairline crack. I had a hairline crack in a coil once and it drove me crazy because I couldn't figure out what was wrong. I finally saw a tiny blue arc when I opened the hood at night on a humid evening. __________________ Present: 2015 Tacoma. Yeah, not a GM, but I love it. 1969 GMC 32,000 - fix, drive, relax, fix... 2019 BMW R1250 GSA - Yahoooooooo 1979 Honda GL 1000 - retro touring at its best. Past: '05 Sierra 4x4 - Had 270,000 KM and running well when it was written-off by a stop sign runner. '94 F-150 from the "F word" company. I'll admit it...good truck. Sold what was left of it for $800 to a guy who came to pick it up at 11:00 PM with cash in hand. Hmm. '79 Sierra Grande (Black) organ donor - perfect rebuildable 4-bolt 350 and a good TH350. '76 Sierra Grande (Orange) - hate isn't too strong a word. Kid who bought it turned it into a hot rod. '68 C-10 R.I.P. - Dad's old truck...too far gone to resurrect. '59 C-50 - with hoist. Truck is gone, wife isn't. Nuff said.



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11-18-2003, 11:05 AM	#16
Huck Senior Member Join Date: Jun 2001 Location: Shelbyville, KY Posts: 3,269	CAN WE SAY ''''CONDENSER'''-----IT WILL FAIL IRATICALLY AND DRIVE YOU NUTS. AFFECTED BY HEAT, MOISTURE, ETC. It is simple and cheap to swap out.

11-18-2003, 11:56 AM	#17
redbowtie Account Suspended Join Date: Nov 2003 Location: Fort Worth, Texas Posts: 0	HEI, no condenser...

11-22-2003, 11:55 PM	#18
WRMZ71 Cause the Chicks DIG IT!! Join Date: Nov 2003 Location: Beaufort SC Posts: 509	I'd have the ignition module tested, make sure you got a good keyed hot and if you have a tach wire hooked up to it make sure it doesn't touch the hot one. I have that problem a lot and the truck will just die!!!

11-23-2003, 12:55 AM	#19
71GMC_3/4T Weapons Of Construction Join Date: Apr 2000 Location: Colorado, USA Posts: 1,095	I'd guess a loose connection at the "BATT" contact on the cap. Either that, or you're still running the resistive wire, like I was. Hey, it worked most of the time, up until the time it just decided to start working occasionally! Had me chasing ghosts for a while... God, I hate intermittants!! New wire from "IGN-UNFUSED" on the fuse block solved it. Check your ignition feed wire. If it's yellow and comes out of the factory harness, it's WRONG for HEI! Trust me, go check. __________________ 1971 GMC 2500, 402/TH400 4.10 Daily Driver Lafayette, CO

11-23-2003, 01:04 AM	#20
smitty62 Registered User Join Date: May 2002 Location: North Carolina Posts: 1,234	Dollar to a donut that Old Dave has the answer!!! __________________ Stepsides look like real trucks! Smitty

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