No spark '85 chevy 4x4 1/2 ton - The 1947 - Present Chevrolet & GMC Truck Message Board Network

hrc200x · 01-22-2006, 11:38 PM

Has the stock HEI distributor and a 305. Was running fine this winter, sat 2 or 3 weeks, tried to start it and no go. Narrowed it down to no spark. Has power to the BAT plug in on the distributor cap. Changed cap/coil and have installed a new ingnition module. Is there a pickup coil under 3 screws sort of under the rotor? What about any grounds that could be dirty? Is there any exploded view/partsfishe diagrams of HEI distributors? Thanks.

60-66 Nut · 01-24-2006, 12:07 PM

The pickup coil is right below the rotor next to the module. You have to pull the distributor out and remove the shaft to change the pickup coil. Did you replace the rotor? HEI rotors were known to short out even though they look OK. Just a thought, hope that helps.

60-66 Nut

greg0380 · 01-24-2006, 01:54 PM

another thing to consider is the ESC module (electronic spark control). The V6 and V8s used them that year. It is mounted behind the glovebox. The spark reference signal goes through the module and back out to the distrubutor. it works with the knock detector to retard spark if necessary. I had trouble with mine, it did not cause the truck not to start, but I would think that it could. There is a way to bypass (which I would recommend anyway). Let me know if you want the link (I think Mike Ervin wrote it), its pretty easy. hope that helps...

hrc200x · 01-24-2006, 10:50 PM

Thanks for the replies, I think the Electronic spark thing is disconnected already. There are wires that go from the right side of the ign. module out the back of the dist. into a 3 or 4 prong plug in, Out of that plug in there is only one wire that makes a loop back to the 3/4 pronged plug in. I'm assuming if things were the way Chevy made them that the plug in would go through the firewall or somthing?

I have tried a different rotor. Neither the rotor or cap was new, but they came from a parts truck and don't look like they had many miles on them.

Are 305/350 distributors interchangeable? Looking back now after spending $40 on the module and another $30 for hardly used coil/cap/rotor it would have been just cheaper to take one of my complete distributors from my parts engines and swap that in since this one probably has to come out anyway???

Thanks.

chevyjr73 · 01-25-2006, 09:37 AM

305/350 distributors are interchangeable

01-22-2006, 11:38 PM	#1
hrc200x Registered User Join Date: Sep 2002 Location: Minnesota Posts: 201	No spark '85 chevy 4x4 1/2 ton Has the stock HEI distributor and a 305. Was running fine this winter, sat 2 or 3 weeks, tried to start it and no go. Narrowed it down to no spark. Has power to the BAT plug in on the distributor cap. Changed cap/coil and have installed a new ingnition module. Is there a pickup coil under 3 screws sort of under the rotor? What about any grounds that could be dirty? Is there any exploded view/partsfishe diagrams of HEI distributors? Thanks. __________________ '75 Chevy 3/4 4x4, 6" suspension lift, 3" body lift, 3" lifted gas tanks, '83 cab, '88 clip, 35" cooper tires, American Racing Baja rims, 350, 700r4, 208.

01-24-2006, 12:07 PM	#2
60-66 Nut Professional Beer Tester Join Date: Aug 2004 Location: Louisiana Posts: 453	Re: No spark '85 chevy 4x4 1/2 ton The pickup coil is right below the rotor next to the module. You have to pull the distributor out and remove the shaft to change the pickup coil. Did you replace the rotor? HEI rotors were known to short out even though they look OK. Just a thought, hope that helps. 60-66 Nut __________________ 60 Ford F100 Custom Cab 61 Apache Short Fleetside 64 C10 Short Stepside 65 C80 409 V8 5spd(X-Firetruck) 83 GMC 350 Olds Diesel 85 GMC Short Bed 86 GMC Short Bed 90 GMC R3500 Crew Cab 92 GMC 1500

01-24-2006, 01:54 PM	#3
greg0380 Registered User Join Date: Dec 2003 Location: CT Posts: 454	Re: No spark '85 chevy 4x4 1/2 ton another thing to consider is the ESC module (electronic spark control). The V6 and V8s used them that year. It is mounted behind the glovebox. The spark reference signal goes through the module and back out to the distrubutor. it works with the knock detector to retard spark if necessary. I had trouble with mine, it did not cause the truck not to start, but I would think that it could. There is a way to bypass (which I would recommend anyway). Let me know if you want the link (I think Mike Ervin wrote it), its pretty easy. hope that helps... __________________ 1985 GMC Sierra 1500, 1/2 ton, 2WD, LWB, TBI 305 5 speed, 3.42 rear 2007 GMC Sierra 1500, xtended cab, 4X4, flexfuel 5.3L 1999 BMW 528i

01-24-2006, 10:50 PM	#4
hrc200x Registered User Join Date: Sep 2002 Location: Minnesota Posts: 201	Re: No spark '85 chevy 4x4 1/2 ton Thanks for the replies, I think the Electronic spark thing is disconnected already. There are wires that go from the right side of the ign. module out the back of the dist. into a 3 or 4 prong plug in, Out of that plug in there is only one wire that makes a loop back to the 3/4 pronged plug in. I'm assuming if things were the way Chevy made them that the plug in would go through the firewall or somthing? I have tried a different rotor. Neither the rotor or cap was new, but they came from a parts truck and don't look like they had many miles on them. Are 305/350 distributors interchangeable? Looking back now after spending $40 on the module and another $30 for hardly used coil/cap/rotor it would have been just cheaper to take one of my complete distributors from my parts engines and swap that in since this one probably has to come out anyway??? Thanks. __________________ '75 Chevy 3/4 4x4, 6" suspension lift, 3" body lift, 3" lifted gas tanks, '83 cab, '88 clip, 35" cooper tires, American Racing Baja rims, 350, 700r4, 208.

01-25-2006, 09:37 AM	#5
chevyjr73 Registered User Join Date: Mar 2004 Location: chesapeake,virginia Posts: 117	Re: No spark '85 chevy 4x4 1/2 ton 305/350 distributors are interchangeable



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