No crank/heatsoak issue

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Tiny Trucker

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For quite some time, I've had an issue where in summer, with regular on/off driving and traffic, I've turned my truck off and it hasn't started again for a while. In the past I've normally had to wait 1-2 hours before it will crank. Dash lights come up but no crank at all. For the longest time, I thought is was the oil pressure sender at the back of the block, (fuel/oil) as I used to have my guage reading faulty. I've replaced that with an ac delco one some time ago and it reads fine, but now the trucks started doing it again. No codes come up. Is it more likely to be a starter solenoid, or something like ICM, coil etc? Being that it only happens when the engine bay temp gets up makes me think it could be some kind of electrical heatsoak. She's a 350 Tbi
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HotWheelsBurban

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I had this problem on my Burb a few years ago, and it was a combination of bad (corroded) battery cables and dirt/oil in the starter. Replaced both positive cables and cleaned up the starter, and that fixed it. Mine is a Vortec but those parts are pretty much the same. The funny part is that it was happening (bad enough to get the wrecker called this time) in January! Was fairly cool, in the 40s, but I guess it was bad enough to not work whatever the temperature, as long as it was hot. Took a couple hours for the road service guy to arrive, and of course then it starts up fine! He was willing to follow us home though; Mom and I were at work 25 miles from home so that was good.
 

HotWheelsBurban

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Yes that reminds me, the ignition terminal on the solenoid (the little one) was loose. I tightened up the nut with my small Vise Grips cause on my starter solenoid it was a weird size.
I had totally forgotten about it until I saw the other post!
 

Schurkey

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I've normally had to wait 1-2 hours before it will crank. Dash lights come up but no crank at all.

Sometimes a bad ignition module will give you a hot no start. Check the easy stuff first. Big three !!!
The ignition module CANNOT cause a "no crank". It can cause a "cranks but won't start".

The usual problem with NO CRANKING when hot, is high resistance from corroded wire or corroded/loose connections in the circuit connected to the starter solenoid "S" terminal.

You turn the key, the solenoid gets some fraction of the power it's intended to get, and the starter won't even click.

The first thing to do is to perform a voltage drop test on the wire connected to the S terminal. You turn the key, it better have very close to system voltage (which could be reduced because of the current draw of the starter motor dropping battery voltage to ~11-ish volts--IF the starter cranks during your VD test.

It's common as dirt for the conductor in that wire (insulation color is purple, often fades to pink with age and heat) to be completely green or even black with corrosion. My '97 had the last eight inches of that wire replaced before I bought the truck, and the new section that was spliced-in was black with corrosion. By the time I bought the truck, the corrosion had gone so far up that wire that I couldn't get it all cut out from underneath the truck, the wire disappeared into a loom that ran up the side of the transmission and eventually over the top of the engine. I had to splice in from the top, and route 3 feet of fresh wire down to the starter.

The spliced-in "repair" that was connected to the "S" terminal. Conductor rotted.
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The OEM wire, that the "repair" wire was spliced-to. Conductor black with corrosion at splice, and better--but not "acceptably good" about eight inches back into the harness--which was as far as I could reach and still have some hope of soldering to the stub coming out of the harness bundle. Even the "better" end of this wire had too much corrosion to solder to.
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Spliced (crimped, then soldered, and eventually sealed with heat-shrink tubing that has adhesive on the inside) into the purple wire up by the intake manifold/valve cover area where the conductor was still genuinely copper-colored and in great condition. About three feet of fresh (red, because I didn't have any purple wire of the correct gauge size) wire all the way down to the "S" terminal on the starter solenoid.
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While this purple wire is a common cause of voltage drop due to corrosion of the conductor, it's also possible that the entire circuit has some amount of corrosion anywhere/everywhere from battery to ignition switch, through the neutral safety switch or clutch switch, (if used) through the bulkhead connector, into the starter relay (if used) and then to the "S" terminal.

This sort of problem goes back DECADES to the 1960s if not before. It is BEYOND COMMON.
 
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Tiny Trucker

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@Schurkthank you for the very informative post. I will definitely perform a VD test and if under voltage check the purple wire to the S terminal and check it back through the harness. Very much appreciated for your help!
 
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