Truck turns over but wont fire

[K10-Kansas]

EDIT 4-30-23: I did start today!!!

1) I had my kill switch set up wrong so I bypassed it.
2) The plugs were completely fouled so I replaced them.
3) When I pulled the distributer I put in back in incorrectly so I fixed that (Thanks Ironangel for all of the great advice).
4) I had mislabeled the plug order on the distributer and therefore, connected the wrong distributer origin wires to the wrong plugs so I fixed that. LOL, check out the picture in post #22
5) The ignition wire had a bulky plastic housing over the female connector so it was very hard to know if it was actually ever properly connected to the battery male blade on the distributor.
6) It's also entirely possible that it wont start with the tach wire connected to the distributer. I'll try to start it tomorrow with the tach wire connected.


I have a 1971 K10. I bought it, had a mechanic put in a crate engine and transmission. It took him 4 months. The wiring was a disaster under the dash so I drove it onto a trailer and brought it home. I drove it off the trailer and parked it. I pulled every inch of wire bumper to bumper and replaced it with the American AutoWire Classic update. It took me 4 months because I could only work on it for a few hours per week. I'm done and was overjoyed to start the finished product. It turns over but wont fire.

I don't see where any wires got knocked lose. I thought about syphoning out the year old gas and adding new gas. What should I look at? Thanks for the help on this.

[PbFut]

Gas could be problem given the 8 months down time but I would verify you have spark first. Then verify fuel at the carb.

[kaycee]

Start with the basics does it have spark, fuel check to see if you have spark if you do go to fuel is it getting fuel. Did it ever run after engine replacement

[K10-Kansas]

Originally Posted by PbFut

Gas could be problem given the 8 months down time but I would verify you have spark first. Then verify fuel at the carb.

Thanks. I looked up some videos on how to do that and I'll check it out.

[K10-Kansas]

Originally Posted by kaycee

Start with the basics does it have spark, fuel check to see if you have spark if you do go to fuel is it getting fuel. Did it ever run after engine replacement

Yes, it ran after the engine and transmission were put in. Thanks for your help on this.

[Getter-Done]

I will add when trying to restart a vehicle that has not run in a while.

It is best to have a water source or fire extinguisher close by.

[guyryan100]

My truck sat for 19 years and the gas in the tank was fine when I fired it up late last year. Today I used gas from the lawn mower gas can because I needed to, that gas was 3 years old and ran fine. Both of these surprised me, just saying I bet old gas isn’t your issue. I bet power to the distributor.

[72SB]

Given it ran before you replaced all wiring....I would focus on wiring. Specifically, ignition (12vdc to yellow wire with key on)

You need to confirm if you have spark. pull a plug lay on block, crank...do you see spark?

If so look for fuel delivery issue

Your gas age is not a issue

[rockyrivermark]

Timing light is also a very easy way to check for spark

[Ironangel]

Does the truck have an HEI or points ignition? I dont think your problem is fuel, it's something you've done or didn't do in installing the new harness.

[ghackett1]

Originally Posted by Ironangel

Does the truck have an HEI or points ignition? I dont think your problem is fuel, it's something you've done or didn't do in installing the new harness.

Yep agree, if it’s HEI be sure you have a solid 12 volts (I usually use the Fused ignition from the under dash fuse block) going to the coil/dizzy etc.. tape up that yellow wire and don’t use it — it’s a resistor wire to be used with points only.

[geezer#99]

Yellow wire isn’t a resistor wire.
It’s the wire used to supply 12v to the coil (from the starter solenoid) when starting.

[K10-Kansas]

Originally Posted by Getter-Done

I will add when trying to restart a vehicle that has not run in a while.

It is best to have a water source or fire extinguisher close by.

Thanks. I strapped a quick release auto fire extinguisher to the truck before I began replacing the wiring harness. Good info for people to read.

[K10-Kansas]

Originally Posted by guyryan100

My truck sat for 19 years and the gas in the tank was fine when I fired it up late last year. Today I used gas from the lawn mower gas can because I needed to, that gas was 3 years old and ran fine. Both of these surprised me, just saying I bet old gas isn’t your issue. I bet power to the distributor.

Thanks. Good to know it's probably not the gas.

[K10-Kansas]

Originally Posted by Ironangel

Does the truck have an HEI or points ignition? I dont think your problem is fuel, it's something you've done or didn't do in installing the new harness.

Yeah, it was my first time doing anything like this so I bet that's it.

[K10-Kansas]

Originally Posted by ghackett1

Yep agree, if it’s HEI be sure you have a solid 12 volts (I usually use the Fused ignition from the under dash fuse block) going to the coil/dizzy etc.. tape up that yellow wire and don’t use it — it’s a resistor wire to be used with points only.

Yeah, American Autowire had 2 sets of directions for HEI versus points so I followed the directions to sidestep the ballast resistor option.

[ghackett1]

Originally Posted by geezer#99

Yellow wire isn’t a resistor wire.
It’s the wire used to supply 12v to the coil (from the starter solenoid) when starting.

Yes correct—poor selection of words but I still also get rid of it when switching to HEi.

[RustyPile]

Originally Posted by ghackett1

Yes it does but it also drops the voltage down once engine starts, so I may be wrong but I have always have seen it described as the resistor wire. I always disconnect when upgrading to HEI.

The yellow wire is not a resistor, therefore it does not "drop the voltage".. It is a simple jumper that runs between coil and starter solenoid. The resistor wire also connects to the same terminal on the coil. While the starter is engaged, 12 volts from the solenoid appears on the yellow wire at the coil.. When the engine starts and the solenoid disengages, the voltage to power the coil comes through the resistor wire where the "voltage drop" occurs.

Now, back to the regularly scheduled program.

[ghackett1]

Originally Posted by RustyPile

The yellow wire is not a resistor, therefore it does not "drop the voltage".. It is a simple jumper that runs between coil and starter solenoid. The resistor wire also connects to the same terminal on the coil. While the starter is engaged, 12 volts from the solenoid appears on the yellow wire at the coil.. When the engine starts and the solenoid disengages, the voltage to power the coil comes through the resistor wire where the "voltage drop" occurs.

Now, back to the regularly scheduled program.

Got it

[Ironangel]

Our trucks didn't have ballast resisters, they use a resister wire usually coming from the wire gutter along the firewall to the coil. If your truck had an idle solenoid for the TSC system it used a 10 or 12 gauge pink wire. Buy installing an HEI that resister wire is of no use any more. All you need to do is find a switched terminal on the fuse box, an open spade terminal that is hot only when the key is on, and run a 12 gauge wire from that terminal to the BAT terminal on the HEI. You can actually run a wire straight from the battery + to the HEI and crank the starter, if it fires up you know you had a power issue and need to run that wire from the switched terminal in the fuse block so the truck shuts off with the key. You can 86 that yellow wire too, dont need it anymore. Only two wires for an HEI, the red power supply and the tach wire. Battery should ground to the engine block, the HEI gets it's ground through the block. I mentioned that pink wire because that's what many use for the switched power to the HEI. Since you stripped the factory wiring it may not exist anymore. No biggie, just do the above and your golden. I'm in KC pretty regular, where are located, north hopefully? I ask because I'll be in KC probably tomorrow and later in the week...I'd be glad to swing by and help.

[Rust_never_sleeps]

Maybe verify the condition of the grounds first. If you had to replace the wiring, those might be a mess too. Bad grounds will make troubleshooting a nightmare

[K10-Kansas]

Originally Posted by Ironangel

Our trucks didn't have ballast resisters, they use a resister wire usually coming from the wire gutter along the firewall to the coil. If your truck had an idle solenoid for the TSC system it used a 10 or 12 gauge pink wire. Buy installing an HEI that resister wire is of no use any more. All you need to do is find a switched terminal on the fuse box, an open spade terminal that is hot only when the key is on, and run a 12 gauge wire from that terminal to the BAT terminal on the HEI. You can actually run a wire straight from the battery + to the HEI and crank the starter, if it fires up you know you had a power issue and need to run that wire from the switched terminal in the fuse block so the truck shuts off with the key. You can 86 that yellow wire too, dont need it anymore. Only two wires for an HEI, the red power supply and the tach wire. Battery should ground to the engine block, the HEI gets it's ground through the block. I mentioned that pink wire because that's what many use for the switched power to the HEI. Since you stripped the factory wiring it may not exist anymore. No biggie, just do the above and your golden. I'm in KC pretty regular, where are located, north hopefully? I ask because I'll be in KC probably tomorrow and later in the week...I'd be glad to swing by and help.

Thanks. I'm in Lenexa Kansas. I the American Autowire has a 12V wire running to the batt side of the HEI and the tach wire running to the tach side. I put my multimeter on the batt wire and it is sending 12 volts to the HEI. I pulled a spark plug, put it back in he wire and laid it on the block so that it is grounded and cranked the engine but got no spark. My HEI is brand new and worked fine before I replaced the wiring harness.

[K10-Kansas]

Originally Posted by Rust_never_sleeps

Maybe verify the condition of the grounds first. If you had to replace the wiring, those might be a mess too. Bad grounds will make troubleshooting a nightmare

Thanks. Yeah I put in ground straps and then doubled up by also adding ground wires.

[Palf70Step]

It is not uncommon at all for the HEI module to just give up with out warning. If you take it out, most auto parts store can test them. I know a lot of folks always carry a spare one in the glove box.

[K10-Kansas]

The voltage on the 12v wire running to the battery connection on the HEI drops to 9.2 while cranking. The battery itself drops to 9.5 when cranking.