More electrical problems.. :(

[71GeneralMotorsCorp]

hey guys, need some assistance. My truck has been down for quite a while, and I've been putting all new stuff in, and I'm down to the final stuff.. I've replaced the cap, rotor, ign control module, coil, main power wire from battery to starter, starter, power wire from starter to distributor. All grounds are clean, but my truck just cranks, with no fire. I get no power to the distributor, all I can think that is left is the battery, external voltage regulator ( the one that fits on the core support), or the ignition switch. Please help me figure this annoying problem out, I'd really appreciate it!

[mmiddle]

Check actual cranking voltage at the distributor. Must be more the 9.5

The original ignition uses a ballast resister from the Ignition switch to the distributor to reduce the 12volts to 9.5 volts for points. Remove this resister and replace the original 16/14 gauge wire with a 10 gauge wire from switch to dist. Tie in the starter solenoid wire(NOT purple wire) from the starter to the new 10 gauge ignition "ON".

[LockDoc]

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I'm presuming you have an HEI distributor since you mention replacing the module.

First, there is no power wire from the starter to the distributor on an HEI setup.

Run a 12 ga. wire from the IGN UNFUSED terminal on the fuse block to the "BAT" terminal on the distributor cap. Make sure the wire is not on the "TACH" terminal. You do not use the yellow wire that used to feed the points distributor from the "R" terminal on the solenoid. Tape it off or completely remove it. The picture below shows the IGN UNFUSED terminal on the fuse block.

LockDoc

[mmiddle]

That's right generally you do not need the wire from the starter solenoid to the dist. But, it does not hurt to have it. The extra assurance that it provides in cranking voltage is a good thing on a weak battery or failing starter. HEI's are very voltage sensitive.

During the production run 74-~85 some cars/trucks had it some did not. Chevrolets generally did not have that wire.

[franken]

If it cranks at a good rate, it's not the battery, switch or regulator.
Measure the Voltage at the distributor.
Check for spark.
Or shoot some ether, B12, or carb cleaner in the carb and cranking it. This is the easy test...

[71GeneralMotorsCorp]

It does have HEI, and I forgot to mention, I was driving it when it broke down. It acted basically like it ran out of gas and before you ask, It does have gas in it lol. It just cranks now and does not fire. There is almost no voltage at the distributor at all, so do I just put a wire in from my fuse block to the battery terminal on my distributor? Or can I run a wire from my battery to the distributor? AND do I keep the wire from the starter to the distributor? Also, since my truck has been down, I put my new Tach dash in.. before I replaced, my old one was working fine. The new dash has a problem with the backlights and fuel guage. The backlights do not light up at all and the fuel guage is way below empty. Help please? Thanks in advance!!

[68gmsee]

One thing to remember is all voltages begin and return to the battery. A good ground loop is needed to return voltages from the engine, cab, bed, frame and radiator support. New trucks relied on new metal to metal contact which has long ago diminished contact due to road grime and rust.

If you haven't done it already, and to keep from having to chase electrical gremlins, start by installing ground straps from engine to cab, bed to frame, radiator support to frame (I put another one from cab to the frame).

Once you do that, then you can proceed with the above trouble shooting.

forgot to mention: make sure the gauge panel has the ground wire attached to metal dash.

[kcsa75]

Originally Posted by 71GeneralMotorsCorp

It does have HEI, and I forgot to mention, I was driving it when it broke down. It acted basically like it ran out of gas and before you ask, It does have gas in it lol. It just cranks now and does not fire. There is almost no voltage at the distributor at all, so do I just put a wire in from my fuse block to the battery terminal on my distributor? Or can I run a wire from my battery to the distributor? AND do I keep the wire from the starter to the distributor? Also, since my truck has been down, I put my new Tach dash in.. before I replaced, my old one was working fine. The new dash has a problem with the backlights and fuel guage. The backlights do not light up at all and the fuel guage is way below empty. Help please? Thanks in advance!!

For what it's worth, the same thing happened to me. Mine quit at a stoplight to get on the freeway during rush hour. After I got it home, I replaced the module in the HEI and the coil. When that didn't work, I gave up and took it to my mechanic. Turns out is was the ignition switch.

[71GeneralMotorsCorp]

Boy oh boy. I'm lost.. still! I replaced my ignition switch, recharged my battery, and put a new external voltage regulator on. still has less than one volt while cranking! GAH! Although, I did put a ground wire on my dash panel, and it solved all my problems for the dash!

So, If you don't feel like reading back through it, I have replaced my cap, rotor, coil, ignition control module, starter, main positive battery cable, cable from starter to HEI distributor, and Ignition switch. I'm about ready to just take it to the shop, and get it over with!

[71 super]

Did you run the wire as Leon told you to do? If not a 10 gauge or greater the hei will not get voltage it needs and could fry the new module. Did you place the dielectric grease per instructions for module? It sounds like you are not powering the hei adequately and that is the root of your problem. You have changed alot of things all at once and any of those could have compounded the issue. Run the bigger wire from fuse box directly to "bat" terminal on cap, prime the carb and spin the motor over. If no go pull number one plug out and see if it is getting spark or if it had been fouled out, if fouled get new plugs and try again.
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[mmiddle]

Originally Posted by 71GeneralMotorsCorp

Boy oh boy. I'm lost.. still! I replaced my ignition switch, recharged my battery, and put a new external voltage regulator on. still has less than one volt while cranking! GAH! Although, I did put a ground wire on my dash panel, and it solved all my problems for the dash!

So, If you don't feel like reading back through it, I have replaced my cap, rotor, coil, ignition control module, starter, main positive battery cable, cable from starter to HEI distributor, and Ignition switch. I'm about ready to just take it to the shop, and get it over with!

Well, there's yer problem right there!
These trucks have a very simple electrical system. Ether you have something wired wrong or the "ignition on" wire has a brake in it. Do you have a wiring diagram for it?

Use the Fuse box diagram shown and confirm you have Battery voltage at the "IGN. ON unfused" terminal. Then with meter hooked up to this terminal crank engine. What is you voltage. If less than 10volts cranking, unhook Dizzy wire at Dizzy. Recrank engine. 10 volts or more at terminal. Check wire going to Dizzy for ground-out. still less than 10volts? Check battery, check all connections.

Another test you could do is run a wire 10ga.From Batt straight to Dizzy, Then crank engine. Did it start? Yes- continue tracing electrical short.NO-something in Dizzy is bad.

You can do it....We can help!