HEI converted ignition - Ignition module hot wire from harness only has 10 volts according to multi meter

[MadMax_636]

OK. I'm hoping that @RonD comes back and weighs in the voltage drop when running.

I looked everywhere for a Ballast Resistor under the hood and under the dash. Nothing.

A idea that I had was splitting the 2 wires and running the 12v run (red/light green wire) and running it directly to the HEI "B" post. Since its only powered with key on RUN and the (Brown/Pink wire. Mine just looks brown) and keep it on the harness. Or even running a T from the harness connector and the HEI "B" directly?

 

[RobbieD]

I would lean toward just adding a simple relay to switch good battery voltage to your ignition, the relay being triggered by the original wire.

 

[RonD]

just did that. in the RUN position im getting around 12.65v and when running I'm getting 10v

And what was battery voltage at that time of the 10v test engine running, past battery voltage test doesn't matter for something like this, have to retest everything at that one time.

And test running voltage from "red wire" to alternators metal case and then to battery negative
Also test HEI ground to battery positive engine running

A corroded connection will cause this kind of voltage drop
A volt meter is not "a load", maybe 0.02amps, a running coil and HEI is "a load", 5 or 6amps

So static test of key on voltage can show correct battery voltage, but "load" test can show significant voltage drop if higher AMP draw is restricted by a poor connection

 

[RonD]

I looked everywhere for a Ballast Resistor under the hood and under the dash. Nothing.

A idea that I had was splitting the 2 wires and running the 12v run (red/light green wire) and running it directly to the HEI "B" post. Since its only powered with key on RUN and the (Brown/Pink wire. Mine just looks brown) and keep it on the harness. Or even running a T from the harness connector and the HEI "B" directly?

There is no Ballast Resistor if you see Battery Voltage at the coil and HEI in key on static test

You can redo the Splice of red/green and brown/pink wires to one new wire in the cab
And run that new wire to coil and HEI

But you must have BOTH of these wires hooked up to the one wire for coil and HEI

 

[MadMax_636]

And what was battery voltage at that time of the 10v test engine running, past battery voltage test doesn't matter for something like this, have to retest everything at that one time.

And test running voltage from "red wire" to alternators metal case and then to battery negative
Also test HEI ground to battery positive engine running

A corroded connection will cause this kind of voltage drop
A volt meter is not "a load", maybe 0.02amps, a running coil and HEI is "a load", 5 or 6amps

So static test of key on voltage can show correct battery voltage, but "load" test can show significant voltage drop if higher AMP draw is restricted by a poor connection

I will say I didn't test all of that but all throughout the tests. Ive tested the battery voltage before and after starting and running. They all read 12.75 (Not running) and 14.25 (when running).

I'll run a direct ground from the battery, engine, and the HEI once I've got wires and the connectors. Since I'm currently all out. The only place near me that sells wire is Harbour Freight, and they want way too much since it comes with some sort of storage thing.

 

[MadMax_636]

There is no Ballast Resistor if you see Battery Voltage at the coil and HEI in key on static test

You can redo the Splice of red/green and brown/pink wires to one new wire in the cab
And run that new wire to coil and HEI

But you must have BOTH of these wires hooked up to the one wire for coil and HEI

So your saying I could run a wire T? Keeping the wire on the connector but running a new lead directly to the coil/HEI?

 

[franklin2]

I would keep investigating this.

Instead of guessing it's a ground problem, set your meter up like you have been doing and get the 10v reading at the HEI. While it's running with the 10v reading, keep the + of the meter on the HEI. but move the negative meter lead over directly to the negative battery post. If the meter reading is higher with the negative of the meter on the negative of the battery, then you do have a ground problem. If it's the same, it's not a ground problem.

If it's not a ground problem, go into the fuse panel and poke around in there with the truck running. If you get 10v in there also, then you have a main power feed problem somewhere. When you find it, the whole truck is going work better.

 

[MadMax_636]

UPDATE: I did a few ground test. I dont think its a ground issue. So I went under the dash and poked around with the multimeter and honestly didnt find anything out of place. Will do more testing later. I did run a jumper wire from a 12v HOT on run to the HEI "B" and it ran and stopped perfectly... until it overheated and shut off... I unhooked the wire and it fired right back up zero issues... I touched both the HEI and it was hot but the small heat sink was ultra HOT. Like to the point, a drop of sweat turned to steam as it dropped off my face... So then I said... NOPE! I left it at the 10v until I can get a more active heat sink with a fan before I go w/ 14+ volts...

Im gonna try and repurpose a old intel or AMD desktop heatsink and fan and wire the fan and "B" to the same hot lead.

 

[franklin2]

If your fuse box is good, then you must have a problem just on that wire feeding the HEI. I will have to test mine and see what voltage I get on the HEI module. It's been running fine but I am curious now.

 

[MadMax_636]

If your fuse box is good, then you must have a problem just on that wire feeding the HEI. I will have to test mine and see what voltage I get on the HEI module. It's been running fine but I am curious now.

Let me know what your findings are.

 

[MadMax_636]

If your fuse box is good, then you must have a problem just on that wire feeding the HEI. I will have to test mine and see what voltage I get on the HEI module. It's been running fine but I am curious now.

Find any issues?

 

[franklin2]

Find any issues?

Sorry I dropped the ball on this one. I have a complete different engine in it now, totally forgot about this post.

 

[MadMax_636]

Sorry I dropped the ball on this one. I have a complete different engine in it now, totally forgot about this post.

Hahaha, Your all good! What engine did to swap in?

 

[franklin2]

A 1986 2.9. Swapped in the fuel injection and all. The fuel system was the biggest pain, I had to get a new 1986 fuel tank and sending unit. I then transferred over and mounted the external high pressure fuel pump, and had to run new fuel lines supply and return, and the wiring for the fuel pumps. Swapped in the computer and the fuel injection harness around the engine. It has a lot more power than the 2.8. I can run the mountain everyday in 5th gear with the 2.9.

I had a little snafu with the 2.8. I was climbing the mountain, had it floored, went to downshift and the throttle stuck wide open. The rpms went sky high when I pushed in on the clutch. It then started popping and then it quit on me. I thought I blew it up, but when I went to take the engine out I could not get to one of the bellhousing bolts because the distributor was in the way. That is when I noticed the distributor had spun around and jammed itself into the firewall. I tried to move it but it was not loose, I had to loosen the dist bolt to turn it back out of the way. So that was probably all that was wrong, the timing got off when the distributor swung itself around. Too late though, I had committed myself to swap in the 2.9.

 

[MadMax_636]

A 1986 2.9. Swapped in the fuel injection and all. The fuel system was the biggest pain, I had to get a new 1986 fuel tank and sending unit. I then transferred over and mounted the external high pressure fuel pump, and had to run new fuel lines supply and return, and the wiring for the fuel pumps. Swapped in the computer and the fuel injection harness around the engine. It has a lot more power than the 2.8. I can run the mountain everyday in 5th gear with the 2.9.

I had a little snafu with the 2.8. I was climbing the mountain, had it floored, went to downshift and the throttle stuck wide open. The rpms went sky high when I pushed in on the clutch. It then started popping and then it quit on me. I thought I blew it up, but when I went to take the engine out I could not get to one of the bellhousing bolts because the distributor was in the way. That is when I noticed the distributor had spun around and jammed itself into the firewall. I tried to move it but it was not loose, I had to loosen the dist bolt to turn it back out of the way. So that was probably all that was wrong, the timing got off when the distributor swung itself around. Too late though, I had committed myself to swap in the 2.9.

Damn! That is one hell of a story! I hate when you think you fucked something up so you end up replacing it. Then while replacing it you learn its not fucked haha.

Personally Id go with a 3.0 or the 4.0 v6 since they share the same bellhousing and because they are all EFI. The EFI would have been the killer for me hahah. I HATE EFI only because of past nightmares with early EFI system failures.