I know there are a lot of threads about this and I am trying to comb through them all, but each situation appears to be totally different. Here's mine: 1970 GS 350 with an HEI Ignition System. Motor totally rebuilt, broken in and timed correctly at idle (12* BTDC) New rotor, cap and coil (in cap - MSD 8225) Hasn't been driven Car ran and I checked the timing - put the timing light away. Next day I started it up to put bumper and remaining trim on the front of the car. It ran REALLY rough, almost like one of those hit and miss engines. I got it out of the garage and shut it off since i know I was low on fuel. I'm assuming there is fuel because the bottom of the carb is wet and the spark plug is wet. Sprayed starting fluid down the carb and when I tried to start it, not a backfire, spark, poof or ANYTHING. Here is what I have done: Added two gallons of fuel - needle reads at 1/8 tank Replaced module in the bottom of distributor. Replaced spark plug wires. Checked to make sure rotor turns (it does.) Checked to make sure there isn't a hole in the rotor that's shorting out the distributor (there isn't). Placed the old cap and coil that was working from before the rebuild on the motor (still no spark). placed the old #1 wire on the car, still no spark. Double and triple checked the wire sequence - it's right. Checked for power heading to the coil - test light works so there is power to the coil. Car turns over and sort of "coughs" but it won't start. My question is this: How likely is it that I bought a bad module? Three national (Napa, Auto Zone & Advanced) auto parts stores around here don't have the ability to check the module, but I was thinking of swaping it out again anyway. I can't think of any other place it could be if there is power going to a NEW coil and no spark to the wires. Unless I am really missing something. Which I sure I am - I need a remedial course in ignition systems, but from what I read they really are not all that complicated. Any help is greatly appreciated. BH
I'm on a little thin ice here but do have the wire from the ign going straight to the coil (full 12v) or is running through the resistor block?
I believe it's going straight in. I didn't mess with the wiring harness before the rebuild, it seemed to be working fine.
HEI needs full 12+ volts or it won't be happy. You need to take a couple of minutes to verify before you waste any more time looking elsewhere. Also keep in mind you may have a bad pickup module in the belly of the HEI. They are a low failure item but at 30+ years old and with you in the dizzy installing the new module recently then you may have angered it. They are not hard to swap bu you have to pull the dizzy, knock out the gear pin and slide the shaft out to get to it. Good luck let us know what you find.
Yes, the pick up coil can fail. The leads flex with the vacuum advance, and they can develop an intermittent open condition. I had that happen to me. Drove me nuts until I changed it. I literally changed everything but the pick up coil. Every so often, the engine would refuse to start. I found that if I took the cap off, and moved the pick up coil leads around, it would start, until the next time it wouldn't. I could go months like that and then suddenly, it wouldn't start. Changing the pick up coil requires removing the distributor, knocking out the roll pin and removing the gear. Slide the shaft out, and there is a small locking washer that has to be removed. Before you go through that though, make sure that is the problem. You mentioned that the carburetor was wet at the base. That shouldn't be unless the carburetor is flooding. Take a plug out and make sure it isn't fouled. Also make sure you have 12 volts to the HEI. The half:moonu: way to connect the HEI, is to go to the fuse block. That will make the engine hard to start all by itself.
Thanks Larry - I want to go your route before pulling the distributor. THAT makes me nervous being a rookie. Hey - I know what I don't know...right? It just seems like when I make some progess something major sets me back and here I am again. More to come. Anyone have a beer? BH
Got a few! But your kinda far away Had the same issue a while ago and ended up being the module. Everything was new but I wired it backwards once and I guess I upset the unit. New module and I was away.. But listen to Larry on this one, they don't call him "the wizard" just because it's a cool name
How is your ignition powered? With a standard points ignition, the power comes from the "R" terminal on the starter solenoid during cranking. The engine continues to spin when the key is released to the "run" position, for normal ignition. If you have the HEI wired in the "run" position, you are depending on that spin to let the engine catch once the ignition switch is in the "run" position, without actually having fired during cranking. In all my experience with HEI on GM cars, I've replaced one pickup. Many rotors, and a few modules. As has been noted, plugging them in backwards puts a serious hurt on them. If you go to a shop with a friendly mechanic, he may let you use the professional troubleshooting manual. This one gives a nice flow chart with results, and WILL tell the answer. Some of the "civilian" versions will tell you at some point to take it to a mechanic...which is quite annoying to those of us who may not have access to those since we quit working as professional mechanics.
If I'm reading the multimeter correctly it looks like I have 5 volts to the coil - not enough. Can I get the correct wire from Year One and just unplug the old one? It goes from the distributor into the abyss of the wiring harness. I don't know if it's hooked up to a resistor wire in between or what. But ut must hook up to something somewhere!!! I'm hoping I can run the wire from the firewall to the distributor directly and be done with it (?) Can I leave the tach wire alone since the tach works or should I replace that as well? Thoughts? BH
You'll have to unwrap the abyss, and trace that wire back to where it is attached. Sounds like the resistor wire is still in place. You can buy the Year One wire, but you will still need to clip it into the front half of the firewall connector. I know you want to just run one wire and be done with it, but that is the wrong way to do things, and when you do things the wrong way, you end up doing it again, or breaking something else. Unwrap the wiring harness and separate the wires. You can always re wrap everything. Read up, http://www.v8buick.com/showthread.p...nd-HEI-System-function-tests-and-modification
I was afraid you were going to say that!! I'll start tearing into it. I may have some more questions along the way. Can I get rid of the resistance wire all together? It's just the one wire I need, from the firewall to the distributor, correct? I truly appreciate your guidence and patience, Larry!! BH
Oh...and it would have been nice if this little "problem" happened a couple of weeks ago when the hood and fenders were still off of the car. Never seems to happen that way, does it? BH
While that wire is braided iron (that's how the resistance is achieved), buried in tape, the resistance shouldn't have changed all that much. Try connecting an ohmmeter at each end and wiggling the connector back at the firewall plug and see if the resistance changes. A little resistance goes a long way when you need some current to flow. Do you have access to a wiring diagram to help you locate that wire? I've never had to peel a harness all the way back and replace the ignition resistor wire. But then, I live in the desert, and a lot of corrosion problems other people experience don't pop up here.
I'm already 3/4ths of the way there. How this is going back together neatly is beyond me. The wire to the coil was definitly connected to the wire going down to the starter. I don't need the wire headed to the starter, correct? BH
Okay - replaced the feed wire and I have a full 12 volts to the distributor. Still nothing. I'm going to check the little wiring harness in the distributor and I want to make sure there is no way I installed the module incorrectly. The old one was bad and the new one is good. I really don't want to take the distributor out of the car, but I may just do that and replace the whole thing. BH
Here's a good troubleshooting article on the GM HEI http://www.hemmings.com/mus/stories/2008/11/01/hmn_feature19.html Shurkey also has an excellent page on the HEI, can't find it right now.
Fantastic - I'm just combing over all my work to make sure there isn't something stupid that I missed. I'll compare notes. Next question - the tachometer wire on the car goes through a grommet through the firewall by-passing the plug on the firewall. The tach wire from Year One has the same barb that the power wire does. Should that plug in at the "gauges" part of the plug on the firewall and then run to the tach behind the dash instead? Thanks for the pointers Larry. BH
