Hello all. I've been chasing down what I believe to be an ignition issue with my 79 pickup for the last few weeks. It all started when the weather started getting warmer. Noticed it was kinda hard to start while the engine was still warm. Talked to a buddy and he suggested that my igniter may be on the way out, so I did the HEI conversion with a Standard Motor Products module. Not sure how much difference that made, but it's still kind of sluggish starting. Generally it's fine once it's started and revved up for a few seconds, but the sluggish starting does make me a little nervous.

At this point, I've replaced everything in the ignition system other than the distributor and the signal generator/pickup coil. Plugs/wires were denso (gapped correctly). Ignition coil was NGK at first, but got another one from Standard Motor Products thinking I'd roasted the coil not using a ballast resistor when I did the HEI conversion, but that didn't seem to help much either. Cap and rotor were also replaced, and timing was set to 8 degrees BTDC at 850 rpm. Ignition switch was not replaced, but I tested all contacts, and even took the damn thing apart to verify and clean it and there's not any resistance building up inside of it. I'm getting around 11.7 volts at the wires going from the switch to the coil and module, but I don't think that's enough drop to cause problems. Battery is good - 12.4 volts.

As for the signal generator/pickup, I of course checked the air gap, and even adjusted it to the bottom of its tolerance range to ensure I was getting maximum signal from the pickup to the HEI, but that didn't seem to help either. It tests between 170-180 ohms when the engine is cold, but when it gets hot the reading goes up over 200 (factory spec is 190 max, but doesn't specify hot or cold). I've tried a few aftermarket replacements for this part, but every single one has tested over 190 out of the box, except one which tested around 180, but that's putting me back where I started. They were all returned because I didn't want to risk installing it and not being able to get my money back if it didn't work (these pickup coils are kinda pricey). I tried Intermotor, Import Direct, and one Formula Auto Parts (VERY cheap - couldn't even get the connector to fit properly lol). Intermotor was the one that tested 180. I remember reading somewhere that the HEI module is sensitive enough for a good pickup, but in general expects a bit more voltage, so I'm wondering now if my signal generator being borderline is compounding the problem.

Has anyone here had similar luck replacing this part, or have any suggestions of anything else to try? I feel I should also mention that the compression on this truck is damn near perfect. Tested last weekend and read 155, 150, 155, 155. That being said, it sat up for a long time before I got it, and the valve seals are leaking a little as evidenced by the blue cloud from the tailpipe on startup. If I can't find an aftermarket part that will test good out of the box, I'm considering making a simple signal amplifier to go between the dizzy and the HEI module to beef up the signal a bit to see if that helps, but I'd rather not fool with that if there's a simpler option out there.

 

The spec on the ignitor is 190 max. Doesn't matter hot or cold, 190 is max. It is liable to change with temp, but no matter what, 190 is it.
It's a good idea to use a heat gun to make sure. Not a paint stripper heat gun, an electronics type. Lower temp.

It would help us a lot to know year model, engine type, and so forth. I presume is a 22R engine, as I don't think the 22RE existed yet, but I could be wrong. I often am...

I am a big fan of OEM parts. Not aftermarket. But if they work for you...

Just my 2c worth.
Pat☺

 

Hi 2ToyGuy. It's a 1979 SR5, 2wd 5-speed with a 20R engine, stock carb rebuilt about a year ago. I haven't been able to find an OEM replacement for this part unfortunately. I too prefer OEM parts when I can find/afford them, but I've been having quite a time locating OEM ignition parts for this truck. If you have any resources you could share I'd love to hear about them. From what I've been able to dig up online and looking at old manuals, I believe at the very least the plugs and wires I bought were the same kind they shipped with from the factory.

 

Good old pick-n-pull yards are actually a amazing resource. Also, Toyota tends to stick with "what works" for a long time. They may have used the same ignitor for several generations. Worth a look.

Have you tried calling the local dealership, and giving them the VIN? They can check not only if there are any available, but also if maybe there is an alternate source for that part. I PREFER OEM parts but if there's just none available, well, you have no choice


BTW, did you check/clean/replace all the grounds involved with the engine? I'm not sure about your year, but later ones (87, for example) have a ground wire from the head (the bolt that holds the lifting hook) to the firewall. Vital for good spark, as the head is isolated electrically from the block. Also, of course, from the body to the battery. Usually a wire from battery negative to a bolt right in front of the battery, behind the headlight. Even a small amount of corrosion can have major effects on electrical systems. You have some someplace, as shown by the 11.7 VDC reading. Grounds are often an unchecked on source of interference with electrical systems. Kind of a pet peeve of mine.

Sorry I wasn't more help.
Pat☺

 

Thanks for the insight. I have checked every ground I've been able to locate and they're all clean and reading good. I even checked the one under the dash thinking something was robbing my ignition switch but it's perfect too. Though now that you mention the head, I don't remember seeing one near that hook. There is one going from the alternator to the block just below the head which I checked, but if the head is truly insulated from the block that may not mean much. I should also mention that 11.7V is when the key is in the on position but without the engine running. I might see if it's any higher with the engine running to rule that out. If the ignition coil and igniter are getting 12v running/cranking that shouldn't be causing problems. I'll add a ground strap to the head too and see if that works.

We lost several good scrap yards to luxury condos and other gentrification efforts these last few years. The only one left near me is Pull-a-Part, and it's pretty picked over for anything made in the past 20 years or so. Going to a wedding in Alabama this weekend, so I may see if there's any good scrap yards on my way there. If anyone can recommend any between Atlanta and Gulf shores that would be great

 

Yeah, try placing a ground wire from one of the bolts that hold the drivers side hoisting hook, which goes directly into the head metal, to a spot on the firewall behind the head. There should be a hole there with threads in it, or even a bolt. You may need to scrape the paint of down to bare metal. A 10 or 12 ga. wire with ring terminals on it is quite adequate.

The wire from the alternator should, IIRC, go to the PS's mounting bracket.

The alternator should maintain 13.5 VDC, or there-abouts, with the engine running. During cranking, the system's voltage may get as low as 9 VDC, due to the load the starter puts on the system. All this is a no-load condition. No head lights, brakes, radio, etc etc.

I wish you good luck finding a scrap yard. Enjoy the wedding, too
Pat☺