I've got a tricky one and the posts I've read so far haven't gotten me very far. I just replaced the starter on my 88 3VZE (which I know for sure was bad because I would hit it with a hammer and it would start) with a remanufactured Denso off RockAuto. O'Reilly tested it for me and it works great so I know that's no longer the issue. When I first put it in it would either click or crank really really slowly. Now it just clicks when I try to start it, but if I put a charger on the battery and get it to about 85% it starts right up. I went to a few junkyards to try to find a new starter relay to no avail (only the early ones have the relay outside the fuse box and there's essentially no first gens in junkyards). At this point, I'm hoping it's the battery that's bad but it's a new Napa battery that I bought about a month and a half ago. The battery seems to be losing juice faster than it should but immediately after shutting it off (at least most of the time) it will just do the click. The alternator is working; the battery percentage jumps by like 5% within a second or two of starting it up. If I can find the right starter relay I plan on replacing it but I'm starting to think that that's not the issue. I don't have a multimeter handy but I do want to see if there's a discrepancy between the voltage at the battery and the voltage at the starter. The other reason I think the battery could be faulty is when I shut the car off the charger reads about 13.3 ish volts, but if I turn the headlights on it drops below 12.5 within about 7 seconds. I let it sit without charging for about 20 minutes and the voltage read around 12.6 or 7, which was not enough to start the truck 2 months ago before the starter went bad. Anything I'm missing or should be trying?

 

Welcome to YotaTech.
Your problem has nothing to do with the starter relay. You just don't have enough juice in the battery. I assume your "percentage" is some fiction your charger serves up. Spend $7 on a real multimeter. https://www.harborfreight.com/7-func...ter-63759.html

Measure your alternator output at the battery terminals. You should have around 13.9v to 15.1v with the alternator running. (temperature dependent) http://web.archive.org/web/201102051.../2onvehicl.pdf

 

I am pretty sure that your starter relay was wired wrong AT THE FACTORY, so the current to starter solenoid has to travel an unnecessarily long path...


However, before you tear into your wiring, pls check if this CONSISTENTLY makes your starter solenoid (piggybacked on the starter motor) clunk ENERGETICALLY when you apply 12V directly from battery to its control pin as shown on my post here (https://www.yotatech.com/forums/f199...l#post52367443), then report back.
#ClickNoCrank