KatahGii Posted April 8, 2020 Share Posted April 8, 2020 Ok for those that have seen my posts I officially got my 86 running. After replacing the fuel sending unit, pump filter and tank. I replaced the crank sensor and then the fuel pump relay. I finally got it running. Ok new question it’s still not road worthy so still got some kinks to work out. I need to jump it for it to start but after it’s fine. Oddly my multimeter’s battery load test says it’s fine. But if I shut it off I need to jump it. Is that gonna be the alternator? Link to comment Share on other sites More sharing options...
Dzimm Posted April 8, 2020 Share Posted April 8, 2020 What's the voltage on the battery with the engine running? If it's 14+V your alternator is fine. Link to comment Share on other sites More sharing options...
Pete M Posted April 8, 2020 Share Posted April 8, 2020 the auto parts stores will run a more thorough check of the batter for free. also be sure to clean the connection between the cables and the terminals. Link to comment Share on other sites More sharing options...
JMO413 Posted April 8, 2020 Share Posted April 8, 2020 Old school trick to test the alternator. Start the truck disconnect the battery if it stays running the alternator is charging. I would also check the ground cable to the block and all the connections at the starter are clean. Resistance is the Renix systems kryptonite. Link to comment Share on other sites More sharing options...
KatahGii Posted April 8, 2020 Author Share Posted April 8, 2020 2 hours ago, Dzimm said: What's the voltage on the battery with the engine running? If it's 14+V your alternator is fine. It reads at 13.5-13.7 when running. I think I might just have a bad battery. Link to comment Share on other sites More sharing options...
87Chief Posted April 9, 2020 Share Posted April 9, 2020 I would say a bad battery. What's the battery voltage after the engine is shut off for 10 minutes?Sent from my SM-G930V using Tapatalk Link to comment Share on other sites More sharing options...
AMC86Kid Posted April 9, 2020 Share Posted April 9, 2020 Keep in mind the 86 doesn’t have a real alternator it’s just a simple 2 wire charger so it’s very common that your battery goes bad and you have to change it depending on how much you drive and what weather cycles it goes threw Link to comment Share on other sites More sharing options...
KatahGii Posted April 9, 2020 Author Share Posted April 9, 2020 47 minutes ago, AMC86Kid said: Keep in mind the 86 doesn’t have a real alternator it’s just a simple 2 wire charger so it’s very common that your battery goes bad and you have to change it depending on how much you drive and what weather cycles it goes threw It’s been sitting for like 4 months while I found the time to fix it. I’ve tried to start it so many times. I'm thinking about charging the battery outside the truck. Can I throw a regular alternator in it? Link to comment Share on other sites More sharing options...
AMC86Kid Posted April 9, 2020 Share Posted April 9, 2020 Yes you can put a real alternator in it but you got to modify it to fit where the old one was and you have to add new wiring to accommodate the new alternator in other words its not just an easy swap since you can’t use the old plug from the old alt on a new alt Link to comment Share on other sites More sharing options...
Green Mesa XJ Posted April 10, 2020 Share Posted April 10, 2020 For no start: One of the issues can be bad battery cables, when I first got my old 2.8 xj the battery and battery cables were crap. Replaced the battery to have a random no start but have plenty of power. If it was running the weak @$$ alternator kept up with the power needs. Replaced all the cables and it got power to the starter just fine. Still fine after all these years. For the 2.8 one of the upgrades using the original set up was alternators off a Pontiac with the same clocking. It ups the amp from 55 to something better, I can’t remember which alternator I got now. Since the 2.5 and 4.0 use similar alternator it could be a possibility. Of course there a kits to add much better gm alternators Sent from my iPhone using Tapatalk Pro Link to comment Share on other sites More sharing options...
AMC86Kid Posted April 11, 2020 Share Posted April 11, 2020 the 2.8 has an alt thats around 70 amps the 3.4 alt is around 100 amps Link to comment Share on other sites More sharing options...
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