1991 Suzuki Tracker

I have been trying to help out a neighbor. They bought a 91 tracker. We put a new battery and alternator in it. We have to jump the vehicle to get it to start. While running with the light on, the lights are extremely dim. Sometimes the vehicle will start again, but most times it won’t. What I mean by it won’t start is nothing happens when you turn the key. No clicking starter does not engage. Sometime the car will not stay running with out charger attached. Then again sometimes everything is fine. I do not want to recommend new parts and have him spend money and it not be right. Thanks

Start by removing each end of each battery/starter cable and making sure they are clean and tight.

Let's not assume the battery and alternator are OK.  Many auto part stores will check them for you for free.  They generally do a good job and the price is right.

You’ll want a voltmeter. Get the car running and measure the voltage output directly at the alternator. If the voltage output measured at the alternator is not between about 13-15V then the “new” (probably rebuilt) alternator is bad. If it was bad, you would not be the first person to have run into this issue.

If the alternator is putting out a fairly steady voltage somewhere between about 13 & 15 then move on to power cables and their connections.

And don;t forget to check the ground line from the engine to the chassis. That’s subject to corrosion, and if the connection is sketchy it’ll “drop” voltage as if you had a resister in the circuit.

Internal corrosion in the battery cables, especially where they attach to the clamps and connectors, is another possibility.

“I have been trying to help out a neighbor. They bought a 91 tracker.”…
All great suggestions but be aware…
Had a Suzuki Sidekick (the same) From experience, the biggest problem was compatible after market parts. Though the basic mechanics were sound, It was a frustrating vehicle to own.

thanks for the advise. I just replaced the battery cable connections at the battery. No change. I will check the grounds and try to check the alternator tomorrow. Would you consider changing the battery cables completely?

You have to leave changing out the cables on the table as a possibility. But its not something to do just on a guess. You can measure what they do electrically with a meter. You can look for corrosion - often you have to remove some insulation to look underneath.