Help- 96 ranger strting problems

[the pirate]

96 ford ranger 4 banger FI

I need to have this fixed by tomorrow so i can go to work. I need help narrowing the problem down so I can fix it fast as i dont have alot of time to do the work.

Here are the symptoms.

When key is turned to acessory volt gauge only goes up to 1/4th instead of middle. When turned all the way starter tries to turn over but engine will not start. When jumped truck will start and run with no problems but will not start again if turned off.

Steps taken Pulled battery charged it and tested. Tested as borderline bad. Put in new batery same problem. Pulled new battery tested. No charge but will take one. Put in truck jumped to start and drove for 4 hours. Turned off truck same problem. Batery tester shows batery is hardly charged. Clened all corrosion on neg terminal. still nothing.

My ideas about the problem

Bad alt that is not producing enough to run truck and charge battery. How ever when truck is running volt gauge shows mid line suggesting alt is working correctly.

Bad battery cable or cables. possibly corrosion at the neg terminal. This truck seems to have an onging problem with this I have yet to solve.

Possibly a bad starter that is requiring to much to turn it over but i doubt this as I can jump off another car rather easily.

An un identified drain some where in the electrical system.

I would like to hear what you guys think.

 

[tomw]

How about an alternator that is not charging the battery. When the engine is running and has a working alternator, the voltage at the battery should be around 14.6. Why? Just because that will charge the battery and run the headlights, blower motor, etc.
Charge whichever battery you plan on using. Check the voltage drop between the + post and the post on the relay. Check the voltage drop between the relay and the starter solenoid + post while cranking. There should be little drop between either connection.
You can also check the voltage drop from one side of the relay to the other. It should show little voltage drop.
What you are doing is seeing if there is + voltage on the battery end of the large wire, and if there is the same or close voltage at the other end. If there is a voltage difference, that means the conductors aren't doing a good job.
With a 'jump' battery it starts. That points to the voltage coming from the battery sitting in the battery box. Are you jumping to the battery posts? If so, your connection between the posts on the installed battery and the cable terminations are not very good or the battery would be supplying the starter.
tom

 

[the pirate]

Turned out both my positive and negative cables were bad with corrosion up the wires into the insulation. Replaced both. Working great now