I have a 1993 T100 with the 3.0 that I'm having problems with. The truck will start but is sometimes difficult to start. Once started it idles rough and will not take full throttle.HOWEVER, if I connect a battery charger to the battery the truck runs well and starts better too. I have checked the battery and it is fine and even put a different battery in but had the same results. I then took the alternator off and had it tested and it tested good. I just keep thinking it is electrical related because of what happens when on the charger but I could be wrong. I have cleaned connections but results have been the same. Thanks in advance for any suggestions.

 

Dang, does no one help on this forum?

 

IF both the battery and alternator are tested good, all connections are nice and clean and shiney, have you checked grounds? Have you checked the Fusible link between the alternator and the battery? IMHO, it sounds like the power from the alternator is not getting to the battery, and thus the rest of the electrical system at full power. Check the heavy duty connection on the alternator that goes directly to the battery. It's a bolt on the side of the alternator, with an apparently heavy duty wire on it, and a red rubber boot over it. Make sure it's good and clean, no corrosion, dirt, grease, etc. Read the voltage on it with the truck running, no battery charger or anything hooked to the truck. Then read the voltage at the other end of the wire. If the voltage at the fuse box end of the wire is significantly lower than on the alternator end, the fusible link may well be bad. Burned, or partly burned.

Also, check the voltage on the "sensor" wire in the plug on the alternator. It should be identical to the battery voltage. If it's not, and if it doesn't vary as the battery voltage does, the alternator won't increase it's output to charge the battery back up after heavy use, like starting. It should also increase it's output when the system's load increases. The lights are on, etc.

Make certain the fusible links in the fuse box are in good shape. The screws that hold the wire on them are in good shape, no dirt or corrosion on them, and tightly screwed down.

Hope something is helpful. I don't own a T100, but Toyota tends to make their systems virtually identical in different vehicles. If it works good in vehicle A, let's use in in B, C, and D too!
Good luck, and let us how things go for ya1
Pat☺

 

First, thank you for your response and suggestions. I have checked all of the electrical systems throughout the vehicle including relays, fuses, fusible links, batteries, alternator, etc and cannot find anything amiss. The truck is really difficult to start and it seems as if it is not getting sufficient fuel. Now when I add additional voltage it is easier to crank and runs better which I believe may be because the fuel pump is producing better. I am going to check the pump and fuel filter next and see if that might be the problem. I also changed the distributor and rotor but no additional help on that end. A mechanic friend suggested a weak pump and the extra voltage making it pump a little harder. I don't know but willing to try things.

 

Make sure you check the connections where the wires go down into the fuel tank to feed the pump. Especially the ground connection. It's know to corrode, and cause problems. The positive too, but not as much. Anywho, check both connections, and if you pull the fuel tank hanger, check the voltage at the pump itself. Good up top, lower ON the pump, hanger connections probably bad.

Good luck!
Pat☺

 

Thanks for the suggestion and I checked all of the connections at the fuel pump and everything tested good. Voltage, resistance etc all within parameters I found on here so I'm thinking it is getting fuel and maybe something else. It starts but rough idle and backfiring. I thought it might have been the throttle position sensor but I just checked it and all of the resistance numbers are perfect. At this point I am just going through and testing everything that I can until I hit the right one. Going to clean the throttle body and reinstall and see what happens. We are having a little ice storm here in eastern NC so I'm on hold for a little while and just doing research. Thanks again.

 

This a very tardy reply, sorry, I'm not on the forum often these days! These symptoms somewhat match a problem I had in a Nissan truck a few years ago. this applies to fuel injected systems. The fuel pump was not delivering enough pressure. I hate going to mechanic shops but had to in this case, they were easily able to test that & identified the problem. In my case it got worse after the engine heated up a bit.

Let us know if you found the solution to yours - thanks!