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On my 86 EFI 5.0L, I have this problem(?) Being that it's still fairly cool in Idaho, when I'm cruising around, lights on, heater going, and stereo bumping, my rig seems to be lacking of power(hp) and stuttering. If the alt. is not able to keep all the eletrical systems powered, can or will this cause not enough spark energy of cause the injectors to fire inefficiantly? I want to upgrade to 130 amp alt. from some other car (I've seen the posts about the swap), and am wondering if this would be the right road to cure this. Thanks in advance. I'm not sure if this is the right forum, but being electrical....
It could be any number of things. Having said that, if your alternator is not supplying enough power to the coil, you won't be getting a good spark, especially at higher RPM's. I would check and see if your getting good voltage (13-14 volts) to the battery while the truck is running. If you aren't, you can pull the alternator and have it tested. Also, turn on all of your aacessories, and check again to see if you are still charging. Sometimes, if you are running a lot of extras on your truck, (stereo amp, offroad lights, etc.), the alternator can't keep up. If you do the swap, do your resarch first, because you can fry voltage regulators, fusible links, etc. with the over amp alternator.
Well, I went to the junkyard and found 130 amp alt. $45.00. I din't buy it though. Not yet. It came off a 93 Taurus and I still need to research that it will work for me. Connectors, mounting, what I need to upgrade any wires, and as you mentioned, voltage reg. and everything else. I really do think that lack of electrical power is causing some problems, but it could also be a simple as getting bad fuel. I'll try to keep you updated.
If the voltage is getting low enough to make the engine run rough, you should be noticing other things not working right either. The lights will be noticeably dimmer, and your stereo will start distorting and not getting as loud as it normally does. All these would point to a voltage problem.
Try to do some more experimenting and carefully watch for clues. Like when the engine runs rough, turn everything off except the lights, and see if it gets better. Also try to narrow down when the engine fails to run correctly. Is it only when pulling hills, or only when cruising? Does it hesitate just when you push on the gas, or when you are holding the gas steady. Clues like this help narrow down what it could be.
Franklin, it seems to be when I'm cruising on the freeway going to or from work with all accs. running, or just running around town in traffic. If I turn the stereo off and just have lights and heater it improves. But say like after work, no lights or heater, just stereo, it "seems" like it's acting up again. The stereo is nothing special, Alpine deck, 200w amp.
I have recently put on a new cap and rotor, new fuel filter, air filter, checked timing (I have it at 14 BTDC) plugs gapped at .0054.
200 watts, at 12 volts would only be about 17 AMPs of drain.
I think you should try cleaning (with a small wire brush) the alternator charge connector (if you can), and the battery posts making sure you actually LOOK at the positive terminal.
Many people pull off the negative and find it sorta clean - so they skip checking the positive. Be thorough, it pays off!
You may have bad contacts just about anywhere in a truck that old - look at your fuse contacts too...