I have a 1989 f150 2wd inline 6. The truck seems to have some sort of system short. At first everything seemed fine, but then the starter and solenoid/relay switch went out. Since then it seems as if there is some sort of short or resistance in the electrical system. I would drive, lights on, radio blaring, heater on, and everything would be fine. The battery gauge would read almost exactly the middle of the good zone, with a slight lean towards high. Suddenly, and with no perceivable reason, everything would dim. Lights dim, radio loses reception strength, the battery light would come on, and the batttery gauge would say 8 volts. Oddly, it is a rather steady 8 too. No flicker, or bounce, or spikes or anything. 8 also happens to be the first red line on the battery gauge. Then as if nothing ever happened, everything goes back to normal.
I tried everything I could think of to create it at will, but it seems to have a mind of it's own.
I have tried:
Going over bumps
Going faster/slower(maybe the wind was wiggling a loose connector)
Wet vs. dry weather
Cold vs. hot weather
Still I got nothing. But the engine ran so I let it be. It kept getting more and more often and longer priods of "half power" and it also seemed to be getting lower. One time I was driving from Houston to Dallas(In Texas) and it was happening throughout the trip. One of the episodes, about 3/4 of the way there, was so bad the car almost died. I had to use the gas pedal to keep it on. Flooring it to keep the engine from sputtering to a stop. I noticed that it was a electrical problem that has an added mechanical effect. During that episode, my power steering and braking got a whole lot stiffer due to the power loss and it's effect on the engine. From then on I payed attention to these two as well, and noticed in the usual "half power" mode, they get a bit stiffer as well. Everything goes back to perfect and smooth when power returns. The car only has 73,000 miles on it. (Yes I checked. I know it sounds ridiculous, but it's true. I got it from a community college. They kept up with it flawlessly and it never even left the campus.)
Now, it doesn't even have the power to start, even though I have just changed out the engine, and switched from efi to a 500cfm edelbrock performer series carb.(My brother wrecked it and blew the engine, I did all the work myself, but I am the farthest thing from a mechanic.) It stared and ran succesfully but now it seems to be stuck in low power mode. It turns over freely, but not fast enough to start. It seems a bit young for broken major parts. But I still checked these anyay...
Battery: Checks great.
Starter solenoid: checks great.
Starter: checks great.
Ignition coil: Checks great.
Alternator: won't stop a car from starting, though it may or may not be an issue later on.
Battery cables: Check great, except the hot wire to the starter. It got a little burned by the exhaust manifold, but this was after I started having these issues.
Whatever it is, it seems to affect the whole system, not any one part. The only place I know that EVERYTHING comes together is at the battery, but I had it tested at autozone, and "tested" it on my own, and it passed with flying colors.
If you even think you thought you had an idea of what it could be, tell me everything about every idea you've got and I'll try it. I'm as desperate (and stumped) as they come!
-Corey

 

My moneys on a bad cable or connection. My 83 had a junction block on the firewall that became resistive and caused voltage drop problems like you had. I ended up replacing the cable that fed it from the alternator along with the bad terminal block. I have also had bad battery cables that caused problems like you described.
I miss that 83
happy holidays
rikard

 

possibly relays? ive had realys cause problems where sometimes it would die, and fire right back up, sometimes not for a while. sometimes not at all. but never a drop in power as descriebed.. really wish i could come see the truck to test things myself its the only way im good at figuring it out. ill think about this one and get back to you, also check and recheck all body grounds. make new additional ones with some crimp connectors, new wire, bolts and washers, grind an area clean on the frame and make an additional gound to the body from the frame and from the frame to the battery..replace the positive and negative cables alogn with the solenoid none the less of their condition they may be ok but then again the trucks ok sometimes

 

Is that like a voltage regulator? I have heard from other places with similar situations, and theirs was the voltage regulator. I can't seem to find it, but I didn't get this far to stop now. I will investigate it and tell you what I find. Thank you so much!

 

Thanks Duramax!
Auto parts stores are closed already and won't be open tomorow for christmas, but I will be there first thing on saturday morning.
In the meantime I'll be cleaning and adding body grounds like you said, I also heard this idea from one of the guys at the parts store. He said "Battery to engine, engine to body." for a good ground pathway.

 

a relay is pretty much a light switch with a solenoid on it to turn it on and off..sounds kinda weird but there used to be able to turn something on (such as a fuel pump) that demands heavy amps a relay has 4 terminals 2 for an electric solenoid a positive and negative when you apply voltage it creates a magnetic field pulling a hammer attached to a hinged device which connects a seperate positive source with an in and an out (a switch if you will) the purpose is to be able to have something turn on and off that demands a lot of amps from something such as the ecm that cant provide a lot of amps...i doubt its a relay but it could be a place too look i only say that because on my truck i had one that got corroded and rusted inside and even tho it "clicked" when it turned on it wasnt making a good connection. like i said best bet is to ground the negative of the battery to the frame and mean time check all other grounds.ground to engine is good to do as well .hope this helps .also do you live in pretty crummy conditions? such as a place where they salt roads or it rains alot ect?

 

I just finished adding the grounds, but it still doesn't seem to help. At least I know I don't have to worry about it later. I'll keep trying other things and see what happens. I have a few wires I want to mess with too so I can rule them out as well. Thanks guys

 

i wish more guys would shim in on this with me im only one guy here ya know. we have the same year trucks sixxer

 

you know it could be the ignition module under the dash? try taking a long wire and attaching it to the positive of the battery take the other end and stick it on the radio fuse and tell me if everything powers up

 

I live in Houston, Texas. No road salt, or dust, but A LOT of humidity. Now that you mention it, I have noticed rust on the posts of the solenoid, I believe mostly due to me shorting the two posts so much to test it while I was putting in the new engine, and re-instaling the distributor, and ignition coil. I think this was there after the problem started though. It still won't hurt me to replace it though. The wires I was checking turned out fine.
I just remembered a few things...
(I knew this one I just forgot to mention it) I have had it since january 2008. My brother wrecked it in november of 2008, (and with a busted head and coolant rendering 3 of it's six cylinders useless, it got us home for thanksgiving. That is me, my brother, 2 dorm rooms worth of junk and furniture, cold weather, and over heating. It never stopped runing until I took it apart. I don't know why anything else is called a truck, and I wouldn't get a different kind if you payed me.) I took it apart in january of 2009, it sat until october 2009, when I got the engine, and I have been working on it since then (around mid october). The old was efi, the new came with a carburetor, so I just unhooked and/or threw out what I didn't need.
I changed the battery and cables shortly after I replaced the starter and solenoid. (a few months after I got it) I thought a new battery would fix it, but it hasn't, even though the battery is rated twice the original.
When I was testing the carburetor after I put a maintenance kit on it. I was charging the battery for quick starts. To that point all was fine. One morning, I woke up to work on it and it seemed to be stuck in "half-power" mode. I haven't had the power to start it ever since, though I'm sure if I could fix this the thing would purr like a cat.

I keep having nightmares of it being some random wire in a case of millions, but most of the electrical stuff on the truck is there because I put it there. They don't seem to have much that could go wrong on these trucks, and I'd imagine the list would get shorter when we take into consideration that it has to be something that effects everything right? Or is my nightmare a possibilty, or even worse, most likely the case?


I'm gonna go try that wire to the radio idea. I wish there were more people too! But I think it's cause of christmas. Thank you all the more for being willing to help me.

 

And it's good to know somebody other than me has a real truck


And if ANYONE tries to tell you that you need a new one, or somethin foreign, slap him!

 

I can't seem to find a jumper wire yet. I guess it'd be a good time to see if I can't find a meter around here also. I know we have one, I just gotta figure out where. I'll keep looking but I don't want you up all night on account of me. If I don't post again in 10 minutes, I'll wait until tomorrow and I'll post then. It'll also give me a chance to be that much more thorough, and therefore, that much more certain. Thank you so much!

 

Ok. Today took forever. I gotta find a faster way to get around than a bicycle. I guess that's why I'm here. But anyway, here it goes...
I ran the dash test like you said, and nothing got brighter. But it was because they are already as bright as they get. This confuses me a bit, but either way that's what happened...
Today I changed the battery cables and solenoid. I also took the alternator and battery in for testing. They load tested the battery as well. Both passed with flying colors (though I gotta say I didn't expect them to be that good, still, I ain't complaining)
Cable connections are good. Double checked, and tight.
Picked up a digital volt meter and I'll be runing tests in the morning. I got everything hooked up and got some additional symptoms. When I turned the key the engine turned a little stronger and the battery said it had a bit more of a charge. But when I tried to turn the car off it wouldn't stop trying to start. Even after I removed the key, the engine kept turning over until I disconnected the negative battery terminal. This happened twice in a row, and I didn't try it any more after that, incase it might break. Both times when I disconnected the negative terminal, it gave of a sizable spark and a "pop" noise(compared to the usual nothing and nothing)
any thoughts?

 

has to be a bad ignition module located on the steering colum if you jump the solenoid with a screw driver will it crank fast?

 

Sounds like the solenoid (in HVAC we call it a relay) mounted on the fender might be defective. It could also be in the ignition switch circuit or even the starter itself. Some of the replacement solenoids from discount part stores are junk.. My son went through two autozone ones in less than two years. He finally put in one from Napa which has lasted the last two years.
regards
rikard