ok im checkin into this for my neighbor he has a 1991 fox body 5.0 HO straight shift the PO installed dual electric fans aftermarket heads and a bbk cold air intake and the guy before that installed a fly by wire system. so the problems he is havin is that when he is driving the voltage is low we have gone and checked and replaced the battery and he changed the alternator and now the problems he was having is back when he drives and he hs his lights on and or AC it will die. when we changed the alternator it ran great it was quieter and ran awesome and now that was about a week or less ago now its back to where it was when he bought the car he went to autozone for the alternator. what do yall think about this we are both stumped any help or anything would help him alot
problems!!!!!!
fordrangerguy
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ok im checkin into this for my neighbor he has a 1991 fox body 5.0 HO straight shift the PO installed dual electric fans aftermarket heads and a bbk cold air intake and the guy before that installed a fly by wire system. so the problems he is havin is that when he is driving the voltage is low we have gone and checked and replaced the battery and he changed the alternator and now the problems he was having is back when he drives and he hs his lights on and or AC it will die. when we changed the alternator it ran great it was quieter and ran awesome and now that was about a week or less ago now its back to where it was when he bought the car he went to autozone for the alternator. what do yall think about this we are both stumped any help or anything would help him alot
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45 Posts
thats what we thought too thats why we replaced the battery ill let him know to check the terminals tommrrow thanks for the help so far
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854 Posts
I would also check the Alt/body-harness... it runs underneath the battery but it's possible that when you/they/whoever installed the new alternator had a bad/loose connection... I wouldn't keep buying alternators, imo that wont fix the problem... Is the "fly by wire" system like a electronic throttle? If so, I would trace everything from start to finish, it's possible whoever installed it had a shitty connection and now it's your culprit... GL
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45 Posts
yes the fly by wire is an electronic throttle control we checked all the grounds today and they are all good and the alternator wires are tight. i talked to some mechanics around here and they say that autozone stuff is cheap and they dont recomend it so we are going to take it off tonite and take it back and he has ordered a new powermaster 140amp alternator so hopefully that will take care of the problem if not the fly by wire and the electric fans will be checked next
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414 Posts
check the battery ground or IMO you should redrill and find a new place to ground the wire just to be sure. i put my battery in the rear and the ground was too loose. Def worth a check
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7,992 Posts
Check the simple (and free) stuff first... all your grounds. Any rust or paint will keep it from grounding properly. A bad ground will cause all kinds of weird/annoying stuff.
Also, just by reading what you typed.. you said it would work fine until you turned on headlights or A/C.. sounds like the alternator may not be putting out quite enough to power everything at once... I know my volt gauge drops when I turn on the headlights/AC... and I have a new 90 amp alt. from auto zone.
Also, just by reading what you typed.. you said it would work fine until you turned on headlights or A/C.. sounds like the alternator may not be putting out quite enough to power everything at once... I know my volt gauge drops when I turn on the headlights/AC... and I have a new 90 amp alt. from auto zone.
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45 Posts
ok today we changed out the plug that connects the alternator and the negative terminal on the battery was loose so we tighted it and it drove great but the voltage was reading almost 8 but it ran fine and the AC was on with the headlights on and it drove amazing till tonite he was going to work and it died and we got it running to where we could get it in a parking lot and it wouldnt crank again. what could this be we have tried everything its going to a shop monday and have them check it over. what we cant figure out is when its on for a few mins to about 30 mins it runs great but any longer and it will die. this is driving us crazy any more help would be amazing yall have helped alot so far
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45 Posts
ok they think they found the problem the crank udpulley they said was way to small compared to all the rest so hopefully thats the problem what do yall think?
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7,992 Posts
I have an underdrive crank pulley on my car, its about 4 inches diameter. The alternator pulley I have is whatever autozone alternators come with... probably stock size. I have no charging problems.
If you rev the engine to about 2000 RPM, it should be spinning the alternator more than fast enough to charge... that's if the alternator is good.
Like I said before... if you have a lot of aftermarket stuff draining the battery faster than a stock alternator can keep the battery charged... you should consider a high amp alternator.
If you rev the engine to about 2000 RPM, it should be spinning the alternator more than fast enough to charge... that's if the alternator is good.
Like I said before... if you have a lot of aftermarket stuff draining the battery faster than a stock alternator can keep the battery charged... you should consider a high amp alternator.
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45 Posts
the alternator has an underdrive pulley and the guy at the shop said that was the problem cause when we would take the car out when haulin down the roadat about 4 to 5 thousand rpms it would be higher than 8 on the voltage meter
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154 Posts
My 1st thoughts when reading your 1st post were possibly it had underdrive pulleys causing the problems. Some brands of pulleys cause more problems then they are worth. A smaller crank pulley should be fine, but if it has the bigger alternator pulley then that will cause the amps to drop below 1000 rpms because the alternator isn't turning as fast. I would try a higher voltage alternator 130amp or higher with the stock pulley.
When my car was a stock AOD car one of the 1st mods I did was ford Motorsport pulleys & I had charging problems & higher water temps especially when driving in traffic at night & it drove me crazy.
When my car was a stock AOD car one of the 1st mods I did was ford Motorsport pulleys & I had charging problems & higher water temps especially when driving in traffic at night & it drove me crazy.
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45 Posts
so you think it could be the brand of pulleys that are on the car we have no idea what brand they are we didnt put them on the po did so if ur right it could be as simple as replaceing the pullies?
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7,992 Posts
Measure the diameter of the pulleys.. it doesn't matter what brand they are, just the diameter.
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45 Posts
ok we fixed the problem it was the thermostat the car was over heating which was killing the car. now we have another problem when the car idles in gear with the clutch in the oil pressure will drop and bounce till he gets on the gas we are confused i think its could be either the oil pump or sending unit he thinks its just the oil and how old it is what do yall think? and thanks for yalls help so far
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