Changed battery now truck won't run well/undrivable!

[cantspell]

Hi there, a few days ago quite suddenly my truck had a hard time starting. I drive the truck about once a week, always starts on the first crank easily.

Drove about 10 mins away, let it sit, about 2 hours later the truck would not start at all.

Checked and the battery was dying, checked the alternator and it was putting out 13.6+V...

Changed the battery, replaced all the terminals, sanded everything, now it starts but it's running like crap, guages are all twitching, def an electrical problem... I was told it was because the battery was under rated, however I've tried 3 batteries, 2 of them new and it's the same...

I should also note that if i take off the ground the truck stalls...have not tried to take off the positive...

Any ideas? I"m a bit concerned.

Thanks
M

 

[Turdle]

Alternator. It should put out a higher voltage, more like 14.3 v. The truck should stay running when you pull battery cable.

It could be the rectifier is bad. Set the meter to ac volts with the engine running to see how much non rectified ac voltage is getting through--just out of curiosity.

 

[rileyrs]

ya sounds like an alternator problem to me, pull it off and take it to an auto parts store, they usually test them free.

 

[BobWiersema]

Sounds like bad alternator diodes. I say that mainly because of that wierd gauge problem. Disconnect the alternator and see how it runs.

Bob

 

[BobWiersema]

Alternator. It should put out a higher voltage, more like 14.3 v. The truck should stay running when you pull battery cable.

It could be the rectifier is bad. Set the meter to ac volts with the engine running to see how much non rectified ac voltage is getting through--just out of curiosity.

Thats what I was thinking but Turdle posted first.

http://www.nationsautoelectric.com/rectifiers.html

 

[budwich]

don't run without a battery too long as your alternator won't "like" it. It uses a "feedback voltage" to determine how much "charge" to deliver at a "given instance". Anyways, as pointed out, could be an alternator problem or possibly the "standard rotted cable" problem that many a ford owner comes across.

 

[cantspell]

hi guys, thanks for all the feedback!

Unfortuantly today i put in a new alternator and it had the same problem...what is the 'rotted cable' issue?

If not, could it be that i fried the ECU?

 

[BobWiersema]

hi guys, thanks for all the feedback!

Unfortuantly today i put in a new alternator and it had the same problem...what is the 'rotted cable' issue?

If not, could it be that i fried the ECU?

I dont know about the cable thing. Is the Check Engine Light on? Did you have the error codes checked. The CEL may not be on but error codes may be pending and they can pull those. The ECM will report a problem with itself if thats it.

Do any welding on it lately?

Dont just start swapping parts. The guys here know from experience what to check. Before you spend any more money, post first, someone may know.

Just trying to save you some money.

Bob

 

[cantspell]

Hi there, Oh i've been fortunate enough to have not really spent any money on anything, as I've been able to return everything - even the alternator...

the guages/idiots lights are all flashing/twitching...so it's hard to say, though when they are not the CEL is actually NOT on...the only werid/consistant thing is the high oil pressure or temp guage...

 

[BobWiersema]

Hi there, Oh i've been fortunate enough to have not really spent any money on anything, as I've been able to return everything - even the alternator...

the guages/idiots lights are all flashing/twitching...so it's hard to say, though when they are not the CEL is actually NOT on...the only werid/consistant thing is the high oil pressure or temp guage...

This could be a simple diode problem, Ill check tomorrow, I have all the books on the 98 xlt, because I have one.. Have to work tomorrow, but I will make time.

Peace Out, Happy 4th
Bob

 

[cantspell]

This could be a simple diode problem, Ill check tomorrow, I have all the books on the 98 xlt, because I have one.. Have to work tomorrow, but I will make time.

Peace Out, Happy 4th
Bob

Thank you - it would be greatly apprecaited.

 

[rego]

Check battery voltage with the motor running.

 

[cantspell]

Just a quick update, the truck will now not even start...turns over well, but it won't start at all, and the oil temp guage is now sort of way off alignment (I'm sure this is random, but i thoguht i would point it out)...I've now tried the truck with a new battery and alternator to no avail...could it be the ECU?

 

[budwich]

check ALL your fuses

 

[BobWiersema]

Check this little Diode in the fuse box under the hood. It controls the ECU.

Im not sure what would happen if it was bad. Defiantly check all other fuses.

Everything else points to a bad GEM unit.

 

[budwich]

go thru the "no start" procedures / threads. Basically, a quick check is try spraying "quick start" in the intake. IF it starts, you have a fuel delivery issue. IF it doesn't you likely have an electrical / timing related issue.

 

[janolsson]

Here is a thought.
I have read about guages etc goin haywire when battery is low. But as you have a new battery then this rules this out , however is it a suitable one ie cranking amps. Also if the starter is drawing too many amps (tired or poor earth) then this may draw too much from the battery and cause the gauges to play up. Check the connections on the starter, clean em up good especially the earth.
Also the battery earth and the engine block earths