Losing Power

[Tongan310]

Alright so I got a weird issue and I can't seem to track it down. What makes it worse is this same thing is happening to my brothers 04 Avalanche (Ironically).

So here goes:

First off 97 Chevy 3500 454 has roughly 126k miles.

To the Problem:

The problem is I have intermittent power loss. Doesn't matter what I'm doing. I usually notice it the most when pull out of a parking spot or my driveway. It just dies for about a second then comes back and I can start it again and have no issues. Its happened a few times while driving however if I'm on the freeway it stays on and keeps going just super low voltage. (Assuming Alt is powering everything cause if I'm not at speed when it happens it will die).

Its been about a month since it happened and I almost forgot about it until this morning and it happened again. Pulling out it died for about a split second then came back so engine never really stop it just sort of stuttered. (Just FYI I know im completely losing power cause my o2 sensor code disappears as if I reset the battery).

Things I've checked/done.

1. New battery (only about a year old)
2. New Alt (About 6 months old)
3. Checked Battery Connections. (Cleaned and tightened)
4. Checked the positive cables (Looks and feels fine)
5. Checked Ground Cables (Looks clean and ok)

I'm stumped at this point. To note I do have a stereo but its tied into the fuse box not directly to the battery so it dies when the truck dies too. (When the issue happened radio wasn't even on yet) Also another note it tends to cut out more often when say turning than anything. (Only times it usually happens except once going down the freeway where I saw the volts drop dramatically).

Also random note I think this might also be cause me to think my starter is going out (Just a nice clunk on first key turn then 2nd or 3rd turn get a normal start).

 

[DerekTheGreat]

I'm no elechicken but I wonder if your steering linkage is causing something to short out or you have a short somewhere between the battery and firewall. Voltage drop test would be a good thing too if nothing is visually obvious.

 

[Eveready]

Smells like a bad ground. I know you checked it but I would look at chassis grounds and by that I mean unbolting, cleaning and replace. The intermittent quality would suggest either that or a cable that is burned almost through inside the insulation. I would run a jumper cable between battery ground and a nice shiny spot on the chassis. If that clears it you have found your problem and only need to chase down where it is.

If it were not for the electrical gauge indication I would suspect a failing fuel pump.

 

[RawbDidIt]

If the starter won't turn over during these bouts, it's either a bad ground, or a bad power connection. If the starter never loses power I'd say the problem is the connection to the main fuse box under the hood. If it just loses voltage, down to 10-12 volts you may have problem with the belt or the tensioner, but the battery should keep it running if that were the case. Only reason I suggest it is because at above idle it seems to be less of an issue.

Sent from my SM-G965U using Tapatalk

 

[JackE]

This lesson comes from a Ford, but bad electrical is a friend to all. I bought a new Fusion a few years ago. Within a couple thousand miles I started having the same symptoms you are describing. Just over 6000 miles an it had a hard fail that it would not come back from, until it was being loaded onto the rollback and getting jostled around. With that, it came back to full life. Hours and hours later at the dealership, they determined the main power supply wire from the battery to the distribution box had not been tightened enough during manufacturing. They tightened it properly and I finally traded it in with 113K on it without any other problems. I would take a good look at the main wire going from the battery to the power/fuse box under the hood. That is where everything but the starter gets it's power from. It wouldn't hurt one bit to just yank that wire completely out and replace it with a heavier gauge wire.

 

[454cid]

Check the positive cable... if the cable has been overtightened, at the battery, the battery can/will crack, and acid will leak into the cable and travel down the wires inside the insulation. You'll need to remove cable from the battery and pull the plastic hood off, and look for corrosion. Simply looking at the outside won't be enough.

If the PCM looses power the truck will die... when my truck was doing this it was a loose battery connection at the main wire (which wouln't stay tight) and is how I discovered the corrosion inside the cable.

I'd also look closely at the cable going to the fuse box as others have said.