URGENT HELP! Get started, Alternator Fuse blows!!

[jesus888]

EFI, 3G alternator, high torque mini-starter.

Symptoms:
Alternator fuse blows as soon as it cranks up.
When I turn the key OFF, the truck desiels (runs a little longer) for 5 seconds

These two symptoms may not be related... Looking for an alternator guru... maybe a phone number of someone we can talk this through with...

PLEASE! We're SO close!!

 

[jesus888]

Alternator theory:

Seems like the alternator is sending power back to the fuse block... and lots of it, hence the blown fuses... how do we stop that??

 

[Viperwolf1]

What fuse is blowing? What wiring harness are you using?

 

[jesus888]

What fuse is blowing? What wiring harness are you using?

The Alternator fuse on the Centech fuse block is blowing.

Centech body harness and a Ford Motorsports EFI harness.

 

[RRRAAAYYY2]

1-888-214-7774, brian is to sunburned to be writing too much.

 

[Viperwolf1]

Sorry I can't help much. I don't have a centech diagram. Most harnesses don't include a fuse for the alternator. How big is it? If it's a small fuse (5 amp) it might not be able to handle the startup load from the alternator. Or the alternator could be bad.

The deiseling is not related. Poor octane gas in a high compression motor is the most common cause.

 

[astark]

1-888-214-7774, brian is to sunburned to be writing too much.

I hope you have called Ray, he can talk you through this problem and offering to do so on a Sunday night is pretty darn cool

 

[jesus888]

We talked to ray and we're gonna give it a shot. Unfortunately, it being past 8pm in a residential neighborhood, I don't think we'll be able to test out the changes til the morning... May wake up some folks during the 20 minute cam break-in ;D. Especially with headers and no muffler!!

 

[RRRAAAYYY2]

Hope it works out. If not I will have my phone on tomorrow as well, not a holiday up here tomorrow.

 

[Explorer]

You might check the connection on the back of fuse block. The fuse that is blowing, I had one that was shorting out on a brand new Centech.

 

[Broncobowsher]

I hate to ask this question...
The big heavy charge wire on the alternator, that is going straight to the battery, right? I hope you are not trying to put the charge wire through the fuse in the fuse block. The alternator fuse in the fuse block should only go to the turn on wire on the alternator. If it is a one wire alternator, then the fuse and wire are not used.

 

[jesus888]

I hate to ask this question...
The big heavy charge wire on the alternator, that is going straight to the battery, right? I hope you are not trying to put the charge wire through the fuse in the fuse block. The alternator fuse in the fuse block should only go to the turn on wire on the alternator. If it is a one wire alternator, then the fuse and wire are not used.

It is going to the battery

The advice we got from RRRAAAYYYYY looks like it corrected the problem mostly... fuel pumps and alternator are both on different fuses.

We also added an LED in line with the REG-S wire which lowered the resistance... still popped a 10 amp fuse (after a lot of trying to get started for the first time) but replaced it with a 15 amp fuse... gonna see what that does for us.

 

[robinsoncc]

Isolate all your systems while the engine is running. It's a pretty small harness. Just do it one at a time. Also grab the harness a yank on it a little, wires are tough, but pull to hard. Well doing this check if the fuses pops you might just have a chaffed wire rubbing on the firewall, screw, or anything else metal. If you drive around that wiring shakes awhole lot.

 

[jesus888]

Well, just as an update, ended up being a defective new alternator. replaced the alternator and it charges like a champ!