Blown 120amp/ ACG fuse

[pegi]

Hello,

I have a problem now with my nsx.
Car have now new fuel pump and as well as comptech sc + aem ems 2...

I just left fuel station, drive about 2km and I feel something was wrong with my car. It doesn't run properly.
Just moment after engine light come on and engine passed out.
Every fuse working excluding ACG/120amp main fuse which is blown totally. (I had 100AMP fuse in my car at the time this happend)!
Fuel pump relay sounds like it is dead as well as fuel pump of course because this if burn out, right?!

So, tomorrow I have original 120 AMP fuse and new fuel pump relay.

What do you think can cause this?
Too small (100AMP) fuse (underrated for this upgrared setup)?

Could I put new parts and try if there is everything okay with out worrying too much there is any other problems?
What do u think?

Thank you for your help!

Br.pegi

Few pics of that fuse

 

[comtec]

Hi Br.pegi,
Have to ask a few questions but the 120amp fuse should be used.

Mike



How long has the 100amp fuse been in the car?

How long since you installed the fuel pump and SC?

What fuel pump did you install?

Did they upgrade anything else like fuel pump wiring?

 

[pegi]

Hi Br.pegi,
Have to ask a few questions but the 120amp fuse should be used.

Mike



How long has the 100amp fuse been in the car?

How long since you installed the fuel pump and SC?

What fuel pump did you install?

Did they upgrade anything else like fuel pump wiring?

Hi Mike,

I know 120 Amp have to be used.
Car was in the carage last winter and carage owner need to give some extra power to the battery with booster and the original 120 amp broke at the that time. I did not know about it, until yesterday when I explain this thing to my friend. He changed the fuse and he had only 100 amp at that time. So he put that in to the car. He forget to tell that to me, so now when we speak about this prob. he remember what was happened.
With that 100 amp fuse I have driven about 850 km / 1400 miles. About.
Fuel pump and sc installed little bit more what I have driven because tuning before driving .. So possible something like 1000km / 1600+ miles.

Fuel pump was ordered from sos as well as wirings. I have to take a look what I ordered from them.

I update this soon!
I think my fuel pump kitt is this sos set:
Walbro 255 LPH (HP) In-Tank Fuel Pump & Installation Kit
http://www.scienceofspeed.com/products/engine_performance_products/NSX/Walbro/255_LPH_in-tank/

Thank you!

-pegi

 

[03 raw nsx]

x120

 

[Sylvan]

Holy crap. That's a lot of current. The only time I blew a fuse like that on one of my other cars, was when I tried to jump start it and I had the cables on the wrong battery terminal. But, this sounds like it happened while you were driving. Were you running with headlights, high beams, A/C, blasting stereo? Who knows. Maybe 100 was just too small for normal operation.

 

[dirtbag]

That is a LOT of current. I think running every accessory on the vehicle it still wouldn't pop a main.

I don't know exactly how the fuse box or main bus are constructed, but I'd look for loose bolts/nuts used for fastening the bus bars. Also look for chafing points for heavier gauge wire runs. Any smaller wires with that amount of current draw would be instantly melted and obvious, not to mention one of the other fuses would have blown before the main.

The fact that you were driving would most likely indicate a short circuit from vibration.

 

[comtec]

Pegi,
So no work on the car in the past 1000 km and they blew the original fuse about 850km ago?

Fuses are normally sized 25% above the required amps so a 120 amp fuse would normally protect up to a 90 amp draw. A 100 amp fuse isn't much overhead for the system but it has worked for some time so we need to make sure there is no other problems.

First thing to do would be to check the battery cables, battery connections and the ground connections to the body. Look for loose connections, corrosion and frayed cable sheathing

Do you have a volt/ohm meter?


Mike

 

[goldNSX]

Interesting. The Walbro needs more current and a lower fuse than 120A is not a good idea. Anyway, I wonder which component is using how much current. I'm going with a 20A-fuel pump in the future and wonder if the same happens to me.

I'd replace the 120A fuse in your case and see how things behave. Was the 100A fuse a Honda-part?

 

[goldNSX]

That is a LOT of current. I think running every accessory on the vehicle it still wouldn't pop a main.

12V supply system have to fulfill high current demands. Headlight had 110W which is 9A of current alone. 12W need 1A at 12V. That's why some vehicles switch to 24V or even 36V systems to supply the required power.

 

[comtec]

Interesting. The Walbro needs more current and a lower fuse than 120A is not a good idea. Anyway, I wonder which component is using how much current. I'm going with a 20A-fuel pump in the future and wonder if the same happens to me.

I'd replace the 120A fuse in your case and see how things behave. Was the 100A fuse a Honda-part?

Gold, i don't think you will have any problem with that using the correct fuse. Your not actually adding 20amps, just the difference between the oem pumps amps and the new 20amp one.

Mike

 

[jorligan]

I blew my 120 amp fuse when I hit a bump and my battery shifted against the battery hold down which had exposed metal. Discharged my battery completely, car wouldn't turn over until I had it recharged. Replaced it with a spare 80 amp fuse which would normally go to the rear window defroster and drove it the final 200 miles to Vegas for XPO 2010. No further issues. Only a complete dead short could cause that fuse to blow.

 

[pegi]

Hello everyone!

The 100amp fuse was from honda s2000.
I change that fuse yestersay, and it is now again 120amp original nsx fuse. fuel pump and relay sounds to working on now.
Try to start.
Car start but everytime just after about 2seconds it shut down.
Every fuse is okay, cables seems to be okay and so on.
Battery seems to be okay 2, connectors as well as the ground kit is to the body tight enough.
Next tuesday tuner come to see what might be the problem...

Few friends think the problem is now with the fbw/elect throttlebody and that doesnt work right. Dont know, but future will tell.
Anyway it sounds like electronic failure somehow.
Any more ideas?

And hey, code was intresting 3 long and 3 short
I didn't found any explanation for that!?
Yeah thats true... :-D

Grr about this ****. Now way my honda could do this to me
Hope so I answer everything u asked from me. Thanx!

Thank you for your time & help!

-PEGI

 

[StmpoRaceProducts]

check your ground wires...

 

[Briank]

That fuse was subjected to an overload and not a short. You may have a problem or just need the proper sized fuse. The major current that fuse sees is the charging current from the alternator. Have you added some large current draw equipment, a large amp? Your battery may have a shorted cell making for a large charging current.

 

[Briank]

Hello everyone!

The 100amp fuse was from honda s2000.
I change that fuse yestersay, and it is now again 120amp original nsx fuse. fuel pump and relay sounds to working on now.
Try to start.
Car start but everytime just after about 2seconds it shut down.
Every fuse is okay, cables seems to be okay and so on.
Battery seems to be okay 2, connectors as well as the ground kit is to the body tight enough.
Next tuesday tuner come to see what might be the problem...

Few friends think the problem is now with the fbw/elect throttlebody and that doesnt work right. Dont know, but future will tell.
Anyway it sounds like electronic failure somehow.
Any more ideas?

And hey, code was intresting 3 long and 3 short
I didn't found any explanation for that!?
Yeah thats true... :-D

Grr about this ****. Now way my honda could do this to me
Hope so I answer everything u asked from me. Thanx!

Thank you for your time & help!

-PEGI

Fire and die is normally a main relay or ignition switch issue. With how cooked that fuse was your ignition switch may have been damaged.

 

[goldNSX]

That fuse was subjected to an overload and not a short. You may have a problem or just need the proper sized fuse. The major current that fuse sees is the charging current from the alternator. Have you added some large current draw equipment, a large amp? Your battery may have a shorted cell making for a large charging current.

He added a Walbro 255 and takes the power for it from that fuse box. A Walbro can consume more than 10A under load. I guess it's the device with the highest consumption.

 

[StmpoRaceProducts]

That fuse was subjected to an overload and not a short. You may have a problem or just need the proper sized fuse. The major current that fuse sees is the charging current from the alternator. Have you added some large current draw equipment, a large amp? Your battery may have a shorted cell making for a large charging current.

correction.... check your ground wires on all new components and make sure they aren’t hooked up to a loaded wire = overload of current.

I heard walbro in this thread... fuel pumps are close to the fuse box... it's likely to be a cause to a fuse I rarely see blow = 120v

 

[Briank]

A 10 amp fuel pump circuit which has its own fuse fed from a 120 amp fuse is less then 10%, this problem is not related to the fuel pump change.

 

[Briank]

He added a Walbro 255 and takes the power for it from that fuse box. A Walbro can consume more than 10A under load. I guess it's the device with the highest consumption.

As noted the alternator moves the largest amount of current in the system and if there are added loads on the battery side of that fuse it will get cooked. Its hard to guess exactly what is going on with out being there and seeing what has been added/hacked.

The fuel pump circuit is fused at 15 amps which is connected to ign2 which is protected by a 30 amp fuse that is fed from the 120 amp fuse. Clearly no fuel pump issue here.

 

[goldNSX]

I'm just saying that his Walbro is adding for more current than before. But I'm with you on the alternator and maybe battery which was dead over the winter season.

 

[Briank]

I'm just saying that his Walbro is adding for more current than before. But I'm with you on the alternator and maybe battery which was dead over the winter season.

With even an added 10 amps, that is not enough to make an issue with that 120 amp fuse. On a modified car who knows what has been done.

 

[chussey]

Fire and die is normally a main relay or ignition switch issue. With how cooked that fuse was your ignition switch may have been damaged.

My car had the same exact symptoms with dirty ignition switch, start then shut off 1 or 2 seconds later. At first I assumed it was the main relay, but discovered that if I held the key just right after cranking it would stay running. I would take a look at the internals of the switch.

 

[goldNSX]

Pegi, have you sorted this out?