Fusable links?

[boz42]

I have a rig here that has an aftermarket EFI harness. It has 2 wires coming off the battery. One has a 20 GA & the other has an 18 GA fusible link. The 18 is burned up.

My question is does the length of the 18 gauge wire make a difference? I am betting it does. How do I know how long it needs to be?


Can it be replaced with a standard blade style fuse holder? If so, How do I know how many amp fuse to use?

Thanks, guys.

 

[mosesburb]

My question is does the length of the 18 gauge wire make a difference? I am betting it does. How do I know how long it needs to be?
It needs to be the same length as the one you are replacing. If you can not get an accurate length on it, I would go with approximately 5".


Can it be replaced with a standard blade style fuse holder? If so, How do I know how many amp fuse to use?
NO!! It can not. I know many people have done it, but it is never recommended. The wire gauge of the fuse link is four sizes smaller than the wire it is replacing--i.e. 14ga protecting 10ga wire, 16ga protecting 12 ga and in your case 18ga protecting 14ga.

The reason for the smaller gauge protecting the larger gauge is the fuse link is designe to run at a higher temperature than the wire it is protecting. A fuse link wire will always have a thermally cross linked polyethylene jacket on it. This is a very high temp insulation that will not burn through (supposedly--they do burn through under catastrophic circumstances sometimes) when the fuse link fails. To put its purpose in "fuse" terms it is like a super slow-blow fuse. It is designed to only fail after a severe load or circuit failure has occurred. A fuse on the other hand will pop once its 20amp or 30amp load has been reached. Now, because it is designed to run hot, both ends of the fuse link must be soldered AND most importantly heat shrink MUST me applied. This is to keep the heat in the wire. If the ends are left open, the wire will conduct its heat to the atmosphere effectively running cooler thus taking it out of its design parameters and allowing more amperage to flow through it before failing.

One question you should find the answer to before replacing it is why did it fail?? Fuse links typically require a problem somewhere in the circuit to fail. Occasionally they do fail because of age, but not too often.

 

[boz42]

Thanks, I guess I will go with 5" then.

It failed because the fuel pump went out. When the fuel pump went out it shorted & caused it to go to ground. This shorted out the power supply to the fuel pump relay which is the fusable link that shorted out.

 

[Mudstud]

Boz, can you contact the harness mfg to get some more in sight?