after melting a 20 amp fuse situated between my Kenne Bell Boost A Pump and my 267 Walbro fuel pump a few years ago i re-consulted the requirements and swapped in a 30 amp fuse... lesson learned. especially because it ended my first Texas Mile effort and also because i flattened my corner seal springs which lead to a re-do on my motor.

i have been running 32 psi with my EFR9180 recently and noticed, even with a newly installed Walbro Hellcat (285) pump i was getting some falloff as to fuel pressure. i decided to turn up the voltage to the pump. given my prior fuse experience i decided to be ultra careful and upped the fusing to 40 amps.

while i had been ultra careful as to vendors re the purchase of my Hellcat pump, since there are more fake Hellcat pumps being sold versus genuine, i didn't think for a moment that fuse quality was a risk. a fuse is a fuse, right?

maybe not...



fortunately i was on an initial run after Tial rebuilt my wastegate so the fuel quit around 5 psi boost and 20% TPS. the motor suffered no damage.

i will now be doing a bit of research re fuses... fuse suggestions welcome

 

40 Amps is kind of big for that style of fuse, maybe you need the ATO/ATC style?

https://blog.kimballmidwest.com/maki...-of-auto-fuses

 

I avoid over 30 in a mini like the plague. That said, I also avoid fuses in general like the plague. PDM life.

 

Bussman/Eaton (Japan) fuses, for me. I especially like the EasyID ones for critical (i.e. engine system or obscure ) applications. But to dguys point... at least until the PDM upgrade.

I also concur with OPs:

• Mini - </=20a
• ATO/ATC - </=40a
• Maxi </= 100a

 

I do have a little knowledge in this area. Ohm’s law~ As the voltage goes up, the amperage goes down. Since you’re running the “Boost a pump” chances are you are at the upper tolerance that style fuse can handle for an extended period. I would imagine it’s the constant load from the fuel pump generating enough heat to melt that case. There’s not enough surface mass in the case support in blade style fuses as you’ve come to find out. I have to agree with others, if you are not going to use a pdm, stepping up to at least the ato/atc at the minimum. I’m sure you could get away with the Maxi as well but if I were in your position, I would look into the bolt in fuses and be done with it. Here’s a link you can take a look at. https://m.littelfuse.com/industries/...own-fuses.aspx Ideally I would look into the 58v ones here ~ https://m.littelfuse.com/media?resou...n-fuse-bf1-58v

As to how you choose your friends… i’ll leave that at your discretion.


~ GW

 

thanks for the very helpful feedback.
here is a pic of two 40 A fuses, one a mini and the other being the correct (ATC) size for 40 A.



i found i had some Eaton/Bussmann 40 A fuses. Eaton and Bussmann being quality names. the ATC sized fuses wouldn't quite fit the smaller holder however they were only .05 of an inch wider and the internal blade width measurement was the same between the two sizes.
i fired up my sideseal gap grinder and made the adjustment. they now fit properly into the fuse holder. the top fuse after adjusting compared to a stock ATC below.



of course i could have spliced in a larger holder but i am not a fan of splices. the motor immediately fired and all is well.

i am now sending back my Scorpion Racing hat and am officially on the Eaton/Bussmann racing team.

 

Looking at it the legs of the old fuse are so small I'm amazed they held up at all.

Would be worth running a stress test of some kind on that circuit and monitoring for heat. That's what got the old fuse, high resistance = heat = melted plastic.

May also be worth using an ammeter and seeing how much you are pulling through that circuit at full load.

Dale

 

Howard, here's some experience from a longtime electrical contractor/electrician.to beware of. Stab into clamp type connections are subject to becoming high resistance electrical joints which yields heat. The heat from a high resistant joint is often transferred (remember copper and aluminum are great conductors of heat also) to adjacent plastic structures and wire insulation, often enough to melt them.
Corrosion or contaminants on the interface of the stab and clamp will contribute to the high resistance. I always slide the prongs in and out a few times to scrape away any of the aforesaid when making a connection. Then there is the often seen issue of a clamp connection having been overheated, which anneals the metal in its clamp causing it to loose its "springiness" and consequence clamping force and yielding a high resistance joint. Replacing that clamp is the only option then.

This may not be your issue, but some things to beware of going forward.

Cheers, Philip

 

Circuit breaker maybe?
https://www.mechprod.com/hubfs/_2017...0QC-4000-C.pdf