BAP keeps blowing mini fuse on startup

[Formula51]

Kenne Bell BAP is wired pre-FPDM and has blown the mini fuse 3 times in the past several months. I have tried a 30amp and some 40amps I bought off ebay. It is hard wired to be full voltage boost and all connections are soldered. I have the wiring upgrade and Ford GT fuel pumps. I have cleaned the paint off the body where it is grounded and checked that the ground is good and tight.

It only does this on startup. I have read the GT pumps draw a lot of amps at startup, but this seems ridiculous. Any suggestions on what to meter or check?

Not sure if this is related, but the car will often shock me when touching the rocker panel or door when parking and getting out.

 

[DSG2003Mach1]

to me it sounds like youve got a short somewhere

 

[SlowSVT]

Is the fuse protecting the BAP as well as the pumps?

How many amps do each of the 2 pumps said to draw?

If it's primarily doing it on start-up it's "in-line currant rush". A slow-blow fuse may be a better choice if that's the case.

 

[Formula51]

Is the fuse protecting the BAP as well as the pumps?

How many amps do each of the 2 pumps said to draw?

If it's primarily doing it on start-up it's "in-line currant rush". A slow-blow fuse may be a better choice if that's the case.

I just read they draw 23A or 24A so I am not sure what is causing the current spike at startup. If it was a short, wouldn't it do it all the time or at random times (when wire contacted steel)? This only occurs at startup.

 

[MaximumVelocity]

You running a single BAP? or dual BAP with dual FPDM conversion? Wiring upgrade? There are several things that can cause the fuse to pop.

You can test the theory by disconnecting one pump and seeing if it will pop the fuse. You may even have a pump that is starting to fail.

 

[SlowSVT]

I just read they draw 23A or 24A so I am not sure what is causing the current spike at startup. If it was a short, wouldn't it do it all the time or at random times (when wire contacted steel)? This only occurs at startup.

Currant spike (that I call "in-line currant rush") happens when you energize the coil for the first time (it also works in reverse).

 

[Formula51]

You running a single BAP? or dual BAP with dual FPDM conversion? Wiring upgrade? There are several things that can cause the fuse to pop.

You can test the theory by disconnecting one pump and seeing if it will pop the fuse. You may even have a pump that is starting to fail.

Single BAP and single modified FPDM with Lethal Performance wiring upgrade and relay. How would I check if a pump was starting to fail?

Would a failing pump cause a currant spike at startup?

 

[SlowSVT]

Have you tried installing a "slow-blow" fuse?

Most all others are "fast-acting"

The in-line currant rush is saturating the motor field windings is blowing the fuse before the motor returns to a continuous currant draw. This is very common with electric motors.

 

[01yellercobra]

Have you tried installing a "slow-blow" fuse?

Most all others are "fast-acting"

The in-line currant rush is saturating the motor field windings is blowing the fuse before the motor returns to a continuous currant draw. This is very common with electric motors.

Isn't that a band aide fix though? I would think this is a pretty common set up. Is running a slow blow fuse a normal thing? I've only ran a BAP once with a stock FPDM and twin GT pumps. It never popped a fuse.

 

[Formula51]

Isn't that a band aide fix though? I would think this is a pretty common set up. Is running a slow blow fuse a normal thing? I've only ran a BAP once with a stock FPDM and twin GT pumps. It never popped a fuse.

That's what I am trying to figure out. Is this normal or a problem. I have read of others having this "problem" and then others like yourself who did not. In order to run a slow blow fuse I will have to solder in a full size fuse holder, which is not a big deal if the consensus is that is ok or atleast will not hurt anything...

 

[03Steve]

I've popped fuses only at startup before. When you leave the key in the accessory position, do the pumps continue to run after the one second prime period?

 

[SlowSVT]

Isn't that a band aide fix though? I would think this is a pretty common set up. Is running a slow blow fuse a normal thing? I've only ran a BAP once with a stock FPDM and twin GT pumps. It never popped a fuse.

The use of slow blow fuses is quite common for this reason. The alternative is to run a higher rated fuse which can get risky if it exceeds the currant rating of the wire or other devices connected to the system. We used them extensively on computer channel extenders used to back-up Wall Street. Without it the fuse would not survive saturating the caps, inductors and power supplies on start-up where the fuse would pop the second you powered the unit.

 

[MysticRob]

The use of slow blow fuses is quite common for this reason. The alternative is to run a higher rated fuse which can get risky if it exceeds the currant rating of the wire or other devices connected to the system. We used them extensively on computer channel extenders used to back-up Wall Street. Without it the fuse would not survive saturating the caps, inductors and power supplies on start-up where the fuse would pop the second you powered the unit.

I find it funny you repeatedly confuse the spelling of something you apparently know a lot about with that of a small berry. Phone auto-correcting?

OP, ensure you aren't using defective or mis-marked fuses. They did come from ebay and that automatically makes them suspect in my mind. Also, ensure your battery ground is good. The shocking is likely from bad vehicle ground (had that problem myself and required cleaning and tightening ground to frame) or something as simple as different materials you're wearing building up static electricity.

 

[SlowSVT]

I find it funny you repeatedly confuse the spelling of something you apparently know a lot about with that of a small berry. Phone auto-correcting?

OP, ensure you aren't using defective or mis-marked fuses. They did come from ebay and that automatically makes them suspect in my mind. Also, ensure your battery ground is good. The shocking is likely from bad vehicle ground (had that problem myself and required cleaning and tightening ground to frame) or something as simple as different materials you're wearing building up static electricity.

I'm happy you are amused

I also have been known to incorrectly use "then" in place of "than" but I manage to get my point across.

With regard to my knowledge of fuses you have no idea there is a lot more to it then even most engineers realize. I use to develop Telco equipment and visited a company called SOC Corporation http://www.socfuse.com/ who supplied us with grasshopper fuses. I'm am an electro-mechanical design engineer and was accompanied by our chief electrical engineer and met with the director of engineering who held a PhD. He gave us a primmer on the physics of fuse design and when we walked out of his office even the electrical guys heads were spinning. To state I know a lot about fuses nothing could be further from the truth I am only offering advice based on my experience as it applies to circuit protection but I am by no means an expert.

 

[Formula51]

Just thought of something I forgot to mention. Shortly after startup, the battery light on the dash will come on and stay on for a few minutes then go out and stay out. It has been doing this for so long I forgot about it. No battery or alternator issues and I have taken the car on several long drives.

I'm wondering if that lends itself to the current draw at startup idea. Could the pumps really draw enough to suck the battery down such that the low battery light comes on? It's an Optima red top battery.

I do have HID fog lights that I turn on pretty much all the time after startup so that is another possibility.

 

[racebronco2]

A friend had the same problem. First start-up was ok. Once he started the car the fuse was good as long as the car was running. Turn the car off and most of the time it would blow. It ended up being a cheap relay.

 

[SlowSVT]

Just thought of something I forgot to mention. Shortly after startup, the battery light on the dash will come on and stay on for a few minutes then go out and stay out. It has been doing this for so long I forgot about it. No battery or alternator issues and I have taken the car on several long drives.

I'm wondering if that lends itself to the current draw at startup idea. Could the pumps really draw enough to suck the battery down such that the low battery light comes on? It's an Optima red top battery.

I do have HID fog lights that I turn on pretty much all the time after startup so that is another possibility.

That's not your problem unless your fog lights are protected by the same fuse as the fuel pumps. The pumps should have a dedicated fuse(s). Are you running a single fuse to protect both pumps? Each pump circuit should have their own fuse which will allow you to run lower rated fuse on each leg of the circuit which will do a better job protecting the system and will get you home in the event one fails. In other words instead of running (1) 40 amp fuse run (2) 25 amp fuses.

If the battery can turn the starter over, the current draw of the pumps will be a walk-in-the-park.

Question: What gauge wire are you running to the pumps, what type of fuse are you using, blade, AG (Automotive Glass), are you using connectors and what type and where are the fuses located relative to the pumps?

 

[Formula51]

A friend had the same problem. First start-up was ok. Once he started the car the fuse was good as long as the car was running. Turn the car off and most of the time it would blow. It ended up being a cheap relay.

Interesting. The relay is the one that comes with the Lethal Performance wiring upgrade. Are they known for having problems? Do you know what relay he used?

 

[Formula51]

Question: What gauge wire are you running to the pumps, what type of fuse are you using, blade, AG (Automotive Glass), are you using connectors and what type and where are the fuses located relative to the pumps?

Stock wire to the pumps as far as I know. Lethal Performance wiring upgrade from battery to relay. I think it is 10 or 12 gauge wire. The fuse is a 40amp mini blade fuse in the inline holder that comes with the BAP, located in the trunk. All connections are soldered.

 

[SlowSVT]

Stock wire to the pumps as far as I know. Lethal Performance wiring upgrade from battery to relay. I think it is 10 or 12 gauge wire. The fuse is a 40amp mini blade fuse in the inline holder that comes with the BAP, located in the trunk. All connections are soldered.

From your description it sounds like the wiring is sound. Is this a return or returnless system?

Not sure if blade fuses are available in a slow blow configuration but AG type fuses are. General rule of thumb is you locate fuses a close to the power source as possible which has nothing to do with your problem but it will protect the wire which in your case can potentially start a fire if the feed wire shorts to ground.

If I were in your shoes and have not isolated the problem I would remove the in-line fuse hilder spliced into the wiring harness in the trunk and install an AG fuse holder where the power is launched in the engine compartment, install a slow blow fuse and see if that corrects the problem.

I found this link the explains the application of a slow blow fuse which will give you a better idea where it should be applied and why.

http://www.doityourself.com/stry/slow-blow-fuse-vs-fast-blow-fuse