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Thread: Kenne Bell Boost-A-Pump issues?
04-14-2011, 05:49 PM #1
Kenne Bell Boost-A-Pump issues?
I have Kenne Belle Boost-A-Pump wired up after my stage 2 fuel pump driver. Im running the Ford GT pumps. I also have the Wiring upgrade for the boost a pump. All my connections are soldered and secure. When I go to start the car QUICKLY I keep blowing the boost a pumps inline 30amp mini fuse. If I turn my key to the ACC position and listen for the Boost-A-Pump to turn on, then start the car, the fuse does not blow? Any suggestions?
04-14-2011, 06:14 PM #2
First, It should not be coming on until you're under load and need the fuel. Second, all the wiring upgrades are to support the higher current draw from the bigger pumps. The pumps appear to be drawing more than 30A when they first start up. Someone else will have to chime in on the need for a higher capacity fuse on the GT pumps. If that is not the case, I would bet on a high resistance connection somewhere.If you see a turtle on a fencepost, it didn't get there by itself.
04-14-2011, 08:20 PM #3
Also, I know the boost a pump is working properly under load, because I data logged the duty cycle of the fuel pumps earlier in 4th gear at 6500rpms. They ran at .30, which is about 70-75% duty cycle. Thanks
04-14-2011, 08:41 PM #4
Most BAPs are wired full time that I have seen, as the OP is running his.
Mine is too, with the Hobbs switch wires just connected together.
However mine is wired PRE FPDM not POST, and mine is using a 40 amp fuse even though I am only on stock pumps.
I wish I had an answer for you OP, but I don't.
I have heard of people just putting in a 40 fuse instead of a 30, but I do not know if the situation was the same as with yours.
I am just not familiar enough with the post FPDM installation.Jimmy
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04-14-2011, 10:10 PM #5
04-15-2011, 12:38 AM #6
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wire it PRE-FPDM
04-15-2011, 07:24 AM #7
04-15-2011, 08:35 AM #8
Popo, I was not trying to insinuate your level of knowledge. I apologize that it came across that way. My reply was nothing more than my best attempt to help find the cause of your problem. I always start with the basics when troubleshooting.
A non-constant BAP setup is more just my preference than necessity, and it certainly shouldn't cause this issue unless something else is wrong.
A pre-FPDM setup doesn't make sense to me either. Please explain how this is better? A BAP is just a step-up transformer. Why would it need to be applied to anything other than the pumps?
What BAP are you using? Do I understand correctly that the OE fuse was a 20A? If you are running a 20A BAP, that is certainly your problem. I am assuming that you are running the correct 40A BAP, but that should not have come with a 20A fuse.
Edit: Sounds like the hum is just a bad relay. Where is the switched power coming from? Check the voltage on that source?
04-15-2011, 09:59 AM #9
Last edited by POPO30; 04-15-2011 at 10:02 AM.
04-15-2011, 10:03 AM #10
I am using the 40a boost a pump.
04-15-2011, 07:46 PM #11
What capacity fuse is currently on the BAP? if it's not 40A, it will blow. The BAP will supply the 40A, and I guarantee those twin GT pumps will draw close to 40A. I am lost as to why KB would supply anything other than a 40A fuse. If that is a 40A fuse, your problem could be anywhere between the fuse and the fuel tank (BAP, pumps, or associated wiring). How is the FPDM wired in?
I believe the hum is an unrelated issue. If you turn the ignition off, and the BAP continues to hum, it is obviously getting voltage from somewhere. This can be one of two things. Either the relay is sticking, or the fuel pump circuit is still sending a signal to the relay. I doubt the latter, because a properly functioning relay would be on or off, and I understand you to say that the BAP is definitely getting less than 12v. If you're buying quality relays, it is unlikely that you have two bad ones in a row, but if they're Taiwan junk off of eBay, that is very possible. Here's a quick check you can do to determine which is causing the problem. Turn the ignition off, and if the BAP continues to hum, pull the fuel pump circuit fuse under the hood. If the hum does not quit, you have a bad relay. If it does quit, something is not switching properly. We can figure this out, when I know how your FPDM is wired in. GL!
04-15-2011, 08:10 PM #12
Ive never heard my BAP hum...... thats strange.... do they all hum?
I think there is definitely an issue with the way its wired. NO OFFENSE but i had mine with one wire done wrong when i wired the dual fpdms and bap, and it was blowing fuses. I dont remember how i did it, but i am acutally going to go over everything i did tomorrow night, and make sure that mine is post FPDM..... a guy on here black306 or blackz06 or something was the man that helped me, and he knows his stuff ![B]Whipple 2.9 @ 19 psi
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04-16-2011, 12:49 AM #13
Ok, so today I wired the boost a pump pre fpdm and it works absolutely normal. I changed NOTHING but switched to pre fpdm? For those who know the wiring on these cars, I changed it from the brown with a pink stripe wire to the green with a yellow stripe wire. I have no idea why I was getting voltage feed back when it was wired post fpdm?? Everything works perfect now?? I don't understand it at all. I data logged the car in 4th gear at 6k(had to get out of it due to speed), and duty cycle went to .38-.41. Which with two pumps is at about 75-80%.
Before doing this I swapped out fpdm for another and even double checked to make sure that the brown and pink wire was indeed the one that went to the fuel pumps. I had it wired correctly for post fpdm.... I'm assuming that now when the fpdm is signaled to send more voltage to the pumps by the PCM, it will have it from the boost a pump. I'm still questioning how amplifying and amplifier will work with out an issue but it does. Any thoughts?
04-16-2011, 01:58 PM #14
A little late to the game, but I'd like to play.
A BAP was originally designed for a return style fuel system where the fuel pump receives full voltage all the time. The idea was to use a Hobbs switch to kick up the voltage only under heavy load.
When Ford's returnless fuel system came about, and not knowing any better, people at KB probably thought it was best to locate the BAP as close to the fuel pumps as possible. That way, any voltage being sent to the fuel pumps would simply be amplified by the BAP. Part of the problem with the instructions is that it still includes the use of a Hobbs switch. That 'spiked' increase of voltage to the pumps when the Hobbs switch is activated wreaks havoc on a returnless fuel system cause fuel pump control is critical to maintaining fuel pressure. Another reason people at KB probably thought it was best to run a BAP after the FPDM is because they didn't know whether or not an FPDM could be run at up to 17v reliably. Now we know that an FPDM can reliably run with increased voltage* (but it is recommended to run a modified FPDM just in case....but those details should be left for another thread ). Time has shown that running a BAP pre-FPDM is indeed better.
Why is running a BAP pre-FPDM better? Well, an FPDM is really nothing more than a fuel pump speed controller or voltage controller. Depending on input from the ECU, the FPDM will supply more or less voltage. It's really that simple. When you run a BAP after the FPDM, the ECU has no direct control of the voltage getting to the pumps; a BAP can change what the pumps actually receive. When you run a BAP pre-FPDM, all you are really doing is supplying the FPDM with the voltage it needs. The FPDM will still manage the power to the pumps as the ECU sees fit.
If you followed the KB BAP instructions to a "T," then power is being supplied via the stock wiring. That is why the fuse is upgraded from a 20A to a 30A in the stock fuse box; power demand increased due to the BAP. However, if you added a relay and did a "wiring upgrade," then there is no point to installing a 30A fuse in the stock fuse box cause that circuit is simply a low-current signal now to activate the relay. Power would be supplied through a new wire from the battery.
Now, why were you blowing fuses with your BAP wired post-FPDM? No clue. If that has happened to other people, it hasn't happened to many. In your particular situation, obviously there is something causing a significant spike to pop the fuse when you go to turn the key all the way. Assuming everything is wired correctly, it could be that the cranking fuel table is demanding a bit more fuel in your tune and enough to cause the excessive spike. Much like going from off to full on, but I'm reaching on that one.
In any event, the problem is moot. It is good that you switched to a pre-FPDM setup and that you are no longer having the problem.
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04-16-2011, 09:42 PM #15
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YEAH what Derek said^^^^^
PRE-FPDM and the issue is resolved..
Last edited by Brutal Metal; 04-16-2011 at 09:46 PM.
04-17-2011, 09:56 PM #16
Can you guys tell me what the voltage should read when you use a volt meter on the BAP?2003 Satin Silver Cobra #875
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04-24-2011, 09:40 PM #17
04-26-2011, 10:16 PM #18
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08-12-2013, 10:01 PM #19
Old one, but I just installed GT pumps and I'm blowing the 30A fuse at the BAP and running VERY rich. No, the FRP diaphragm didn't blow. I'm going to install a 40A fuse, have seen this in a few places while digging. I haven't had much time to mess w it yet, but thinking some other issue is there.2003 Cobra convertible #69/5082 polished Steggy Stage 4, 4# lower, 2.93 upper, Accufab SBTB and plenum, JLT RAI, Afco single pass HE, Kenne Bell 40A BAP, Siemens Deka 60# injectors, Reische Performance 170 t-stat, Mac ceramic longtubes w Lethal Performance o/r x pipe, Bassani stainless cat back, Ford Racing "C" lowering springs, SRA swap, Ford Racing 31 spline carrier w carbon fiber clutches, Moser 31 spline axles, Ford Racing 3.73 gears, slotted and dimpled rotors, powder coated calipers, MGW orange handle shifter, custom SCT tune 508/522 on a safe street tune *numbers BEFORE LT's*