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The Terminator
Engine/Tuning
Kenne Bell Boost-A-Pump issues?
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<blockquote data-quote="Black306" data-source="post: 10627530" data-attributes="member: 4780"><p>A little late to the game, but I'd like to play. :rockon:</p><p></p><p>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.</p><p></p><p>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 :lol<img src="data:image/gif;base64,R0lGODlhAQABAIAAAAAAAP///yH5BAEAAAAALAAAAAABAAEAAAIBRAA7" class="smilie smilie--sprite smilie--sprite1" alt=":)" title="Smile :)" loading="lazy" data-shortname=":)" />. Time has shown that running a BAP pre-FPDM is indeed better.</p><p></p><p>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.</p><p></p><p>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.</p><p></p><p>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.</p><p></p><p>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. :beer:</p><p></p><p></p><p></p><p>Actually, a "40A BAP" is shipped with a 30A fuse. Go figure. Also, a pair of GT pumps pull closer to a maximum of 23A. Even a pair of Aeromotive 340 pumps, which significantly outflow GT pumps, pull about 26A.</p><p></p><p>You are correct in thinking .38-.41 is about 75-80% duty cycle. Really, that PID has a range of 0-.5 where .5 is 100% regardless of the number of pumps. So your PID showing .38-.41 is really 76-82%. Considering your horsepower, that's about what I would expect.</p><p></p><p>Thanks. I don't have a Z06 yet. I've considered it from time to time. :burnout:</p></blockquote><p></p>
[QUOTE="Black306, post: 10627530, member: 4780"] A little late to the game, but I'd like to play. :rockon: 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 :lol:). 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. :beer: Actually, a "40A BAP" is shipped with a 30A fuse. Go figure. Also, a pair of GT pumps pull closer to a maximum of 23A. Even a pair of Aeromotive 340 pumps, which significantly outflow GT pumps, pull about 26A. You are correct in thinking .38-.41 is about 75-80% duty cycle. Really, that PID has a range of 0-.5 where .5 is 100% regardless of the number of pumps. So your PID showing .38-.41 is really 76-82%. Considering your horsepower, that's about what I would expect. Thanks. I don't have a Z06 yet. I've considered it from time to time. :burnout: [/QUOTE]
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