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I use wire cutters and nibble away at wire coating being careful not to cut any copper strands. Then I do the same with my extra wire and wrap the 2 together. Then solder the wires together. Then shrink wrap them.
Thanks, good to see some pictures of how others have done it.
Thanks, good to see some pictures of how others have done it.
A word of caution: when soldering, make sure wires are as close to final angle as possible. Once soldered, it isn't flexible and forcing the angle to change can break the copper strands. Take the time to remelt the solder so it can reset to the correct angle. Your engine will thank you with a longer life
Also, avoid soldering at locations that need to be flexible. I left the end that bends alone and soldered after wires cleared the connector cover. I wanted to solder at the pins, but decided not to since I can't be certain connection won't be broken when I go to plug it in.
If you are looking to get max voltage, keep in mind that there is a small voltage loss associated with a relay and the additional connections, especially as the relay ages. Voltage loss for a new relay is <0.05 V, but max spec is typically around 0.2 V for a relay that has some miles on it.
sorry to resurrect this thread but I’ve been thinking of doing this for some time. I have a Hobbs switch and I’m about to order the rewire kit. After looking at the different diagrams I started thinking that once the high voltage was applied to the pump could it potentially work it’s way back up the circuit to the ecu?
at that point I started thinking about using the SPDT (single pole double throw) relay. I can pull the power pin from the pump connector and that wire can be placed on the normally closed contact and power from the battery can be placed on the normally open contact. A new line and pin going to the fuel pump can be connected to the common lead of the relay. Of course the relay will be activated by the Hobbs switch.
So in theory, while the relay is de-engerized the factory low/high function will still work since it will be connected to the normally closed leads of the relay. But once the Hobb switch activates the relay, the power from the battery will be switched in providing the higher voltage.
Trying to think of a scenario in which this can cause an issue and what I can think of is in case the relay does not activate but in theory it should still see the factory function. The other thing is if the relay is slow to respond or the internal contacts fail it can cause a lean condition. Is there any other reason this can’t be done? Is there something I’m not thinking off?
sorry to resurrect this thread but I’ve been thinking of doing this for some time. I have a Hobbs switch and I’m about to order the rewire kit. After looking at the different diagrams I started thinking that once the high voltage was applied to the pump could it potentially work it’s way back up the circuit to the ecu?
No the ECU is isolated from the circuit via its own relays.
at that point I started thinking about using the SPDT (single pole double throw) relay. I can pull the power pin from the pump connector and that wire can be placed on the normally closed contact and power from the battery can be placed on the normally open contact. A new line and pin going to the fuel pump can be connected to the common lead of the relay. Of course the relay will be activated by the Hobbs switch.
This is basically how its done. SPDT relay wired normally open in parallel with the factory wiring triggered by a hobbs switch.
So in theory, while the relay is de-engerized the factory low/high function will still work since it will be connected to the normally closed leads of the relay. But once the Hobb switch activates the relay, the power from the battery will be switched in providing the higher voltage.
Exactly. Really what your doing is reducing resistance in the circuit which causes less voltage drop. To get higher voltage you can use a voltage booster like a Kenne Bell boost-a-pump.
Trying to think of a scenario in which this can cause an issue and what I can think of is in case the relay does not activate but in theory it should still see the factory function. The other thing is if the relay is slow to respond or the internal contacts fail it can cause a lean condition. Is there any other reason this can’t be done? Is there something I’m not thinking off?
This is pretty much the main drawback. There are things you could/should be doing though to help mitigate the potential damage from a failure of the additional circuit. For example Tephra V7 has an AFR out of range function that can pull boost and flash the CEL if you cross a programmable AFR threshold above a certain load. You could wire up an LED to come on to verify the circuit is being triggered, you could measure voltage at the fuel pump, measure fuel pressure etc, etc. It really comes down to what your doing with the car and your preferences, or basically what level of precaution you feel comfortable with.
I've thought about it. The resistor that mitsubishi uses I'm assuming is tailored to the factory fuel pump. If one did want to make their own "low power mode" for the fuel pump it might be a good idea to dial something in for the aftermarket pump they are using. I think it would be worth exploring anyway.
A little context. The factory low power mode for the pump uses an inline resistor to restrict current to the pump. My assumption is that the value of the resistor was chosen such that it would provide enough current to the pump to meet low engine load requirements. If you change the pump then it may require more or less current to meet that same requirement. If it needs less, well then no big deal really. If however it needs more, then you would actually get a greater voltage drop across that resistor which would perhaps lead to the pump not meeting that demand. Ideally you would measure fuel pressure at the rail to determine this. A solution might simply be to trigger high power mode at lower load, or you could size the resistor to provide the extra current needed by the bigger pump. I kind of make a bunch of assumptions here, so if someone wants to pop my thought bubble go for it
I'm just going to try something simple...
I have a wally 525 fuel pump. I figured that this pump is rated at 40A and the stock pump is around 16A.
I just bought 2 more oem resistor pack and plan to wire all 3 in parallel in hopes that flows low enough to not overwhelm the return line. Then I can set the demand higher to kick on full power.
I'm just going to try something simple...
I have a wally 525 fuel pump. I figured that this pump is rated at 40A and the stock pump is around 16A.
I just bought 2 more oem resistor pack and plan to wire all 3 in parallel in hopes that flows low enough to not overwhelm the return line. Then I can set the demand higher to kick on full power.
That sounds like a great project. I've only really just thought about different stuff that might be doable. Like measuring different packs from cars at a junk yard and picking up a little collection, or maybe trying to construct a SMPS to control the pump. Probably the craziest one though would be wiring the pump to a subwoofer amp and feeding it wave forms to control the pump. No idea if that would even work but it would be fun to try it. Gluck with your testing, I would love to hear about how it goes.
That sounds like a great project. I've only really just thought about different stuff that might be doable. Like measuring different packs from cars at a junk yard and picking up a little collection, or maybe trying to construct a SMPS to control the pump. Probably the craziest one though would be wiring the pump to a subwoofer amp and feeding it wave forms to control the pump. No idea if that would even work but it would be fun to try it. Gluck with your testing, I would love to hear about how it goes.
I think running 2 oem resistor packs in parallel will work on a wally 450 and 525. The 3rd is more of a safety to avoid burning any of the two out. Lol
Feb 26, 2018, 02:39 PM
