How to wire an accessory to fuel pump relay
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Joined: Dec 2016
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From: RSA
Year: 2000
Model: Cherokee
Engine: 4.0
How to wire an accessory to fuel pump relay
Hey guys,
Need to wire an accessory to turn on only when the motor is running.
I figured hooking it up to the fuel pump relay will be the best solution - Anyone know how to do this?
Alternatively, are there easier wires I can splice into? Suggestions are very welcome.
I got a 2000 XJ 4.0
Thanks!
Need to wire an accessory to turn on only when the motor is running.
I figured hooking it up to the fuel pump relay will be the best solution - Anyone know how to do this?
Alternatively, are there easier wires I can splice into? Suggestions are very welcome.
I got a 2000 XJ 4.0
Thanks!
Thread Starter
Member
Joined: Dec 2016
Posts: 175
Likes: 4
From: RSA
Year: 2000
Model: Cherokee
Engine: 4.0
I'm going to get flack for this, but I'm wiring in an HHO (hydrogen on demand) system.
Basically the hydrogen cell can only be powered whilst the engine is running, as its designed to burn the hydrogen as its being produced.
Storing or creating a build up of hydrogen is dangerous, it has to be used as its created ie. whilst idling or driving.
The HHO system must only be switched on when the engine is running and not, for example, while the ignition switch is on to listen to the radio etc.
Opinions on HHO aside, where would be the best place to wire this? My wiring skill is limited, but I'm pretty good at following instructions
For the record, I'm still sceptical about HHO, I've literally taken a punt at it - if it works awesome, I'll post a thread on it. If not, I'll be one of the many haters online.
For now I just need help wiring it, so any advice on this would be appreciated.
Basically the hydrogen cell can only be powered whilst the engine is running, as its designed to burn the hydrogen as its being produced.
Storing or creating a build up of hydrogen is dangerous, it has to be used as its created ie. whilst idling or driving.
The HHO system must only be switched on when the engine is running and not, for example, while the ignition switch is on to listen to the radio etc.
Opinions on HHO aside, where would be the best place to wire this? My wiring skill is limited, but I'm pretty good at following instructions
For the record, I'm still sceptical about HHO, I've literally taken a punt at it - if it works awesome, I'll post a thread on it. If not, I'll be one of the many haters online.
For now I just need help wiring it, so any advice on this would be appreciated.
Thread Starter
Member
Joined: Dec 2016
Posts: 175
Likes: 4
From: RSA
Year: 2000
Model: Cherokee
Engine: 4.0
Member
Joined: Apr 2018
Posts: 201
Likes: 1
From: Northern Canada
Model: Cherokee(XJ)
Engine: 4.0 Renix
Thread Starter
Member
Joined: Dec 2016
Posts: 175
Likes: 4
From: RSA
Year: 2000
Model: Cherokee
Engine: 4.0
The vehicle manufacturers haven’t entertained it because there is absolutely no insentive for them to.
It doesn’t benefit them whatsoever to spend the time and money to redesign a tried, tested engine design that is accepted by the masses. Plus I’m sure they wouldn’t want to upset the balance between oil companies and government as it would surely implicate them. Bottom line, there are a million reasons why vehicle manufacturers haven’t explored this avenue.
If you have time, perhaps give this a read.
https://www.sciencedirect.com/science/article/pii/S1110016815001714
Its a relatively recent published piece in a scientific journal about the effects of HHO in an internal combustion engine.
The trouble with hho is that it takes a fair amount of fiddling and one single setup and tune doesn’t always match every vehicle it would seem.
Either way it’s set up in my vehicle and wether it works or not, I’ll be reporting back on a fresh thread.
And I’ve figured out how to wire that relay, thanks.
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Seasoned Member
Joined: Oct 2017
Posts: 473
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From: Western Washington
Year: 1990
Model: Cherokee
Engine: 4.0L Renix
Interesting, look forward to the write-up. I would not mess with the fuel relay, to easy to set up something coming off of, say, the orange or yellow wire off the ignition switch, or simply wire in a separate relay to a switch, wire the HHO to a blank fuse in the fuse block, off you go with an easy, reliable relay driven component!
Thread Starter
Member
Joined: Dec 2016
Posts: 175
Likes: 4
From: RSA
Year: 2000
Model: Cherokee
Engine: 4.0
Interesting, look forward to the write-up. I would not mess with the fuel relay, to easy to set up something coming off of, say, the orange or yellow wire off the ignition switch, or simply wire in a separate relay to a switch, wire the HHO to a blank fuse in the fuse block, off you go with an easy, reliable relay driven component!
So just to clarify this is what this is the wiring diagram for the kit.
You'll notice that there is already a relay provided in the kit - The connection from the fuel pump relay is simply from the signalling pin to the HHO cell relay signalling pin to tell it when to power the cell directly from its own fused connection to the battery, would this not be ok?
Having said that I'd prefer not to use the FP relay if its dangerous - "to easy to set up something coming off of, say, the orange or yellow wire off the ignition switch" - Does this wire only become active once the engine is running, or is it hot when the key is in the ACC ON position?
It is imperative that the wire I tap into is only charged when the engine is running as I don't want to be creating a hydrogen build up with the motor off for example whilst, for instance, listening to the radio because...well...KABOOOOM!
CF Veteran
Joined: May 2015
Posts: 4,481
Likes: 18
From: Arizona
Year: 97
Model: Cherokee
Engine: 4.0
There is some good science shared here about hydrogen...
https://www.cherokeeforum.com/f67/hy...sion-kit-4348/
https://www.cherokeeforum.com/f67/hy...sion-kit-4348/
Seasoned Member
Joined: Oct 2017
Posts: 473
Likes: 17
From: Western Washington
Year: 1990
Model: Cherokee
Engine: 4.0L Renix
000t444e yes you are right. And to answer your question, those two wires connect to the Distributer and coil, so yes will run once the car is on. Fuel relay also turn on during the pre-ignition, same time as those two circuits. So there will always, unless you time it yourself, be some pre-energy supplied, from any of those circuits. Can test this yourself by turning the key on to "run". You will hear the fuel pump kick on before you engage the starter.
Whew that's allot of ***** Wonka crap. The short jist is that you should be able to tap into any circuit that engages during the "run" position of the key and be just fine.
Whew that's allot of ***** Wonka crap. The short jist is that you should be able to tap into any circuit that engages during the "run" position of the key and be just fine.
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