Dual Fuel Pump Wiring Diagram.

[AshBhp]

For those who are considering to do this.

 

Credit to my friend Ali from Qatar.

 

Mods please sticky.

 

[SimonB]

The only mod to that I would suggest is to run 1 single power wire to the relays with a single fuse. That way if 1 fuse blows you won't end up with only a single pump running and not notice.

[ajazyasin]

why would you run 2 relays?

[AshBhp]

One relay per pump ensures positive 30amp feed per pump.

[Guest a71ak]

single wire won't take the load of two pumps in my car the wire from battery to relay was completely skinned off because of heat without blowing the fuse ... thats why I went for two and been used for the last 6 years.

 

If one pump fails you should notice a pressure drop in your fuel pressure gauge.

 

 

Regards

 

Ali

[Alex]

single wire won't take the load of two pumps in my car the wire from battery to relay was completely skinned off because of heat without blowing the fuse ... thats why I went for two and been used for the last 6 years.

 

If one pump fails you should notice a pressure drop in your fuel pressure gauge.

 

 

Regards

 

Ali

 

Depends on the pumps, 2x Walbro's draw the same as 1 UK/US spec pump.

 

And as mentioned twin pumps are dangerous as 1 letting go can lead to engine's letting go, as opposed to a single pump setup where the engine would just stop (safely).

 

Out of interest, I'm no electrician, but you say this is for 2x 30amp draws yet the pic has 25amp fuses...how does that work??!!!

[SimonB]

single wire won't take the load of two pumps in my car the wire from battery to relay was completely skinned off because of heat without blowing the fuse ... thats why I went for two and been used for the last 6 years.

 

If one pump fails you should notice a pressure drop in your fuel pressure gauge.

 

 

Regards

 

Ali

 

Not true. You will not notice a drop in fuel pressure - that's what the pressure regulator is for. You would only notice at high injector duty when you are needing the extra flow of the 2nd pump. And by the time you've noticed it would be bye bye engine.

 

Obviously if you run 1 wire and 1 fuse you need to use a new wire, not the stock one! Something like car power amp cable is more than up to it. Walbros actually draw less than 10A, but better safe than sorry. You want the fuse to be rated lower than the wire of course - I think from memory I have a 40A fuse.

[Wez]

Single pump solution is safer, if a single Walbro is not enough go for something like a Bosch 044.

[SimonB]

Single pump solution is safer, if a single Walbro is not enough go for something like a Bosch 044.

 

The Bosch only flows slightly more than a Walbro, 270L per hour rather than 255 IIRC. You simply can't get an in tank pump that flows much more than that, so you either have to go for an external one with all the extra hassle that involves, or twin pumps (assuming you need that much fuel flow of course). I don't see it as particularly risky, I mean how often do you hear of people with pump failures? I can't remember ever hearing of one.

[Guest a71ak]

Alex, 30amps is for the Relays and 25amps in the picture is for fuses which always rated lower for protection.

 

Simon, every time I switch one pump off, in my car my fuel pressure gauge drops from 3.5bar to 2.5 this is a complete 1 bar drop ... Our FPR needs to be re adjusted every time you change the pressure coming from the pumps to mentain the same pressure ... remember it's a mechanical regulator so it's just an ordinary return valve and won't adjust it self to the required pressure every time you change the number of pumps running.

 

Peace

 

Ali