In tank fuel pump retrofit. The worrying bit!

[MarkWebb]

Not sure if anybody else is going to install the pump controller. Following the install of one (not by myself but based on my recommendation) yesterday. I have discovered a slight problem with it.
The controller uses PWM on the negative side of the pump to control the speed/pressure. It is imperative to check that the pump body is not connected to the negative terminal and if it is the pump body must be isolated from any connection to ground. This may include a path to ground through the braiding on the fuel lines as well as obvious bolts to chassis. The in tank pump kit that I am using specifically isolates the pump from the tank. At this time it appears that the Bosch 044 body is connected to the negative terminal. A simple rubber sleeve around the pump to isolate the brackets should cure the connection to the chassis. Not yet sure if the pipe braiding is an issue!!

[Steve_D]

The pipe braid for both inlet and outlet will also connect to negative.

Does the PWM have to work on the Negative?

Steve

[MarkWebb]

Problem now solved. unit working perfectly. Fuel pump body was touching body panelling causing a different earth route. Interestingly & surprisingly the braided fuel lines are not causing a problem (maybe only because anodising acts as an insulator).
I am not sure if all PWM units work on the negative. There may be an electronic reason for it because all of the ECU's that I have worked with do the same i.e. they switch the earth connections off and on for the injector pulses and switch relays using the negative. Electrician yes but electronics not my forte!
If braid becomes a problem. Easy enough to pull back a bit at pump connections and heat shrink to isolate from pump.

Edited by MarkWebb on Tuesday 14th July 10:56

[k wright]

k wright said:

This was a big factor that delayed my entry to EFI, the need to retrofit a high pressure pump inside the tanks.

After Holley released the 12-920 it was a done deal. The pump is smooth and quiet and easily fitted outside the tanks.

https://www.holley.com/products/fuel_systems/fuel_...

It is an external pump that is mounted at the bottom of the tank. My external mounting point is at the frame rail and as a result will be lower than any in-tank pump so I think it will be fine. The specifications are there to allow comparison to other pumps. It is capable of delivering high pressure for EFI.

I have a bad habit of taking the most direct route on projects like this. If the pump goes bad (it is likely made in china (like all other things) then it will be easy to replace it).

I have one pump for each tank that join via a Y connector that follows a one-way valve in each feeder line.

[k wright]

Another option that will make retrofitting a pump for EFI easy:

https://www.radiumauto.com/Standard-Fuel-Surge-Tan...

Edelbrock also makes a very well designed EFI surge tank pump....but it looks like it is made of plastic!

The goal is to leave the low pressure system in place and use it to supply the high pressure pump housed on the surge tank (similar to a dry sump oil tank).

Radium has options for single and double EFI fuel pumps.

[MarkWebb]

Yes good solution. I believe that AB have been doing it like this for a while.

[GtrMan]

I got one like this from Nuke Performance , very well build from Aluminium , billet type and anodized.. and they are based in Europe

http://www.nukeperformance.com/products/fuel-surge...