Fuel System Upgrade - 1985 GL1200 Limited Edition CFI Model

In keeping with my long term retirement project, my '85 GL1200 Limited Edition CFI model, I have embarked on a few projects. the latest that I am still working on is the OEM ECU Replacement/Upgrade. To complement this project, I have decided to upgrade the fuel system to newer, smaller and just as effective components. The main reason for this upgrade is the loss of fuel rail pressure, but more importantly, the air infusion into he fuel rail when the fuel rail pressure dissipates. Air is not the friend of a fuel injected engine, and as such, I am out to change this.

There is not a lot of space to work with, but there are options and work arounds - most newer components are for the automotive sector, much more space available for installs. The upgraded system will incorporate a Russell non-return valve and a Russell 40 micron fuel filter. The non-return valve will prevent fuel from leaking back to the fuel tank through the fuel pump. The OEM fuel pump has a small pintle non-return valve, but after 37 years this is not as non-return as one would like.

The OEM fuel pump crates another issue, in that it is not compatible with the newer fuel banjo bolts/connections because of the OEM fuel pump outlet design; however, the OEM fuel pump outlet banjo bolt/connector can be used with an aftermarket fuel pump. Your choice on whether to change fuel pumps or not.

The connectors I am using are based on the "AN" fitting. These are easy to use and can be taken apart and reused. This picture is a representation of what I am/will be using:


I have installed an aftermarket fuel pump that is supposed to have an integral non-return valve. Even so, I will be installing an in-line non-return valve. The upgrade will have the fuel filter and non-return valve installed in the fuel hose between the fuel pump and fuel injector rail. The fuel filter will be installed first, then the fuel non-return valve, then connect to the injector fuel rail. Did a better job of installing this pump second time round. I would like to install a better fuel pump pre filter - remove the small cone filter that is generally fitted in the fuel pump inlet, but the fuel pump inlet is not conducive to the various "AN" fitting - :

This picture is a better representation of the fuel pump outlet connection:

I will also be installing an adjustable fuel pressure regulator. This will be the subject of another small project, but suffice it to say that the reason for this mod is all about fuel system pressure and how the new ECU will respond.

More to follow regarding this small project, waiting for a couple of fittings to come in.

Adjustable fuel pressure is a good option to add ...on my vettes ...it's somewhat like a adjustable fuel jet ...the fitting are like what I used ...the deal on my mind is proper mixing of the ignition timing and fuel timing ...it takes a certain amount of luck to part mix In this environment

Thanks for the comment. The Speeduino ECU takes into account fuel and ignition timing. Lots to consider when starting from scratch regarding the new ECU.

Another issue that affects fuel pressure and fuel supply is the aged fuel hose from the fuel pump to the fuel filter and fuel rail. The hose is well past the best before date, is extremely soft/pliable. Much like brake and clutch lines, swelling of the fuel hose can affect fuel system pressure and supply. Replacing these fuel hoses should be considered as a must do when replacing a fuel pump, or when doing initial maintenance after purchase.

I AGREE DEALING WITH FUEL PRESSIRES 10X MORE THAN CARBS IS A HIGE CONSODERATION ...SOME OF TJE STUFF OUT THERE NOW DAYS IS ABSOLUTELY INSANE PRESSURE IN DIRECT INJECTION INTO COMBUSTION CHAMBER ...

Fuel system pressure retention once the engine is stopped is the only indicator we have to determine whether the fuel system is filled with fuel or air. My intent with this work is to keep air out.