Fuel Pressure gauge : Install

[Steve Webb]

Had a few hours in the garage this afternoon to get a few jobs done, including fitting the fuel pressure sender and wiring it into the gauge.

All the extra bits and pieces were bought from Demon tweeks in the UK.

Adaptor to break into the existing fuel line:
http://berlinasportivo.com/forumpics/fuelpres/adaptor.jpg

Sender unit in place, sealed with Teflon tape:
http://berlinasportivo.com/forumpics/fuelpres/senderunit.jpg

This is where the adaptor needs to fit in:
http://berlinasportivo.com/forumpics/fuelpres/std.jpg

Luckily I've got a separate switch on the fuel pump power line so I can isolate the pump and then turn the engine over to remove all the pressure from the fuel line.
With all the pressure out, I removed the fuel line from the regulator and added a new piece of fuel hose to this side of things:
http://berlinasportivo.com/forumpics/fuelpres/pipework.jpg

Then its just a case of putting the adaptor in place and wiring the sender unit in. This involves one of my least favorite jobs. Running wires through the bulkhead!! I've already some extra wires and water hose for the waterspray kit running through there so its quite tight:
http://berlinasportivo.com/forumpics/fuelpres/bulkhead.jpg

And the Alfa wiring on the inside doesn't help:
http://berlinasportivo.com/forumpics/fuelpres/interior.jpg

All went fairly well and this is what it looks like in place:
http://berlinasportivo.com/forumpics/fuelpres/fitted.jpg

Back to the interior, here are the gauges, firstly when everything is off:
http://berlinasportivo.com/forumpics/fuelpres/off.jpg

And switched on:
http://berlinasportivo.com/forumpics/fuelpres/on.jpg

All in all not to bad, but I'm not happy with the location of the sender or the quality of the electrical connectors under the bonnet. A couple of things to look at in the future.

[santino]

Nice job! :)

Is there any difference if you wired ground via cable direct to the gauge or wired to the closer place under the bonnet?

[Steve Webb]

I've not tried that yet. I'm going to rig up a short earth strap to ground the sender under the bonnet and take some measurements.

At the moment the gauge reads 2.4bar with the engine off and 2 bar with the engine idling.

[santino]

hmm...

Should't 2.6 - 2.7 bar on idle?

Over 2000 rpm should be about 3 bar?

[Steve Webb]

I'm not sure what all the figures should be, but the workshop method of measuring fuel pressure is done with the ignition on BUT the engine not running.
The figures for that measurement should be 2.5 Bar.

I would have thought that any rise in fuel pressure would be a function of inlet pressure rather than rpm.

[jimnielsen]

yes, its a function of manifold pressure - the reg is connected to the manifold pressure source. just set the fuel pressure to 2.5 bar static - ignition on, engine off.

jim.