Fuel pressure regulator

Tamos
Posts: 22
Joined: Sat Oct 13, 2018 7:04 pm
Location: Maidstone

Fuel pressure regulator

Post by Tamos » Thu Jun 13, 2019 5:58 pm

Am almost ready to start engine so put some petrol in tanker and ran pump to check for leaks. All seemed ok but a bit later I noticed wet patch on floor. Inspection revealed a very slow drip coming from the breather pipe attached to the top of the pressure regulator. Maybe it will sort itself out when the engine is fired up, it has also been suggested that the regulator is faulty but that I can simply plug pipe without affecting running. Any thoughts?
Attach pic that was taken before engine installed to show type and positioning of regulator.
F8401B86-BDDF-4838-A81A-3365285B7E0E.jpeg

Richard and Pat
Posts: 216
Joined: Wed Sep 26, 2018 2:44 pm
Location: Biggleswade

Re: Fuel pressure regulator

Post by Richard and Pat » Thu Jun 13, 2019 6:55 pm

Well that is well tucked in there Tony, I don't recognise that pressure switch at all. Needs someone with more experience than me.

jtdesign
Posts: 12
Joined: Sun Sep 30, 2018 8:47 am
Location: Peak District

Re: Fuel pressure regulator

Post by jtdesign » Fri Jun 14, 2019 7:31 am

For fuel injection systems the port on the top of a regulator is to provide the reference pressure for its operation. Often connected to the inlet manifold (on a car) for the Guzzis it just goes to atmosphere. If there is petrol coming out of it then there is a fault in the regulator, probably a perforated diaphragm.

John

Tamos
Posts: 22
Joined: Sat Oct 13, 2018 7:04 pm
Location: Maidstone

Re: Fuel pressure regulator

Post by Tamos » Sat Jun 15, 2019 1:57 pm

John, thanks for info. There is very slow drip from “breather pipe” but if it only goes to atmosphere would it still work if I simply plugged the pipe?
Cheers, Tony

jtdesign
Posts: 12
Joined: Sun Sep 30, 2018 8:47 am
Location: Peak District

Re: Fuel pressure regulator

Post by jtdesign » Sat Jun 15, 2019 10:31 pm

Hi Tony.
If the regulator is leaking then plugging the reference port will lead to a build-up of pressure wth the result that the fuel pressure will increase above the required 3 bar value.
Looking at your photograph I can't make out the port arrangement on the regulator but if it has only two main ports (plus the reference port) then the pipe that comes up the bulkhead towards the camera should be the fuel return to the tank, and the feed to the engine should be tee'd off between the filter and the regulator. These regulators work by releasing excess pressure fuel (above 3 bar) back to the tank. If there is no tank return then the pump pressure will be very high and all sorts of things will start to leak.
Apologies if this doesn't make sense as I don't recognise the regulator model and can't clearly see where all of the piping goes, but it does look as though you've configured the regulator in line with the feed to the engine rather than in the return to the tank.

Hope this helps a bit, John

jtdesign
Posts: 12
Joined: Sun Sep 30, 2018 8:47 am
Location: Peak District

Re: Fuel pressure regulator

Post by jtdesign » Sat Jun 15, 2019 10:33 pm

Forgot to say that if you're running a low pressure, carb system then please ignore all of the above.
John.

Tamos
Posts: 22
Joined: Sat Oct 13, 2018 7:04 pm
Location: Maidstone

Re: Fuel pressure regulator

Post by Tamos » Sun Jun 16, 2019 8:28 am

Hi John,
Really appreciate your info. The regulator is std type fitted to Cali EV between 1997 - 2000. It has 3 main ports (plus the breather on the top), the one on the underside being the return to the tank with the horizontal ones being the supply from the filter and the feed to the injectors.
As I have the return to the tank the pump pressure should be ok so hopefully won’t do any damage if I try starting engine with the breather pipe plugged. If this fails will have to source suitable aftermarket regulator - will then regret fitting existing regulator in such a “clever” position.
Thanks again, Tony

jtdesign
Posts: 12
Joined: Sun Sep 30, 2018 8:47 am
Location: Peak District

Re: Fuel pressure regulator

Post by jtdesign » Sun Jun 16, 2019 9:20 pm

Hi Tony,
it sounds as if you have got it all plumbed correctly. The two ports on the regulator for filter and engine will be connected together in the regulator.
I really think you will struggle if the breather is plugged - the fuel pressure will rise and the engine will run rich. Will be OK for a trial run (leave the breather open and catch the drips) but look for a replacement before finishing the car.
I think replacement Cali regulators are hard to find but there are generic fuel injection regulators on ebay for not very much - you will need a pressure guage to set the 3 bar fuel pressure.

Good luck with your build, John

Tamos
Posts: 22
Joined: Sat Oct 13, 2018 7:04 pm
Location: Maidstone

Re: Fuel pressure regulator

Post by Tamos » Tue Jun 18, 2019 6:03 pm

Hi John,
Will try starting with “plug” out. Will then buy aftermarket regulator. There is one called a PR159 which is similar to existing with same ports and costs about £80. Most others don’t seem to have a return to the tank so are presumably not suitable.
If anyone can recommend a type that will work, would be appreciated.
Cheers, Tony

EricStarmer
Posts: 93
Joined: Fri Sep 28, 2018 3:51 pm
Location: USA

Re: Fuel pressure regulator

Post by EricStarmer » Tue Jun 18, 2019 8:56 pm

Hi, Tony - you may find this link of some help

https://wildguzzi.com/forum/index.php?topic=70628.0


Good luck

Eric
Last edited by EricStarmer on Tue Jun 18, 2019 10:38 pm, edited 1 time in total.

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