Fuel Pressure Regulator Question

[Guest RACRX]

What looks to be the fuel pressure regulator on the right side of the gas tank,,has an exposed fitting right below the fuel return line. Is there supposed to be a vacuum hose or something connected to this fitting??? Doesnt seem like it could vary fuel pressure according to engine load with out a vacuum connection to the engine. Thanks for any clarification on this.

[pete roper]

Yup, that's what it is and on most cars that I know of it is connected to the manifold. Why it isn't used on Guzzis, (Or any other similarly equipped bike?) I don't know. Perhaps it is simply that the demand for fuel isn't so great as to cause a radical drop in presure in the elivery system when the throttle is cranked? I seem to remember tehre was a discussion on this subject over on Phil's forum a while back. It might be worth doing a search over there.

 

pete

[Paul Minnaert]

you can connect it to one inlet maniforld, it will make things more smooth from what I heard. Easy to try. I had a scura that had it, but never tried without.

[Guest RACRX]

I seem to remember tehre was a discussion on this subject over on Phil's forum a while back. It might be worth doing a search over there.

 

Pete,, where might i find Phil's forums?

 

Thanks

[Guest ratchethack]

you can connect it to one inlet maniforld, it will make things more smooth from what I heard. Easy to try. I had a scura that had it, but never tried without.

FWIW, I tried it for awhile on my Sport - just to experiment. Made no perceptible difference whatsoever.

[pete roper]

Pete,, where might i find Phil's forums?

 

Thanks

89245[/snapback]

 

http://morini.com.au/phpBB2/index.php?sid=...37cc3c1dab9c837

 

I may be wrong about that, not absolutely sure, but I think it was there

 

Pete

[Dan M]

What looks to be the fuel pressure regulator on the right side of the gas tank,,has an exposed fitting right below the fuel return line. Is there supposed to be a vacuum hose or something connected to this fitting??? Doesnt seem like it could vary fuel pressure according to engine load with out a vacuum connection to the engine. Thanks for any clarification on this.

89238[/snapback]

 

Seems like if any FI setup could use the variable pressure it would be an open loop system like we have. I don't know why they would use a vacuum operated regulator and then not apply vacuum. If nothing else it should lean the mixture slightly with closed throttle. Next time I have the MG at work I'll check CO content at idle with & without vacuum applied. I'll attach a fuel pressure gauge as well and see what the pressure difference is.

Stay tuned...

[dlaing]

Lean popping durring decelleration might be a symptom that it is working.

If it does not pop, it may save fuel mileage, egxspecially in on and off again throttle traffic and twisties

[Guest ratchethack]

A regulator needs a reference. This open loop application uses ambient. Seems to work just fine.

[Guest RACRX]

The plugs on my bike have a darker color than i would have thought on an efi engine. With out vacuum on the regulator,, fuel pressure would be at a constant high pressure causing a richer mixture at idle. At least thats how it works on efi autos. Just a mystery why MG felt a variable fuel pressure was not needed on this aplication.