[v12-engine] Fuel Pressure Regulators - Lucas


(Kirbert - author of the Book, former owner of an '83 XJ-S H.E.) #21

Rob Roe wrote:

Any recommendations on which in-line filter would work? I
think the molded hose between the sump and the fuel pump inlet
is 1/2’’ ID.

Any inline filter with 1/2" hose barbs will work. Admittedly that’s
already a tall order, most fuel filters aren’t that large. They’re
available, though.

The length of that hose that could accommodate an
in-line filter is very short, around 2.5’’.

My solution there was to reroute that hose. Rather than going from
the surge tank directly to the pump inlet, I wrapped about three feet
of 1/2" hose in a big loop. That meant I could fit any size filter I
wanted.

Another option, I think, might be to cut the outlet pipe on the
surge tank down to a stub, and connect a hose to that. Not sure how
much it would help, though. If you could find a piece of 1/2" hose
molded into an elbow shape, maybe that would help.

Remember that the whole point is that the filter is replaceable, and
that you toss all the garbage it’s picked up when you toss it –
rather than leaving it in the surge tank. Ideally, you want enough
hose on either side of the filter to be able to pinch it shut. This
makes replacing the filter a snap.

– Kirbert

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(Rob Roe) #22

In reply to a message from Kirbert sent Sun 19 Sep 2010:

Just installed a fuel pressure gauge in the fuel rail outlet
hose to the left (outlet) fuel pressure regulator. The fuel
pressure measures 26 psi with vacuum line connected to the
regulator, and 36 with the vacuum disconnected. Since the
fuel pressure is supposed to read 36 psi, I suspect I have a
problem, but just don’t know what the problem is.
Disconnecting the vacuum line to the right fuel pressure
regulator makes no difference in the fuel pressure.

The left (outlet) regulator is new, but I wonder if it’s the
wrong one (the fuel pump is new as well). I have another
new outlet regulator that is a different Bosch part number.
I’ll install it when the fuel pressure bleeds down and see
what happens.–
87 XJ-S V12 Coupe
Bellevue/WA, United States
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(Rob Roe) #23

In reply to a message from Rob Roe sent Wed 22 Sep 2010:

Just changed the left FPR to the other Bosch number (from
0280160293 to 0280160214. I think the 0214 let the pressure
drop to about 25 from 26, but other than that, is about the
same as the 0293.

Welsh sells the 0214 and Coventry sells the 0293 under the
same Jag part number (73232).

I’m starting to wonder if the right FPR is not letting
enough fuel pressure in from the fuel pump. I have a spare
and might swap it out to see if that makes a difference.–
The original message included these comments:

Just installed a fuel pressure gauge in the fuel rail outlet
hose to the left (outlet) fuel pressure regulator. The fuel
pressure measures 26 psi with vacuum line connected to the
regulator, and 36 with the vacuum disconnected. Since the
fuel pressure is supposed to read 36 psi, I suspect I have a
wrong one (the fuel pump is new as well). I have another
new outlet regulator that is a different Bosch part number.
I’ll install it when the fuel pressure bleeds down and see
what happens.


87 XJ-S V12 Coupe
Bellevue/WA, United States
–Posted using Jag-lovers JagFORUM [forums.jag-lovers.org]–
–Support Jag-lovers - Donate at http://www.jag-lovers.org/donate04.php

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(Rob Roe) #24

In reply to a message from Rob Roe sent Wed 22 Sep 2010:

My spare right FPR gave me the same PSI (26) at the rail at
idle with vacuum lines connected. Fuel pressure at the pump
and at the inlet to the right FPR is 90 PSI. So it’s clear
that the right FPR is restricting fuel pressure from the pump.

Should I replace the right FPR or just remove it and install
hose directly to the fuel rail?–
The original message included these comments:

wrong one (the fuel pump is new as well). I have another
new outlet regulator that is a different Bosch part number.
I’ll install it when the fuel pressure bleeds down and see
what happens.


87 XJ-S V12 Coupe
Bellevue/WA, United States
–Posted using Jag-lovers JagFORUM [forums.jag-lovers.org]–
–Support Jag-lovers - Donate at http://www.jag-lovers.org/donate04.php

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(jim) #25

I am very confused about fuel pressure. I am getting 130psi on the rail. I understand that the rail should be about 35-40 psi. Is this all due to the inlet regulator, or is my pump way too strong?..Thanks…Jim


#26

Whoa! That’s a bit high.

Have you had anyone service it lately? I suspect a crushed or clogged fuel return line. I don’t think that a regulator can jam shut or clog. Best test is to disconnect exit line from the left FPR and route a new line to a fuel can. Run the pump and recheck the pressure.


(jim) #27

Thanks 4 the info. This car has sat in barn 4 ten years, and I am trying to bring it back 2 life. Will try your idea tomorrow. Thanks again…Jim.


(Philip Lochner) #28

I bypassed this inlet regulator on my '84 DD6. (it was leaking fuel out the vacuum barb)

Interestingly, after doing so, the car started MUCH quicker, so quick in fact that I could turn the key to start and release without actually hearing the engine run before releasing. Practical faith…


(ronbros) #29

my fix for the over engineered jag junk,
poly tank NO rust, aeroquip SS flex lines and fittings, shut off valve(so i can change fuel filters), SS steel pump no rust /debris, 13MM ID,lines , custom rails 15MM bore, and Aero design FPR(adjustable pic). just the edge showing? i’ll see if i can find better pix, and my fix for adjustable lean /rich mixture control,100% ethier side of O%.center%20consol%20J%20-bond%20system%20002

YES expensive system but should last the rest of my life!
rontrunk%20XJS%2Cfuel%20system%2C%20union%20jack%20001

.
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