Hi all,
I'm trying to track down why the fuel pressure on my 78 Series II V12 bleeds downs a few seconds after the ignition is turned off. I have so far eliminated various components including the pump itself uo to the fuel rail.
Going back over the rather complex fuel rails a question suddenly occurred to me, why does the car have two totally seperate fuel regulator valves, one on each bank? Wouldn't one do exactly the same job and halve the likelihood of a failure?
Anyway, I'll keep looking for the leak, I have pulled one bank of injectors and they hold pressure on a test bed, but have yet to do the other bank, cold start injectors or fuel pressure regulators. Is there an expected culprit?
Al

 

The PreHE had those 2 rails etc because basically its 2 X 6 cyl engines on a common crankcase.

The FPR units are the most common failure item on these.

A lot of owners have fitted the square HE fuel rail and the single FPR on the B Bank outlet, and never looked back.

Some cars had a one valve in the fuel inlet hose (below the brake booster on RHD cars), some did not.

 

Hi Grant,
Thank you for your reply.
The entire plumbing system of the fuel injection does appear to more resemble a prototype than a production item. How many hose clamps can one engine have? It reminds me a bit of my Triumph T160 bike, great reliability on the track, problematic on the road. Tridents made race records whilst Honda 750/4s made sales records.
I have discovered the culprit, you are correct, it was the fuel pressure regulator on the LH bank.
I blew some compressed air through it and a small piece of debris flew out. It now appears ok. I wish I had of checked the regulators first. Of course it was the last
It did give me a chance to put all the injectors on a test bed and they do seem (visually) ok. You might remember on my long journey to get the engine running after a very long lay up that 5 of the injectors were totally gummed up and took considerable effort to get them flowing.
regards all
Al

 

BEER O'CLOCK IS NOW CALLED.

44C here and North wind to lift the hair piece right off the crown.

Well done on the eventual find.

 

-1C up here with 8" of fresh wet snow. Balmy for me, but I wish I could ship you some of this to help with your fires.

Dave