BBi Fuel Pressure Testing

When one removes the crossover

When one removes the crossover line, one has to get a shorter banjo bolt. The original one is long to accomodate "2" banjo fittings.........one of which is the crossover line. I used a short 14mm head bolt from the TR FD!!!!!!!!!! Well, it worked.

I only did the right side:

Primary Pressure = 5.5 bar

Cold WUR Pressure = 0.6 bar, with electrical connector off.

Warm WUR Pressure = 2.8 bar, after about 5-7 minutes, with the electrical connector attached.

When I applied some vacuum to the base line, the warm WUR pressure rose to 3.5........release of pressure and it fell to 2.8. I didn't measure the vacuum, but more applied and the pressure went beyond 3.5 bar. There is a larger line, which lowers the control pressure when vacuum is applied..........? The larger line comes off the top of the WUR, and the smaller diameter line comes off the base of the WUR........purpose of these lines?

Turning off the pump, the primary pressure dropped to 3.2 bar, and stayed there.......3.1 after 10 minutes.


I had the fuel injection lines disconnected from the fuel injectors and saw no leaks.

Keep in mind that I was not able to start the car from a cold sitting.

BTW: Ambient air temperature is 39 degrees F. I have read that the colder the air, the lower the cold control pressure........thus a reading of 0.6 bar.......does this seem a little low?

Hi Hank,

.6 is way to low..

Hi Hank,

.6 is way to low...way out of spec. the lowest possible in spec reading would be 2.6-2.8 warming up to 3.2-3.4...

run the test again to make sure you have performed the test correctly and those are 'in fact' the readings.

Like the saying goes, "repeatable, verifiable results.

and yes you must use a shorter fitting...

JRV: OK.......I gave it my be

JRV: OK.......I gave it my best shot. I re-tested the left side, and then went back to the right side, and re-tested it.......this time I even used vacuum, per manuals.

Both WURs are acting the same, under all conditions.

Applying vacuum (16" Hg) to the cold pressure raises it from 0.9 to 1.4 bar.

Applying vacuum (16" Hg) to the warm pressure raises it from 2.4 to 3.1 bar.

Residual pressure from the warm WUR, with fuel pump off is either 3.2 or 0.8.......sometimes it goes to one value, and other times, to the other value. What is strange that this is happening to both WURs!!!!!!!! Comment?

Also strange is when I read primary pressure and turn off the fuel pump.....the reading either goes to 3.4 or 0.7, again, on both sides!!!!!!!! Comment?

Why can't comething that is broken just STAY broken!!!!!!!!!!

Just giving some thought to th

Just giving some thought to the situation. Since the "low to high to low, etc." residual pressures, both from primary pressure and from the warm pressure occurred on both sides, I am thinking that either fuel testing gauge is off, or, both accumulators are bad. The latter is unlikely, so I am thinking of the former.

I ordered a new WUR and accumulator. I will test the new WUR, just to see what the readings should be.......then I will keep it as a spare.

Tomorrow I will do a fuel pump volume test. This will measure the amount of fuel coming out in 30 sec from the fuel return line, going to the tank........should be about 850cc. I will report the readings.

I was hoping to take the car to Chicago this weekend, for Easter. Oh well!!!!!! I will visit Continental Motors while there (a Ferrari dealer). I will see what they have. Since I have 2 Ferraris, and BOTH are down now......it just seems appropriate that I get a "third" one........haha.