Fulvia mechanical fuel pump fuel pressure

[lancialulu]

Anyone measured the pressure output of a Fispa etc mechanical fuel pump. I know the spec which is c 3psi but is it fairly constant or fluctuating. I put a mechanical guage on the carb feed and saw steady 3psi from the Facet priming pump but wildly fluctuating from the mechanical when the engine was started (electric pump off). It stabalised at 3psi at around 2-2,500 rpm for a while but then went mad around the 3psi mean.

I plan to remove the elctric pump tomorrow and take more readings (and probably buy a red top Facet to use instead).

Tim

[1,6 HF]

Tim,

As I mentioned on the other thread, I no longer run any mchanical fuel pump, so I can't give you any readings. But mechanical pumps will fluctuate somewhat depending on rpm and load conditions. So I'm not the slightest bit sur[rised by your observations.

[Geoff]

Can't speak to Fulvia but a mech'l pump on an Aurelia is very sensitive to setup and to its internal workings. Finally got one with the right pressure (setup w/ gasket thickness just right off the block), but it fluctuated with RPM. New pump didn't do that anymore and is much steadier. So its a combination (I think) of both how it is setup and the condition of the internal bits.

Typically, add an electronic pump (located by the tank) in series withthe mech'l, but have them both running at the same pressure. Use the elec pump to start the car, and in very hot weather, or very high speeds. Setup seems to work well.

FWIW - Cavalitto now supplies a mech'l pump (not sure about Fulvia) with double diaphragms, to protect from the new gas eating up the diaphragm. Also has a priming lever to start the car from cold, like they did originally some 60 years ago....

[niko14311]

Hi Ed (sorry for the hijack!)

But how do you have the fuel system set up?
Just by-pass the mechanical pump all together but leave it attached or have you blanked it off completely or something?

Im guessing you've got some sort of regulator but how do you find it? Do you get alot of over/under fueling?
Thanks

Nick

[lancialulu]

Update.problem solved. I overhauled the mech pump with some NOS metal body flap valves (dont know how I came by them) to replace the seemingly working Fispa valves. I also removed the bypass plumbing and fitted my facet priming pump in series before the mech (fispa) pump. I have this set up (as fitted by a prior owner) on my1600 sport. The engine fired without priming (I had run it the day before) but managed also to pull fule through empty pipes with out priming. A fast test run showed all is well with the world!! Pressure now c 3.5 psi and much steadyer across rev range. Seems I might be in the market for a regulator now, as Solexs only really like c 3psi max even with the S2 fuel return line.

Tim

By the way I think I have the same set up as Ed on my HF1600 with a silver top Facet feeding a filter king regulator and filter bypassing the mech pump. Indeed, prompted by Ed I removed the redundant fispa at the weekend and rebuilt it for the above. I made a blanking plate quickly out of an old fuel pump chopping the mounting section off and filling with metal loaded epoxy!! Dont forget to remove the push rod....

[fay66]

Tim,
I've been very satisfied with the glass bowl "Filter King" that I bought from Demon Tweeks about 6 years ago, and I fitted it to the drivers side (on RHD) inner wheel arch with the mounting bracket supplied, so it's right next to the fuel line, within an easy fuel pipe run to the carburettors.
Besides anything else it stopped a lot of the crud that had been coming from the fuel tank, and you can see how much of it is building up without having to take it apart first.

Brian

[lancialulu]

Brian

I already use one of the glass cylindrical in line filters (no crude in 7 years - as evidenced by the clean tank etc from my low mileage car) before the pump(s). I think something like aSytec line regulator will do. Just got to buy one...

Tim

[fay66]

Brian

I already use one of the glass cylindrical in line filters (no crude in 7 years - as evidenced by the clean tank etc from my low mileage car) before the pump(s). I think something like aSytec line regulator will do. Just got to buy one...

Tim

That's what I tried fitting first off, but the damned thing kept unscrewing itself, and more by luck than anything else I didn't have a fire, binned that one and fitted the filter king, in some way like yourself I've had no crud from the tank in years to speak of, although I still seem to get a bit of sediment from the fuel?
Brian

[lancialulu]

Brian

Interesting. It was recomended by le Colonel... May think again...

Tim

[fay66]

Brian

Interesting. It was recomended by le Colonel... May think again...

Tim

Tim,
I was referring to the glass filter not the sytec unit.

Brian

[lancialulu]

Oh!

Never had a problem with it but will chk as opened it up during all the faffing about....

Tim