fuel flow check with mechanical fuelpump

[barnym17]

It would seem to me a fuel pressure gauge you can see plumbed after the carb would tell you if the pump is sufficient, if it maintains the correct pressure at full rpm and load during a run it is all good.If the pressure is good the volume has to be , because if it isn't the pressure will drop the only way the pump can build pressure is if it is pumping more fuel than the engine can use .

[steve cowan]

thanks to all who posted,
there is some great ideas there
certainly easier to do with an electric fuel pump setup,done it before in the past with good results.
barnym - i have a fuel pressure guage in bypass regulator,after the carb,fuel pressure does not move ever
when i check the idle fuel pressure between the fuel log and bypass return the pressure is the same at idle,going down the road i dont know,cant see under the bonnet
i think the only way to check is set up a electric and a separate tank with mechanical pump still running into separate fuel cell to measure after a quarter mile run

[cjperformance]

Fuel 'pressure' means nothing if flow 'past' needle&seat and n2o jet are not enough. I have seen MANY times where pressure is consistently fine but delivery to the engine is no good.
You need to know pressure AND volume OR pressure and A/F ratio.
Personally , if you are going to use n2o I like to know if pressure & volume are good BEFORE I run at full song and find out needle/seat dont flow enough fuel when it's at full fuel demand and run too lean in the gas!!

[treyrags]

For me, testing gets you in the ball park. In the end you need to be able to maintain your running pressure (whatever suits your setup) at WOT. I have a pressure sensor plumbed into the line that feeds my rear bowl that I data log on an LM-1 unit. It reads to .1 psi. I like to run 5 psi with larger N/S. My pressure usually stays between 4.5 and 5 at WOT. Occasionally it will dip to 2 or 3 psi momentarily and that's when I either have less than 1/2 tank of fuel (probably uncovering pickup) or when it's really hot (90+ ambient probably a little fuel boiling).

[ClassicComp]

Run the line intended for the fuel solenoid to a pressure gauge then plumb the intended fuel jet inline. Run that back to the fuel tank. Make a pass and watch or data log the pressure. Should not change pressure.

[C.A.R.E.]

We did some testing on mechanical fuel pumps for circle track apps awhile back. We pulled fuel from our electronic fuel injection tank to the pump and returned back to our mechanical fuel injection tank that uses two Holley fuel Bowls with .125 n&s that emptied into a 5 gallon fuel jug from the bottom outlet. We ran the motor on the standard Dyno fuel supply. You will be surprised how much less they flow to the jet then advertised. This way the Dyno read how many lbs of fuel was consumed and this is with out forward motion. PS : we marked the jug level and refilled it at the gas station to verify true volume (you can't trust old plastic jugs )