Fuel pressure flux

[drawson]

I was out and the freewaya and was doing some full throttle run and noticed that as the RPMS get above 2500 the fuel pressure really fluxs bad. On some older gasser with fuel injection we would add an accumulator between the fuel pump and the injectors and they would make better power and get better fuel milage. What I remember from way back when is these old gasser didn't have any where near as much flux.



I am thinking we could just get an accumulator that would screw onto a modified banjo bolt on the outlet from the fuel filter housing.



What do you think???

 

[illflem]

Dee, I assume you mean fluctuation. Do you think larger fuel lines might help? Sort of sounds like the lift pump can't keep up with the IP. An accumulator will only help for very short periods of time.

 

[drawson]

Bill, Yes Flux is my two finger typing way of saying fluctuation. The Pressure seem high enough, well at least at the top of the flux. the needle bounces from 15-32 above 2500 and it is getting worse the higher it goes. Even at cruising throttle position I see some flux say 4-6 psi. A new overflow valve I put on a couple of weeks ago help the flux alot, but I want more.

I am thinking this would help the injection pump deliver the same amount of fuel to each delivery valve. I am also thinking that the flux would airate the fuel some also.

 

[illflem]

Dee, I think you may be worrying about something that's a minor concern. If you are pulling your fuel pressure from the IP banjo bolt you will see more flux (you're right it is easier!) than off the fuel filter. I think this is due to pulsations from the IP. My solution would be to crank down my fuel pressure gauge needle valve snubber a little more. Put one in if you don't have one. You know how it goes, out of sight out of mind.

 

[BigYellowIron]

What should the pressure be at idle and under load?



Bill, BTW I have the stuff for the gauge now!



Adam

 

[illflem]

Adam, 18 - 22 psi at idle, 20 - 28 at full throttle.

 

[BigYellowIron]

Well I have 15- 20 at idle then if i raise the rpms to 1800 it goes to 30psi. Then i checked it on level ground full load and full throttle and i got 10 psi.



Adam

 

[illflem]

Might want to change the overflow valve, 10 psi is too low.