vacuum reference on regulator - Page 2 - Lateral-g Forums

**camcojb** · #11 05-26-2009, 04:48 PM

I have never had the pressure "hunt" like yours when everything is correct and working properly. It's possible the pump is going, or there is some sort of restriction at the inlet, either in the tank or filter. Also, if the voltage is fluctuating the pump will speed up and down with the volts going up and down.

Jody

67ragtp · #12 05-26-2009, 05:01 PM

Jody,

Thats a good idea, I will put my voltmeter on the terminals at the pump and monitor it. I have a relay mounted in the DSE shock crossmember and ran 8guage wires from the battery back to the relay, because I didnt want to take a chance of not supplying the right voltage /current. I really tried to do this right, thought I bought the best parts and really over killed the plumbing for a 500hp engine. I wonder if aeromotive can do a load test on the pump.

Thanks again for your help- Rich

**GregWeld** · #13 05-26-2009, 08:04 PM

I'm no expert - at anything - but I was told that the vacuum reference port on the regulator should be open to atmosphere unless you're running boost. These port are for boost reference...

They should NOT be plugged or blocked however. Just open to atmosphere.

**GregWeld** · #14 05-26-2009, 08:21 PM

One thought on the high engine room temps -- this really shouldn't affect your fuel temps - since these are RETURN style systems the fuel is flowing all the time - returning to the nice big tank! If it was a closed system with no return - ala the old carbs etc - then I could see the fuel / heat being a problem.

Just my 2 cents... which isn't worth a nickel.

**GregWeld** · #15 05-27-2009, 06:48 AM

Checking with my expert - he says - either way AS LONG AS you tuned it that way -- i.e., if you tuned with the vacuum hooked up, fine.

67ragtp · #16 05-28-2009, 10:04 AM

I spoke with Jarrod at Aeromotive, he thinks its normal for the fuel pressure to drop the instant the throttle blades close, due to a spike in high vaccum seen by the regulator. The important part is that the pressure rises once the vacuum is taken off the regulator for wide open throttle operation and acceleration. I also did a flow test and got 1.5 gallons out the return on 11.5 volts at the pump in 1 minute. Thats over 500lbs/hour, way more than whats needed to supply a 500hp engine.Running voltage is 13.8v which increases flow a lot.
It appears the filter was the reason it was not rising, a restriction in flow, Ive found out that a fuel system is at its dirtyest when its new especially when a new tank is also in the equation. Jarrod told me he's seen them clog up in 100 miles from new. contaminants in the tanks and pump during manufacturing along with crappy fuel.

Thanks again for the help and change your fuel filter on those new built cars

Rich