I wanted to inform the community about a fuel pump failure we ran into this last weekend on the dyno.
2013 A6 TVS on E85 and Gasoline (car dipped into the 9's previously).
4100 miles, mostly street. Around 2 dozen 1/4 mile passes.
I was re-tuning on a larger pulley and gasoline to drop power down for street use now that the car had run single digits. 4 runs in and everything was fine. 5th run we ran out of fuel at 7200, 6th run ran out of fuel at 6K.
We checked the voltage at the fuel pump (volt meter on the harness under the back seat while making a dyno run) and saw a steady 18.5 volts (JMS BAP at 70%). This verified the BAP was working properly.
Car still drove and ran fine, but the fuel pump is going out and could no longer support 600RW SAE on gasoline with 18.5 volts.
We are not sure if this is an isolated issue or not as this car exhibited fuel delivery issues previously on E85 at the drag strip. We'd originally had the JMS BAP at 21 volts. Dropping it down to 19.5 (75% on the dial) resolved the fueling issue at the time. We are still not sure if it was pump cavitation or something else.
Just an FYI to all.
At this point we are unsure if it's a 'faulty' factory pump, or if it was taken out from head pressure, voltage, or some other cause.
2013 A6 TVS on E85 and Gasoline (car dipped into the 9's previously).
4100 miles, mostly street. Around 2 dozen 1/4 mile passes.
I was re-tuning on a larger pulley and gasoline to drop power down for street use now that the car had run single digits. 4 runs in and everything was fine. 5th run we ran out of fuel at 7200, 6th run ran out of fuel at 6K.
We checked the voltage at the fuel pump (volt meter on the harness under the back seat while making a dyno run) and saw a steady 18.5 volts (JMS BAP at 70%). This verified the BAP was working properly.
Car still drove and ran fine, but the fuel pump is going out and could no longer support 600RW SAE on gasoline with 18.5 volts.
We are not sure if this is an isolated issue or not as this car exhibited fuel delivery issues previously on E85 at the drag strip. We'd originally had the JMS BAP at 21 volts. Dropping it down to 19.5 (75% on the dial) resolved the fueling issue at the time. We are still not sure if it was pump cavitation or something else.
Just an FYI to all.
At this point we are unsure if it's a 'faulty' factory pump, or if it was taken out from head pressure, voltage, or some other cause.