ImprezaRSX

iTrader: (1)

As you probably know I've been having fuel problems.

Could someone please fire up their car and feel the fuel line?

I know it sounds funny, but my fuel line pulsates A TON. I'm not sure if this is a normal thing or not, but it seems like it would create abnormal fuel pressures.

With the car idling, the fuel pump is screaming (which is pretty typical of Walbro pumps) however the discharge is.... very...

bang bang bang....

not a smooth feeling at all.

Please check your car and let me know if this is normal.

Best place to feel is right off of the fuel filter. Just grab the line and squeeze.

Thanks a ton!!!
Dominic

mario

iTrader: (7)

Man that sucks maybe you bought the wrong Walbro fuel pump??
I heard there were to types one that was the one you want and the other to steer clear of

IS2Scooby

iTrader: (3)

Most modern electric fuel pumps will "pulse". That's why there's a fuel pulsation damper on most fuel rails.

Have you screwed in an EFI fuel pressure gauge to see what you've got at idle, at rev (no load), and at load?
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IS2Scooby

iTrader: (3)

P.S. Just came back from feeling my hose at your request... Errr, well - anyway - yeah it pulses like a ****.
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ImprezaRSX

iTrader: (1)

k thanks.

I'm trying to get rid of as many things as possible.

If it wasn't supposed to pulse I was going to say fpr or pump.
But the oscilations lead me to think maybe it is a controller problem. Of course it could still be any of those things.

I'm going to put a RB25 FPR on there tomorrow to see what happens. They bolt right on the fuel rail.

IS2Scooby

iTrader: (3)

Have you measured voltage to the pump, current draw, and fuel pressure yet? Can you monitor AFR? IDC? MAF signal voltage? These are all things we look at when determining idle quality/surging/driveability concerns.
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IS2Scooby

iTrader: (3)

By the way, the "pulse" you feel is not the pump doing anything out of the ordinary - it's the opening and closing of the injectors in unison that sends low pressure reverse shockwaves through the fuel (from what my tech. teachers told me).
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Huby

iTrader: (2)

i have a walbro pump you can come feel my fuel lines if you want...let me know

hugh

ImprezaRSX

iTrader: (1)

unison?

so we aren't sequential?

I went out again last night and I felt the fuel line on the injector side of the filter and it pulsated.
Felt the line on the fuel pump side of the filter and it was smooth.
Some logical reasoning told me it was either injectors or fpr.

gpatmac

iTrader: (3)

My dumb butt has to chime in. I thought they were sequential, too.

IS2Scooby

iTrader: (3)

I didn't use the right word. They do fire sequentially right at the time that the intake valve opens for each intake stroke (VERY QUICKLY) - you simply can't feel all the pulses individually. You feel a pulse AS IF the injectors were firing in unison.

P.S. This is a pretty techy. discussion - Alex and Cliff are going to be a bit ticked on the recent flood of tech. posts I think.
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gpatmac

iTrader: (3)

It's my fault.

I'll be the fall guy on this one (and the other 2)

ImprezaRSX

iTrader: (1)

no, I believe this was my question.

However, we can blame it on you if you want because it usually is you!!!