Normal for Aeromotive Eliminator pump to make varying noises?

[dville_gt]

Never had a huge pump like this before. Is it normal for a big ass pump to make differing noises, not just a consistent humm. If the idle falls the pump changes sound. Since I bought the pump used I am trying to figure out if it is okay. Fuel pressure stays constant, but it seems like it changes sound with the need for fuel or something. Normal?

[turbostang]

Yes. When the engine idles down the voltage drops because of the alternator turning slower.

[Beenfetchedlately]

I'm glad you have the patience to respond to all these silly questions Brooks.

[TrueStreetMotorSports.com]

You may have a step down box to keep the pump cool. Basically it runs less power to the pump durning normal driving to keep big pumps alive on the street.

[dville_gt]

I'm glad you have the patience to respond to all these silly questions Brooks.

I am also appreciative that Brooks takes the time to answer, this weekend was the first time I got my swap started and I was probably abusing the forum a bit trying to get some of the issues that popped up resolved as quick as possible, the largest pump I've previously ran was dual 255 and inlines (t-rex) and if they sounded like this there would be no question that they had failed. Granted I've been running with very low fuel since there is not point in filling it at this point (been fighting a leaky Summit fitting and my third replacement will be here today so I am hesitant to fill it knowing I will just have to turn around and drain it) so that could have something to do with the strange noises that the pump has been making since with very little fuel >2gallons I could be experiencing cavitation I suppose.

On Sunday night after I was putting it in the garage I was testing the tach wiring and noticed that the pump was having trouble building up pressure and when it would it was low >40psi and was fluctuating. I assume that since I had so little fuel in the cell it had started boiling, but I supposed it could also be this used pump is on it's way out (hense the silly post).

You may have a step down box to keep the pump cool. Basically it runs less power to the pump durning normal driving to keep big pumps alive on the street.

Yes, I have looked into these a bit. I figure (from both advice I've received here and my unwillingness to drop coin on a part that I might not need) that I would try running without the step-down box and see if keeping the cell fairly full would keep everything cool enough to live. Since this car is a weekend cruiser/track toy I do not plan to spend much time idling through traffic. If they'd bring the price point down a bit from $350 I might be more interested, but at this point it seems like just another part to break.