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Old 03-29-2015, 08:58 AM   #31
T-Bolt Racer
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Default Re: Failing Fuel Pumps

John gave me some advice to put a return on the regulator with a jet to take out the cavitation,I also run a T-Bolt 5 years on the same pump a BG 400 go though the traps at 8000
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Old 04-11-2015, 02:08 AM   #32
screamingchief
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Default Re: Failing Fuel Pumps

Quote:
Originally Posted by Tom Nolan
Aeromotive guy said the little bit extra hose will not cause cavitation! Only way to have cavitation is to suck air....the hose is full.
Not remotely true.

Sure the extra hose may not be a problem,but there are plenty of other ways that fuel can/will cavitate/aerate in the lines w/o "sucking air" as he states.

Also not too sure I would take advice from someone that does'nt know better than to say something like that.

Quote:
Originally Posted by Sean Marconette
Cavitation can be caused by a low pressure area at the inlet of a pump and fluid will boil. With the pump mounted where g-forces are acting on the pumps ability to have fluid being pushed into it on acceleration it may be the problem for the mechanical failures. We run into similar problems like this on open hydronic systems.
This ^^^^.

Gasoline has a very low boiling point @ atmospheric pressures & temps,that's why it evaporates as rapidly as it does.

See,it's like coolant in a cooling system,raise said system pressure,you've just raised said fluids boiling point.

Lower the system's pressure below ambient pressure,you've just lowered said fluids boiling point.

Any restriction on the inlet side of the pump will inturn cause negative pressure (ie: vacuum) thus lowering the fuels boiling point,and yeah it can & will boil the fuel in the lines and that absolutely can & will lead to aeration/cavitation issues,that's just basic fluid dynamics @ work.

Fighting G forces,use of hard 90° fittings (or sharper),using too fine of an inlet side filter (<100 microns),using a filter with insufficient surface area,using improper hose size,inadequate system venting,all will be "seen" as a restriction to the inlet side of the pump.

All can lead to cavitation/aeration issues.

And cavitation/aeration left uncorrected absolutely will cause pumps to fail.

Funny thing is even Aeromotive says so in their tech bulletin #TB-101 on their website...

Quote:
Originally Posted by Aeromotive Tech Bulletin TB-101
Aeromotive fuel pumps are engineered to be efficient, and can create both high outlet pressure and high inlet vacuum. The boiling temperature of any liquid varies with pressure. For example, the engine’s cooling system is purposely designed to pressurize the coolant in order to raise the boiling point. So how does this apply to fuel delivery?

When a fuel pump has to pull through a restriction to get fuel from the tank a vacuum develops which lowers the fuel’s boiling temperature, cavitating the fuel and turning it from liquid into vapor.

Bottom line: Inlet restrictions create vacuum, which causes cavitation, which in turn causes vapor-lock and fuel pump damage.
So it would seem the Aeromotive tech guy needs to read his own co.s tech bulletins and absorb said material more fully.

I prefer/use the Product Engineering pumps,and follow his (John Rademacher) system recommendations to the T.
(someone already posted the diagram in an earlier post,and do note that he advises no 90° fittings on the inlet side whatsoever)

FWIW ~ HTH

Bret P.
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