So am I safe to assume that if I keep replacing my filter before the pump at "regular" intervals there is likely no advantage to adding the high pressure type filter after the pump as well? Thanks Pascal "84 Westy -----Original Message----- From: tabe johnson [mailto:xtabe@yahoo.com] Sent: October 8, 2004 5:24 PM To: Vanagon Mailing List; pascal.giasson@GNB.CA Subject: Some Fuel Pump Theory
Some people may not know this yet, so here ya go: Our fuel pumps live under the sliding door, just to the rear of the gas tank. Some Vanagon models come with filters before the pump, some with filters after the pump. Both filter locations have their advantages and disadvantages. The high pressure fuel pumps used on our vans are great at blowing, but are bad at sucking. That is, they can develop >100 PSI of pressure, but can only suck a small amount of (fuel) vacuum. In many other vehicles with similar high pressure pumps, they use TWO pumps: The first is a low pressure transfer pump, which pumps the fuel to the high pressure pump. In our vans, VW chose to put the outlet of the gas tank on its bottom, eliminating the need for a transfer pump. I think they did this for packaging and manufacturing cost reasons. What this means for us is if you have a fuel filter before the high pressure fuel pump, you run the risk of losing fuel flow because the pump isn't able to suck through thge clogged fuel filter. On the other hand, if you have a filter after the high pressure fuel pump, you run the (minor) risk of damaging the pump when it tries to pump marbles or bolts or whatever goodies come in with the unfiltered gas. It has been my experience that the high pressure pump will pump rust, water, and any number of interesting things and suffer no obvious damage. Maybe long term longevity suffers.
--tabe johnson xtabe@yahoo.com '87 Westy ______________________________________________________________________ Post your free ad now! http://personals.yahoo.ca |
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