Date: Tue, 31 Jul 2007 05:23:27 -0400
Reply-To: Sam Payne <bungeegull@HOTMAIL.COM>
Sender: Vanagon Mailing List <vanagon@gerry.vanagon.com>
From: Sam Payne <bungeegull@HOTMAIL.COM>
Subject: Re: screen in gas tank?
Does his '85 van have a plastic pre-pump fliter (goes inbetween the
tank outlet and fuel pump?? This was discontinued on '85 up vans, because
it restricts fuel flow to the pump. There are differing opinions about
this in the archives, but it did happen and was causing problems on my
van. Another possiblity is that the fuel outlet line in the gas tank is
plugged or kinked--replace the tank if so.
In either case, when the pump can't suck enough fuel through the
plastic filter it cavitates and starts pumping air into the fuel. Fuel
pressure and fuel delivery amounts may still read good, but only takes a
little air in the fuel to cause varying idle, sudden semi-stalls, etc.
I jumped the fuel pump relay so the fuel pump ran with the engine off
and could clearly hear the pump process a burst of air, then suck better,
then cavitate and push more air through. It's quite noisy. I do believe
that many of the listees noisy fuel pump complaints come from restricted
flow to the pump. I could also hear and feel the bubbles pass through the
fuel line by pinching the return hose between my fingers. Replacing the
prepump filter made no difference. I cut the used prepump filter in half
and found that the inlet is very restrictive, and also forces the fuel to
pass around the sealed tin end of the filter element as soon as it enters.
Not suprising it cavitates, the engineers were on vacation.
On my Van (an '86) the tank outlet is 8mmm, but the pump inlet is
12mm. I have heard that earlier vans had a 12mm tank outlet, which should
flow much better. Why VW engineers reduced the later tank outlet, I don't
know. I'd guess that between reusing a tank designed for aircooled buses,
getting laid off, and maybe bad beer that year, they just blew it. Bear
with me a moment, I have to vent: the vanagon fuel delivery system is
CRAP. I have owned only old vehicles, this system is by far the worst
designed, most difficult to work on, and most dangerous. Got that off my
chest. Sorry.
So I threw out the prepump filter, as specified on later vanagons,
went down to the local hardware store and bought a 3/8" brass hose barb
(5/16" is closer to the correct size, but I wanted FLOW), threaded it into
a 1/2" hose barb, and so adapted the hose diameters that way. About $6.
Your friend's '85 may have a 12mm tank outlet, so no need to adapt if so.
1/2" fuel hose works for the 12mm stuff, 5/16" for the 8mm.
I would recommend ditching the prepump filter and adapting the hose
diameters if necessary. If the pump still cavitates, check the tank
outlet. If it is restricted, you may have to replace the gas tank too. I
did, which was not a joyful experience. Replace and carefully check all
the grommets and seals before reinstalling the tank--if they pop off gas
spills all over, potentially barbecuing you.
Once fixed, the engine runs well, solid idle, no more speed variations,
loss of power, etc. And the fuel pump runs quietly.
Good luck, Sam
On Thu, 26 Jul 2007 09:52:57 EDT, Alan Hosage <UCMYVW@AOL.COM> wrote:
>Still trying to help friend that has 85 westy. The van does sit for
periods
>of time. It will run and drive fine but periodically it just looses
power
>and he has to pull over and feather gas till it gets going again. I
have not
>checked fuel pressure yet but plan to. He told me that his fuel pump
whines,
>(I am not sure if this is constant or periodically), and from my previous
>post it was suggested that it is a fuel delivery problem. The pump,
filter,
>and relays have been replaced. I am wondering where the screen is
located and
>if it is accessible without dropping the tank? Is it internal or
external?
>By the way the van sits inside, does not get driven in rain or snow, but
I am
>not sure if he stores it with a full tank of gas.
>
>Thanks,
>
>Alan H.
>Mountain Top, PA
>2-87 Syncros
>03 VW Jetta TDI
>90 Audi V8 Quattro (for sale)
>98 Ford Contour 24v V6
>_www.rustedbarncandles.com_ (http://www.rustedbarncandles.com/)
>
>
>
>
>
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