[T3] Breather cap

[William J]

 I brought up the FPR because of an artical with photo's that deals with the 
rust and also normal wear of the disc that regulates the pressure yet also 
acts as a check valve so if the disc is even worn enough because of the 
pulsations during injectors operating and the pulses the pump create over 
time the regulator will still adjust the pressure fine yet won't seal 
allowing the pressure to bleed off . One my 73 I put a pressure gauge on and 
ran it then shut it down and used two of the clamps one uses to pinch off 
lines . I put one on just the pumps discharge line and after 24 hours it 
still had 4 PSI . Then I removed that one and pinched off the FPR hose just 
where is exits the return hose close as I could to the FPR and it was near 
20 PSI as soon as I removed the clamp it bleed down to 0 PSI. They are not 
cheap and mine runs if I prime it and drives fine and once primed it will 
start right up even after sitting 3 hours and this is because it will hold 
20 PSI for at least 4 hours then slowly bleed down to nothing over night . I 
don't know exactly how long it takes to drop below 20 PSI because I would 
need to stay up 24 hours and keep going down to check it. Not something I 
care to do. I have 30 PSI running and as soon as I shut it off it drops to 
20 PSI which is fine . Even if it held 16 PSI even  less like 12 PSI it 
should still start with no priming like it did about a year ago. I can't 
speak about if mine has rust without cutting it open .
----- Original Message ----- 
From: "Jim Adney" <jadney at vwtype3.org>
To: <type3 at vwtype3.org>
Sent: Saturday, August 26, 2017 2:01 PM
Subject: Re: [T3] Breather cap


> On 26 Aug 2017 at 9:50, William J wrote:
>
>>  What about the fuel pressure regulator ?  I've only seen drawings of one
>> showing what's inside . It has a metal disc and a sort of machined end 
>> bore
>> and the spring pressure against the disc is the actual adjustment when 
>> you
>> turn the adjustment screw increasing /decreasing the pressure on the
>> disc/valve . From what I can tell not ever cutting one open the fuel port 
>> on
>> the side connected to the pressure side of the ring seems sealed from the
>> spring area and one side of the disc other wise fuel would find it's way 
>> out
>> the adjustment screw. What I don't know is when the system is shut down 
>> is
>> if the disc closes all fuel flow to the return . If it does then it could
>> bleed off the pressure.
>
> It's certainly possible for the regulator to be the leak, but in general, 
> they
> don't. The seal is a metal to metal seal between very nicely polished
> surfaces. If water got in there and rusted something, that could cause the
> problem.
>
> A "fix" that Bosch came up with for the big Mercedes V-8 D-jet cars was to
> drill an extra hole in the regulator so it would bleed down instantly. 
> This
> forced boiling to push gas forward in the fuel ring, rather than backward.
> This meant that there was fuel closer to the engine, next time you tried 
> to
> start. I've never tried this solution, as it would be hard to implement, 
> but it
> has always seemed intriguing.
>
>>  Also reading the post on worn pump brushes and dirt and or water finding
>> it's way into the tank because the over flow hose is cracked . Wouldn't 
>> even
>> rust caused by ethanol based fuel because it absorbs water since these 
>> old
>> systems closed venting is by now shot cause the pump brushes to fail . 
>> There
>> is a filter before the pump some of this crap rust , dirt has to be 
>> trapped
>> by the filter or are we talking very tiny particals the filter cannot 
>> stop.
>
> The internet is full of ethanol haters who will grab at any symptom and 
> blame
> it on ethanol. You won't have a water or rust problem unless excess water
> gets in your gas tank. This can happen if you drive with your gas cap off, 
> if
> you drive in the rain with a cracked overflow hose, or if you happen to 
> buy
> gas at a station that has a bunch of water in its gas.
>
> The latter is extremely rare, but it can happen. Even if that happens, it 
> won't
> cause a rust problem unless that water/gas is left in the tank for an 
> extended
> period, months or years. In normal use it gets mixed up with the gas and 
> is
> pumped thru the engine harmlessly. A larger bubble of water might cause a
> momentary burp and loss of power, but then it's gone.
>
> By far, the most common water problem in our fuel systems is due to the
> overflow hose, which has always cracked by now. When these cars were
> newish, I typically had to replace them every 2-4 years. The OE hose just
> didn't last very long. I've drained as much as a half gallon of water out 
> of the
> gas tank of a type 3 that had been driven in the rain with a cracked 
> overflow
> hose, until that brought it to a stop. (Water is more dense than gas, so 
> the
> water collects at the bottom of the tank, where the gas pickup goes.)
>
> The Bosch filter has a paper element which captures water, making it hard
> for gas to get thru. This can cause a problem if there's lots of water, 
> but if
> there's just a bit of water, and ethanol in the gas, the water gets 
> dissolved in
> the alcohol and passes. I don't think the filter paper is particularly 
> fine, so my
> guess is that the dirt in some areas contains particles that are fine 
> enough to
> pass thru and still be abrasive enough to stick in the copper and eat away
> the brushes.
>
> -- 
> *******************************
> Jim Adney, jadney at vwtype3.org
> Madison, Wisconsin, USA
> *******************************
>
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