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Re: [T3] fuel pump did the trick (was vapor lock)


On 21 Nov 2005 at 10:35, David Y wrote:

> I went out and bought a new T3 Brosol pump ($23) and noticed the second I 
> pulled it out of the box that the spring(s) on my old one were shot to 
> hell: I could operate the action with my pinky! I actually thought the new 
> one might be defective/stuck since it took so much more relative pressure 
> to actuate. 

I don't have much experience with the mech pumps, but I thought they were ALL 
rather hard to depress with your finger. It's hard to imagine what would make 
one go this bad. It's usually the diaphram that goes, not the springs.

Will you be able to take the new one apart in the future if necessary?

It's the springs which control the supplied fuel pressure, so your old pump 
would have been putting out an extremely low pressure. While others have always 
pointed out that type 3s take a higher pressure pump, I once calculated how 
much difference in carb bowl filling depth this would make and it was only a 
few thousandths of an inch. I think the fact that your old pump worked fine 
once it was running, demonstrates that pressure is not all that important.

OTOH, if it was also putting out low FLOW, then this might have been making 
your carbs run lean and might explain your engine temp.

Keep watching your temps now and let us know what you find.

> So, the immobilizing vapor lock problem is gone, but is it normal to have 
> to turn a hot motor over a few more times than cold?

I would expect to have some trouble. There's really just no way to avoid having 
some of the gas boil away, which will leave your carb bowls low or empty. Once 
it gets running at all, the pump should fill everything up rather quickly, as 
you observed.
-- 
Jim Adney
jadney@vwtype3.org
Madison, WI 53711-3054
USA

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