Subject: Re: [Tigers] Fuel pumps - more information for myself

From: Alex Haugland <[email-masked]>
Date: Sat, 31 May 2014 09:10:12 -0700

The AZX 1308 is the same pump used on 3.8 and 4.2 liter E-Types and 
other Jaguars of the same era while the AZX 1307 is commonly used on 
Austin Healey 3000s, MGBs and other cars with smaller engines of the mid 
to late 1960s.  I believe the flow rate is also the same as I'd suspect 
that the AZX 1308 is the pump that is closest to the original spec of 
Tiger pump, as it supplies high performance engines with similar 
displacements readily, but I've so far been unable to find concrete 
proof one way or the other.

You mention that the rebuilt SU pump failed...  The symptoms can be an 
indicator of the problems as well.  If the pump simply and suddenly 
stopped ticking it is a points issue and won't tell you much as to what 
the other problems might be,  but if it kept ticking and was ticking 
quickly with no change of pace, but was still functional, then either 
there is no fuel coming into the pump (i.e. empty tank or line blockage 
on the inlet), there's a leak, or your float isn't shutting off the flow 
of fuel into the fuel bowl for some reason.  SU pumps do not handle 
restrictions in the line from the tank very well, as, if they run dry, 
they can overheat and cook themselves, so you want to have any filter 
after the pump rather than before it.  Likewise, any significant 
blockage in the line from the tank could cause similar issues, and might 
explain why the Carter pump died as well.  You'd potentially have the 
fuel pressure you need as the fuel seeps through the blockage and gets 
pressurized by the pump, but not have the flow you need, especially at 
any point of sudden high fuel demand.  At the same time, the pump is 
working harder to try to draw the fuel through the restriction, killing 
the pump.  I'd think the only really likely place for such a blockage 
would be in the 5/16" fuel line from the balance pipe to the pump, as 
well as the fitting on the balance pipe itself, so it might be worth 
taking it off and making sure it's clear if your problems persist 
without any other obvious cause.

--Alex Haugland
Eugene, Oregon
B9470334LRXFE
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