stalling

My 89 Audi 90 quattro has this strange problem. It starts right up and runs strong for about 25-30 min. Then it stalls out. Start it right back up and it will do it again. No matter how much you press the
accelerator it will make its way to stall in a few seconds. the fuel pump does tane to make a louder buzz as it warms up. I feel that the pump is not the problem becasue I drove a CIS Jetta for 3 years that did the same thing. Any ideas.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Intermittent fault in the hall effect module (distributor)?
Maybe a current load heats up the fuel pump relay causing it to fail then recover when it cools.
Differential fuel pressure switch on the front of the fuel distributor can be intermittent.
Vacuum leaks?
Clogged fuel filter?
snipped-for-privacy@comcast.net wrote:

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
I just had another idea. In the 80's the T44 series had a problem with the inside of the fuel tank (lining) flaking off and clogging the intake screen of the fuel pump. The problem had the same symptom as you describe. Later in the series the tank was changed to a molded plastic with no liner which cured the problem.
If your 90 has one of the tanks made like the T44's tanks this would be my best guess as the source of the problem.
The factory recommended fix for the problem was to pull the fuel pump and cut off the intake screen. The result is that the particles are pumped through to the fuel filter. After that you should change the filter several times in the next six months or so.
Tony wrote:

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Ouch! This seems harsh! I'd worry about damaging the fuel pump like this, would I be wrong?
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
That is the factory recommended fix and A number of people on the T44 Audi forum have used the fix to correct the problem.
Before you take this as a solution be sure to check if your tank is one that the lining flakes off from and see if you have crud in the bottom of the tank.
don't worry about the pump itself, the screen is in a plastic cage that surrounds the intake. The pump itself can easily handle the crud being forced through it.
Av wrote:

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

I don't know about the slightly earlier 90, but my later spec 80, and my older mk2 GOlf (the mk1 golf used to suffer from rotten filler necks) both have plastic tanks. I'd suspect the 90 would too.
The problem does sound similar to the hall sender issue my mk2 did suffer from though.
--
Jon B
Above email address IS valid.
  Click to see the full signature.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Motorsforum.com is a website by car enthusiasts for car enthusiasts. It is not affiliated with any of the car or spare part manufacturers or car dealers discussed here. All logos and trade names are the property of their respective owners.