[T3] Need help with erratic no start/start condition

[Jim Adney]

On 27 Sep 2011 at 11:58, Norman Roush wrote:

> My daily driver '68 Squareback with MT and FI has recently developed
> an erratic no start condition.  Car will start and run fine for
> days/weeks.  Ran errand this AM.  Car started fine drove for about 20
> mins.  Stopped for 15-20 mins and restarted fine and went home. 
> After 20-30 mins tried to start car but turned key, heard relays but
> fuel pump did not prime.  Checked relay, fuses and elect connections
> at pump.  All appeared OK but pump would not run.  Waited 30 mins
> while working on options, tried again, pumped primed OK and I drove to
> work.  I do not think I really "fixed" anything.  This sequence has
> happened 3 times in last 5-6 weeks.  I live in Sunnyvale, CA so
> heat/humidity is not a problem.  This has happened at 9:00 PM when it
> was cool.  Any suggestions? 

When you say, "Pump did not prime," do you mean "pump did not run?"

If you can hear both relays click, first check the fuel pump fuse 
(next to right on your '68.) Make sure the element isn't cracked and 
making intermittent contact. Sometimes spinning them in their holders 
makes better contact.

When troubleshooting problems like this I've often hooked a voltmeter 
between the output terminal of the fuel pump relay and ground. It's 
important to see that voltage is getting out of the relay. Sometimes 
it doesn't, even if you can hear the relay click. And sometimes you 
only get partial voltage; you should see a full 12 V.

Check the fuel pump wiring connections under the dash, both ground 
and to the relay.

Check the connections to the pump itself. Make sure they aren't 
corroded so much that contact is iffy.

-- 
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Jim Adney, jadney at vwtype3.org
Madison, Wisconsin, USA
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