[T3] 71 Squareback MT/FI - Intermittent Engine Stopping

[Jim Adney]

On 10 Jun 2020 at 19:37, Wisconsin Spryers wrote:

> Do you get the 2 relay clicks when you turn the key ON, even when it
> won't start. If so, that's a good sign that the FI is still working. If
> not, then we're looking for problems with the FI power relay. 

> > I hear (and feel) the 2 relay clicks when I turn the key ON.

Okay, then this is not an FI power or ground problem.

> If you hear 2 clicks, try holding the primer switch in the momentary
> "prime" position while you try to start the engine. If it starts then,
> but dies soon after releasing the switch, then your fuel pump relay is
> going bad. I have good used OG replacements. 

> > While holding the switch in the momentary "prime" position I was able
> > to start the engine and it continued running when I released the switch.

Sorry, I guess I wasn't clear: This test would only be useful during one of 
those times when the engine dies and won't restart. If holding the primer 
switch allows the reluctant engine to start, your fuel pump relay is at fault.

> If you have a meter you can use to measure the fuel pump current, that
> might help. If the pump is drawing excessive current, that might cause
> the pump relay to overheat. I think normal current is 4 A or a little
> less. 8 A is definitely too much, and might mean that the pump is
> working against some extra load, like gas residue inside it. Some
> SeaFoam gas additive for a couple tanks might help dissolve that. 

> > I'll throw-in some SeaFoam gas additive. This problem just started after
> > filling up with almost 9-gallons of gas last week.

Hmmm, wonder if it could be water in the gas.... However, that would not go 
away after 10 minutes....

> For the amperage measurement, I connected the meter terminal "87" on
> the fuel pump relay and the wire (I disconnected from that terminal)
> that leads to the + fuel pump terminal. I started the engine and was
> only reading between 1.30A & 1.35A. 

That sounds excellent.

> I'm still using the black Bosch Ignition Coil. And I don't recall if
> the trigger points were my original ones when we swapped out my '73
> distributor for the correct '71 version when "de-frankensteining" my
> engine back in 2018. 

Okay, you have a good coil. Did I rebuild your distributor? If so, I reset the FI 
trigger points, so they can't be part of the problem.

> I have a little rig that you could borrow to watch for spark while
> driving. If the engine stops but you still have spark, the problem is
> probably fuel related. If there's no spark, then you need to look at the
> ignition system. 

> I'd be interested in borrowing your "spark" monitor. I'll be doing a
> few more around-the-neighborhood trips to see if this problem occurs
> again. 

I'd be willing to mail it to you for a deposit of $50. I'd refund $40 when I get it 
back.

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