[T3] Chasing Engine Gremlin - Popping

[Jim Adney]

On 31 Mar 2011 at 14:19, Robert Bills  wrote:

> As some of you know, I recently put a '73 Squareback back in service after
> 14 years of storage by the original owner. Stock fuel injection. 

Sounds like you've got a real winner there. Good job. I recommend that you NOT 
try to warm it up by just sitting and idling for 5 minutes. The best way to 
warm up an engine is to actually drive it under light to moderate load. Of 
course it's best to avoid full throttle until it's had a chance to warm up. 
Warmup at idle runs a somewhat greater risk of excessive richness, which wears 
the rings and cylinders.

I generally get in the car, start the engine, and then put on my seat belt. 
This gives a few seconds for oil to reach everywhere in the engine. Then I 
drive off.

You've already checked most of the obvious things, so let me suggest 2 more 
things to check:

1) Twist the dist rotor CW. It should turn smoothly and freely, and snap back 
quickly when you release it. If it does not, the mech advance is frozen and 
this has a BIG effect on performance. If it does not, I can rebuild it if your 
mechanic can't.

2) With the engine warmed up after a drive, stop and measure the battery 
voltage with the engine running at medium rpm. This should be 14.1 - 14.4 V at 
med rpm. If it is less than 13.5 V, your voltage regulator is worn out and this 
will make the D-Jet run rich. If this is your situation, replace your VR with a 
Bosch 30-019.

If it's too hard to make this measurement across the battery, you can do it at 
the fuse box, where the voltages will be ~1/2 V lower, or at the generator 
where they will be ~1/2 V higher.

FI problems due to worn out VRs are extremely common.

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