Thanks Stuart 
Good suggestion. I will replace all the injectors.  I suspect they have over 100000 miles on them.

Dennis Jowell
Scotch Hollow Farm
Newbury, Vermont 

> On May 19, 2015, at 11:48 AM, Stuart MacMillan <stuartmacm@gmail.com> wrote:
> 
> That's not the cause of your backfire, and as long as the plug didn't blow
> out along with the threads, no damage done.
> 
> If you haven't yet, check the timing. It's done at 2000 rpm, so it helps to
> have a helper (see the Bentley). Check for a fuel leak though, I really
> think that's it since it only does it on start up.  First, pull the vacuum
> hose on the fuel pressure regulator and see if there is any gas in it, there
> shouldn't be. Then move on to the injectors.  Personally, I think you should
> just have them all rebuilt, it runs about $20 each from Rock Auto and
> others.
> 
> It might be a good idea to do a compression test too. Engine warmed up, all
> plugs removed, and the throttle held fully open.  Another thing that can
> cause a backfire is an intake valve that doesn't close, but it wouldn't be
> running well if that were the case.
> 
> Stuart
> 
> -----Original Message-----
> From: Dennis Jowell [mailto:dennisjowell@gmail.com] 
> Sent: Tuesday, May 19, 2015 3:10 AM
> To: Stuart MacMillan
> Cc: vanagon@GERRY.VANAGON.COM
> Subject: Re: Start up,back fire?
> 
> Decided to change spark plugs on my new GOWESTY engine and found out that #1
> cylinder spark plug was loose. The compression washer on the plug was not
> compressed and was on an angle with dirt between the washer and plug. Could
> this have caused my backfire issue?
> Plugs where installed by the mechanic who installed the engine.
> Disappointing ! 
> I also changed the distrib cap and rotor.
> 
> Dennis Jowell
> Scotch Hollow Farm
> Newbury, Vermont 
> 
> 
>> On May 16, 2015, at 2:37 PM, Stuart MacMillan <stuartmacm@GMAIL.COM>
> wrote:
>> 
>> Right, but it saves time to first learn if there is a fuel system problem
> at all.  If there is, then you can pinch off the fuel hose to the left
> injector bank and determine which side is leaking, and pinch off the
> pressure regulator vacuum hose to test it.  I hate taking things apart
> unnecessarily!
>> 
>> Stuart
>> 
>> -----Original Message-----
>> From: Vanagon Mailing List [mailto:vanagon@gerry.vanagon.com] On Behalf Of
> Larry Alofs
>> Sent: Saturday, May 16, 2015 10:10 AM
>> To: vanagon@GERRY.VANAGON.COM
>> Subject: Re: Start up,back fire?
>> 
>> It seems to me that if the fuel pressure leaks down too quickly, the cause
> could be an injector, the fuel pressure regulator, or the fuel pump.  The
> first case is more serious than the last two.  You need a way to tell which
> it is.
>> 
>> Larry A.
>> 
>> 
>> On Sat, May 16, 2015 at 11:35 AM, Stuart MacMillan <stuartmacm@gmail.com>
>> wrote:
>> 
>>> Easiest way to do the fuel leak down test is with a fuel pressure gauge.
>>> Bentley says system should hold pressure (30 psi or so) for several 
>>> minutes after shutdown.  If your gauge comes with an open hose 
>>> adapter, slip it over the fuel tap near the distributor, and use a 
>>> clamp.  Otherwise cut it and splice it with a brass barbed coupling 
>>> for other cars. Get the type that drains any residual gas out a 
>>> separate line. Instructions here, including safety procedures: 
>>> https://www.youtube.com/watch?v=QsqBJxKj1KQ
>>> 
>>> Do it soon, backfires are hard on the AFM. I've used mine many times 
>>> over the past 40 years to diagnose fuel system problems.
>>> 
>>> Stuart
>>> 
>>> -----Original Message-----
>>> From: Vanagon Mailing List [mailto:vanagon@gerry.vanagon.com] On 
>>> Behalf Of Dennis Jowell
>>> Sent: Saturday, May 16, 2015 3:19 AM
>>> To: vanagon@GERRY.VANAGON.COM
>>> Subject: Start up,back fire?
>>> 
>>> Question on why do I sometimes get a backfire from my 2.2 GOWESTY WBX.
>>> yesterday I drove the 88 gl Westy an 1.5 hr pulled over to check my 
>>> GPS, shut the engine off. Then 2 minutes later started it and "bang" 
>>> it backfired, it did start. Shut it down and tried again same thing. 
>>> Drove home it didn't occur again. Any thoughts of what is going on? 
>>> The new  Engine has about 5000 miles on it. Maybe to many mice running 
>>> around in there.
>>> 
>>> Dennis Jowell
>>> Scotch Hollow Farm
>>> Newbury, Vermont
>>> 
>