[T3] engine backfiring

Dave Hall dave at hallvw.clara.co.uk
Tue Jul 31 15:47:51 PDT 2012


Like Jim, I couldn't recall whether grey boots are nearer than black when
working on the engine (belt end), but I think that's the way, with black by
the flywheel end squirting cyls 1 and 3, which agrees with your black wires.


It's just one of those things you know is right, and never change round, so
we missed the possibility.  With the original harness, I think it would be
obvious from the lengths and pre-formed shape anyway.

Dave.
UK VW Type 3&4 Club
===================

-----Original Message-----
From: type3-vwtype3.org-bounces at lists.vwtype3.org
[mailto:type3-vwtype3.org-bounces at lists.vwtype3.org] On Behalf Of Dave Hall
Sent: 31 July 2012 23:37
To: type3 at vwtype3.org
Subject: Re: [T3] engine backfiring

I guess we all overlooked that possibility!

The injectors are paired, and the pairs are identified by grey and black
boots, so you can put them on the correct pairs of cylinders. The grey
injectors fire together, then the black pair.  The fuel is squirted into the
manifold two cylinders at a time and gets sucked in as the intake valve next
opens.

Now yours are on the correct cylinders, it's working OK.  It sounds as if
the harness has been re-made, since the protective boots aren't there any
more, and the wire colours have changed.  Normally they would all be white,
and numbered to identify them.  No problem if it works fine.  

Enjoy your trike!

Dave.
UK VW Type 3&4 Club
===================


-----Original Message-----
From: type3-vwtype3.org-bounces at lists.vwtype3.org
[mailto:type3-vwtype3.org-bounces at lists.vwtype3.org] On Behalf Of
BilDylJ at aol.com
Sent: 31 July 2012 22:49
To: type3 at vwtype3.org
Subject: Re: [T3] engine backfiring

Hi Guys
   I think I stopped my Trike engine from backfiring.
I noticed that the wires leading to the injectors on the right side of  the
engine are black to rear injector and red to the front  injector.. But the
left side was red on rear injector and the black was on  the front injector
{front of engine being where the belt is located.} 
   I switched the wires on the left side to match the  wires on the right
side.The red wires are on the front injectors on  both sides of the engine
now and the engine stopped backfiring. I know it's  confusing but I have
been confused ever since I had the first mechanic work on the engine when it
wouldn't start. It never backfired before he worked on it.  
Maybe the wires got switched when he checked the injectors. Maybe  there
wrong now but the engine starts & runs good now and it don't  backfire
anymore.  
                           Thanks Guys
                                                                           
Bill
 
 
In a message dated 5/21/2012 5:32:10 P.M. Eastern Daylight Time,
BilDylJ at aol.com writes:

Thanks  Guys !! 
I'll check it out.
I thought it might be a problem with an  injector.
I ordered 2 sets of injectors seals today.
I'll try that 1st.  I don't think the injectors are bad.
The engine runs strong when your  accelerating.
Thanks Again.
Bill Doyle   





In a  message dated 5/21/2012 7:17:10 A.M. Eastern Daylight Time,   
dave at hallvw.clara.co.uk writes:

Mine  backfired with flame(!)  occasionally after I put in a NOS injector.
After a  week or two it  stopped doing it - I figured the internal seals may
have  shrunk and  were leaking a bit of gas, and had swollen up to  seal
better.   You may find yours cures itself now, having been in use  for  a
while.

Dave.
UK VW Type 3&4   Club
===================

-----Original Message-----
From:   type3-vwtype3.org-bounces at lists.vwtype3.org
[mailto:type3-vwtype3.org-bounces at lists.vwtype3.org]   On Behalf Of Jim 
Adney
Sent: 21 May 2012 02:02
To:   type3 at vwtype3.org
Subject: Re: [T3] engine backfiring

On 19 May  2012  at 19:02, BilDylJ at aol.com wrote:

>   I have a  old home  built trike with a 1972 type 3 fuel injected 
> engine with manual  trans. The Trike ran good for about 2 yrs. Buy I 
> had to  store  it covered over outside for a month and when  I got 
> back, It would  not  start. I got it started but now  the engine is 
> backfiring.  It seams to run  good when you  are heavy on the throttle 
> but  when you hold it at a steady  speed,  like 30 mph and just give 
> it enough fuel to hold  that speed the engine will backfire 
> continually,
always from the same  side muffler.

1) Check the hose  from the intake air distributor  to the pressure sensor. 
If
it has fallen  off, it will act like  this.

2) Get a copy of the Bentley Type 3 service  manual. That's  the ONLY place
I
know of that will give you the right tuneup   proceedure for the '72. It's a
PITA, and different from all the other   years.

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

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