CIS Problem?--AGAIN!!!--SOLVED!!!

Ben Swann benswann at
Tue Dec 26 13:17:18 EST 2006

You absolutely need to relay the fuel pump - A fuse on the power lead to the
pump should blow rather than smoke coming from the fuse box.


-----Original Message-----
From: L DC [mailto:ldc007usa at] 
Sent: Tuesday, December 26, 2006 11:33 AM
To: Ben Swann; 'Cody Forbes'
Cc: quains at; quattro at
Subject: RE: CIS Problem?--AGAIN!!!--SOLVED!!!

Took some time to sort out but finally found the
culprit on the NO start issue with my '86 5KTQ, which
thought is was related to CIS.

It turned out to be a bad fuel pump even though I had
installed a BRAND NEW one to begin with to fix the

Car literally ran less than 5 miles and some 35
minutes at idle to check for leaks.

When I went to start the car 3 days later, all I got
was a spark and smoke emanating from the fuse box in
the rain tray.

I dismissed being a fuel pump problem for long since I
had installed a NEW pump and went on to checking the
wiring harness leading to the pump. The car always
started with starting fluid so new it was not a matter
of spark/timing or air.

At times, the car would get power to the pump and at
other times it wouldn't (now I know it was because the
fuel pump kept on blowing off fuses, but not every
time I attempted to start the car, weird). 

That led me to believe the wires were shorting out
perhaps due to a kink in them somewhere along their

Again, I did not think of the fuel pump being the
culprit for the already stated reason.

To find out for sure if the problem was in the wiring
harness, Cody suggested applying direct power to the
fuel pump in this case by using the power source from
the trunk's little light.

Pump did nothing.

I removed the NEW fuel pump and installed a spare one
I had gotten at the junk yard a while back and

Then engine fired right up!!!

I was still applying direct power via the trunk's

The next day, I checked the fuse box and noticed the
fuel pump fuse was blown out yet again, due to the
previous pump. I replaced the fuse, hooked the wiring
harness back on they way it should be and again the
engine started right up. I have started the car many
times since with no problem so far.

I got 2 leaks to deal with now, one from one of the
power steering hoses connection and the other from the
oil hose that runs from turbo to oil cooler.

I want to thank Cody, Ben, Huw, Denis, Kent and all
others who pitched in to help solve the no start/CIS

-Happy Holiday


--- Ben Swann <benswann at> wrote:

> Yes - watch them weep.  Have a set on hand  - Plan
> on replacing them when you do this so as to not have

> to pull them twice.
> The Quantum injectors will not work.
> Break down and buy new injectors.  This is a penny-
> wise pound foolish using old injectors in these.  I 
> have even seen some relatively new ones be bad.
> I said the same thing when I owned my first 5ktq's. 
> Then I found I was wasting more time on diagnosing 
> than just to replace them outright.  If you know 
> they are not nearly new - do it!
> Ben
> -----Original Message-----
> From: L DC [mailto:ldc007usa at] 
> Sent: Tuesday, June 27, 2006 5:02 PM
> To: Ben Swann; 'Cody Forbes'
> Cc: quains at; quattro at; 'Ben
> Swann'
> Subject: RE: CIS Problem?--AGAIN!!!
> Thank You Cody and Ben.
> Ben wrote:
> >I know in theory - the fuel leaked into your
> > but that leaked fuel is now condensed on the 
> > manifold, and the line pressure has leaked down.
> > Therefore no spray.  It can take 10-15 seconds of
> > cranking to get them charged up again.
> So, can I test for leaky injectors, by, say, pulling
> and placing them in a receptacle to collect any fuel
> sprayed while cranking engine and then let them sit
> and see if they leak (provided I crank engine long
> enough to build pressure if none there) ?
> Yes, pulling them can be a PITA, even when using the
> appropriate tool and big ass screw drivers, as I
> found out when I did that job on the head rebuilt of

> my VW QS. The O-rings had "crystallized" and were
> pliable as rubber should.
> I have a complete set of used but good injectors
> from an '87 VW Quantum Syncro which share the same 
> drive train as the Audi 4KQ.
> I assume they're similar injectors as the ones in
> 5KTQ, so I could swap them to see what happens? 
> I'm not trying to be cheap or anything, but I don't
> want to go and spend more on new injectors unless
> certain that's the culprit.
> Thank you all again!!
> South FL where it's been raining on and 
> off just about everyday for the past month,
> him to open the hood and get to the bottom of it
> all. 
> --- Ben Swann <benswann at> wrote:
> > Not sure what the specific question is.
> > 
> > As I mentioned, old leaking injectors can and will
> > cause hard starting.  I have had this problem on
> > just about every 5kTQ that I have owned or worked
> > on and other CIS cars as well.  Usually among the
> > contributing reason folks get rid of the cars. 
> One thing leads to another and the leaking injectors

> > causes a domino effect on things -too much draw on
> > starter and wiring leading to other failures, etc.
> > 
> > The fuel pump valve and accumulator will cause a
> > loss of system pressure if they are defective, and
> > can also result in line leakdown, but usually this
> > is not the problem.  If you replace your injectors
> > and that does not fix then look at doing these.  
> > 
> > Fuel pressure and leakdown tests can tell you
> > something, but hard to do and difficult to prove a

> > leakdown is not happening with the test equipment.
> > 
> > O-Rings go along with this fix and the combination
> > does wonders.  Of course getting at all those old 
> > vacuum lines may help as  well.
> > 
> > Ben

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