I was wondering of anyone could help me with a problem that suddenly
developed with my AUDI,
The car is a 1987 Audi 4000s 1.8L
Here is the deal, the car will start for second or two, but will not
rev up, then it dies.
Fuel pump and filters are new.
Strong fuel pressure to the Fuel injector unit.
The injector unit is sending fuel to the cold start valve, but not to
the cylinders, thus the car will start but will not continue to run.
The pressure to the cold start valve is strong, but not a drop to the
I replaced the external fuel regulator with a spare one and checked for
vacuum leaks etc.
I am not sure where to look from here, internally on the Fuel Injection
Unit, or to a relay or other control.
As I stated the problem happened overnight.
Any help would be appreciated.
I have not used a internet group before, do I hope I am doing this
This can be due to vacuum leaks (you checked but check again) or deposits on
the rod above the plate.
Open air cleaner and reach up into the intake just above. The plate should move
but with a little pressure. Don't force it.
Differential fuel pressure sensor (just in front of fuel distributor.
Blown engine management fuse (in the side of the relay box.
Failing engine temp sensor. In the T44s it is called the MFTS and it is located
by the upper radiator hose inlet to the engine.
Like TonyJ said..............it might be a Failing engine coolant temp
Or a fuse in the fuse box. It is positioned to look like a spare fuse and
many times I will find it missing on a vehicle that is not running right if
running at all. 8^o
Examine all of the fuses for any broken ones and stick a fuse in all sockets
Or it could be the ground wire for the fuel pressure regulator is broken and
it should be located at the cold start valve.
Or it could be a defective fuel distributor.
Or it could be a massive air leak at the large intake manifold boots. Maybe
a light engine backfire into the intake system along with the gas pedal
being depressed might have caused a hose/pipe to pop off creating a large
Or it could be the ign switch not allowing power to the systems when it is
in the ON position. Telltale signs would be those red idiot lights not
being ON with the ign ON or while cranking over the engine.
good luck and let us know what happens!
Hello Audi 4000 fuel help still needed
Been busy at work, not much time to work on the Audi until last week.
Still having problems getting this car to run, was wondering if there
are any other ideas out there?
I still can not get the fuel injector unit to shoot fuel into the
injectors. It still fires fuel to the cold start valve, enough juice
to run 3-5 seconds.
I checked all fuses, put new ones in the blank spaces.
I checked the fuel injector air-door, it opened fine.
I replaced the entire fuel injector unit with a used one I had from a
parts lot I bought.
I changed the fuel regulator as well, the one on the injector unit, I
believe this is the "Differential fuel pressure sensor (just in
front of fuel distributor." ,that you mentioned
As far as the "Failing engine temp senso" " the MFTS ", is this the
same as the temperature sending switch? . Could this really keep the
fuel injector unit from firing? Can I bypass this to test it?
There is no massive air leak at the large intake manifold
The ignition switch is fine, it is new, it is getting power to the
fuel pump and other systems
Any help would be appreciated!!
Do you have a repair manual? Even a Haynes (cough cough) could help some.
Remove intake boot off of fuel distributor so you can manually lift up the
Remove injector(s) out of the cylinder head and aim into a container so you
can examine spray pattern.
Remove fuel pump and jump correct wires to run fuel pump continually.
Turn ign on but do not start car.
Pull up on fuel distributor plate to check fuel injector spray pattern.
Tell us what happens?
If it sprays out that is good and you might just need to adjust something or
change a sensor.
If nothing sprays out then I suspect either a bad fuel distributor, bad Fuel
Pressure Regulator, bad wiring, missing fuse, clogged injectors, no fuel
pressure or ????
The ground wire for the FPR usually breaks at the cold start valve.
No the temperature sensor for the gauge is different than the one for the
fuel injection. ;-)
(One out of many daves)
Thanks for the reply,
Yup, I have a good old Haynes manual; read it a couple times...!! I will
get a shop manual..
I did take off the hoses to the fuel injectors and cranked the engine,
nothing comes out, except for the line to the Cold Star Valve that
gives a nice spray to the intake...
I tested this with both my original, and a replacement fuel injector
unit, in both cases, plenty of fuel to cold start valve, nothing to
fuel injectors. I already pulled the plate up as you suggest. still
nothing from the fuel injector hoses
Replaced both fuel regulators, car has new fuel pump and filters,
plenty of fuel pressure to injector unit...
The ground to the cold start valve is fine
As I have tried a replacement injector unit, it does the same thing, I
am thinking it I electrical, fuses are good.
I read the voltage of the fuel regulator that is on the fuel
distributor unit or, it shows 8 v, there is an electrical connection
on the other side.
Something is keeping the Fuel distributor unit from shooting fuel to
the injectors, any other thoughts?
Tell me again about the temp sensor for the fuel distributor, where is
it located & would it stop the fuel injector unit from firing?
This car ran fine until a couple months ago, I changed brake lines &
complete exhaust & then it stopped running...
Any help would be cool..
Not to get too picky or exact, but did you perform the tests like I
Cranking the engine brings other things that could cause problems such as
the ign switch which could, if faulty, lose power to key components like the
FPR, fuel pump, ign system, etc! Even the power could drop below 10 volts
while you are cranking over the engine.
It sounds like you disconnected the lines to the injectors instead of
removing the injectors.
It sounds like you did not jump the fuel pump relay.
Now if you are getting correct power to the fuel system and ign system, and
you have fuel pressure at the fuel distributor, and you pull up on the fuel
distributor plate while the fuel pump is running and you get no fuel out of
the injectors................................then it sounds like either the
FPR or the Fuel Distributor might be the cause of your problem. But I am
just guessing here since I am not sure if power gets lost to the FPR while
you are cranking over the engine.
Bentley is the better manual and you can find them on Ebay sometimes.
(One out of many daves)
Sorry, I was not disrepecting your instructions.....I had run the
tests the way I stated a couple days ago before I read
I will dig in & get the Bently manual
If I could bother you with one more Q... tell me about how to jump the
fuel punp relay, did you mean the pump itself, I did this acouple
timnes when I tested, how do I jump the FPR?
fuse in the top of the fuel pump relay to 'jump' the pump to running. This is a
manual override. Some models may not have the fuse slot on the top of the relay
so if this is the case you could use a jumper wire in the slots of the relay if
you pull it out. Careful, as you know sparks / fuel are dangerous.
One other thought is that some people have traced a no start condition on the
T44s to a sticking decel valve located in the passenger finder and hidden behind
the fuel distributor. when the stick they create a vacuum leak. I don't know if
you even have one on the 4000 and I think that lifting the air plate would have
overridden this issue but thought it was worth suggesting.
Good luck. Dave's the authority.
please do jump in TonyJ! Always a free-for-all conversation! ;-)
I don't think I have ever tried the fuse in the fuel pump relay, although my
old '83 Audi 4000S does not have that type of relay. I have seen that type
of relay before, but I did not have to install that fuse/jumper.
I'll have to remember about the 'sticking decel valve' just in case I
encounter a problem.
(One out of many daves)
The temp sensor (in a coolant manifold) is an input to a box located behind
the glove compartment. An output of that box provides current to the gray
box on the side of the mixture control unit (differential pressure
regulator). More current = richer mixture. Open circuit = very lean
mixture. The proper / quick check is to measure the current through the
differential pressure regulator but that is difficult to do without the test
jig and a solid electrical theory in mind.. I believe the normal current is
in the 100ma range. It's in the books but they make it harder to find as
Doubt that the control box would actually fail unless there has been a major
electrical event. Once I found / replaced an open transistor in the box and
we drove it for years, but I'd purchased that car due to it's having an
electrical fire due to the radiator cooling fan.. Oh those days of $1200
I'd be crawling around under the glove box, looking for where the mice have
been unless you have a Fluke 77 and feel like cutting wires.
Try replacing the temperature control switch which could be sending a
false reading to your ECU hence no fuel in cylinders.
> > I was wondering of anyone could help me with a problem that
> > developed with my AUDI,
> > The car is a 1987 Audi 4000s 1.8L
> > Here is the deal, the car will start for second or two, but
> will not
> > rev up, then it dies.
> > Fuel pump and filters are new.
> > Strong fuel pressure to the Fuel injector unit.
> > The injector unit is sending fuel to the cold start valve,
> but not to
> > the cylinders, thus the car will start but will not continue
> to run.
> > The pressure to the cold start valve is strong, but not a
> drop to the
> > fuel injectors.
> > I replaced the external fuel regulator with a spare one and
> checked for
> > vacuum leaks etc.
> > I am not sure where to look from here, internally on the
> Fuel Injection
> > Unit, or to a relay or other control.
> > As I stated the problem happened overnight.
> > Any help would be appreciated.
> > I have not used a internet group before, do I hope I am
> doing this
> > right...........:)
> > Thanks,
> > Richy Jackson
> If the air plate just above the air filter is stuck the
> injectors will not fire.
> This can be due to vacuum leaks (you checked but check
> again) or deposits on
> the rod above the plate.
> Open air cleaner and reach up into the intake just above. The
> plate should move
> but with a little pressure. Don't force it.
> Other ideas:
> Differential fuel pressure sensor (just in front of fuel
> Blown engine management fuse (in the side of the relay box.
> Failing engine temp sensor. In the T44s it is called the MFTS
> and it is located
> by the upper radiator hose inlet to the engine.
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