Audi 80 1.8s 1986 intermittent lack of power problem

Thread view:

Enable EMail Alerts

Start New Thread

Thread rating:

rich86 - 03 Jul 2009 13:29 GMT

Hi,

I have a 1986 Audi 80 Sport 1.8 injection engine, as of last year it
has had a very intermittent problem.

The problem is that the engine seems to have absolutely no power if
you put your foot to the floor it just has no grunt. I've had to pull
over when it has happened on motorways and when you get off the
throttle it manages to stall itself it has so little power. We suspect
it could be a fuel supply problem as there is no miss-firing, that i
would expect with a spark plug problem. We've gone though and check
all the fuel pump connections but they all seem ok. The strange thing
is that is is a very intermittent problem it happened once a year ago,
about 1.5 months ago and 1 week ago. The only slight pattern is that
it has been running for a bit in stop start traffic, the problem then
occurs a little while after getting going again. All the dials are
normal and it is not running very hot.

Once you stop the car and re-start it it is fine, although it can
start the cycle again after a few miles but not every time. The fuel
take is not running on dregs either but as we thought it was a fuel
supply problem we did top it up with high octane fuel after each
occurrence as it was fine after that, but that could also be as it was
stopped for a little while too.

We've also tried disconnecting the vacuum tube that changing the
timing at higher revs to see if it was that but it made no difference.

Does anyone have any ideas for experienced this problem in the past?

Many Thanks,

Richard

Reply to this Message

ovalking - 03 Jul 2009 14:11 GMT

Fuel Pump Relay?

Not sure of common problems on the A80, but on my A100 the joints on the
relay pcb were cracked. Resoldered.... and had no problems since....

G.

Reply to this Message

dave AKA vwdoc1 - 04 Jul 2009 00:43 GMT

Could there be a loose baffle in the exhaust? I had one in my Passat and it
literally killed all power when it closed off the exhaust flow.

Someone already mentioned Fuel pump relay
Bad or loose fuse in the fuse box. It is usually an unmarked fuse that some
people think is a spare fuse. I have seen many Audis where they had been
removed but the owners wondered why they engine was having problems and the
shops could not find the problem. 8^o
Oxygen Sensor wiring
Bad Ign Distributor Rotor. I ONLY use Bosch rotors!!!!
Weak ign coil
Clogged strainer filter to the fuel pump, if so equipped.

OR....................................
Debris in gas tank that floats over to the pickup causing a no-fuel problem.
When you turn the engine off the vacuum is released and that debris gets
released.
Maybe an inner foil from a Gas Treatment bottle.

JMHO and some ideas! ;-)

Signature

later,
(One out of many daves)

> Hi,
>
[quoted text clipped - 29 lines]
>
> Richard

Reply to this Message

TonyJ - 04 Jul 2009 05:24 GMT

> Could there be a loose baffle in the exhaust? I had one in my Passat and it
> literally killed all power when it closed off the exhaust flow.
[quoted text clipped - 17 lines]
> JMHO and some ideas! ;-)
>

I would suspect the debris in the tank that Dave suggested. Some of the
Audi's from that time had a plastic coating in the tanks that degraded
over time and caused this type of condition.

Open the tank when it is low on fuel and clean any particles with a rag.

Another fix that Audi suggested was to cut the pre-filter off the fuel
pump which causes the debris to be caught in the fuel filter. Change the
fuel filter several times in the if a performance problem occurs and
then the problem should not occur again.

Reply to this Message

rich86 - 04 Jul 2009 09:09 GMT

> > Could there be a loose baffle in the exhaust? I had one in my Passat and it
> > literally killed all power when it closed off the exhaust flow.
[quoted text clipped - 27 lines]
> fuel filter several times in the if a performance problem occurs and
> then the problem should not occur again.

Thanks for your suggestions guys,. I changed the fuel filter a few
weeks ago which didn't instantly solve the problem, unless as you say
it is getting clogged up again. I really hope its not debris in the
fuel tank though as if they have got into the injection system then i
would suspect it would have wrecked it by now.and make the problem
much more regular. Unfortunately i don't think there is a way into the
fuel tank, its a sealed plastic unit so i am not sure how i would get
inside i can try looking in but i don't think i will see much.

As for the fuel pump relay that was our first thought but its very
strange for it to be such an intermittent problem with a relay like
that.

Thanks for all your ideas though i will look into as many as i can.

Richard

Reply to this Message

dave AKA vwdoc1 - 04 Jul 2009 13:30 GMT

On my '83 Audi 4000S I have a pre-filter before the fuel pump AND a fuel
filter (2 filters).
I thought your '86 would also have a pre-filter but you say you changed it
or are you saying you only changed the main fuel filter?
I usually can hear an external fuel pump strain as it can not get supplied
with enough fuel. It gets louder and whines noticeably.

You look inside of the fuel tank CAREFULLY (explosive gasses) with a mirror
through the sending unit hole. This would be a rare problem but when you
rule out all other theories..............(Sherlock Holmes)
My Audi A4 AND my '83 both required fuel pump relays for either starting
issues or dying out issues. The relay was a cheap test which was well worth
it since I HATE to be stuck with a non-running vehicle. <g>

SO CHANGE THIS FIRST!

JMHO

Signature

later,
(One out of many daves)

On Jul 4, 5:24 am, TonyJ <"tonyjnospam at nospam visi.com"> wrote:

> dave AKA vwdoc1 wrote:
> > Could there be a loose baffle in the exhaust? I had one in my Passat and
[quoted text clipped - 32 lines]
> fuel filter several times in the if a performance problem occurs and
> then the problem should not occur again.

Reply to this Message