golf 1.8 no power

[and]

I have an '85 1800 gti (DX engine) golf that has suddenly lost it's power. At all throttle openings it's struggling to gain revs, anything more than a tiny opening and it splutters a bit and the revs start to fall.

I can hear I'm at least one cylinder down but don't know whether to start by checking fuelling or electrical. I'm not losing water or oil so I don't think head gasket.

Aside from an earth strap between the body to the bonnet falling off before the journey it started to play up on nothing unusual has happened.

Any suggestions where to start ? I'm tempted to begin with distributor cap / leads / plugs ?

[deltaf]

Sounds like a huge vacuum leak to me. All the symptoms including a misfire.
Check all the vacuum pipes that connect to the carb/manifold before going any further.

[and]

turned out I had a fuel filter full of sludge and bugger all fuel pressure. i guess i should clean out the tank really..

[and]

The fuel filter change sort of worked for about a week (it really needed doing anyway) but now it's as bad as ever.

Checked all the vacuum pipes - seem okay, ran forte cleaner through the injectors & CIS which didn't really help, but now it doesn't even seem so much like a fuel system problem anymore..

Intermittently it sometimes runs perfectly hot or cold for a while, then it's messing around refusing to rev up, misfiring on different cylinders, not starting for a few attempts but then idling okay. Revs dropping when tapping the accelerator. Though it sounds bizarre I'm sure it smells funny too..

The spark plugs look good, the leads look okay. Does this sound like a knackered coil ?

[nel]

Change the plugs - unless you KNOW that they haven't done many miles. After about 12k miles the triple electrode plugs on the Gtis stop working properly - the central electrode is by then a bit triangular rather than round. This always manifested itself by the engine stuttering and failing at even minor throttle openings.

Best of luck

Nel

[and]

Still stuck on this... To cut a long and painful story short my Golf spent 3 months (!!!!) at a 'specialist' who allegedly cleaned the fuel tank & lines, changed the fuel neck, filter, metering head, dizzy cap, rotor arm & injectors and then gave up.

The symptoms (still) are:

- If you leave the car on the drive for days it will start first time and run relatively smoothly (perhaps the odd flutter) for about 5 minutes, then it chokes splutters and dies as it warms and won't start.

- If you try to start it within 8 hours it fires on the first crank for a second then cuts out. Then it won't start on either the second or third try, but catches on the fourth. Like the fuel system is struggling to maintain / re-pressurise.

The RAC man who recovered me most recently ran some tests and we found :

- Strong sparks, ignition system is fine. Engine starts and runs fine on Quickstart into the inlet manifold.

- Fuel pump is running although I don't know if enough pressure is being delivered or whether the pressure delivered remains constant as the engine /pump warm up.

- Found some dirt in the replacement metering head so either it was in the metering head when fitted or dirt is still coming through the filter. I'm going to change the filter for the 3rd time before going any further.

- With the engine cranking and the airflow sensor held wide open there is NO fuel coming out of the metering head to the injectors. ... but if you crack the return pipe off the metering head and retighten the engine will run (almost) properly for 5 minutes.

- Bypassing the warm up regulator makes no difference.

The suspects are:

- Weak fuel pump / blocked pump filter
- Duff replacement metering head
- Intermittent fuel pump relay

Subjectively it feels like when the system is under pressure the pump can't force enough fuel through to start the engine or keep it running, but when the pressure drops either by leaving the car standing for a day or by releasing the return pipe the pump can cope for a while...

I've got a fuel pressure gauge being sent to me later this week so any advice on troubleshooting what's happening with or without the gauge would be most appreciated !

Andy

[edc]

If you ask on CGTI I'm sure fellow owners could crack this one for you.

[deltaf]

Ahhhhh its a K-jetronic system?
Why didnt ya say so?

Ok, specs are as follows.

CO% level- (EG,YS,YH)=1.5%
(DX,KT,JJ,EV,GZ,YZ,DZ,MU) 1.0%

Delivery Rate- fuel pump with screw type terminals-(1976-82) 1.5 litres minute(2.7 pints)

Fuel pump with push-on terminals-(1976-82)-1.8 litres/min
All models for 1983- 1.8 litres/min(3.2 pints)

Main system pressure.
All models(1976-82) 4.5-5.2 bar
1982--> 4.7-5.4 bar

Control pressure, engine cold.
1.8 engines.
@20 deg C 1.0 -1.4 bar
@25 deg C 1.2 -1.7 bar
@30 deg C 1.3 -1.9 bar

Control pressure, engine warm.

After 2.5 to 5.0 minutes- 3.4 -3.8 bar.

Warm-up regulator electrical resistance- 20-26 ohms

Can give you more than this if needed but will most likely need to scan it for you.
HTH

[steve_D]

Have you checked to see if the return pipe is clear.
Can't see how cracking the joint would alter anything unless it was blocked.
Steve

[and]

thanks for the info deltaf & steve, sounds like before I get my pressure gauge I can check the fuel return is clear, and the delivery rate on the fuel pump is correct.

Is there a trick to bypass the fuel pump relay and keep the fuel pump running for 30 seconds or so while I measure my 1.8 litres / min without having to keep the engine cranking ?

Then I can check this little lot when I've got my gauge.

Main system pressure.
1982--> 4.7-5.4 bar

Control pressure, engine cold.
1.8 engines.
@20 deg C 1.0 -1.4 bar
@25 deg C 1.2 -1.7 bar
@30 deg C 1.3 -1.9 bar

Control pressure, engine warm.
After 2.5 to 5.0 minutes- 3.4 -3.8 bar.

Thanks for your help,

andy

[deltaf]

Bypas the realy by removing it and then applying a "Jumper" wire across the switched terminals.
Thatll fire the pump continually and the engine can be off with no need for cranking.
Terminals 87 and 30 are the ones to bridge.
hth.

[and]

tvm I'll try that tonight

[nel]

Just a thought Andy - how full is the fuel tank? My mk2 Golf Gti started stuttering and dieing once the fuel tank level dropped to half full. This was rectified by replacing the lift pump in the tank - this supplies the suction side of the HP fuel pump that pressures up the injection system. It also has the advantage of being relatively cheap and a piece of piss to change!

Best of luck.

[and]

i filled it right up and still have the same problem.. meanwhile I'm awaiting the arrival of my pressure gauge so maybe I'll get to find out what's going on soon

[weed]

You might have leaking injectors, or constant on cold start injector or its control, or at any rate, an overrich mixture.
car starts and runs ok when cold because it needs more fuel to run(cold fuel means poor fuel vapor to ignite). When it warms up, the mixture is too rich (or wet) to burn so the spark is gradually snuffed out.
When cold, the cold start valve squirts extra fuel for starting and maybe a few seconds of cold running, then the thermotime switch cuts power to it. But if it is not having the power cut or is leaking, then the mix is too rich for requirement.
The mainpump, may have been weakened by having to strain its guts out trying to suck fuel thru a clogged filter but this would be evident at times of high rpm/demand.
m.

>> Edited by weed on Sunday 1st August 15:11

[and]

weed said:

You might have leaking injectors, or constant on cold start injector or its control, or at any rate, an overrich mixture. car starts and runs ok when cold because it needs more fuel to run(cold fuel means poor fuel vapor to ignite). When it warms up, the mixture is too rich (or wet) to burn so the spark is gradually snuffed out. When cold, the cold start valve squirts extra fuel for starting and maybe a few seconds of cold running, then the thermotime switch cuts power to it. But if it is not having the power cut or is leaking, then the mix is too rich for requirement. The mainpump, may have been weakened by having to strain its guts out trying to suck fuel thru a clogged filter but this would be evident at times of high rpm/demand. m. >> Edited by weed on Sunday 1st August 15:11

I've replaced the injectors so should be okay from that perspective.

Did the checks I could yesterday without a pressure gauge and the pump is delivering the right volume. However after 5 mins running fuel stops being fed from the metering head to the injectors - just dries up.

So (i think) either my pump is unable to maintain pressure or my replacement metering head isn't working. The pump does sound like it's labouring but i've never had reason to go listen to it when it's running normally..

[weed]

There's a hidden 3mm Allen screw on the Flat of the airflow sensor unit between the fuel metering head and the airflow sensor mouth.
You can drill through the aluminium plug just enough to thread a screw into it a little ways, then clamp on a pair of mole grips and yank it out. Don't drill too far because there's a steel ball bearing beneath it that will skew your drill bit off center.
Then you can use a 3mm allen wrench to turn the screw 45 degrees anticlockwise to lean the mixture while the engine runs. Either way, Idle should speed up to a point if the engine likes a leaner mixture. If there's no change fiddling with this idle mixture screw then the plunger in the metering head might be sticking.
You probably have a control pressure regulator near the oil filter flange... see if there is 22 Ohms resistance at the terminals of the regulator. It functions as a temperature dependent control of fuel pressure.
m