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Topic: Mk 2 1.6 Driver Fuel Problem? (Read 2002 times) previous topic - next topic

Re: Mk 2 1.6 Driver Fuel Problem?

Reply #15 –
Yes, I've now learned that that is the site of a GTI supplementary pump, so the plan is to use such a mount to fix the pump and damp it at the same time.

Still having some intermittent issues, though, and now the fuel supply is OK, it must be something else.  What would be the symptoms of a failing coil?  Can they fail intermittently?  Maybe loose connection in the wiring associated with the coil.

Re: Mk 2 1.6 Driver Fuel Problem?

Reply #16 –
Quote from: Martin109 on
Yes, I've now learned that that is the site of a GTI supplementary pump, so the plan is to use such a mount to fix the pump and damp it at the same time.

Still having some intermittent issues, though, and now the fuel supply is OK, it must be something else.  What would be the symptoms of a failing coil?  Can they fail intermittently?  Maybe loose connection in the wiring associated with the coil.
I would put money on it being the wiring that feeds the coil from the ignition amplifier. I feel the factory routing leaves little slack and the cable over the years is stretched and breaks down inside. I found my break with the car running and wiggling the wire about and got a massive shock, not recommended! Best bet is to continuity test the wires at each end with a tester with a built in buzzer. Wiggle the wiring and if the buzzer stops you have found your break. I cut the wiring back past the break and added in a new slightly longer section of wire so it didn't happen again and it has been spot on ever since. Mine still has the original coil from 1990 too.

Re: Mk 2 1.6 Driver Fuel Problem?

Reply #17 –
The under-car fuel pump assembly from a GTI looks like this


But the base of this is the metal bracket it fits onto



This is what fixes to the floor pan using the threaded lugs that are already on your car body.
There are rubber mounts that take out the vibration, so my thinking was if you could get one of these brackets you could mount your electric pump to this then mount this to the underbody of the car in the same way the original equipment would be mounted.

Re: Mk 2 1.6 Driver Fuel Problem?

Reply #18 –
Thanks, EP & Kartman

That's really useful to see.

I'm planning to get Rory in Berkley to do that for me along with some painty stuff.

Would you happen to know a part number for that bracket?

Re: Mk 2 1.6 Driver Fuel Problem?

Reply #19 –
There seems to be a lot going on at the moment with this car!

I’ve recently had a stalling issue where the car would just die when stopping at a traffic light or junction.  Trusty garage decided the carb base plate/gasket was leaking and it needed to be replaced, but they couldn’t get one in time for my next journey, so I had to use the car again and try and work around the same stalling issue.  However, not just this, but on my regular 100-mile journey to Bristol the running got rougher and rougher, and more and more erratic, and I only just got home, with the car refusing to start and I had to wind my way backward to park by using the starter motor.  (Thought the battery would die at that point, so I put it on charge but it was showing the green light in less than an hour).  Phew!

Had to call AA Home Start, we tried starting and it wouldn’t, so he removed each plug in turn and these proved to be wet, so the engine had been flooding.  We thought this might also be a result of the leaky base plate, and once he’d dried out the plugs and vented the cylinders, the car started just fine.  Got back the 100 miles to Slough OK, though not an easy drive, just better than before.

Back in Slough my garage replaced the carb base plate, and enthused about how beautifully the car was running.  And indeed it was doing great around town in Slough.  So I set off again on my 100-mile trip to Bristol.  The car seemed a bit under-powered, and about a third of the way in started running rough and being really low on power, but using more fuel.  I was able to struggle along at around 60 (M4, this is), and then off the motorway at Bristol I really had to work hard to manage it and prevent stalling at lights, fearing I wouldn’t be able to restart.  In fact, I did have to restart a couple of times, which it did, but reluctantly.  Then, suddenly, it was back to normal and running as sweetly as anything again!! Justlikethat! [Tommy Cooper].

That’s strange enough, but what is stranger is that during the nightmare motorway journey, while it was misbehaving, the temp gauge dropped and went right down to zero.  When later the car started to behave properly again the temp gauge was back up to its normal position (first white line on the dial)!

This suggests there’s an intermittent electrical issue going on, which reminds me of your comment upthread @kartman:

Quote
From kartman
I would put money on it being the wiring that feeds the coil from the ignition amplifier. I feel the factory routing leaves little slack and the cable over the years is stretched and breaks down inside. I found my break with the car running and wiggling the wire about and got a massive shock, not recommended! Best bet is to continuity test the wires at each end with a tester with a built in buzzer. Wiggle the wiring and if the buzzer stops you have found your break. I cut the wiring back past the break and added in a new slightly longer section of wire so it didn't happen again and it has been spot on ever since. Mine still has the original coil from 1990 too.

Would the wiring you refer to have any association with the temp gauge sender or the wiring to the gauge itself?  If this is an electrical issue, what would be causing these two things to be happening simultaneously?  Does the wiring you refer to just consist of a single wire or multiple strands.  Where is it on the wiring diagram?

Any ideas gratefully received.
[Edited To replace 'fuel' with 'temp']

Re: Mk 2 1.6 Driver Fuel Problem?

Reply #20 –
Quote from: Martin109 on
Would the wiring you refer to have any association with the fuel gauge sender or the wiring to the gauge itself?  If this is an electrical issue, what would be causing these two things to be happening simultaneously?  Does the wiring you refer to just consist of a single wire or multiple strands.  Where is it on the wiring diagram?

Any ideas gratefully received.
As far as I am aware, the coil wiring has nothing to do with the fuel sender/guage.
From your descriptions however, it does sound a bit like an poor earth issue.
If you have the original battery earth cable it is probably past its best (as it has no covering).
You could try cleaning up all battery contact points, and all the earth points too (battery/gearbox and rocker cover).
A good upgrade is a battery negative cable from a mk4 golf, as that has the connector in the middle, but also is shielded so will not corrode as quickly.
I don't have a diagram to hand but it should be easy to trace the wiring from the coil (should be 2 wires) back to the igniton amplifier, under the drivers side scuttle.
Test for continuity along these, whilst also giving the wiring a good wiggle.
If all of these check out fine that electrically there is not a lot it could be, either: coil, dizzy (hall sender), ignition amplifier.
But seeing as your guage misbehaved too I would definitely check and clean all the earths and cables first.

Re: Mk 2 1.6 Driver Fuel Problem?

Reply #21 –
Many thanks @kartman, that's really helpful.

Re: Mk 2 1.6 Driver Fuel Problem?

Reply #22 –
If I were to replace the wiring between amplifier and coil, what ampere rating of cable should I choose?

Re: Mk 2 1.6 Driver Fuel Problem?

Reply #23 –
Fuel gauge or temp gauge? I think you switch between them in your post so not sure which it is. But I think you mean temp.

If temp, would I be right in thinking the carb if hooked into the cooling system? Sorry, never had a carbed version only ever had GTIs.

My thinking, is could it be a thermostat issue?

Rather than stuck shut which would have different effect if it were stuck open then on the motorway the airflow would overcool the car, putting the gauge to cold. I'm not sure what effect this might have on the carb, but since this in winter, with cold airflow and wind chill on the motorway I suspect it could be carb freeze. And I'm fairly sure there's a coolant supply to the carb which under normal conditions would prevent this.

Other symptoms would be taking a long time to get up to temp.

The gauge should reach the optimal half way mark in about 10 mins. Lots of local small journeys may mask this.

Here's a test you can perform to check for good circulation (although you need the car running reasonably well).

Start the car and let it idle, you can give it some revs if you want to speed up the process.
From the engine bay grasp the bottom radiator hose. It should remain cold, stone cold, and not even start to get warm and be easy to hold for a while with no change.

This will prove the thermostat is closed and the engine is keeping the water within the block till the engine gets up to temp - this is what you want.

If the thermostat is operating properly then at the point the engine gets up to temp, the thermostat will open and very suddenly the bottom radiator hose will get very hot, it's unlikely that you'll be able to hold it for very long. This is what you want, that quick change from cold to hot, as it the tap has been opened.


However, if the bottom radiator hose starts to get warm and warms up slowly from the start then this will prove the stat is stuck open and letting water freely flow around the system. Eventually with the car not moving and on idle the car will get to the correct operating temp. If this is the situation when driving, especially on the motorway, or when freely moving the airflow through the radiator will cool the water before it gets chance to get warm. The engine may never get up to temperature properly under these conditions, although it may in traffic, and overheating will be managed by the fan so this issue can go unnoticed in city cars.

I have had the above on my last two GTI's pretty much as soon as I got them. But on a GTI, the water temp doesn't effect the running of the car. But as said, I think it may have more effect on a carbed car.

If you find this is indeed the problem then my advice is to be prepared with a good quality water pump and thermostat housing as well as a good quality thermostat (including the o-ring seal - cheap brands don't always come with this).

Although the housing should be a reusable part it's plastic and my experience is they warp. They are cheap and not worth refitting an old one as it's likely to leak.

The water pump itself is metal and should be fine for the lifetime of the car (assuming the bearings last) but both times I've done this job I've had the studs snap off, due to corrosion. The pump is about £30, so it's just not worth the hassle of driving to get out snapped studs.

Re: Mk 2 1.6 Driver Fuel Problem?

Reply #24 –
Thanks, EP, for you very detailed reply and thanks for pointing out the typo, where I erroneously stated 'fuel' instead of 'temp' (corrected in my post upthread, but still extant in kartman's quoting of my post).

You have a very good point about the thermostat, and this is something I will check.  Not sure if carb itself is connected to the cooling system.

I acquired a Golf Mk4 negative earth cable, which is indeed beefier, but I couldn't undo the bolt fixing it to the engine block.  This is currently being sorted out by my garage man.  But just applying vaseline to the battery terminals and the first earth point near the battery seems to have eased things.

As always, I suspect more than one intermittent issue with this car - been the history all along.  Carb seating sorted.  Earthing getting sorted.  Thermostat to be investigated.  Just hope the wiring between the amplifier and the coil isn't the issue as suggested upthread!
The puzzling thing was how quickly the car returned to normal once I was off the motorway and onto the ring road.

I'm intrigued now to investigate the functioning of the thermostat once I get the car back, unless my garage man gets there first!

Re: Mk 2 1.6 Driver Fuel Problem?

Reply #25 –
Sounds like you are getting there with it fella, as you say a mixture of niggles more than likely.
Weber carbs have no connection to the thermostat as they are manual choke unlike a pierberg carb.
Worth checking and renewing for piece of mind though.
EP makes a good point about carb icing and you symptons seem to match, motorway road speed and airflow will not help with this.
You should have a corrogated pipe coming of the top side of the exhaust manifold into the underneath of the airbox.
This carries hot air from the exhaust into the carb to prevent carb icing.
If it is missing or damaged then it may not be getting the hot air that is needed.
If you have an aftermarket airfilter and no airbox then replacing with a standard airbox setup is best in winter as the k&n type have no hot air feed/flap and are notorious for carb icing in winter.

Re: Mk 2 1.6 Driver Fuel Problem?

Reply #26 –
Quote from: kartman on

Weber carbs have no connection to the thermostat as they are manual choke unlike a pierberg carb.


I wasn't sure what carb was fitted and assumed it was still the original Pierberg. If it mentions this elsewhere then my mistake for not reading back through the thread properly.

Re: Mk 2 1.6 Driver Fuel Problem?

Reply #27 –
Quote from: kartman on
Sounds like you are getting there with it fella, as you say a mixture of niggles more than likely.
Weber carbs have no connection to the thermostat as they are manual choke unlike a pierberg carb.
Worth checking and renewing for piece of mind though.
EP makes a good point about carb icing and you symptons seem to match, motorway road speed and airflow will not help with this.
You should have a corrogated pipe coming of the top side of the exhaust manifold into the underneath of the airbox.
This carries hot air from the exhaust into the carb to prevent carb icing.
If it is missing or damaged then it may not be getting the hot air that is needed.
If you have an aftermarket airfilter and no airbox then replacing with a standard airbox setup is best in winter as the k&n type have no hot air feed/flap and are notorious for carb icing in winter.

Thanks kartman.

Can confirm that corrugated hose for warm air is intact, and air filter housing is standard.

Re: Mk 2 1.6 Driver Fuel Problem?

Reply #28 –
A bit of a progress report.

I’ve had the 10-year-old Weber carb serviced by an old-school VW specialist in his 60s – a dying breed!  He also checked the gauze on the fuel uptake pipe in the tank.  I’m reasonably confident now that the carb is in good nick.

Intermittent problems persist, however, which lead me to wonder whether the long-standing intermittent rough running has been a combination of things, so now excluding the carburettor might be helpful.

Current issues: occasional rough running and stalling.  Today's example – rough running almost from the start on a short local trip (usually it’s been OK whilst warming up and problems only arose after running at normal temp for a while).  This time, very marked stalling whenever the car not in gear under motion.  Restart every few yards in traffic!...

BUT

Suddenly, back to normal!  No stalling, smooth running, all purring sweetly again!  The question is: what is going on?

What might be the symptoms of faulty ignition in the distributor?  The only electronics in this 1990 Golf Driver 1.6 are the amplifier and the distributor I believe.  Can such electronics malfunction intermittently, or are they a case of binary working vs not working.

Up-thread was a suggestion to check the wiring between the amplifier and the coil, which I admit hasn’t been done yet (new coil a couple of months ago).  There was also a suggestion of upgrading the battery earth wire to that of a Mk4, which has been done.

My theory at the moment is that some kind of electrical problem has been masked by a carb fuelling problem.  Does that sound reasonable?

Re: Mk 2 1.6 Driver Fuel Problem?

Reply #29 –
Hopefully you have ruled out anything other than electrical now.
I still think it is worth checking continuity on the coil feed wire seeing as the problem persists with a new coil.
If thats ok it can really only be the ignition amplifier, distributor (hall sender may be breaking down) or wiring between them.
The only other thing could be a vacuum leak but due to the on/off nature of the problem I still suspect electrical, a vacuum leak would be all the time.