car trouble

[rowdy]

hello orgers got a bit of a problem with the wifes car, it's been cutting out as if it's running out of petrol. It's a 1990 golf mk1 cabriolet with a 1.8 carb engine. I bought it privately for her about 15 mnths ago and changed spark plugs, leads, dizzy cap, rotor arm air filter fuel filter, the oil and filter having been changed just before I bought it. It started playing up about April this year with us having only covered about a thousand mile or so in it. We took it to a mechanic that we know and he looked at it and said there was a vacuum pipe that had come off under the carb so we went and picked it up and it cut out again on the way home so we took it back for him to have another look. We then picked it up again after he had cleaned the carb out, road tested it and said it was fine, but it conked out on the way home again. We phoned the AA and a man came out and looked at it and came to the conclusion that the carb was knackered. So yesterday I spent a good few hours taking off the old pierburg 2e2 autochoke carb and replaced it with a new weber 32/34dmtl but it is still cutting out, although with the new carb(manual choke) it has stopped idling as if it was running on three cylinders. Just wondered if anyone out there has any idea of what to try next.:confused:

[phil24_7]

Petrol and match!!!!

Sorry I ain't more use to ya!

[Ace-T]

Not able to help directly but what about posting your q on a car site like www.pistonheads.com? (http://www.pistonheads.com?) They have a VW section. http://www.pistonheads.com/gassing/forum.asp?h=0&f=86

Trace :)

[Demonz]

So you think its fuel related? Fuel lines and filters - fuel tank itself - drain and clean....?

[rowdy]

Petrol and match!!!!

Sorry I ain't more use to ya!
Don't think that that hasn't crossed my mind lol. It's too good for that really, when working on it yesterday I got two people commenting on what a lovely motor it was, which happens pretty much every time we go out in it, and it was parked next to our Impreza wrx (03) which they didn't seem so interested in.

[600+]

have you checked the coil packs? they do go on VWs u know ;)

[rowdy]

have you checked the coil packs? they do go on VWs u know ;)
Was wondering if it could be the coil as this happened on a mk3 golf driver (1.8 sfi) we had a couple of years back. It will sit on the drive and tick over all day long, it's when it's being driven it plays up so not sure if it's the coil.

[skumlerud]

So yesterday I spent a good few hours taking off the old pierburg 2e2 autochoke carb and replaced it with a new weber 32/34dmtl but it is still cutting out

First of all, install the original carb again, that way you don't have to debug two problems at the same time. Unless it's a very high mileage car, it's unlikely that the carb needs replacement. Most carburation problems are due to vacum leaks, so make sure that ALL vacum pipes are sound before you start messing with the carb itself. Also, the flange that the carb is mounted on can crack and cause lots of problems. It's not always easy to spot this.

What happens when it "conks out"? Does it stutter and then dies, or just dies without warning? If it dies without any warning, it's probably not fuel related. I suspect an electrical problem. I used to work at a VW dealership for five years, there are a few well known problems with these engines. The coil can cause intermittent problems, suddenly the engine dies and it won't start again until the coil has cooled off. There is also a Hall effect sensor (for the ignition) in the distributor that can cause the exact same problem. I've replaced loads of these on the old 1.8 engines.

It's highly likely that either the coil or the Hall sensor is the problem on your car. Unfortunately you can't be sure until you've replaced them. I suggest replacing the coil first, as it's the cheapest part. If this doesn't help you should replace the Hall sensor. Unfortunately not all VW's use the same distributor, and one some distributors it's not possible to replace the sensor. In this case the entire distributor must be replaced.

If it stutters and then dies you might have a faulty fuel pump or fuel pump relay, this is also a relatively common problem with these cars. When the car conks out, try pulling the fuel line off the carb and see if fuel is coming when you attempt to start the car.

[skumlerud]

Was wondering if it could be the coil as this happened on a mk3 golf driver (1.8 sfi) we had a couple of years back. It will sit on the drive and tick over all day long, it's when it's being driven it plays up so not sure if it's the coil.

Can still be the coil, but most likely the Hall sensor in the distributor.

[rowdy]

First of all, install the original carb again, that way you don't have to debug two problems at the same time. Unless it's a very high mileage car, it's unlikely that the carb needs replacement. Most carburation problems are due to vacum leaks, so make sure that ALL vacum pipes are sound before you start messing with the carb itself. Also, the flange that the carb is mounted on can crack and cause lots of problems. It's not always easy to spot this.

What happens when it "conks out"? Does it stutter and then dies, or just dies without warning? If it dies without any warning, it's probably not fuel related. I suspect an electrical problem. I used to work at a VW dealership for five years, there are a few well known problems with these engines. The coil can cause intermittent problems, suddenly the engine dies and it won't start again until the coil has cooled off. There is also a Hall effect sensor (for the ignition) in the distributor that can cause the exact same problem. I've replaced loads of these on the old 1.8 engines.

It's highly likely that either the coil or the Hall sensor is the problem on your car. Unfortunately you can't be sure until you've replaced them. I suggest replacing the coil first, as it's the cheapest part. If this doesn't help you should replace the Hall sensor. Unfortunately not all VW's use the same distributor, and one some distributors it's not possible to replace the sensor. In this case the entire distributor must be replaced.

If it stutters and then dies you might have a faulty fuel pump or fuel pump relay, this is also a relatively common problem with these cars. When the car conks out, try pulling the fuel line off the carb and see if fuel is coming when you attempt to start the car.
Hi the car has done 115000miles. I checked the rubber mount that the base plate bolts to and this appears to be in good condition. Was wondering if it was the distributor, as when a friend and I checked the car over before getting it seen to by the mechanic it was ticking over lumpy and when the plug lead to the cylinder (gearbox end) was taken off it seemed to make no difference, haven't tried this yet with the new carb but deffinately idles a lot better. The car was just dying, and when i put my foot on the clutch it would rev up ok again until i let the clutch out then it would die again. This indicates to me there is enough petrol getting through for it to tick over but when you try and make it drive it seems to be starved of fuel, but then there is also a strong smell of petrol. Was wondering about the fuel pump also, and have also been told that a leaking exhaust manifold may cause this. I am not going to put the pierburg back on as these are known to be problematic pieces of s***e.

[skumlerud]

condition. Was wondering if it was the distributor, as when a friend and I checked the car over before getting it seen to by the mechanic it was ticking over lumpy and when the plug lead to the cylinder (gearbox end) was taken off it seemed to make no difference,

Try this again. If there's no difference in rpm when you pull a plug lead, somethings wrong! Remove the plug, connect the plug lead, earth the plug and start the engine to check for sparks. If it doesn't spark, you have an ignition problem. Could be the distributor, but check the cap, rotor and lead as well even if they have been replaced recently. Some aftermarket igniton parts are crap and have even been known to literally burn up (Biltema distributor cap). If there's spark, check that the other cylinders are firing correctly. If so, you might have poor compression on one cylinder. If a problem only affects one cylinder, it's unlikely that it's a fuel problem on a single carb engine. It's possible though, you might have a bad plug that fouls when the engine is working hard. That shouldn't cause the engine to die completely though.

The car was just dying, and when i put my foot on the clutch it would rev up ok again until i let the clutch out then it would die again. This indicates to me there is enough petrol getting through for it to tick over but when you try and make it drive it seems to be starved of fuel, but then there is also a strong smell of petrol.

The same can happen if it doesn't fire on all cylinders. The strong smell of fuel is an indication of this. But check that fuel is coming to the carb when the engine dies. The smell of fuel can also be a leak, but most likely a leak large enough to starve the engine of fuel would be a constant problem, not intermittent. I still suspect a problem with the ignition or a vacum leak.

leaking exhaust manifold may cause this. I am not going to put the pierburg back on as these are known to be problematic pieces of s***e.

Well, since you apparently have the same problem after you replaced the carb, it's most likely not a carb problem and the original carb is probably OK. But do you know that the replacement carb is OK? By replacing it you have introduced another potential source of problems, you don't need this when debugging ;-) It would probably be easier to find the fault with the original carb in place.

[rowdy]

Thanks for the info skumlerud , don't really want to be changing the carb again though. Guess I'll just have to try new plugs ,leads ,cap, rotor, coil etc again, cheapest options first. Vacuum pipes all seemed ok, think that coils are quite cheap for the car (as opossed to the mk3 one which cost hundreds). Thing that winds me up most is because I done mechanics at college 15yr ago my wife expects me to know what the problem is just like that and gets the ar53 when I say I don't know!

[skumlerud]

Thanks for the info skumlerud , don't really want to be changing the carb again though. Guess I'll just have to try new plugs ,leads ,cap, rotor, coil etc again, cheapest options first. Vacuum pipes all seemed ok, think that coils are quite cheap for the car (as opossed to the mk3 one which cost hundreds).

It's even cheaper to locate the problem before you replace any parts ;-) Checking that you really get fuel and that there indeed are sparks on all plugs would tell you a lot.

Vacum pipes: Have you checked the crankcase ventilation pipes? They usually crack on the inside of the bend where it connects to the cylinder head cover. Hard to spot unless you know what to look for.

Thing that winds me up most is because I done mechanics at college 15yr ago my wife expects me to know what the problem is just like that and gets the ar53 when I say I don't know

I know exactly what you mean! Friends and relatives expects me to know everything about computers as I spent five years at university studying those damn things. I can program them quite well, but that doesn't mean that I know anything about how to USE them ;-) I'm a geek, I don't need to know how to use Word! Why don't they ask me about interrupts on AVR microcontrollers, or how to fix the DMA timings on Atari Falcons??

[embee]

Skumlerud has given very sound advice, and in view of his experience I'd go with that.

I have been in the auto industry for many years and as a general guide the most likely reason for these kinds of issues is ignition, even when it seems like it could be fuel related. This is the reason why cars have evolved through points/condensers, to electronic distributors, to double ended coils/distributorless, to what we have now which is on-plug coils. Providing it is engineered properly {unlike some efforts including VW/Audi} the on-plug coil is the most reliable system, minimising the HT circuit length.

Coils can definitely fail progressively, causing just the sort of problems you are experiencing.

[rowdy]

Just tested car again left it outside ticking over fine took it up the road and cut out after 5 mins , took another 5 mins to start again , drove back home left car running and took ht leads off one by one and revs drop by couple of hundred rpm or so on each cylinder. Can't find the vacuum pipe running from crankcase to cylinder head cover. Can't check if fuel is getting to carb when it does it because it will sit and idle all day long it's only when on the move it'll do it. Surely if it was vacuum leak it wouldn't be so intermittent?

[skumlerud]

Just tested car again left it outside ticking over fine took it up the road and cut out after 5 mins , took another 5 mins to start again , drove back home left car running and took ht leads off one by one and revs drop by couple of hundred rpm or so on each cylinder.

You should have done this immediately when the car cut out! That could have told you if you have an ignition problem. There's no point in checking this when the engine is running properly. But the way you describe it I'm 90% sure that either the coil or the Hall sensor in the distributor is at fault. They fail when they get hot, and starts working again as they cool off. Idling is not a proper test, the coil will get much hotter at higher RPM's. These two components was always the first thing we checked when we faced the problem you describe.

Can't find the vacuum pipe running from crankcase to cylinder head cover. Can't check if fuel is getting to carb when it does it because it will sit and idle all day long it's only when on the move it'll do it. Surely if it was vacuum leak it wouldn't be so intermittent?

You must check spark and fuel when the engine won't start. And you're right, it's probably not a vacum leak.

[rowdy]

Aye but find it difficult when on my own to check spark when it cuts out cos i need to be able to turn the ignition and check for spark at same time , take your point though , and yes I think it's got to be heat related but will this not affect the running on idle?

[cuffy]

my wife expects me to know what the problem is just like that and gets the ar53 when I say I don't know!
Trade the wife in for a newer model :D

[skumlerud]

Aye but find it difficult when on my own to check spark when it cuts out cos i need to be able to turn the ignition and check for spark at same time , take your point though ,

Indeed! You need to take your wife with you on test runs. After all, it's her car, she has to put some effort into it too ;-)

and yes I think it's got to be heat related but will this not affect the running on idle?

The coil will heat up more when running at higher RPMs. At 2500rpms (which IIRC is normal cruising RPM for this car) it will fire more than twice as often as when idling, leaving less time to cool off between each discharge.