engine cutting out

[thecherryB]

Ok, so a month ago the engine,(1982 CU), started intermittently cutting out instantly, advised by AA man to replace rotor arm as damaged and sparkplugs and HT leads, did this but the problem still there.
Replaced ignition coil and transponder, still the same.
Bypassed idle control unit, still the same. All the time the engine would just cut instantly. Intermittant though, sometimes 30-40 miles between times. Sometimes would start again straight away, sometimes take a few tries and about 10 minutes.

Now it has changed slightly, when it cuts the engine will often backfire, run for 4-5 seconds but while all power is lost at the pedal then cut out. restarting is same as before but needs a push of the pedal when turning over to get it to fire.

Any ideas, input greatly appreciated as it always seems to play up on a sunny friday afternoon as we are planning to get off for the weekend!!!

[VWCamperfan]

When it cuts out, do the ignition lights on the dashboard come on, ie. oil and alternator warning light?

[thecherryB]

The ignition light does but not the oil, not sure the oil one isnt faulty tho

[thecherryB]

sorry, meant the alternator light does.

[VWCamperfan]

Ok, was just checking as I wondered if the ignition switch was at fault here.
The oil light won't come on for a few seconds as there is still pressure in the system but as you say, the ignition/alternator light does, so thats covered then!
With the backfiring it does sound like a fuel starvation problem as a backfire can be produced by a weak mixture.
A push of the pedal will allow a squirt of fuel down the carb (accelerator pump) and provide the engine with a shot of fuel to kick it into life again.
I'm guessing you have changed the fuel filter. I would be tempted to try another fuel pump and pushrod but can't guarantee that would cure the problem.
The only other possibility I can think of could be your float valve sticking. Mine did this a few years ago on a number of occasions. Sometimes the shaking of the engine coming to a stop would free it, sometimes a bit of a whack on the carb would do it but needless to say I sorted that pretty sharpish once I found out what it was!

[thecherryB]

sorry, im still learning here, where is the float valve?

[VWCamperfan]

It's inside the carb. It's the device that controls the fuel flow from the fuel pump. Basicly it keeps the fuel level at a constant height inside the float chamber. The float rises and falls with petrol usage and when the fuel is being used the float drops slightly, opening the float valve and allowing fuel into the float chamber.
We are only talking small amounts of fuel to stay 'topped up' so it's nothing drastic. It sits just inside the carb where the fuel line attaches but can only be accessed by removing the top of the carb.

[thecherryB]

Thanks a lot for the info Mark, wish me luck....

[VWCamperfan]

Good luck!

[thecherryB]

So I'm told that the mechanical fuel pump for mine is no longer available, can anyone tell me if its much of a job to fit the electric one ive been advised to try? I'm ok at taking bits off and replacing them but dont know how different this is.

[thecherryB]

....Also, if it is the float valve in one of the carbs, can I tell by looking in the carb? Can I just remove and clean it to sort the problem or do I need to replace the part/s, I've seen carb rebuild kits on jk, would it be worth rebuilding anyway using one of these? any answers/help on this would be great!

[phade]

The mechanical fuel pump is still available from the VW Classic Parts Center and costs about £90. The part number is 021127025B

[thecherryB]

OOps just ordered the other from jk, is one any better/more reliable than the other?

[phade]

I would advise against the electrical fuel pump from a safety point of view (I suspect that the quality of them may not be up to scratch as with some of the other stuff I have bought from them), but by all means use it as a quick fix for now.

Anyway to order the genuine pump have a look at my Volkszone thread from here http://www.volkszone.co.uk/VZi/showthread.php?t=566945" onclick="window.open(this.href);return false;

[oldspeedracing]

had a lot of this type of problems in my workshop, and 9 times out of 1o, it turns out to be an air leak on the intake system! check all rubber hoses to balance pipes, and to the vacuum advance on the dizzy, and especially the one that goes to the brake servo, which sometimes tees of the balance pipe, and splits quite often, if this does split, it will never tick over!!!! hope all ideas help!

cheers
Lee

Kraftwerk vw
Stoke-on-trent

07889 178 638