Fuel Problem

[Dean]

Been thinking about my VP woes (you get a lot of time to think while on the M1) I changed the fuel filter too see if that made any difference.

Managed to get it to start, even though I killed the battery and had to jump start with my Metro battery! It didn't die straight away like it normally does. I revved it a little to see if it cut out. It still cut out but not as easily as it did before filter change.

I think I can rule out fuel pump, 'cos when it's warm it revs quite freely and sweet. My theory is the carb clogged up with muck.

Any ideas anybody?

Dean.

[B18 GPC]

Erm.. Ive forgoten the name ..

In the top of the carb might be a black cap.. this pot has a name but i cant think of it.. make sure it has oil in

It sould just cover the top line on this little dip stick

[ben rawlings]

carbretta (not any good at spelling) oil dash pot. i think thats what you mean.
good luck getting it sorted

[B18 GPC]

Thats the one , thanks :)

[E_T_V]

If you are getting fuel starvation then it could still be a faulty pump or blocked fuel lines or dirt in the carb. To check the fuel lines remove the hose from the fuel pump and then blow down through it. you should be able to blow fairly easily through it and you should hear bubbles in the fuel tank (you might like to remove the fuel cap to make this easier and to make sure the tank doesn't get pressurised, (it should have a vent but just to be safe!).

[Jack]

Presumably you've left other messages about this car and are still having problems. If the car has been off the road for more than about 2 months the fuel could have gone stale.

I have heard of this happening and always dismissed it as I can't believe fuel becomes so non-flammable so easily. However, I've had friends who have been baffled by such problems and when they changed the fuel all was sorted.

I would suggest either a makeshift fuelling set-up with fresh fuel to check the theory or if your tankis nearly empty, a few gallons of fresh fuel in it and some fuel conditioner should sort it out.

If it's not been off the road for that long then I would suggest the usual. Check you are getting a good healthy spark (sound like you are or it would not start at all), then remove the air filter and get some carb cleaner and just follow the instructions.

Any other clues? e.g. when it does start, what colour is the smoke from the exhaust, if any? What colour are the tips of the spark plugs?

[Dean]

Jack,

Car been off road for a fair few month, got 3/4 tank of LRP in it.

Already checked HT for condition of spark and it's good, it's had new plugs too. I'm going to check for blocked fuel lines and clean carb out. Once engine is hot it runs perfect, no coughing or spluttering.

The Auto choke is working well too. When it's idling when cold you can hear it adjusting tick-over speed

First on shopping list, new battery!

I'll keep you all posted.

Dean.

[E_T_V]

A random shot it the dark here but when you replaced the steppermotor O rings were the old ones perished? It is "just" possible that a sliver of rubber has come off of them and blocked the fuel enrichment jet which causes it to run lean when cold. when you clean out the carb check this out and also the ORFCO valve too.

[Dean]

Not the changed 'O' rings! Choke seems to work fine. Anyway one of the screws on the stepper motor won't budge.

[E_T_V]

Well I'd suggest you change them when you strip the carb to clean it. (it'll need the mixture resetting anyway after you've stripped it). An impact driver might help shock the seized screw loose as they are originally locktite'd in place.

If the worst comes to the worst you can grind the crew head off then wind out the rest of the screw with the thread that is left when you remove the stepper motor.

[e692wtt]

Presumably you've left other messages about this car and are still having problems. If the car has been off the road for more than about 2 months the fuel could have gone stale.

I have heard of this happening and always dismissed it as I can't believe fuel becomes so non-flammable so easily. However, I've had friends who have been baffled by such problems and when they changed the fuel all was sorted.

...

I've been working on a Ledbury which has been off the road for 6 months (although it has been run regularly while standing, always starts first touch of the key). The car runs like the proverbial bag of nails despite recent tuning and a change of O-rings.

I reckon it needs a top up of fuel (it has half a tank of unleaded in it) and a good run to sort it out. Then probably the carburettor retuning again :laugh: .

It is the lighter fractions evaporating off that cause fuel to go 'stale'.

[Beaker]

There are some additives that you can put in to stop fuel going off.

[e692wtt]

There are some additives that you can put in to stop fuel going off.

I've seen these advertised, often available from Garden Centres. From reports in Car Mechanics mag they seem to work too... :thumbup:

[E_T_V]

Chuck a litre of alcohol/meths/IPA in the tank and see what it runs like then.

[SimonR]

Not the changed 'O' rings! Choke seems to work fine. Anyway one of the screws on the stepper motor won't budge.

Yeah, they can be a pain, can't they?

The trick is to get a really bic screwdriver bit which fits the screw properly and put all your weight pushing in while you turn. Last time I had problems I had to hacksaw the head off and then stilson the stub out when I removed the motor. Time before that I used an electric screwdriver/drill thing and the correct screwdriver bit.

O rings will almost certainly make the car happier.

[Dean]

Been tinkering with the VP (again) today and still can't come to any conclusion.

I've checked the vacuum pipes to/from ECU and carb all ok. Fuel pump is also ok, a good flow of fuel came out. What colour should the fuel be? What came out was a pale lime green colour.

Also sprayed some carb cleaner down the float chamber and topped up with oil.

The vacuum switch on the side of the carb came off really easily, is this normal? Also one of the small pieces of vacuum tube was split, did temp. repair with some insulation tape, local motor factors closed :(

Managed to remove stepper motor from carb and checked 'O' rings. One was slightly split, but intact. Both seemed to have swelled on the motor and didn't feel tight.

When it had burst into life, finally it ran ok when it had got warm, and started every time, I checked the fuel transducer. It was full of air!

Would changing all the fuel pipes under the bonnet help? Bet the ones that are on are the factory originals from way back in 1984!

Anybody got any more ideas or suggetions?

Dean.

[E_T_V]

Changing all the rubber items could well be a good idea, a split pipe here and a perished one there can at best make fault finding hard and at worst can be a cause of an engine fire. Also the vacuum switch should probably be tighter on the carb than you mentioned. The split pipe on it probably won't help matters.

[Dean]

Is there meant to be anything retaining the vacuum switch on the carb?

[E_T_V]

From what I recall, (a long time ago I'm afraid) the switch is only held on by the two rubber pipes that connect it to the carb I think. I don't think there are any mounting brackets or pipe clips to retain it.

[Dean]

Any idea on what size the vac. pipe should be? It's bound to have gone big over the years.

[e692wtt]

Just measure the outside diameter of the 2 pipe stubs that the vacuum pipe fits onto, then get rubber hose with an internal diamter slightly smaller than that.

I did this to my Monty 18 months ago and the vacuum pipes have split (on their outsides) again but they weren't leaking the last time I checked.

[Dean]

VP Now running again! :thumbup:

This afternoon I changed the 'O' rings on the auto choke and the two little vac pipes on the vacuum switch and fired first time! No flat spot either when revved. I'll try again in the morning just to make sure it wasn't a fluke.

Next job is to replace all the rubber fuel pipe. Anybody know what size it is offhand?

Dean.

[Beaker]

Excellent News! :beer: