Blumming pierburg carb probs

[ADO]

Hi all
Have a problem with my van(1987 1900DG petrol Autosleeper) It runs fine in choke mode but as soon as the choke comes off it dies. I've changed the pull down unit to a new one . Rebuilt it with a brickworks kit and still the same. But have just put a second hand carb off a running van on it and it still does the same thing, dies after choke stage. My fuel pump gave up a while back so I changed that but still the same thing. I'm at a loss it seems strange that this other carb is doing the same as the other carb...I've noticed when the choke is on there is a small gap I think it should be about 3 mm but if I pull the accelerator on the choke flap opens to half open and the van dies as if the carb isn't getting enough petrol or to much air. Anyone had the same problems. Cheer Adrian.

[itchyfeet]

Does it do it while driving or just when idling
Is this on petrol gas or both
Check you have 12v to the bypas air cutoff valve and that it clicks when you unplug and reconnect
Check your timing incase a small airleak is just enough to kill the revs because its out
Check all your small vac hoses and servo vac hose connection

[kevtherev]

Hi all
Have a problem with my van(1987 1900DG petrol Autosleeper) It runs fine in choke mode but as soon as the choke comes off it dies. I've changed the pull down unit to a new one . Rebuilt it with a brickworks kit and still the same. But have just put a second hand carb off a running van on it and it still does the same thing, dies after choke stage. My fuel pump gave up a while back so I changed that but still the same thing. I'm at a loss it seems strange that this other carb is doing the same as the other carb...I've noticed when the choke is on there is a small gap I think it should be about 3 mm but if I pull the accelerator on the choke flap opens to half open and the van dies as if the carb isn't getting enough petrol or to much air. Anyone had the same problems. Cheer Adrian.

to much air.

brake servo hose
vacuum lines
gasket failure
cracked inlet manifold
distributor diaphragm
choke pull down

good luck!

[ADO]

Cheers Itchy and Kev.
Will try and check all the things you've suggested.
My van seems to run ok on LPG but as soon as the chokes off in petrol mode that's it. I can set off in LPG and switch to petrol but as soon as I slow down the engine dies but is ok when in LPG mode. I've tried the bypas air cut off valve and that's clicking when connector is pulled in and out.Can I get new gaskets for the bottom of the carb and inlet manifold with out having to buy a £40 kit.... Again
Plus how would I check the distributor diaphragm.
From reading what other members have gone through it sounds like an air leak ....wish me luck guys and any more suggestions would be much appreciated. Adrian.
Ps I love my bus... Most of the time

[itchyfeet]

Remove vac pipe to dizzy and suck if you can suck fresh air its punctured
Remove the dizzy cap and you should see the mech move a bit when you suck

Strange to have such an airleak to kill petrol but gas still works maybe your gas is running rich or perhaps you have more than one fault

Cheapest manufold to head gasket solution is to buy the df ones and trim the inner appertures

http://www.brickwerks.co.uk/index.php/i ... -9-df.html" onclick="window.open(this.href);return false;

The lower carb gasket can be made from gasket sheet if you can recover the old one it is easier to use as a template

[itchyfeet]

Also an old trick is to spray wd40 around the gaskets if you find an airleak the revs should increase as its drawn in at the point of the leak

[ghost123uk]

My van seems to run ok on LPG

So it is unlikely to be an air leak.

So not too much air, more likely too little fuel (same end result, ie weak mixture)

Check petrol filters, there should be 2, one near the tank and a tiny gauze inside the brass pipe on the carb where the petrol feed pipe goes. Usual way to get that one out is with the careful use of a small self tapping screw.

Next might be insufficient flow from your (new?) pump. This can be carefully checked by taking the pipe off the carb, putting it into a plastic bottle and getting an assistant to start the engine (it will run off the fuel in the carb) Just check to see if a healthy flow squirts out of the pipe. Be careful with petrol and running engines, have an extinguisher to hand in case of accident

Also worth checking the fuel line and connections from the tank to the pump. A cracked pipe or loose connection here can cause it to suck in air, thereby reducing the flow of petrol. Surprisingly, it might not leak petrol out. This can be a tricky one to trace if present. It took me a whole day (years ago) to trace this as the problem on our Scirocco.

Least likely but not impossible is a blocked strainer in the tank itself. If you take the pipe off the tank side of the pump and blow hard down it, and find that after re-connecting all, this cures it, you have crud in the tank. It will soon find it's way back onto the strainer though

[itchyfeet]

If there was not enough fuel then why does it run on choke which uses more fuel than when off choke?

[kevtherev]

If the lpg is set a bit rich then it would not show the symptoms.
maybe the OP has his emissions results on gas?


my money is an air leak, as the symptoms are classic.

[ghost123uk]

If there was not enough fuel then why does it run on choke which uses more fuel than when off choke?

Because on choke there is much more of a vacuum in the carb, so it sucks the fuel harder from the float chamber / float valve. You can occasionally pull a blockage through by putting a book or similar over the carb mouth with the engine at a fast tickover and as you put the book there, whack the throttle full open. That creates a hell of a vacuum and pulls lots of fuel through from anywhere it can get through. Usually floods the motor a bit in the process

[itchyfeet]

Yes but it can only pull it from the float chamber im not sure if it can pull it from the fuel pipe as the float chamber is vented

[ghost123uk]

Yes, that's true

I still bet it's fuel starvation

Cr@p on TV tonight

[itchyfeet]

Hi all
Have a problem with my van(1987 1900DG petrol Autosleeper) My fuel pump gave up a while back so I changed that but still the same thing.

what does that mean, did it do this before you changed the fuel pump and continues to do it after?

To rule out fuel supply you can try removing the fuel pipe to the carb and point it into a jar, disconnect coil and get somebody to crank the engine, you should get a healthy supply of fuel into the jar.

[ADO]

Hi everyone..
Thanks for all the replies....first of all the problems started with my engine revving its t.ts off when I first started it and I found if I dipped the accelerator a couple of times it would settle down and every thing seemed fine. But I found some plastic on top of the engine which I later found out was off the choke flap assembly. So off came the carb and a replacement second hand carb picked up at vanfest to get the bit which had bust. So I tried this on my old carb and it didn't make much difference if anything it was running crap in petrol mode even the choke didn't want to work.. I'd start the engine and the rev would be really low but if you went for a run it seemed to pick up and tick over a bit better... Strange. Anyway a friend of mine had a look at it and turned the co2 screw in abit but said he had turned it in all the way closed and the engine still ran which he found strange because he said it shouldn't run with this screw completely closed. So I've bought a replacement carb off a van which was running and the choke seems to work ok .. On for about 5or 6 minutes but then she just dies. If I keep the accelerator on it will run but foot off the accelerator and she dies. I can run in gas but it does feel like I haven't got has much umph as I used to have.I've changed the fuel filter under the van blown down the fuel line but one thing I did find strange was I got a new fuel pump from gsf ... Topran and found the inlet side bore from tank was different from the outlet side bore to carb which was the same as the original petrol pipe size. So was told at gsf to put a fuel filter onto my old petrol pipe from tank next to carb and cut the thin part of the filter on the other side and put a new wider bore piece of pipe to make it fit the wider bore on the new pump does this sound right. I was wondering if the pump was pumping enough fuel or if the push rod was worn.. Going to test that pump and length of push rod any idea what length it should be. Cheers people for the help and have a chew over what I've said. Adrian

[itchyfeet]

You don't really want that second filter you can get a step adaptor
Plastic link in the carb is common to break
Check the fuel flow at the carb as I described its the only real way of knowing if there is a pump problem

Try increasing the throttle stop until it just runs when off choke could be something as simple as that