Poor idle running, ideas?

[westbay]

Not sure how the van was running before i got it as its an import but it has a brand new engine and gearbox and i only saw it running when it was delivered and i decided i should check it starts today (rather than wait till tuesday when i take it for mot and find it doesnt start) as not been started for about 5 weeks since it was delivered.

It took ages to get it going (good 5 mins) and then virtually cuts out on idle (ticks over so slow its about to cut out that the generator light comes on), if i rev it a bit it picks up but then when releasing the accelorater it cuts out, if i restart it and leave it it gets to the just ticking over/stalling for about 10 seconds, then it will pick up and idle fine for another 10-20 secs before it goes back to its just ticking over/stalling.

I thought maybe not enough fuel getting through but then with it picking up fine and also reving fine on gassing it?

Does it just need a tune up to sort it?

I dont have any knowledge of how these aircooled motors run

 

[noddy]

What carb and distributor are you running?

Are you plugs, rotor arm cap and leads in good nick?

At a guess it sounds like you carb idle is badly set up, stock settings for the idle circuit on a 34 pict 3, and 30 pict 3 are fuel screw from fully in about 2.5 to 2.75 turns out (small screw on lhs of carb body), then adjust tick over with the larger air bypass screw till you get a tick over of about 850 rpm +/_ 50 rpm. Also worth checking the setting on the throttle arm screw this should be just a touch to the lowest step on the choke cam.

It could also be that your choke is not working properly, when starting one of these vans from cold depress the throttle to the floor and release to set the choke, do this and before you turn the key have a look at the carb and see if the throttle arm is sitting on one of the higher choke cam steps, if not your choke is eith goosed or out of adjustment.

If you getting lots of smoke out the exhaust once running you idle mixture is set too rich. On most stock carb the only thing that can be adjusted is the tick over mix, all the main running side is done with fixed jets.

 

[westbay]

What carb and distributor are you running?

Are you plugs, rotor arm cap and leads in good nick?

At a guess it sounds like you carb idle is badly set up, stock settings for the idle circuit on a 34 pict 3, and 30 pict 3 are fuel screw from fully in about 2.5 to 2.75 turns out (small screw on lhs of carb body), then adjust tick over with the larger air bypass screw till you get a tick over of about 850 rpm +/_ 50 rpm. Also worth checking the setting on the throttle arm screw this should be just a touch to the lowest step on the choke cam.

It could also be that your choke is not working properly, when starting one of these vans from cold depress the throttle to the floor and release to set the choke, do this and before you turn the key have a look at the carb and see if the throttle arm is sitting on one of the higher choke cam steps, if not your choke is eith goosed or out of adjustment.

If you getting lots of smoke out the exhaust once running you idle mixture is set too rich. On most stock carb the only thing that can be adjusted is the tick over mix, all the main running side is done with fixed jets.

Its running a 34 pict 3 & 009 distributor.

all the gear looks new, only old thing i can see is the starter motor and exhaust silencer.

I did the depress pedal to floor before starting (same as my old T25) but it didnt start up, so ended up doing the hot start (as shown in Haynes manual) procedure of slowly depressing pedal as starting and holding pedal to floor till it starts.

no smoke from the exhaust, very clean, i will have to see about the idle screw and auto choke tomorrow.

is it a possiblilty that it could be old yankee fuel causing it, because as far as i know this van has been subject to a 2 1/2 year restoration so may not have been used much and the fuel could be pretty old in the tank?

 

[PIE]

Mine did this after I had the engine out, turned out to be a small piece of dirt in the idle jet, blew it out and it ran sweet as a nut.

 

[streetboy]

Same as pye with my import, blocked idle jet. Possibly an iffy cut off valve?

 

[westbay]

Had a go at sorting this today but got nowhere, still runs like a bag of sh#t. Going in for MOT tomorrow so will see if the garage can have a look.

I setup the carb how it should be according to the Bentley manual but wouldnt even tickover like that so had to put it back to how it was to get it to stay running (nowhere near the bentley settings).

I was hoping that the engine would run sweet as a nut as its supposed to be built by some top engine buff in the states but going by the amount of loose or missing screws/bolts and seals i have found plus slight oil weep from the crankcase i think it must have been a friday afternoon job.

 

[ronmidg]

could check your heater pipe is warming up, had similer idling with no heater on a central carb install with all new parts

 

[chrisby]

Ive had this also with imports its usually ,blocked carb jets / old dirty fuel / choke not connected or adjusted. So clear carb jets, put an in-line fuel filter in and put some new fuel in.Check that the choke is operational.
Some good info to be had at http://www.vw-resource.com" onclick="window.open(this.href);return false;

 

[westbay]

Ive had this also with imports its usually ,blocked carb jets / old dirty fuel / choke not connected or adjusted. So clear carb jets, put an in-line fuel filter in and put some new fuel in.Check that the choke is operational.
Some good info to be had at http://www.vw-resource.com" onclick="window.open(this.href);return false;

Thanks for the link, some interesting reading on there and by the sounds of it i could have an air leak somewhere after the carb as what they discuss as being the problems you get with an air leak are exactly the problems i am having as in wont idle, idle speed will flucuate, not being able to set the carb up etc.

I might start by disconnecting the brake servo pipe from the inlet manifold and plugging the hole (as it was when i got it) to see if it runs any better as i have connected the servo pipe up to the manifold myself but saying that the carb settings were well out anyway so i dont think it was running right before, might need to strip and clean the carb too as no fuel filter fitted to it at the moment (i have a new one and new hoses and cut-off solenoid to fit).

 

[cyberdyne systems]

Good idea to check for air leaks, and blocking off the servo connection, mine was leaking vacuum causing stalling so it might be your problem. Other than that do the usual spraying around the joints etc to see if you have a leak. If the timing is out it will be difficult to set up the idle too.

I would change your plugs/points, set up the valve clearances, check your timing and then try to set up the carb again - after you made sure there are no leaks. All this along with new fuel and checking the idle jet is clear and shutoff valve is working.

Gareth