hesitation / loss of power

[Smiffo]

Morning all.

I have been using the van faultlessly of late, but last night the inevitable happened.
Pulled out of a junction, and thought the van felt like it had a slight lack of power. Not too much, and so little I questioned myself a bit, but I certainly thought I had to give it a bit `more` to pull off at the same rate as I would normally experience.

Some miles later, approaching a junction, the van stalled.

It started straight away, but had a lot less power than normal - I had to rev a lot more for the van to not stall when I released the clutch.

Anyway, I limped on for a mile or so, only for the issue to suddenly clear. On the `home stretch` it started to return though.

Symptoms at idle now: Slightly lower idle rate, but doesn't stall if left.
Symptoms trying to pull away: Dies immediately if a lot of pedal action isn't applied.! Very similar to if you run an engine cold with no choke.
Symptoms when cruising: Runs smoothly, but as soon as you let off the throttle, it is like you have turned the ignition off and I get a lot if `engine breaking`

The experience of the above changes a bit with severity, but captures a general picture of symptoms.

What do you think?
I have a spare carb I was going to change after the summer - the old one has a faulty choke - but does this sound like a carb issue to the more experienced here?

I initially thought it might be a jet blocked, but the tank, filter, filler neck etc and fuel lines are all `new` after changing this past winter, which suggested to me that there shouldn't be particles in the fuel..?

[kevtherev]

I think you need to clean the float bowl out and the idle jet.
Don't assume.

[Smiffo]

I assume I need to remove the carb to do that though?

( I know you told me not to assume anything )

[kevtherev]

Yes you need to remove the carb
clean it and be sure the idle jet (the smallest jet) is clean
While you're there take a look it the accelerator pump diaphragm
If there is any wear or damage replace it.
Search CJH posts for the relevance to peirburg carbs

[Smiffo]

Cheers Kev.

I have a spare carb, so if I have to take the old one off to clean it, I may as well just check / service the spare one and change out the old.

[CJH]

I worked my way through as many adjustments of the carburettor as I could find/understand (in this thread), and got my spare carb (with my two plastic parts fitted) working well - it's the one I have in my van at the moment and it's clocked up a couple of thousand miles with no problems so far. I started making a document with a description of these adjustments, but I was missing a couple of photos so I never completed it sufficiently to want to share it. It's still missing those photos, but as you may find it useful for setting up a spare carb you're welcome to it in its unfinished state. It's in my Dropbox account:

https://www.dropbox.com/s/947t3aw8t11m5 ... 1.pdf?dl=0" onclick="window.open(this.href);return false;

[bigherb]

I think you need to clean the float bowl out and the idle jet.
Don't assume.

Don't assume it is a fuel problem a weak ignition spark can cause similar symptoms.

[Smiffo]

I think you need to clean the float bowl out and the idle jet.
Don't assume.

Don't assume it is a fuel problem a weak ignition spark can cause similar symptoms.

I see.
Thanks for the heads up Big Herb. Would that necessarily be weak spark on all 4 cylinders, or could it be just one or two etc?

I get the impression this is going to take some thinking to work out.

[Smiffo]

I worked my way through as many adjustments of the carburettor as I could find/understand (in this thread), and got my spare carb (with my two plastic parts fitted) working well - it's the one I have in my van at the moment and it's clocked up a couple of thousand miles with no problems so far. I started making a document with a description of these adjustments, but I was missing a couple of photos so I never completed it sufficiently to want to share it. It's still missing those photos, but as you may find it useful for setting up a spare carb you're welcome to it in its unfinished state. It's in my Dropbox account:

https://www.dropbox.com/s/947t3aw8t11m5 ... 1.pdf?dl=0" onclick="window.open(this.href);return false;

That is excellent CJH..!!
I appreciate this - I can't view it at the moment as my phone won't let me access the link, but I will take a browse this evening.

Thanks again

[bigherb]

I see.
Thanks for the heads up Big Herb. Would that necessarily be weak spark on all 4 cylinders, or could it be just one or two etc?

I get the impression this is going to take some thinking to work out.

It would be weak spark on all cylinders caused by a faulty component from the rotor arm back.
You need a nice little diagnostic tool like this to give you a window into the spark operation.
http://www.ebay.co.uk/itm/BRAND-NEW-SIN ... Swo6lWNlwW" onclick="window.open(this.href);return false;
You place it between the spark plug and HT lead and it flashes every time it sparks what you are looking for is change in intensity of the brightness it should be the same if it dims then the spark is weakening a simple way of eliminating an ignition problem before you go stripping carbs down.
But like a lot of diagnostic tool you need to get to know how bright the spark looks when it is working correctly first.
You can also get them in Halfords/motor factors etc

[Smiffo]

I see.
Thanks for the heads up Big Herb. Would that necessarily be weak spark on all 4 cylinders, or could it be just one or two etc?

I get the impression this is going to take some thinking to work out.

It would be weak spark on all cylinders caused by a faulty component from the rotor arm back.
You need a nice little diagnostic tool like this to give you a window into the spark operation.
http://www.ebay.co.uk/itm/BRAND-NEW-SIN ... Swo6lWNlwW" onclick="window.open(this.href);return false;
You place it between the spark plug and HT lead and it flashes every time it sparks what you are looking for is change in intensity of the brightness it should be the same if it dims then the spark is weakening a simple way of eliminating an ignition problem before you go stripping carbs down.
But like a lot of diagnostic tool you need to get to know how bright the spark looks when it is working correctly first.
You can also get them in Halfords/motor factors etc

Thanks for this too BH.

I am at work at present, so will ponder what to do when I get 10 mins. I would change the carb for my spare as a process of elimination if I knew the new one was `good.` As it stands this electrical check might be the best way to proceed first, due to the effort and cost factors..!

[bigherb]

As it stands this electrical check might be the best way to proceed first, due to the effort and cost factors..!

That's how you do diagnostics do the quick simple checks first before you start dismantling or playing parts darts.

[Merrsh1]

Just my 2p...

I had very similar problems : https://club8090.co.uk/forum/viewtopic.php?f=37&t=152481" onclick="window.open(this.href);return false;

Turned out to be atrophied servo T piece and manifold elbow. Check them and check them well. From above mine looked fine but they were not.

Good luck!

[Smiffo]

Just my 2p...

I had very similar problems : https://club8090.co.uk/forum/viewtopic.php?f=37&t=152481" onclick="window.open(this.href);return false;

Turned out to be atrophied servo T piece and manifold elbow. Check them and check them well. From above mine looked fine but they were not.

Good luck!

Does a water cooled 1.9 petrol, have all that?
Yours is an Aircooled van.

[Merrsh1]

Just my 2p...

I had very similar problems : https://club8090.co.uk/forum/viewtopic.php?f=37&t=152481" onclick="window.open(this.href);return false;

Turned out to be atrophied servo T piece and manifold elbow. Check them and check them well. From above mine looked fine but they were not.

Good luck!

Does a water cooled 1.9 petrol, have all that?
Yours is an Aircooled van.

Ah! Ignore me