Engine lurching problem

[Santa79]

Hi all!
So I have had the annoying engine lurching problem for a week or so now. I changed the fuel pump and pushrod yesterday and it hasn't really got any better.

Basically, for the first few miles (and when cold), it runs ok. But after a short while, when you hold steady revs, the engine lurches.
Since changing the pump, it has got slightly better, but now it also cuts out when I press the clutch in and is a bugger to start.

I have fuel hose and a new filter so I am going to replace these to eliminate any air getting into the system and a clogged filter. But does anyone have any other ideas as to what could be causing this? ...just incase these don't solve it!

Ta

[Santa79]

It's a 1.9 DG, by the way!

[Santa79]

no it just cuts out every time I start it as soon as I drop the revs.
brill.

[marlinowner]

If it runs OK when cold but not when warmed up, it could be the choke not opening. Take the trunking off the top of the carb and check that the choke butterfly opens as the engine warms up.

[itchyfeet]

Or an air leak, when on choke it's rich so ok but when choke comes off it's lean, not enough fuel.
if over fueling you can smell fuel.

as you suspect could be fuel starvation because of blocked filters, check the tiny conical filter on the carb inlet

[Santa79]

Or an air leak, when on choke it's rich so ok but when choke comes off it's lean, not enough fuel.
if over fueling you can smell fuel.

as you suspect could be fuel starvation because of blocked filters, check the tiny conical filter on the carb inlet

I'll have a look at this tonight.
I have so far checked the fuel filter (It doesn't look blocked so I am leaving it for now... especially since the replacement I have bought is one of the small ones from JK and it is a larger one on the van).
I have replaced the fuel pump and pushrod (the pushrod was worn so would have needed doing anyway).

The vac hoses all seem ok to me, no air leaks there. I am going to check for air leaks around the engine too tonight. I checked the king lead to the dizzy too to make sure this was ok (ignition on, remove and replace, listen for click) and the plug fell apart as I removed it! So I am replacing the HT leads too tonight!

As a last resort, I have bought a replacement choke. But I am a little concerned about replacing that since I am not an expert with carbed engines and am not sure if there is anything I need to look out for.... or indeed the process! But, like I say, this will be the last resort.

[CovKid]

Could be ignition. How old are the leads and plugs.

[Santa79]

Could be ignition. How old are the leads and plugs.

They all look pretty new. I replaced the king lead today anyway.

As of this evening, I can now say that it is not...
The fuel filter
pushrod
the fuel pump
engine bay fuel lines
small filter in carb inlet
choke unit
I've done the wd40 check around the base of the carb etc. and there was no engine note change.

The only other thing I can think of is that there was not really a lot of fuel from the pump inlet when I changed that. A bit of a dribble came out then it stopped so I wonder if there is a problem with the fuel line somewhere behind the filter.

I also noticed an occasional blowback sound from the exhaust under revs, it wasn't much, but noticeable...

[Santa79]

I realised I hadn't checked the choke pulldown unit.
Is the one I have on my van the correct one? It has some kind of screw cap on the back that wasn only about half way done up.
I took the pipe off the carb side and was able to suck a little bit of air through it.

[itchyfeet]

Choke pull down won't affect it when hot, it just reduces choke when cold, choke is on and under load,
Air leak could be responsible if it's leaking.

checked the by pass air cut off valve clicks with ignition on?
large cylinder thing left of pull down in this pic

[Santa79]

I take you mean turn the ignition on and unplug/plug the bypass air cutoff and see if I can hear it click?

[Santa79]

Tried that and it clicks.
I rebuilt it all and had it idling for about 15 minutes whilst warm and it was absolutely fine.
I thought I'd take it up the road and got about 500 metres from home and it lost all power then cut out.

Now I am sat trying to restart it to try and get home. Brilliant.

[itchyfeet]

Well perhaps it is ignition then check the coil resistances and wiring may be a bad connection or earth
http://www.brickwerks.co.uk/index.php/b ... g/tag/t25/" onclick="window.open(this.href);return false;
also check fuel delivery as you suspect that need to disconnect coil take fuel pipe off carb and point into a jar, get somebody to crank engine
worth having an extinguisher handy

[Santa79]

Thanks for the advice.
I will have a look at the coil once the rac has turned up to tow me home!

[Santa79]

Well.
I got towed home and we had a look. The RAC guy told me I had already done everything he would have and more to cure this fault.

Then he got the hand pump out to put on the fuel pump inlet. I could hear the air coming through... So I have a problem with air getting into the fuel pipe somewhere from the filter forwards by the looks of things now.

And yes. I have 1/2 a tank of petrol! haha