Age old questions, but please do read.... loss of power etc

[davidvincent]

Hi all

Regarding my 1980 2.0 Petrol twin carb van.

For a while now, when first pulling away cold, the van would feel a little bit choked with a restrain on power... then it would kinda spit out what it was choking on and the power restores, off we trundle. No bosh.

Well seems the cough is now an infection, and I'm stalling at idle speed and having very little power etc.. common thread, i know, sorry.

So here's what I've done so far....

- New bosch ht leads
- Swapped the coil with a spare
- Swapped the dizzy and rotor arm with spares
- Swapped the ignition module with a spare
- New fuel filter
- Tested each cylinder for dead plugs
- Cleaned out both carbs (using spray)
- Taken out air filter as is grubby, just to test, then reinstated (will get new this week)
- Checked all air hoses are functioning and well attached

Next I plan to replace the fuel pump (mechanical pump which is caked in oil from my mysterious leak). If anyone could offer any other tips while I'm at at it, I'd appreciate it.

For my van could I assume that the correct replacement pump would be this: http://www.brickwerks.co.uk/index.php?p ... t&Itemid=3" onclick="window.open(this.href);return false;

Thanks for reading
Dave

[CovKid]

Lots of things you could check but how much play do you have in throttle flap shafts (up and down)? If it leaks air here it won't run too well.

[HarryMann]

So, are the air pipes, balance pipes all connected properly and no leaks ?

Vac hoses to disi Ok, no splist leaks and good connections, both sides, and no play in butterlfly(s) ?

[kevtherev]

Reads like it's fuel related, mixture in particular.
An induction leak would resemble those symptoms.
If you have servo brakes check the hose isn't porous
gaskets.. Old pershed vacuum pipes.
Chokes not closing when cold.

[davidvincent]

Hi all

Okay thanks for these replies, I'll work through your suggestions/questions... Then I'll come back with some feedback.

Cheers
Dave

[HarryMann]

[davidvincent]

Hi again.

Okay, done a bit of work but still no joy plus I'm stuck on a couple of your suggestions so would really appreciate a little clarification if poss...

So firstly I decided to replace all of the vacuum hoses as they were tatty and probably not helping things, I also replaced the airfilter and installed a new set of plugs while I was at it. Oil level/quality is good. There are no air leaks on the hoses, have checked using carb cleaner to detect a change in engine note.

There was a brief moment where power was restored and we didn't stall on idle, this only lasted a few minutes though before the problem returned. This puzzles me because it must mean that something is playing up intermittently, something is perhaps loose and adjusting itself... hhm.

Again, all tips appreciated, and please could you kindly divulge further on the following suggestions/questions:

Covkid: "Lots of things you could check but how much play do you have in throttle flap shafts (up and down)? If it leaks air here it won't run too well". - I hoped to have been able to suss out what the flap shafts are but failed, could you please point me in the right direction?

HarryMan "no play in butterlfly(s) ?" - Not sure where to look on this one either, sorry - could you clarify please?

Kevtherev "If you have servo brakes check the hose isn't porous" / "Chokes not closing when cold". - I'd really appreciate more details on these two please, thank you.

Finally - does anyone think that the fuel pump could be the problem here?


Okay, thanks again - hope to hear from ye soon.
Dave.

[kevtherev]

Do you have a mechanical or electric pump?

Do you have vacuum servo assisted brakes?

Do you have automatic choke?

[davidvincent]

Further more...

It occurred to me that the evening before this problem really came to a head I did put in £50 worth of petrol at a local garage, I know it's unlikely but has anyone ever heard of a dodgy batch of fuel? Looking at the fuel in the filter it seems clean, not separating or looking odd, so I doubt it, but it was just something which came to mind.

[davidvincent]

Do you have a mechanical or electric pump?

Do you have vacuum servo assisted brakes?

Do you have automatic choke?

Hi Kev

The pump I think is mechanical, this is at least what I've read about my van and I haven't changed it since owning the van (4 four years).

There is a brake servo unit at the front of the van, with the brake cylinder etc.

The choke would appear to be automatic, ie the RPM would always start high from cold and then drop once up and running, and/or if you blipped the accelerator a few times.

Dave

[kevtherev]

Do you have a mechanical or electric pump?

Do you have vacuum servo assisted brakes?

Do you have automatic choke?

Hi Kev

The pump I think is mechanical, this is at least what I've read about my van and I haven't changed it since owning the van (4 four years).

It should pump in strong squirts
the pushrod has a specific length 100mm I think

There is a brake servo unit at the front of the van, with the brake cylinder etc.

Then it will have a vacuum hose going to it.

The choke would appear to be automatic, ie the RPM would always start high from cold and then drop once up and running, and/or if you blipped the accelerator a few times.

You are describing the fast idle for cold start
Take off the ducting from the top and look for the choke flap. It should be closed when cold.
Fully open when warm.

If you suspect the pump check the pushrod before you buy a new one or replace it with an electric one

[davidvincent]

Hi again

Okay, when I take off the airfilter ducting the carbs the metal flaps (slides? butterflies?) inside are always open, they seem to be only able to move slightly.

http://www.youtube.com/watch?v=vvXwEWegMM4

Here's a clip I just took of me revving the engine with the ducts off the carbs - no/little movement at all. As soon as I stop manually increasing the revs the engine stalls.

Thanks again.

Dave

[davidvincent]

Also, I've checked the (accessible parts of) vac pipe to the servo unit and all seems fine, no splits or excessive wear. Topped up the brake fluid while I was in the dash

[davidvincent]

Hi again

So looking at the butterfly / choke flaps, they do only move slightly when moved by hand - this is when the engine is not running.

With the engine running I am able to adjust these fully to the closed position - does this seem correct? Should they move freely regardless?

Thanks
Dave

[john1]

With the engine running I am able to adjust these fully to the closed position - does this seem correct? Should they move freely regardless?

Dave, this is what the choke does when on mate. Go to the the van cold, press the pedal and look at the carbs, they should be closed, auto choke now on.

Have you changed the black T bit below left carb to servo and L pipe below right carb? I know they may look ok but Kev told me to change anyway and when I took them off the underside had cracks. Just an idea mate, hope you get sorted.

John