Club 80-90 Forums

So I poked all the correction jets and sprayed carb cleaner in all the holes. There was no resistance at all so I don't think there was a blockage.

I then checked the locking lever on the U bracket. There was significant side to side movement and the secondary throttle flap felt loose. I squeezed the U bracket closer together with pliers and took the van for a run. It's FIXED!

So to recap:

SYMPTOMS

- Whilst driving and the van reaches a certain speed the revs get stuck really high with the engine racing
- Touching the throttle makes no difference
- Van speed does not decrease when releasing the throttle
- The only cure is to restart the engine

CAUSE

- Secondary throttle flap remains slightly open

HOW TO FIX

- Adjust the U bracket on the locking collar below the secondary vacuum diaphragm

It's seems as though by fixing all the air leaks and replacing the missing gasket I exposed other issues the carb had.

Thank you everyone for your time looking into this, it's really appreciated.

The van drives like a dream now, I actually had to blip the throttle when at the lights because I thought the engine had stalled. It's that quiet. We're off to Cornwall tomorrow so it couldn't have come at a better time.

good news

I still wonder about the amout of fuel pouring into the secondary choke.
it may drive well but I urge you to check thats not still happening and over fueling.

jamesakers wrote:
I then checked the locking lever on the U bracket. There was significant side to side movement and the secondary throttle flap felt loose. I squeezed the U bracket closer together with pliers and took the van for a run. It's FIXED!

yes it's all here on 80-90

kevtherev wrote:

jamesakers wrote: The plastic interlock part looked OK when I had the carb off:

The U channel holding the interlock. It should have a 0.4mm gap
Might aswell adjust it while it's off

OK, will do Itchy.

Thanks Kev, it was your post which prompted me to check.

Good , this explains the air leak but a slight opening of the second barrel won't cause excessiveey high revs, it's still overfueling I bet due to a gasket leak or float overflow.

itchyfeet wrote:Good , this explains the air leak but a slight opening of the second barrel won't cause excessiveey high revs, it's still overfueling I bet due to a gasket leak or float overflow.

I didn't replace the float needle from the rebuild kit when I had it off the van so I'll look at that when I'm back.

Is the .4 gap between the bottom of the white plastic and the u. If so mines been pinched so there's no gap at all would it matter. As my carb is on the kitchen worktop i might as well check

It's a specific measurement.
So I would say it matters.

From the document on Syncroandy's website:

jamesakers wrote:

itchyfeet wrote:Good , this explains the air leak but a slight opening of the second barrel won't cause excessiveey high revs, it's still overfueling I bet due to a gasket leak or float overflow.

I didn't replace the float needle from the rebuild kit when I had it off the van so I'll look at that when I'm back.

now you tell us

Good teamwork fellas! I remember several years ago another well known LPG fitter telling me he (or she [WINKING FACE]) often squeezed that u channel together to cure a fast idle. I looked into it and found it was often due to the white plastic lever being partially seized or just a little bit tight on the shaft so the return spring couldn't quite close the choke fully. Better cure was to free off and lube the lever, spring now closes the flap and u bracket can be set properly.