• Hi Guest!
    You can help ensure that British Car Forum (BCF) continues to provide a great place to engage in the British car hobby! If you find BCF a beneficial community, please consider supporting our efforts with a subscription.
    There are some perks with a member upgrade!
    **Upgrade Now**
    (PS: Subscribers don't see this gawd-aweful banner
Tips
Tips

General Tech Carbs flooding and Plugs Fouling

Share this page

KVH

KVH

Darth Vader
Silver
Country flag
Offline
What have I done wrong. This is happening the moment I pull the choke on cold start. Right now I'm missing like a cylinder is dead. Where do I start? The float bowls? The choke setting?
 
What happens if you open the throttle just a bit and push the choke back in? I'm thinking you may just be giving it too much.
 
Is this a TR6 with 2 Zenith Stromberg carbs ?
If so, remove the air filter so that you can get a good look at things and see if there is gas accumulating or dripping from any place on the carbs where it shouldn't.
 
Not knowing what kind of car or make of carbs you are talking about it is impossible to know what might be happening.
But if it is a TR6 and has Strombergs and happened to be a sudden problem I would check to see if the carb diaphragms may have a tear in 1 or both.
 
KVH has TR4As (a red one & a black one) -- so does that mean it will have SUs? If so, I would start by opening the float bowls to see if a valve has stuck closed.

Stuck open will also cause crappy running but I think that would be visible and smellable. Okay, just what is the word that is the olfactory equivalent of 'visible'?
 
I believe early 4As came with the non-emission version of the ZS carbs; later ones had the SU HS6 carbs. But my SPC doesn't give a change point.

Sorry, no help on smellable. Odorous is the best I can do, and it's not quite the same. "Threshold of odor" seems to be the accepted scientific name for it.
 
Sorry guys, I should've been more specific. Yes, as Geo says, I've got HS6 carbs. I opened the float bowls and to my surprise they were filthy, with the lead bowl containing a fine sand of some sort. The valve was definitely stuck, and that carb was leaking all over that front area--from the bowl. Cleaned it all up, and now it's running great.

But, I just don't understand the mechanics here. What was happening? Here's a guess, and I suspect I'm wrong: the valve was stuck open and with the choke added to the problem. I had gas flowing into the bowl, out through the overflow, and with excessive fuel coming up through the jet and needle. Close?
 
KVH, one backfire and it could have got very interesting. Over the years I have seen lots of hoods (bonnets) less some paint over the carbs.
Glad all is sorted out.

Wayne
 
KVH said:
...Here's a guess, and I suspect I'm wrong: the valve was stuck open and with the choke added to the problem. I had gas flowing into the bowl, out through the overflow, and with excessive fuel coming up through the jet and needle. Close?
Click to expand...

That sounds right to me. Not so much flooding as to prevent starting & running until the choke pulled the jet down and lots of fuel was being sucked in.

You might consider (if you do not already have one) installing an inline filter, at least temporarily. I don't use one and just rely on the bronze screen above the glass bowl - but it sounds like whatever you found in the bowls might be fine enough to get past that.
 
Back
Top