88" IIA 2.25 petrol ran great, but not now. Seeking help after dumb mistake...

[slowpatina]

Our 88" 2A motor was running flawlessly. Then while working on the truck (oil bath air cleaner removed) I accidentally 100% blocked off the carb air intake at idle. Dumb, I know. As expected, the engine promptly died.

That's the ONLY thing that has occurred since it ran perfectly at any RPM.

So now, every time I try starting, it won't idle. It fires up and dies within 20 seconds. I can manually keep it running at likely around +/-1200 RPM or more but it runs rough and bellows out black smoke (fuel rich). Not drivable. I'm so bummed.

If I bring it back down to idle, it dies again whether engine warm or cold... and a lot of fuel can then be seen dripping/flooding carb throat, as well as dripping from vacuum advance line at distributor (likely since carb is overly full and fuel is flowing into vac line when it wouldn't normally).

Before ongoing start attempts the last few days, I've:
- Cleared vac adv line of fuel
- Checked choke is not stuck on
- Checked PCV diaphragm is good
- Checked fuel is clear and full in glass at pump
- Removed top of carb and inspected the float needle and float(s). They seem fine, not stuck, no hang ups, float not full of fuel

I'm handy and do much truck work myself but not a lot on engine/fuel things.

Anyone have any idea why this is happening/ongoing after I stalled the motor via blocking the intake at idle?

Thanks much for any detailed help/resolution.

[erik88lr]

What kind of carb do you have? I remember in the 1970s working on cars with Weber carbs that would frequently suffer from clogged idle jets. Maybe you somehow did that?

[slowpatina]

What kind of carb do you have? I remember in the 1970s working on cars with Weber carbs that would frequently suffer from clogged idle jets. Maybe you somehow did that?

Thanks for the reply, erik88lr. It's a Zenith 361V, I believe original carb. I've since removed the top of it ("float cover") and inspected/cleaned/blown air through the jets, and tested float for leaks, but everything seems fine, super clean inside, not gummy. I've ordered a new float cover gasket, thus not yet retried starting it... but seems carb is okay.

Still keen on more thoughts from more experienced folks than myself... with regards to my dumb mistake.

[jimrr]

are you absolutely, with no doubt, positivley, quite sure nothing went down the air intake and is messing up a intake valve?
sometimes it can be unrelated, last summer i had a catastrophic failur that turned out to be a ignition wire at the fust block (S3), it'd only run when i bumped it with my knee.
Plz come back here and tell us wth it was, ok?

[slowpatina]

That's a valid question, jimrr... I'm embarrassed to answer. I'll spare details but the air blockage was accidentally the full palm of my hand over the air intake , so... I know nothing went down it. Agreed something else unrelated could have gone wrong... but she ran flawlessly just hours before.

Been hoping for standard answer like, "When blockage suddenly stalls an engine then such and such situation can be the after effect."... but that seems unlikely.

Since the carb floods, I can't imagine it's not carb related. If it was the float that stuck, then when I removed the top off of the carb to inspect the float, it sneakily fell back in place and thus didn't seem to be the issue.

A question then (for anyone knowledgeable), could a rapid air intake blockage (ie: radical/immediate pressure change) cause the float to stick?

[erik88lr]

That's a valid question, jimrr... I'm embarrassed to answer. I'll spare details but the air blockage was accidentally the full palm of my hand over the air intake , so... I know nothing went down it. Agreed something else unrelated could have gone wrong... but she ran flawlessly just hours before.

Been hoping for standard answer like, "When blockage suddenly stalls an engine then such and such situation can be the after effect."... but that seems unlikely.

Since the carb floods, I can't imagine it's not carb related. If it was the float that stuck, then when I removed the top off of the carb to inspect the float, it sneakily fell back in place and thus didn't seem to be the issue.

A question then (for anyone knowledgeable), could a rapid air intake blockage (ie: radical/immediate pressure change) cause the float to stick?

I wouldn't think so, but I wonder if it could have done something to the accelerator pump plunger, such that now fuel is running through the accel pump circuit even though you're not opening the throttle to make it "squirt".

[slowpatina]

Ya, thanks, that too would be in line with how flooded it was and rough running with black smoke. I’ve inspected/tested the plunger, and like the float, it seems all good.

Perhaps during disassembly, anything that may have stuck didn’t show any issues since the intake blockage was a quick one-time abnormal occurrence and they fell back into place and seemed all good. It’s a head scratcher to me.

When the float cover gasket arrives I’ll reassemble and try restarting - not sure what else to check…

[roverp480]

Is the large "O" Ring seal intact ?

[slowpatina]

Is the large "O" Ring seal intact ?

Hi roverp480, thanks for thinking of that. Yes, that large o-ring is still intact and quite pliable. I just checked... a new one is coming in the carb kit so I'll use it and toss the old one regardless.

[slowpatina]

…well, after doing/checking things mentioned above, I’ve reassembled and refit the carb with new float cover gasket. All carb needles examined and in superb order. Installed new large O-ring as roverp480 suggested, and thoroughly cleaned the already very clean carb body and internals/jet passages. Turned the key and all is well. Found nothing out of order, so it’ll remain a mystery as to what went wrong when I stalled the motor via my hand accidentally covering the intake. Thanks to you guys for all the input on troubleshooting!

Now I can get back to the actual project I was working on, the brakes and servo. Series Rovers… they’ll keep you busy…

[jimrr]

shuttting the engine off with our palms is nothing new, don't feel like it's a ''dumb mistake'' ............ i really thot eric88 was onto something there as that act puts a lot of vacuum on the air system. too bad you didn't find a 'O' ring or something half into the throat body or something to determine what happened. if you do it again for us, come back and tell us what happened?