Strange problem?

[Bret]

Hey gang,

Well while the rest of the Union seems to be dealing with severe cold weather, here in Sunny California it’s hovering in the 80s. BTW the Patriots playoff game with Tennessee tonight looks to be a very interesting event with sub (-) Zero temperatures.

That said, this afternoon I finally had to pull my 78B out of the barn not to take it for a drive as I would have liked but to access some yard tools. Yeah I know but what can I say the wife’s in one of those busy’ buzz-buzz clean-up modes.

Anyway (Oh how the mind wanders) back to the problem – upon attempting to start the old gal after what has been about a two-week nap. I discovered that the battery was dead thanks to a door that had been left ajar and had to jump her. With that out of the way something strange happened when I finally started my car it wouldn’t kick down a revving about 2000 RPM. Popping the hood I figured I just adjust the idle speed. I immediately noticed that my catalytic converted was glowing cherry red!!!

Shutting the car off I started to collect my tools & test equipment (much to my wife's dismay, the lawn was going to have to wait), in preparation to correct what appeared to be a fuel richness problem. After I got all set-up I turned over the car and low & behold the problem didn’t reoccur again. Heck I even took the car out for a long 20 to 30 minute drive to see if that might bring on the glowing cat again. But as hard as I tired it never happened again.

Any of you Zenith/Stromberg guys know what’s going on? I’m stumped and need to mow the lawn before the wife kills me.

[ 01-10-2004: Message edited by: Bret ]</p>

 

[adam90009]

well i've read about this before and it could either be the cat is cloged and time to get a new one or your carb is running too rich or your timing is off. those would be the things i would check first

 

[Bret]

<blockquote><font size="1" face="Verdana, Arial">quote:</font><hr>Originally posted by adam90009:
well i've read about this before and it could either be the cat is cloged and time to get a new one or your carb is running too rich or your timing is off. those would be the things i would check first<hr></blockquote>

Well I’m not saying your right or wrong about the catalytic converter. But I replaced the original cat a little over two years ago. I know for a fact that the smog pump is still working and it seems a bit unlikely that the platinum screen element would have burnt away already because I’ve kept the car fairly well tuned since it was replaced. But that is still a possibility I guess, so I’ll look into that.

However as I said before is that the glowing cat problem didn’t come back again after I shut it off & restarted it again after about 20 minutes. Just so you know, I even revved the engine up to 2000 RMPs in the driveway for about 4 or 5 minutes and it didn’t come back. I’m starting to think that something on my carburetor just got stuck or clogged and shutting it off allowed everything to right itself again.

That said this is still very confusing? I just want to make sure I’m not missing something.

 

[Bret]

Hmm? I don’t know if this is related but I just thought about something else that happened.

When you start a B you normally hear the fuel pump clicking away for about a second or two when you first turn the key. Well I normally start my B I tend to let it click away until it stops before I actually turn the ignition key the remainder of the way to start the engine. This is normally about two or three clicks. But this time it clicked for several seconds before stopping.

At that point I pumped the accelerator twice (as I always do) and start the car. But I was wondering where does all of that fuel in the Carburetor go when the engine is shut off? I don’t see any fuel leaking.

Could it have leaked down into the manifold pudding up and then forced (upon start) through the combustion chamber and in turn collect down streem in the catalytic converter?

Mind you I could be grasping at straws but that might explain the cherry red cat.

What do ya’ll think?

[ 01-10-2004: Message edited by: Bret ]</p>

 

[Carl Heideman]

I'd say your auto choke got stuck on. Your cat was glowing red because you were running real rich and fuel was going right out the exhaust. We see this fairly frequently with ZS-equipped cars at the shop.

--Carl Heideman, Eclectic Motorworks LLC
www.eclecticmotorworks.com

 

[Bret]

<blockquote><font size="1" face="Verdana, Arial">quote:</font><hr>Originally posted by Carl Heideman:
I'd say your auto choke got stuck on. Your cat was glowing red because you were running real rich and fuel was going right out the exhaust. We see this fairly frequently with ZS-equipped cars at the shop.

--Carl Heideman, Eclectic Motorworks LLC
www.eclecticmotorworks.com<hr></blockquote>

Wow!?! This never happened to me before, do you think the Cat is OK?

 

[tony barnhill]

Never happened to me before either...I'd bet on clogged cat & that's the reason it was getting so hot....if the Zenith was running rich enough to turn the cat hot, it'd have dripped enough raw fuel out of its bowl to burn the czar to the ground! Nope, clogged cat!

 

[John S Farrington]

A clogged catalytic usually will not allow the engine to achieve high rpms. Usually the clog does not go away without surgery. I have never had an MG ZS carburator heat up a catalytic, but I have on several ocassions had Jaguar catalytics burn cherry red from too much fuel injection. I would bet that your auto choke got stuck on full rich.

 

[Basil]

I see others have already suggested the first thing I was going to say - that the choke was stuck. You might want to take a look at it just to be on the safe side.

Basil

 

[Bret]

I think it’s the Choke too. It seems to need some adjustment – I’ll let ya’ll know how that turns out when I’m done.

 

[Guest]

check Tony's site for info on how to set the Z/S choke

 

[aeronca65t]

I'd vote on a stuck choke too (probably the little sliding brass piston in the mechanism is gunked up).
But a comment about "pumping the gas twice": pressing the gas to the floor once will help "engage" the auto-choke. Pressing the gas pedal a second time won't do anything (remember: there's no accelerator pump in a ZS carb). The second "press" isn't hurting anything....it has no affect at all.

 

[John S Farrington]

The best repair you can make on a ZS water heat choke is to convert it to a manual. The MG will run much better and it will start in cold weather much easier. Manual kits are available from Moss Motors. I recently was supplied a conversion kit from Engles in Kalamazoo that was a better package than the Moss kit for aabout the same money. The manual choke will be a very substantial improvement to your Zenith.

 

[Bret]

I have considered installing a Manual choke in my B for sometime now. The only thing that has been really holding me back, is this screwy state’s strict emissions standards. Because the auto-choke is required on Zenith/Stromberg equipped MGBs – if I convert to the manual choke I will have to re-install it each time it is smogged. As it stands right now I speed a good day tuning and preparing my B for the smog test. Throwing a choke swap & setup into the mix isn’t going to make my life any easier. Hmmm? Is it worth it?

But on the plus side by my calculations I shouldn’t have to do the swap more than twice before my 78B is 30 years old and exempt from any further testing. Maybe it is worth it?

 

[tony barnhill]

Actually, the "automatic choke" isn't really a choke...&, if you follow the instructions on my web site for cleaning/repairing & setting it, it'll give you no more problems...I have my original Zenith on my '79 I bought brand new - 100,000 miles with only 1 carb rebuild but the 'auto choke' is properly maintained....something 99.9% of Zeniths have not had

...would I change to manual? No! But, if I were going to keep the Aenith, I would clean, repair, adjust properly!

 

[Bret]

<blockquote><font size="1" face="Verdana, Arial">quote:</font><hr>Originally posted by tony barnhill:
<<SNIP>>
...would I change to manual? No! But, if I were going to keep the Aenith, I would clean, repair, adjust properly!<hr></blockquote>

Fair enough Tony,

Seems logical to try this first before investing in a Manual Choke. I’ve never really had any problems starting the car on cold morning of course the coldest it ever gets around Poway is maybe in the upper 30s at night. Anyway I have looked over the procedure on your web page and will try it this week or next.

Thanks,
Bret

 

[adam90009]

well i have a used manual choke i used for maybe a month or so. still works just fine. email me if your interested. adam90009@yahoo.com