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Gas, hot days, carburetors and emission control...

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M

MGNoir

Jedi Hopeful
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Backstory first. In some past life, my midget had some of the emission control system removed - specifically the pipes that come off the two float bowls and return back to that canister who's name escapes me. So the float bowl tops have just the little stub pipes sticking out and nothing else.

And now to th epresent. We're in our yearly bit of 100 degree weather, and the Midget is not a happy camper.

I had to drive it on the highway and noticed that after I stopped, it basically died - like it was starved for fuel.

I looked under the hood and saw air bubbles coming into the fuel filter. I let it sit for a while and eventually it ran fine.

Fast forward a day (another hot one). Had to do another drive. I pull over to check it after about 20 min of 55-60 driving, open up the hood and there is gas bubbling out of the old gas fume/emission pipes (mentioned above) on the front float. Yikes! Dribbling down onto the manifold cover right over some very hot stuff!

I really debated about what to do (drive, tow, wait until evening) and in the end attached an 18" piece of fuel line I had handy to the stub, so that any overflowing gas would just go straight down towards the ground and away from the hot manifold. I drove back home slowly, taking several breaks in shady spots to let it rest.

So questions:

1) Anyone else driving around without the fuel reclamation pipes on their carbs? Do you plug them up? Should I get them replaced?

2) Bubbles in the fuel filter - heat related? Any suggestions? It definitely quit once the car had cooled down, and came back after it got hot.

3) Anyone else have similar problems on hot days?
 
MGNoir said:
3) Anyone else have similar problems on hot days?
Click to expand...
This sounds incredibly familiar.
I have the pipes (and canister) on mine, but noticed gas last night on the rear carb, linkage and heatshield.
I don't have a fuel filter, but have always had the suspicion that gas gets cooked, your 20 minute analagy represents mine.
I have nothing to add to assist in solving, so I'll follow the thread.
 
I've seen fuel stains around the carbs before but this is the first time I've seen it coming out. It reminded me of an old percolating coffee pot - sort of bubbling and spurting gas like there was a lot of vapor behind it.

Ah yea - temperature was 104 yesterday I found out.
 
Nobody has any comments on operating in hot weather? My reason for posting is because this seems to be a real danger and advice would be appreciated.
 
I operate in hot weather all the time here in Fl. but unfortunately have no experience with emission equipped engines as mine is much older /bcforum/images/%%GRAEMLIN_URL%%/eek.gif !! I have not encountered the problems you describe, perhaps somebody else out there?? /bcforum/images/%%GRAEMLIN_URL%%/thumbsup.gif
 
I had similar experiences until I rectified restricted fuel supply to the fuel pump and put a heat sheild under the carb and the filter.This is on a 1500 with single ZS.
Have been driving in hot weather and haven't had any more problems.
Not sure whether you should plug the pipes or replace them.If you replace them,I'd think you'd need to have canisters too.

Stuart. /bcforum/images/%%GRAEMLIN_URL%%/cheers.gif
 
"""""""come off the two float bowls """"""

so if we then assume you have two SU carburetors......

Check the fuel pressure....2.5 psi. no more than 3 psi. set the float level to 1" inch down from the bowl lid.

You do have the factory heat shield on...yes?

The fuel bowls need venting to atmosphere. If you are not using the charcoal cannister (stock hose and cannister) you can use a small hose and a tee and run the hose up high on the firewall with a coil of hose then back down below the motor. do not block the vents.

You can add fire sleeving to the fuel line(s) from the firewall forward. If you cant find any , use kitchen aluminum foil wrapped on the fuel hoses to form a heat sink. You can expand on the stock carb heat shield also so as to keep exhaust heat downward.

Run a fresh air vent from the radiator bulkhead or fan area to the carb area.
 
Two correct.

Have heat shield and also charcoal cannister, just missing the line that comes from the floats over to the cannister.

Given that fuel was literally bubbling out of these vents I'm guessing I do not want to just run the hose to air as it will just be dribbling (wasting) gas somewhere else. Better I'd think to run it back to the cannister so it can get sent back to the gas tank (?)

re: adding a heat sink. The bubbles coming into the fuel line are sort of odd since it's metal fuel line until just before the fuel filter - about a 4" piece of fuel line at that point. As far as I can tell the fuel lines are all stock/normal and nothing has been rerouted or done differently.
 
Have you done anything to the motor recently? New valves, head shaved, or done something else 'new'? I'm trying to suss out if you and I have done similar things to the engine at some recent point, one of those may be it as your symptoms are uncannily close to mine. (Heat wise).
 
Re: Gas, hot days, carburetors and emission contro

Hmm no all stock. I did get a new distributor (rebuilt) a while back. It has in general run like proverbial "crap" as of late - really weak at lower RPMs. Also my temperature gauge on the dash quit working at some point.
 
Re: Gas, hot days, carburetors and emission contro

Sorry, I know I'm coming late to this thread, but, yes, I've had very similar problems. Here is my experience, plus a solution: https://www.nonlintec.com/sprite/fuel/.

In any case, you shouldn't get fuel coming out of the bowl vent pipes. The obvious suspect is the float valve.
 
Re: Gas, hot days, carburetors and emission contro

That is a really good link Steve. I would add this thought to it as this has worked well for me and is no doubt why I do not have the problem this thread is devoted to.

When running the fuel line from the pump to the engine compartment, bring it up the passengers' side, to the front of the engine, across the car below the steering rack and up to the carbs on the left side (you can follow the brake lines!). This avoids the hot exhaust side of the engine altogether!! /bcforum/images/%%GRAEMLIN_URL%%/thumbsup.gif
 
Re: Gas, hot days, carburetors and emission contro

Mike, is the fuel line usually routed up the exhaust side? Mine has it routed exactly as you describe--I've always wondered if that was the original way it was done, or if the guy who restored the car just chose to do it that way.
 
Re: Gas, hot days, carburetors and emission contro

Bugeyes go up the exhaust side when arriving at the engine room crossing over at the rear and up to the front motor mount under the carbs and up.
 
Re: Gas, hot days, carburetors and emission contro

Steve, I'm glad Jack answered that 'cause it's been so long I really didn't remember, but since the pick-up at the tank is also on the righthand side, it just makes more sense to me! /bcforum/images/%%GRAEMLIN_URL%%/wink.gif
 
Re: Gas, hot days, carburetors and emission contro

Thanks--yeah, I don't know where I would find out these things, if not for you guys--this kind of thing never will appear in any shop manual.
 
Re: Gas, hot days, carburetors and emission contro

BTW on the midget it's away from the exhaust
 
Re: Gas, hot days, carburetors and emission contro

If it is a newer midget the exhaust is on the passenger (rt) side, isnt it?
 
Re: Gas, hot days, carburetors and emission contro

Naw... it crosses under the tunnel and runs down the drivers side.
 
Re: Gas, hot days, carburetors and emission contro

Ah! But the manifold is on that side, right?
 
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