Fuel starvation in hot WX after shut down and restart

[Brian T]

Bill ,
Pre pumps for Volvo came out as a retro fit kit in 76, then as a factory fit in 79, the tanks suffered from a very high heat build up for many reasons, the hot return fuel from the injectors, the placement of the return pipe in the tank, which caused air entrainment, to say nothing of the exhaust system within inches of the tank.

Its amazing how well these model A,s run as most of them do with the carb temperature so high, reducing the fuel and air temperature to a lower level would certainly help the power somewhat, it would be most welcome with a double A.

[Napa Skip]

"I have made a 3/16" insulating block which I install between the carb and manifold."

Aerocraft - a photo of this insulating block (installed) would be appreciated. I made a similar item (out of tempered masonite) and the only problem was that the choke/AF adjusting rod tended to bind up on the lower edge of the firewall grommet (solved by a dab of silicone lubricant). However, I'd like to see what you came up with (with an explanation of the material if not masonite). Thanks.

[Tom Wesenberg]

Originally Posted by MrTube

Ah, so when we add the fuel injection we have to make sure we use an in tank style pump. I have to wonder, is this part of the reason in tank pumps are so common?

Yes, and it's a wonder the government allowed an electric motor inside the gas tank.

[Duffy1]

Is this only happening on engines with a Zenith cas iron housing . Cast iron acts as a heat sink. So with you stop the engine and leave it for say 30 min the liqiud gasoline turns to vapor . I also have this problem and a fellow model a`r with tons of experience says it is the cast iron housing causing the problem . He changed to a carburator without a cast iron housing and had no more problems . Maybe the folks that are not having problems are not running Zenth carburators. If I let the engine set for 5 min I do not have this problem . IT TAKES A LITTLE WHILE FOR THE GASOLINE IN THE CARB TO TURN TO VAPOR .

[Patrick L.]

Copper fuel lines ?? I've seen quite a few and don't have much of a problem with them as long as they are seamless and installed correctly.. I've seen them mostly on small engine equipment, farm equipment and mostly on boats.. The USCG approves seamless copper fuel lines.. Any time I install the stuff I'm pretty careful how its installed and have had a fair amount of practice bending vibration coils.. I remember reading a GM service bulletin back in the 60s about copper brake lines and was surprised that they didn't seem too concerned about it.. They made the spiel about the pressure flex annealing the tube and recommended against using it,, but,, stated if it was to be used to make it was seamless and double flared.. Even back then I thought this was nutz..

[Aerocraft]

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Napa Skip: Here is a shot of one of the insulators with one inch long stainless attaching bolts. It also requires two gaskets which are not shown. I don't remember what the material is but I bought it online from McMaster-Carr (www.mcmaster.com). It is synthetic, is rated for something like four hundred degrees, and machines very well.

I have made a lot of them for our local club members and all report that the boiling problem was solved. I have found that they do cause some binding on the choke / GAV rod, especially on the '28 & '29 models.

Gar Williams

[Milton]

Originally Posted by sphanna

OK, I've been told in no uncertain terms that Model A's do not experience vapor lock.

I would have said the same from a logical standpoint but sometimes my logic does not prevail. I have two sources that I posted on the vapor lock thread to contradict my assumption.

[kevinmac/toledo]

sir; i do know from working in the refineries , that they allow a certain amount of diesle to be introduced into gasoline , but never any gas into diesle...the gas would be too explosive for diesle engines...maybe your getting a mix that is more rich in diesle than gas....maybe not mixed up real good,ect,ect,ect. years past i swear my gas wouldnot burn in my lawnmowers....changed to fresh fuel, all was ok.....just my .$.02...cant find the cents button..........kev

[BILL WILLIAMSON]

Originally Posted by Duffy1

Is this only happening on engines with a Zenith cas iron housing . Cast iron acts as a heat sink. So with you stop the engine and leave it for say 30 min the liqiud gasoline turns to vapor . I also have this problem and a fellow model a`r with tons of experience says it is the cast iron housing causing the problem . He changed to a carburator without a cast iron housing and had no more problems . Maybe the folks that are not having problems are not running Zenth carburators. If I let the engine set for 5 min I do not have this problem . IT TAKES A LITTLE WHILE FOR THE GASOLINE IN THE CARB TO TURN TO VAPOR .

Yo, Duffy,
In years past, working on Datsuns with the large glass window in the front of the float bowl, in the summer, drive a warmed up car in the shop, turn it off, and in 2 minutes, gas was boiling in the bowl!! Never saw one boil the bowl empty.
I've never had these fuel flow problems, whatever is causing them??? If I had chronic problems like some are having, seriously, I would run hood off when it was really hot, or maybe take hood sides off to see if it helped. When stopping for pee time, maybe open R/H hood to let stuff cool off. Bill W.
(You get lots of attention when you run NO hood!
WAY COOL!!)

[kingbee]

This is so incredibly frustrating. I've got a beautiful Marc of Excellance roadster I 've retired so I can enjoy it. If it's over 80 degrees out and been driving for a bit, if I happen to kill it, or shut if off, it will not re-start for 30-40 minutes. I've covered the sediment bowl, fuel line and carb with thick pipe insulation and put in 2 ounces MMO per gallon of fuel in the tank, all to no avail. When she doesn't start I'll pull the choke out for 20-30 seconds of cranking. There should have been a river of fuel coming out of the carb - but not a drop to be seen.
When she runs, it's a beautiful thing - lots of power, very responsive to throttle and an incredible slow idle when desired.
So what I have is a very expensive car I can't drive in the summer, or the winter due to being in the salt belt.
There's one more thing I want to try. I want to mill .050" off the intake manifold where it bolts to the exhaust manifold and put some kind of insulating material in there. If it doesn't work, or in cold weather, to get back to design intent, I can place a .050" steel shim in there to get the heat transfer back.
Other than trying a fuel pump, I'm stumped as to what to do to be able to enjoy my beautiful roadster. I've searched and read all the threads on the subject on the Barn and haven't seen a solution that works for me. More MMO?
OK, if I have to, I could try installing my Weber downdraft manifold and carb, but I shouldn't have to do that, as my Zenith runs so sweet, when it runs.
Any help out there?

[steve s]

Originally Posted by kingbee

...Any help out there?

If you're seriously considering installing a downdraft carb, here's a less drastic alternative, which worked for me, that you might consider--maybe your "summer" carb. It's an easy swap and a good fit. Totally solved the vaporization problem for me; I've removed all of my insulation on the sed. bowl and fuel line, as well as my heat shield. And, as a bonus, it's impossible to stall on a hard stop. You will need to rig some fuel line adaptation.



Steve

[kingbee]

Interesting. And no FAV?

[JimK1930A]

Would you please post a picture of the insulating block you mentioned in your article.
Last weekend I drove 50 miles each way at 45-50 mph to a car show in 95 degree temperatures here in Minnesota. I use non-oxy 91 octane gas in my A and use a reliable Tillotson Carburetor. No problems of any kind with my car below 80 degrees outside temp, but on that particular drive, at every stop light or stop sign, my car acted as if it were running out of gas. After the second time it happened, I tried to prevent it from happening again while coming to a slow stop with left foot on clutch, right foot on brake, right hand on steering wheel, reached through steering wheel with left hand to use the hand throttle. Whew! Out of feet and hands! I tried the hand throttle to prevent from stalling, to no avail!
When I looked under the hood hoping to see something that I could fix or adjust, I noticed inside the glass sediment bowl that it was fizzing like a 7up commercial.
My car would not start immediately, but after letting it sit for 5 minutes sometimes through one cycle of stop lights, it would start and away I would go until the next stop sign a few miles down the road. Very frustrating and dangerous even though I was in the right lane with modern traffic right on my A_s!
I have engine pans and all the other stuff mentioned that my car should have. As said in the beginning, my car runs perfectly at 80 degrees or below.
Also, I have been searching the Model T, A, and early V-8 archives for answers on the subject.
Thank you in advance.
Jim

[Aerocraft]

The picture is shown on entry number 26 (above). Here it is again. Gar Williams

[BrianBurkert]

I just add some Marvel Mystery Oil, 2-cycle engine oil, or diesel fuel to the gas. It seems to fix the problem. I don't measure, but maybe I add a pint of diesel which seems to be the cheapest solution.

When I drove the car to the midwest for a national meet, it was even worse. When I stopped for gas, I'd shut the tank valve off and let the car run out of gas. When I wanted to go again, I'd open the valve up and the cool gas from the tank left me drive away without fits and starts.

Different areas seem to add different amounts of ethanol. This may explain why some folks have no problems, depending on where they buy their gas.

[Tom Wesenberg]

Back to #30, kingbee's problem, I had the same thing happen when parked at the Ford plant in St. Paul on a hot day. I had to remove the fuel line at the carb to get the fuel flowing again, then I was off and driving until an hour later when I stopped to see the antique cars come in at the New Brighton run. I had to remove the fuel line at the carb again to get the fuel to flow. Since using the good gas I haven't had the problem.

Bob A. made a heat shield to fit between the carb and exhaust manifold, and that's what I'd do if the problem comes back. You could even buy a sheet of asbestos and wire tie it to the exhaust manifold to see if that wouldn't help. Some cars have used fans that take cooler air from the front of the radiator and blow it towards the carb.

[steve s]

Originally Posted by kingbee

Interesting. And no FAV?

Not on the choke rod. There is a T-valve on the front end of the carb that does the same thing, I think, except you just set it and then leave it alone. The GAV absence doesn't seem to be a problem: car starts cold and warms up ok. May require a tad more choke.



Steve

[steve s]

Originally Posted by JimK1930A

... When I looked under the hood hoping to see something that I could fix or adjust, I noticed inside the glass sediment bowl that it was fizzing like a 7up commercial. ... Jim

I noticed vaporization in my sediment bowl (but no fizzing!). At idle, I could watch the bubble build up until it covered the top of the bowl, then burp on down the line and, amazingly, the motor barely stumbled at all. This was with a Zenith-1 carb. So, this may or may not be a serious problem. Here's my growing bubble:



I don't know whether your problems are due to sed bowl vaporization or something that's going on in the carb. It's possible for a vapor bubble to form a blockage that shuts down the flow, especially if you have a filter in the line. If you haven't already, I suggest you remove everything, including the screen, from the sed bowl to minimize blockage likelihood there. If that helps, add things back one at a time until you've gone too far. Also, be sure that the fuel line is not inserted too far into the sed bowl top, or into the carb.

Steve