Hereditary No Fuel start up.

[OUTFXD]

Our cars have an issue.  After driving the car to operating temperature, especially on a hot day,  Turn the car off,  walk away for a while.  Come back and try to start the car.   Guess what?  No fuel in the carb.  Means you need to crank the engine for quite a bit before the carb sees fuel and will start.

 

This is a common enough problem that many will put an electric fuel pump in simply to "prime" the carb. 

 

But why?  What causes this condition?   Corn syrup fuel (read Ethanol) having a lower boiling point?  Surely our cars did not come off the assembly line like this!

 

So.  Is there any other work around other than installing a "prime" pump?(I no do electric good) E.G. Heat shields etc

 

Just looking to expand my infoz.

[bacelaw]

I think a carb spacer between the intake and carb, a fiberglass type heat shield wrap around the steel fuel line, routing the fuel line farther away from the hot manifolds, are all options that should help vapor lock or boiling fuel.

 

 

[Sam Buchanan]

37 minutes ago, OUTFXD said:

Our cars have an issue.  After driving the car to operating temperature, especially on a hot day,  Turn the car off,  walk away for a while.  Come back and try to start the car.   Guess what?  No fuel in the carb.  Means you need to crank the engine for quite a bit before the carb sees fuel and will start.

 

This is a common enough problem that many will put an electric fuel pump in simply to "prime" the carb. 

 

Most likely the problem is not lack of fuel but too much fuel. The hot carb boils fuel and it overflows and puddles in the intake manifold. When we try to restart the engine the puddle creates a mixture that is too rich to run until the engine turns over enough times to pull the over-rich mixture out of the manifold and cylinders. Once that happens, the mixture returns to normal and the engine starts.

 

I run a full-time electric pump and still have this heat-soak issue in my car so the electric pump isn't the solution. Some have suggested adjusting the carb float to lower fuel level in the carb to inhibit boil over and flooding the intake manifold. Using non-contaminated gas might also help but I've always used cheap 87 ethanol. This is a well-known problem, best remedy is probably a healthy battery that can spin the engine until the flooding is cleared.

[keithb7]

 

[Sniper]

Hmm, I live in west Texas, 100+ degree days are the norm.

 

I run whatever gas Shell has, no effort to use ethanol free gas.

 

Stock fuel system, from tank to carb.  Nothing added to it in the way of heat shielding, or anything that wasn't on the car when the factory rolled it out the door.

 

My exhaust flapper works properly.

 

I have never had this problem.

 

So, either Shell isn't selling gas with ethanol in it (doubtful) of it's not "hereditary".

 

In fact, I believe it's more a confirmation bias than a wide spread issue.  You hear from people that have this issue, you do not hear from people that do not.  So the impression is that this is a widespread issue.

 

 

[keithb7]

Sniper you have mentioned before your engine has low compression . Maybe 50 psi per cylinder has something to do with it? Maybe lower psi cylinders can take a higher mixture of fuel and still fire?   Just guessing. In my engine I could see raw fuel spitting out of the carb’s idle orifice at the throttle valve. I witnessed raw fuel in the intake manifold, pooling. My exhaust flapper valve works properly. My engine labor’d more to fire when the A/F mixture was rich. 
 

My conspiracy theory allows me to mostly make sense of what’s going on here with my car.  I don’t quite understand why its not happening to all of us. Aside from bringing my car to Texas and driving it in 100F heat, I  don’t think I’ll find answers to Sniper’s comments. 

Edited October 19 by keithb7

[plymouthcranbrook]

I have the Langdon Empi carburetor on my 52 which sits on an adapter that is somewhat tall. If the outside air temp is really high sometimes there is a momentary delay but usually not. I have more issue with my stock 80 Volare than the Cranbrook.

[Los_Control]

What many have done, I do not know anyone on this forum that has done it .... but out in the world many have,

Add a return line to the fuel tank .... The idea is, when you are driving slow through town, or looking for a parking spot at the supermarket .... you are not using much fuel, and the float in the carb closes and all the fuel in the line between the fuel pump and carburetor is getting heated up.

 

The heated fuel can turn to vapor and get vapor lock .... mechanical fuel pump can not pump vapors. .... When you shut the engine off you get heat soak as temps rise.

This makes the already pre-heated fuel easier to turn to vapor as the engine gains 20 degrees with no cooling system working.

A electric pump near the tank pushes fuel so it will push the vapors through.

In my twisted little brain, this gets you past the problem .... It does not fix the real problem .... it is a pretty good "get ya by"

 

 

With this style of filter many manufacturers .... some Jeeps used the filter to create the return line. 5/16" going through with smaller 1/4" on the side to go back to the tank.

Now when you are not using much fuel, it is always recirculating through the system and staying cooler and not getting a chance to heat up.

This style of filter does not work well for our engines, it needs to be past the fuel pump which puts it over the exhaust manifold and requires rubber lines to connect.

You get the idea though.

 

With a brass T and scrap lines for demonstration, you can add a T and then convert one side to 1/4" and run it back to the tank to duplicate what early car manufacturers did.

 

 

The main idea is to keep the fuel cooler in the first place, now when you shut the engine off the extra degrees in temperature will not be enough to vaporize it.

In my twisted little brain, this is a actual cure, because you prevent the fuel from becoming heated in the first place .... no electric pump to save you is needed.

Remember though, a electric fuel pump is a desirable option to have and worth installing. For other reasons then just vapor lock.

 

How you get back into the tank is up to you, some have used the filler neck to install a fitting. I have a aftermarket tank that accepts a universal in tank electric pump, I can remove the cover from it and install fittings and gaskets to get into the tank .... A old original tank may be difficult and need the filler tube option.

 

So this is an alternative to the electric fuel pump .... I have all the various fittings and still need to get the 1/4" line when I'm ready. I have installed a extra filter near the tank, where I plan to install a future electric pump .... even though I will have a return line, it will be easier to start after it sits for weeks without driving it to fill the carb. Or if the mechanical pump goes out on a trip, can just switch over .... if I still encounter vapor lock .... I will be prepared for it.

[Sniper]

3 hours ago, keithb7 said:

Sniper you have mentioned before your engine has low compression . Maybe 50 psi per cylinder has something to do with it? Maybe lower psi cylinders can take a higher mixture of fuel and still fire?   Just guessing. In my engine I could see raw fuel spitting out of the carb’s idle orifice at the throttle valve. I witnessed raw fuel in the intake manifold, pooling. My exhaust flapper valve works properly. My engine labor’d more to fire when the A/F mixture was rich. 

 

I suppose it's possible, though I have never heard this theory before?

 

My fuel lines are routed way away from the exhaust manifold. 

 

 

[soth122003]

16 hours ago, OUTFXD said:

But why?  What causes this condition?   Corn syrup fuel (read Ethanol) having a lower boiling point?  Surely our cars did not come off the assembly line like this!

Ok time for my thesis on why. Now I learned my thermodynamics from my Professors. Professor Ludwick Von Drake and Doctor Vinnie VoomBots.  I know, I know, you guys are already saying this ought to be good and it will be. Now where was I?

 

Oh Yes! When crude oil is taken out of the ground it doesn't see the light of day (the Sun) and it is heated and separated by heat into it's component liquids (gas, oil, plastic, nylon what have you), Then cooled and sent to it's proper tanks for other additives to be introduced to screw it up into winter and summer blends. After this it doesn't see heat again until used. It is then transported to the white holing tanks for distribution. The white reflects the sun to keep it cool. (Can you see where I'm going with this?) 

 

After this it is put into truck tanks that are silver and transported to the gas stations. You may not be aware of why the tanks are silver but it is my belief that wind rushing of silver tanks at 60-70 mph keeps the temps of the gas stable at 62.6 degrees through the process of aluminum foil on a bologna sandwich in a lunch box. (That is why the bread is soggy when you unwrap it)  When the trucks reach the gas station the the contents are pumped into under ground tanks that store gas and keep the temp around 65 degrees. 

 

Now when we pump the gas into our cars of different colors we lose the thermal properties of silver and under ground tanks. Which now brings us to the eggheads and nerds screaming about global warming, climate change or what have you. The fuel in the cars now have a new playground to expand and contract with no rules at all. In the case where the outside air temp fluctuates thru-out the day it leads to vapor lock and flooding at the same time. The engine heats up and the fuel expands next to the heat source and leads to vapor lock when the car is slow or stopped due to no airflow thru the engine compartment. The fuel in the carb boils and settles into the intake which is kept cool by the air being sucked in and by the vacuum effect is cooled down. This results in the 5minute stop being subjected to flooding because the exhaust manifolds can't heat the intake manifold to evaporate  the fuel. 

 

Conversely in hot areas like the southwest, the air is always hot and does not cool down as much as in the above described process so the fuel in the intake evaporate in 2.7 minutes so no flooding. This does however leave the issue of vapor lock. It is my belief that the warmer fuel in the southwest is less prone to vapor lock because it has evolved to enjoy the warmer weather. This is why so many people flock the Florida and Texas from New England in the colder times. Also since most of the Mopar owners above the Mason Dixon line only drive there cars in the nicer weather the gas is going from cold to hot to cold and so on, this leads to more case of flooding and vapor lock. 

 

So in conclusion to my thermal thesis I think I have demonstrated that:

1. fuel likes to be in a atomized or gaseous state so that it can enjoy the warmth it has been deprived of and 

2. Either move down south to enjoy your Mopar or only drive it in the cooler or cold months where your heater doesn't work or is not installed so the fuel doesn't know what it's brethren in the south has discovered. 

3. The climate of the 40's and 50's wasn't subjected to the thoughts and ideas of the so called experts we have now a days so it stayed stable and not effected by the whims of the internet, thus the cars and fuel back in that time had no idea that things could be otherwise and did what they were supposed to do.

And for goodness sake don't drive your Mopar from south to north so the fuel can let the secret out.

 

Now that concludes my thesis and I will humbly accept any discussion and feedback on the matter.

 

Joe Lee

 

[Sniper]

Lol, I like your thinking.

 

And your thinking got me to thinking (oh no).

 

I ran into an issue with my gas cap venting sometime back, it didn't vent.  Neither pressure nor vacuum.  So I bought a new one and it didn't either.  The original cap vented to atmosphere via some holes.  The new cap(s), had some sort of emissions doohickey that used springs and check valves.  Whatever, i could hear my gas tank oil can when it heated up.  I ended up lobotomizing the new cap and now it vents.

 

I wonder if this is playing into those of us with the issue?  The tank builds pressure and forces gas into the carb?

Edited October 19 by Sniper

[Sam Buchanan]

In addition to the vented cap on my P15, which I have verified is venting, I have a small hole in the filler neck that will vent the tank in case the cap malfunctions. I'm convinced the reason a hot start can take longer for my car is fuel percolation in the carb.

[soth122003]

Quick thought on the silver tankers I listed above. Our original paint on the engines was silver as well right. Now most are rust colored or a different color other than silver. I think my thesis is starting to hold more water. (or B.S. if you have an opposing view).

 

Joe Lee

[DJK]

On 10/18/2024 at 10:14 PM, Sam Buchanan said:

 

Most likely the problem is not lack of fuel but too much fuel. The hot carb boils fuel and it overflows and puddles in the intake manifold. When we try to restart the engine the puddle creates a mixture that is too rich to run until the engine turns over enough times to pull the over-rich mixture out of the manifold and cylinders. Once that happens, the mixture returns to normal and the engine starts.

 

I run a full-time electric pump and still have this heat-soak issue in my car so the electric pump isn't the solution. Some have suggested adjusting the carb float to lower fuel level in the carb to inhibit boil over and flooding the intake manifold. Using non-contaminated gas might also help but I've always used cheap 87 ethanol. This is a well-known problem, best remedy is probably a healthy battery that can spin the engine until the flooding is cleared.

Sam, I installed a switch to shut the pump off to drain the carb of fuel, this works very well for me. I also run electric, Carter P4259, full time, no manual pump.

[Merle Coggins]

I agree with the other statements that it's a fuel percolation issue due to the heat. I learned early on that to restart my truck, after it sat for a few minutes, that I needed to crack the throttle open a little. This allows more air in to lean out the gas that gets pooled in the intake from the percolation. I've gotten pretty good at using my heal on the gas pedal while stomping the starter with my toe. It starts right up every time that way. If I don't give it a little throttle it'll crank a long time before starting. I've lowered my float slightly, and I mostly run premium gas without ethanol, but I still use this starting procedure, mostly out of habit now, when I start the engine hot. It never fails. 

[Dan Hiebert]

I had the hard-start-when-hot problem when we lived in west Texas (El Paso).  My issue was that the Sisson choke was not adjusted correctly and did not have that high-temp gasket.  When I wanted to start the car when it was still hot, I'd have to have someone manually hold the choke open while I cranked it.  Otherwise, I'd have to wait often more than an hour for it to cool off enough to start.  If it had been adjusted correctly and had that gasket, it wouldn't have fully closed when starting hot.  That matches the too much fuel description, as well as Merle's starting procedure to let more air in.  I corrected it at the time by removing the Sisson choke and installing a generic manual one, and I never had the hot starting problem again.  That and actually following the manufacturer's starting instructions once I obtained an owner's manual - partial throttle when starting hot - may have helped.  (I re-installed the Sisson choke earlier this year.)  

 

In what could be a reasonable study between ethanol and non-ethanol gasoline.  When we lived in El Paso was during the time ('94 or so) the EPA mandated that El Paso County sell ethanol laced gas during the winter months, so we got to involuntarily compare the two.  And - with the hot-start problem, there was no difference between summer and winter gas.  That's just an observance on the hot start, there were several other issues with notable differences, such as fuel economy.  We rued the onset of winter because gas mileage went down considerably, and I had a 42-mile one-way commute.   

Edited October 21 by Dan Hiebert

[Sniper]

Interesting, one of the first things I did when I got my Cambridge was to adjust the automatic choke. When I started I pump it once and hold the throttle about a third of the way open and crank it over and she fires right up.

[Sam Buchanan]

15-20 minutes seems to be the threshold for my P15 when the engine is hot. Hot start prior to that is immediate (as is a cold start with choke applied), but after a lunch break the excess fuel requires about 4-5 seconds to clear which seems much longer as visions of a drained battery dance through my thick head.   😜

 

It has never failed to start, but it cranks long enough to get my attention. I too use the partial throttle method when hot starting.

[Dan Hiebert]

7 hours ago, Sniper said:

Interesting, one of the first things I did when I got my Cambridge was to adjust the automatic choke. When I started I pump it once and hold the throttle about a third of the way open and crank it over and she fires right up.

Indeed.  Too long ago, I don't remember exactly why I gave up on the Sisson choke so quickly.  I didn't mess with it afterwards because the manual choke worked well.  Couldn't help but chalk myself up as a recovered dunderhead when I put it back on and got it starting well with little to no fuss.

[Sniper]

When I bought the car I had no history on it's servicing and what I saw of some of the work I did not care for.  So I went thru everything.  Here's my write up on the choke adjustment.  Not too tricky,

 

http://www.yourolddad.com/choke

 

Edited October 22 by Sniper