Difficult re-starting, '40 LaSalle

[John Barry [CLC17027]]

Here's the situation, sports fans: when the temperature gauge is about 20-25% of full scale, it is difficult to nearly impossible to get the engine to start shortly after shutting down (e.g., a re-start from a stall, or an immediate re-start when getting situated in a parking space at a show).  I doubt that it has anything to do with ignition, since the plugs and wires are essentially new.  I suspect it has to do with vapor locking instead.

The fuel pump is located, as you may suspect, under the hood, at the left front.  There is no insulation on the fuel lines at any point, nor is there a heat shield of any sort on the pump.

First: might anything be accomplished by adjustment of the thermostat on the carburetor?  I suspect not, but I'll defer to the experts on that one.

Second: the car has a period-correct auxiliary electric fuel pump, but it's disconnected at present.  At one point, it was connected in series with the mechanical fuel pump, using rubber tube for the hookups to the electric pump.  That had problems of its own: the pressure drop in the fuel line through the electric pump was sufficient at times to collapse the rubber tube and starve the engine for fuel.  As such, the electric pump and rubber tube were taken out of service, with an all-steel fuel line getting installed.  I have to wonder if it might not be worth it to get the electric pump back in service, using nothing but steel tube for the fuel lines?  I realize this would mean using tees and check valves in the fuel line (some recommend against this practice), and it necessarily implies two fuel lines in parallel.  There would be a common line from the tank to a tee: one tee outlet would go to the electric pump; the other, to the mechanical pump.  The electric pump discharge line would run in parallel with the mechanical pump suction line along the frame to the area under the hood.  Another tee would be located in the line feeding the carburetor, joining the two pump discharge lines.  There would necessarily be check valves on each of the inlets of that tee to prevent backflow of fuel.

So what's the consensus?  Should I look into a re-connect of the electric pump?  Adjust the thermostat?  Try something else?  Give up?

Thanks in advance.

[TJ Hopland]

Check in your area if there is ethanol in your fuel.   Many parts of the USA now have it in at least the lower grade.  Some places have it in everything year round.   You may be able to change brands or grades and get fuel with no ethanol and that may be enough to help your issue.   Much simpler than reworking your fuel system.   The ethanol lowers the boiling point of the fuel so getting fuel with no ethanol may be just enough better that this wont happen as often. 

[Otto Skorzeny]

Does it start with a jump or boost from another car?

Does the starter turn slowly or does the engine keep turning strong but just not fire?

How long does it have to sit before it re starts?

Any noticeable problems while driving before shutting it off and suffering the no start? If not, I don't think vapor lock is the cu;prit.

[John Barry [CLC17027]]

Check in your area if there is ethanol in your fuel.   Many parts of the USA now have it in at least the lower grade.  Some places have it in everything year round.   You may be able to change brands or grades and get fuel with no ethanol and that may be enough to help your issue.   Much simpler than reworking your fuel system.   The ethanol lowers the boiling point of the fuel so getting fuel with no ethanol may be just enough better that this wont happen as often.

You may have hit on something there: I live in the metropolitan Philadelphia (PA) area, and I believe that there are oxygen-containing species such as ethanol added to the fuel for much of the year (perhaps year-round).  Would shifting to the midgrade or premium grade likely eliminate ethanol and/or any other oxygen-containing species?

Does it start with a jump or boost from another car?

Does the starter turn slowly or does the engine keep turning strong but just not fire?

How long does it have to sit before it re starts?

Any noticeable problems while driving before shutting it off and suffering the no start? If not, I don't think vapor lock is the cu;prit.

Not sure about jumping from another car.  I've tried kick-starting it with a push, and that seems to be a sure bet.  The starter cranks at a normal speed; i.e., doesn't turn slowly.  It simply doesn't fire.  I haven't put a stopwatch on the time from (let's say) a stall to a successful re-start, but it's on the order of at least an hour or so.  Finally, I haven't noticed any driving problems before shutting off.

[Otto Skorzeny]

The pumps will normally list the ethanol content of the fuels. In Atlanta their is no escape. It's all mandated 10% ethanol.

Since you aren't experiencing any problems other than a hot start, I'm inclined to think that ethanol is not your problem.

[35-709]

First.  Thermostat on the carburetor, hmmm you must be talking about your automatic choke?  If it starts correctly when cold, leave it alone.

Second.  Get the electric fuel pump working again.  Why run 2 lines all the way to the mechanical pump?  Plumb it in parallel, make sure there is a check valve so the pump does not pump the fuel in circles.  I have sent a picture to you which I could not download here  in a PM.

In my opinion your problem is vapor lock, pure and simple.  More and more are experiencing it as Ethanol creeps into our fuel supply more and more.
Geoff N.

[Otto Skorzeny]

Why would the vapor lock problem not affect the driving and only the starting?

The easiest way to rule vapor lock in would be to have a bucket of ice water handy and dump it over the fuel pump when the car won't start. If it starts after that then vapor lock is your culprit.

[35-709]

My guess is he is not experiencing vapor lock when he is driving along because there is enough air movement to keep things cool enough, and fuel is flowing through the lines at a faster rate helping to keep cooler fuel coming.  His problem comes when he is trying a restart right after shut down or stall when parking, vapor lock --- the car is not moving and the under hood heat has built up significantly, a perfect recipe for vapor lock.
Geoff

[Jim Beard]

Had the same problem on a friends 1939 Lasalle. This is how we fixed it.
1. Use only premium - no ethanol fuel
2. We wrapped the manifolds, crossover and the exhaust pipe all the way down past the firewall with racing exhaust wrap copper impregnated cloth. My friends use it on their race cars and it works great for keeping the heat in the exhaust. We had the car up to full temperature and I could still touch the heat wrap on the manifolds with no problem with my bare hand. This stopped the fuel line, carburetor and starter from getting cooked. We also rebuilt the starter which helped allot. Of course this does not look the greatest and is not correct, but my friend likes to drive his car without problems and this was our cure for it. The underhood temperature is now much lower and we have had no problems since. It seems to run better now too. Here is a qoute about the heat tape - "Exhaust wraps help to retain heat in your exhaust system, which increases horsepower while reducing radiant heat damage. By wrapping the header and exhaust system it maintains hotter exhaust gases, decreases the density, and allows the exhaust gas to exit the system faster! Greater exhaust scavenging is produced and lowers intake temperatures: that equals more horsepower"

[Otto Skorzeny]

I don't know what kind of gas they sell where you guys live but all grades of fuel in Atlanta contain 10% ethanol by EPA mandate so buying premium won't help you here.

[35-709]

That's the way it is here in the area of Florida I am from also.
Geoff N.

[Jim Beard]

I am in north central Illinois and there are still gas stations that sell E-0 fuel. Some are the low octane and some are the premium grade it just matters what type of station it is. You can always run racing fuel blended with your ethanol laced stuff. 

[buicksplus]

I have a '40 LaSalle that has had hot starting, vapor lock issues for years.  I have learned how to control them to a degree (see below) but John's problem sounds a bit different to me.  Unlike John's car, mine starts fine immediately after shutdown when hot -- but it starts poorly if it sits for about 5 minutes or more.  That's long enough for the gas in the carb to boil off and the carb gets too hot to accept more fuel.  If it sits for an hour, all is OK, the fuel condenses and the carb is cooled off.

For the poor starting problem immediately after shutdown,  I suggest you measure the voltage at the battery side of the coil during cranking.  I suspect your voltage is dropping to 4V or less, and this diminishes the spark enough to make starting your hot engine hard.  The clue is you said it starts immediately if you bump start it on a hill with the transmission.   A bump start has no voltage drop.

If the voltage is dropping, get some larger cables to the starter, have the starter checked, look for dirty terminals, etc.  You really need 5V or more at the coil to ensure quick starts when the engine is hot.   Note that even if the engine cranks fairly fast there can still be a substantial voltage drop at the coil.

Vapor lock is another issue, though the voltage drop during cranking also enhances vapor lock.  I found with my car, I use an electric rotary fuel pump mounted low at the tank only, completely by-passing the mechanical fuel pump.  That mechanical pump is like a boiler, it gets hot and preheats the fuel before it goes to the carb.  I run my fuel line from the fender directly into the carb, keeping it away from the mechanical fuel pump and the exhaust manifolds.  With this setup, it is still hard to start when hot but it does start every time -- and it runs poorly until enough fuel gets into the carb to cool it off.  This may take a mile or two on the road with some surging and bucking.  But then it smooths out and runs OK for hours.  Don't use a pulse type electric pump.  They are very weak and don't have enough flow for a Cad flathead. 

Have fun, you will get it going.  We have driven our LaSalle across the country many times in the summer and it can do fine in 100 degree plus weather.  Don't worry about the thermostat, just wire those louvers open!

[Tom Kelly]

I have this problem sometimes with an old truck that I have, when this happens the way to get it restarted is to hold the gas pedel down to the floor. This lets alot of air in and the engine restarts. Do not pump the pedel as this will just pump more gas down the intake and the engine is allready flooded. The problem is that gas boils over in the carburetor and runs out the main nozzle and into the intake- OR the float needle valve leaks alittle and when I shut the motor off the pressure in the fuel line leaks past the valve and floods the engine-  OR the float is just set too high and it floods alittle. Any way just holding the pedel to the floor works every time.

I see your starter cranks the engine fine, so give this a try, if it works, the engine is flooding. just don't be like me, putting up with it, try to fix it.

[35-709]

That sounds more to me like the needle valve (or a float) is sticking and flooding the engine.  Vapor lock is caused by the boiling of the fuel and you get --- vapor, as in vapor lock --- no fuel can get in.  If you are having fuel "boiling" out of the carburetor and are having to hold the accelerator to the floor to start it, your car (or truck) is flooding, not vapor locked.  The problem YOU are having is an open invitation to a FIRE.  Ask Bill Podany.  Not a problem to be ignored or to "live with"!
Geoff N.

[Steve Passmore]

Its interesting reading these posts and makes me glad that we don't get your type of temperatures here in England, I have never had a car suffer from Vapor Lock, guess I can thank rainy old Britain for something

[Mike Josephic CLC #3877]

Some additional info on the "vapor lock" issue.

What some of the previous posters stated is correct.  If you live in a mandated ethanol
state, buying "high test" will not help you.  It will also contain ethanol.

In Pennsylvania, non-ethanol fuel is available and PA ia also a "must post" state.  In
other words, the pump must state "CONTAINS 10% ETHANOL" if the fuel does.

However, there is one solution that hasen't been discussed.  The lack of
tetraethyl lead is one reason the fuels today have a lower boiling point.  Alcohol
addition is another.

Adding the appropriate amount of a TEL additive can RAISE the boiling point by
15-20 degrees.  TEL is not easy to find and in most places must be labeled "off road
use only" (wink, wink) -- but who's going to know?

One such product is called "Max Lead 2000" and is available from several distributors.
One is:

http://www.jackpodellfuelinjections.com/maxlead.htm

Mike

[John Polychron]

I had the same problem with two of my cars when hot.  One has a manual transmission and
it would start with the push. The other has hydramatic.  I changed the modern narrow
battery cables to heavy duty 0 or 00 cables. Also I added these heavy cables from the
starter motor to the engine block.  No more problems after these fixes.  Good luck.

[Bray]

I would reconnect the electric fuel pump.  I have it on my '39 and have no problems with restarting or with vapor locks on hot days as I turn it on as needed if a vapor lock is developing then turn it off and roll on.   Good luck.

[Jim Thompson]

Our gas here is 10% Ethanol too. Can't get away from it.