Pre-war (up to 1942) 1939 LaSalle 5019 Fuel Pump-PART II Trouble Rears It's Head

[z3skybolt]

USNTar,

Probably of no help but my 40 LaSalle behaves much as yours except I have no fuel smell or over rich indications.  I have a rebuilt manual fuel pump backed up by an AirTEX electric.  During moderate or cool temps the car will run for many miles using only the manual pump. Longest non stop trip using only manual has been 65 miles.  On hot days it will usually run on manual for 20 or 30 miles then begin to vapor lock.  I turn the electric pump on for a few seconds and then back manual. It will run on manual again for 1 to several miles before requiring the use of the electric.  If it gets real bad I will just run the electric.

I drove the car many miles this summer at temps of 95 degrees and above. Usually my drives one way are under 30 miles.  No problems with damage to the manual pump or other issues. After more than 3,000 miles using this technique. I have decided to just live with it as is. But I hate running the electric.   

By the way I have tried many fuels from 100 octane low lead aviation fuel to 87 octane regular. Settled on 91 octane  non- ethonol.  She starts instantly, runs well on non-ethonol and averages 11 miles per gallon cruising about 50 mph.             

Best Wishes,

Bob

[39LaSalleDriver]

I think your pump is overpowering the float needle. The two screws you mention are only idle adjusters and will not affect fast running.

Distinct possibility. I'm back to maybe a carb rebuild is the solution here unless there's something else I should try first.

USNTar,

Probably of no help but my 40 LaSalle behaves much as yours except I have no fuel smell or over rich indications.  I have a rebuilt manual fuel pump backed up by an AirTEX electric.  During moderate or cool temps the car will run for many miles using only the manual pump. Longest non stop trip using only manual has been 65 miles.  On hot days it will usually run on manual for 20 or 30 miles then begin to vapor lock.  I turn the electric pump on for a few seconds and then back manual. It will run on manual again for 1 to several miles before requiring the use of the electric.  If it gets real bad I will just run the electric.

I drove the car many miles this summer at temps of 95 degrees and above. Usually my drives one way are under 30 miles.  No problems with damage to the manual pump or other issues. After more than 3,000 miles using this technique. I have decided to just live with it as is. But I hate running the electric.   

By the way I have tried many fuels from 100 octane low lead aviation fuel to 87 octane regular. Settled on 91 octane  non- ethonol.  She starts instantly, runs well on non-ethonol and averages 11 miles per gallon cruising about 50 mph.             

Best Wishes,

Bob

Thanks Bob, but quite the contrary...that is EXACTLY the kind of first hand experience I am looking for. Your situation is virtually identical to the trouble I'm having. I too hate relying on the electric pump, but I may just have to live with it for now. I think one thing I am going to do is give this stuff a spin:

https://www.amazon.com/dp/B002UPMU60/?coliid=I3L6W90NKD2J95&colid=YF559K95UCQH&psc=0&ref_=lv_ov_lig_dp_it

It's not period accurate by any means, but doesn't look too offensive from what I can tell. I think I'll run it from tank to pump, and even from pump to carb (putting the asphalt covered insulation over the top) and see if that helps any. If it doesn't, at least I'm only out $30 for trying something that may work great.

I may also start experimenting with fuels, but as we all know, that isn't always feasible. May be a pipe dream, but I'd like to get it as reliable as possible with what is commonly available but that 11 mpg you're getting sure sounds appealing to me!

[Tom Beaver]

You need to make up a new fuel line that runs from the mechanical fuel pump to the carburetor and put a T-fitting somewhere in the line that you can mount a pressure gauge.  Somewhere that will be visible while running the engine.  Something like a 0 - 15 psi pressure gauge would do the trick.  Then you can determine exactly what pressure the mechanical pump, the electric pump and the combination are putting out.  If the maximum pressure you measure is something like 5 - 5 1/2 psi then you should be ok, if not, you probably have to do some fixing.  Those pressure gauges are not all that expensive you should be able to find one for under $15.

Tom Beaver

[39LaSalleDriver]

You need to make up a new fuel line that runs from the mechanical fuel pump to the carburetor and put a T-fitting somewhere in the line that you can mount a pressure gauge.  Somewhere that will be visible while running the engine.  Something like a 0 - 15 psi pressure gauge would do the trick.  Then you can determine exactly what pressure the mechanical pump, the electric pump and the combination are putting out.  If the maximum pressure you measure is something like 5 - 5 1/2 psi then you should be ok, if not, you probably have to do some fixing.  Those pressure gauges are not all that expensive you should be able to find one for under $15.

Tom Beaver

Good suggestion. I have a pressure gauge that I can test with, so I think I'll rig something up to see what it's putting out. Thanks.

[Bob Schuman]

If you are using a Carter rotary vane type electric pump in series with the engine pump, the occasional "vapor lock" symptoms are quite possibly the result of the periodic inability of the engine pump to suck through the resistance of the Carter electric. I had the exact same symptoms on my 41 for several years. Jack Hoffman engineered a solution, using a Carter flow valve(basically a check valve) piped in parallel with the electric pump. After installation, the fuel starvation symptom never again recurred in about 20,000 miles of driving.
The Carter part number is 169-1002, was available at NAPA stores, but now may be hard to find.

[39LaSalleDriver]

If you are using a Carter rotary vane type electric pump in series with the engine pump, the occasional "vapor lock" symptoms are quite possibly the result of the periodic inability of the engine pump to suck through the resistance of the Carter electric. I had the exact same symptoms on my 41 for several years. Jack Hoffman engineered a solution, using a Carter flow valve(basically a check valve) piped in parallel with the electric pump. After installation, the fuel starvation symptom never again recurred in about 20,000 miles of driving.
The Carter part number is 169-1002, was available at NAPA stores, but now may be hard to find.

See above, I'm not running a Carter pump. That's what came with my car and I didn't like it so I replaced it with an Airtex months ago.

The good news is that the temperature finally broke around here and today was only about 75 degrees out. With no further modifications such as additional insulation on the fuel lines, running standard 87 octane 10% ethanol I was continuously on the road for around 5 hours today! This is by far the furthest I have driven the car in one shot. To date, I had only gone about 40 miles at most. Drove 200 miles total and other than stop and go traffic in the city and when I restarted after filling up, I had zero vapor lock issues while running purely on the mechanical pump! The couple of occasions when it did happen, I fired up the electric pump for a couple of minutes until back up to speed, then turned it off and kept on going. This has been a major leap forward in my book. Best of all, I now seem to be averaging around 11 mpg at 55 mph on back roads. I couldn't be any happier with the results of today's shakedown cruise. When I get the insulation installed on my fuel lines I'll report back my findings. The manufacturer claims that it will reduce radiant heat by 60% but I'd be shocked if it comes remotely close to that. Then again, a 20 or even 10% reduction will be better than nothing. As someone who drives it 2-3 times per week here in the South, I have no intention of being sidelined just because the temperature goes over 90 degrees 

[tripwire]

Jon,
The cooler weather is your friend. 

Gasohol tends to vaporize at temps near mid 90s depending on the blend the particular fuel company uses. In the winter they make it more volatile so cars start better in the cold, maybe not so much down south but up here it's a real thing.  In the summer they adjust the mix for slightly less volatility.   

Insulating the fuel pipe from the pump to the carburetor was done by the factory back when, with a cloth type material and now folks can use better stuff like fire-sleeve, etc. 

You can also insulate the fuel hose from the frame to the pump but I don't see any point in insulating the entire length of pipe back to the tank.  Remember, the fuel in the tank is going to be at ambient temperature anyway, maybe a few degrees cooler. 

One of the reasons people add an electric pump is to pressurize the system which will increase, by a few degrees at most, the vaporization point.  Just like what adding pressurization does to a car's cooling system (fluids under pressure have a higher boiling point, approx. 2 degrees per pound of pressure).  I couldn't find a document to tell me how much the 3 or 4 lbs of pressure in your fuel system increases the boiling point but I doubt it makes a huge difference.  But, as you've already seen, any little bit helps. 

Back in my race car days, it was very common to add a "cool can" to the fuel system to reduce the fuel temperatures and help it stay liquid and dense.    I'm not sure there are any systems out there to do this sort of thing for long drives.  Typically, we'd have to refill the cooler with ice or dry ice after every run down the 1/4 mile but that's a different animal.  I have seen fuel line coolers that look like little radiators but I have doubts about their effectiveness, blowing warm air over something the same temperature isn't going to cool anything.

I don't know the extent of all of your vapor-lock reduction techniques but there are many and all make a bit of a contribution to this very common situation on these flat-head Cadillac engines.  There is no, "oh just do this and you're good to go solution."  What works for someone else might not work for your situation. 

Have you read any of the other postings on this subject?  There are many threads here and on other old car forums discussing this issue.  Many makes, years and models are affected.  Flathead Fords because the fuel pump is on top of the engine behind everything, some straight 6 & 8 cylinder engines because the fuel pump is near the exhaust manifold, even newer cars in the post-war era. 

On my car, I have the same electric pump as you do, I have an insulator under the carb., insulated fuel hose to the pump, insulated pipe from pump to carb., an insulator between the fuel pump and engine block, a 6 blade radiator fan, Heat Wrap on the exhaust manifolds and crossover pipe.  At some point in the near future, probably this winter, I'll be making and installing the Mud Pan Shield that is missing from my car.  See http://forums.cadillaclasalleclub.org/index.php?topic=150458.0  I'm told this will help to keep the air flowing over the front of the engine rather than down and away.  I have also been experimenting with adding a small amount of kerosene to the non-ethanol gas I buy when I tank up.  This reduces the octane of the fuel, which these cars don't need but they do like gasoline rather than gasohol.  It also increases the vaporization point of the fuel by a small amount.  Thickens the soup if you will.

Other people have had luck with: adding a heat shield behind the carburetor to deflect heat from the crossover pipe, and others have blocked the exhaust passages under the intake to keep the carburetor cool and I'm sure there are other techniques I failed to mention but they're out there.

I think you are going to have to come to accept the fact that these cars were built for a different world than the one we live in and making some small changes to have it continue to function in our current reality is a simple fact of life.

Additional Reading: I typed "Vapor lock" in the search box at the top of the page and got back 16 pages of discussion on the subject.

On the AACA forum I got 57 pages on the subject.

I googled, "vapor lock" and got about 18,400,000 results

Good luck.

Wes in VT

[39LaSalleDriver]

Have you read any of the other postings on this subject?  There are many threads here and on other old car forums discussing this issue.  Many makes, years and models are affected.  Flathead Fords because the fuel pump is on top of the engine behind everything, some straight 6 & 8 cylinder engines because the fuel pump is near the exhaust manifold, even newer cars in the post-war era. 

Oh yeah...definitely have studied up on the topic here. I always try to search around before I post anything. This circumstance I couldn't find the exact scenario I was having, but did find similar variations of a theme. While I suspected that was potentially the problem, I had so many other things going on that I couldn't be sure until now.

I think you are going to have to come to accept the fact that these cars were built for a different world than the one we live in and making some small changes to have it continue to function in our current reality is a simple fact of life.

This I think really hits the nail on the head. That is why I have decided to try using a modern insulating material to see what it yields. This isn't a points car, but I do try to walk the straight and narrow, making/keeping it as authentic to factory spec as possible. I think in this case it is a sacrifice I am willing to make in order to keep it driving which is what I do.

You can also insulate the fuel hose from the frame to the pump but I don't see any point in insulating the entire length of pipe back to the tank.  Remember, the fuel in the tank is going to be at ambient temperature anyway, maybe a few degrees cooler. 

My thinking on this, though I'll admit it may be faulty, is that there is a LOT of heat that comes up off the pavement here in the South. We don't measure temperatures by a day or two here and there in the 90+ degree range...we have weeks of such temperatures on end with many days in the 100+ range. That's a lot of continuous sun beating down on asphalt which stores that heat well into the night or even next day. I have to believe that heat can radiate into the small surface area of the fuel line in a quick fashion and contribute to my problem. Either way, it shouldn't take long to run that insulation along the length, and I already have it in hand so why not give it a try? Thanks for the comments, and I'll be sure to report back what my findings are.

[tripwire]

Jon,
You may be on to something with the radiant heat off the road surface thing.  If that is a real thing, I doubt the radiant heat is concentrated on that tiny 3/8" pipe next to your frame rail, I would think it would be affecting the big flat surface you have on the bottom of your gas tank.  Maybe that's where you would think about putting a layer of heat insulating material.  Like this stuff: https://www.heatshieldproducts.com/automotive/heat-shield-and-thermal-barriers  If you shop around somewhat you'll find lots of products like that one and there may be something more suited to what you are attempting to accomplish.
Good Luck.

Let us know if your theory proves to be sound.  I'm sure we'd all like to find a final solution to this concern. 

Wes in VT.

[DaveZ]

Wes,
  Are you looking for the pan that has four bolts that mounts on the frame just under / behind the radiator? If so I have one for you.
Dave

[tripwire]

Dave,
Pm sent.

Wes in VT

[39LaSalleDriver]

Well, after running with my new setup for 2-3 weeks I am saddened to report that I can't tell if installing HeatShield insulation on my fuel lines has had any effect at all. Of course all of these things can be highly subjective, and while it may have helped things slightly, it certainly falls short of what I would expect to be a 60% drop in radiant heat which they advertise. Admittedly, I haven't taken an actual temperature reading, just basing it on "feel."

Ditto for their HeatShield Stealth fabric which I have inserted underneath the passenger matting to cut down on exhaust heat. It may help a bit, but nothing dramatic to the point I would jump up and down to sing their praises. I had already cut down a lot of heat with the use of the fake asbestos wrap around the exhaust pipe which works pretty good and made a noticeable difference. But the missus reports not much of a change with the installation of HeatShield Stealth.

[Steve Passmore]

Have you tried advancing the timing very slightly?  Worked for me on a 36 that created massive engine compartment heat.

[39LaSalleDriver]

Have you tried advancing the timing very slightly?  Worked for me on a 36 that created massive engine compartment heat.

Definitely did that a couple of months ago when I did a complete lube and timing job on the car. As a rule my gauge pegs itself just above the halfway point...even on very hot days. At least until you sit and idle for a few minutes. Amazing how the gauge can take a while to go from "C" to the halfway mark, and take mere seconds to go from the halfway mark to "H". But no, I'm not especially having any overheating issues, though I definitely keep an eye out for it.

I'm just trying to reduce the bake oven effect inside the passenger compartment as much as possible. It's definitely not as excruciating as it was, but could stand some improvement. Definitely wrapping the exhaust with the fake asbestos insulation helped immensely. To be honest, I may have the whole thing as insulated as well as it can be (which is tolerable for now), and will just have to learn to live with it as is.

[tripwire]

Jon,
It sounds like you are working on two different problems.  Cabin heat and vapor lock. 

I'm not sure what you were expecting the fuel pipe insulation to do for you regarding cabin heat.  I thought that was for your vapor lock problem.

If you are trying to reduce cabin temperature this is a different problem.

If you only added insulation on the passenger side of the car you aren't going to see much reduction in heat transfer.  Heat moves like sound.  If you only close a door half way the noise you are trying to get away from still comes in.  The door has to be closed entirely to be effective. 

Are all of the holes in your firewall closed with either grommets around wires/cables etc.?  If not seal them up.

Get some more of the heat shield material and cover the entire floor starting as high on the firewall as you can.  Take the seats out and go all the way to the back of the passenger compartment.

You might also consider adding exhaust wrap to your exhaust manifolds and crossover.
http://designengineering.com/titanium-exhaust-wrap/


Edit: I added a photo to show the exhaust wrap I used on my car.  It seems to heat somewhat on getting the heat out of the engine compartment and consequently out of the passenger compartment.


I'm also wondering if you use the cowl vent.  I've noticed a significant reduction in heat in the passenger compartment with that vent open even just a little.  My wife, who hates drafts of any kind, even prefers to have it open rather than closed. 

Please clarify so we can better assist you.

Wes in VT

[39LaSalleDriver]

Jon,
It sounds like you are working on two different problems.  Cabin heat and vapor lock. 

I'm not sure what you were expecting the fuel pipe insulation to do for you regarding cabin heat.  I thought that was for your vapor lock problem.

If you are trying to reduce cabin temperature this is a different problem.

Oh, this is definitely two different issues. This whole thread was dedicated to my fuel pump issues, my resolution of such, and eventually my attempts to defeat vapor lock. I was just following through with my report on using HeatShield fuel line insulation and what results I got from it. I've noticed most times people start threads and never follow through to completion. Many promise to report back what results they came up with, but never do and leave others with a cliffhanger that never gets resolved. I don't want to be "that guy."

So far as vapor lock, I've pretty well got a handle on it. I just run my electric pump when it's very hot out, or if I'm going to be in stop and go traffic and want that extra insurance that it won't crap out on me. The HeatShield product...meh...it might help a little, but I see no real noticeable difference. I'm not going to tear it out or anything now that I've got it installed, but I'm not overly impressed with it. Might save somebody down the road from buying a product that doesn't live up to it's advertising hype.

I only brought up the cabin temperature issue because I also bought some HeatShield stealth insulation at the same time to put in the floor pan with the hopes it would bring the temperature down inside. Directly over the exhaust, on the passenger side it seems to make no noticeable difference according to my s/o. Again, I would have to observe that the HeatShield product doesn't come close to living up to it's own advertising of "reducing residual heat up to 60%". That's all I was getting at.

Keep in mind, I've been driving this car 2-3 days a week all this summer with temps in the high 90's (and high humidity) and it hasn't smoked us out yet! Just experimenting with stuff to see if we can bring the discomfort level down a bit. Standard practice is to open the side and cowl vents ALL the way before we even leave the driveway. 

I'm back to, the best thing I did was wrap the entire exhaust pipe from manifold to muffler with this product:

https://www.amazon.com/gp/product/B008HQ78Z4/ref=oh_aui_detailpage_o06_s00?ie=UTF8&psc=1

Which, from what I can tell, is the exact same stuff that our old car vendors are selling for over 4x the money as an exhaust wrap. For $50 I got enough product to cut in half, and cover the whole pipe rather than just a 24" section. When I put that on, the comfort level changed immediately from positively hellish to uncomfortably bearable.

[harry s]

Forgive me for bringing up something so simple if you have already done it. Is the coolant flow through the heater (if you have one) turned off?    Harry

[39LaSalleDriver]

Forgive me for bringing up something so simple if you have already done it. Is the coolant flow through the heater (if you have one) turned off?    Harry

I do have one, but I removed it this past spring for restoration. Will be reinstalling it soon.