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

[39LaSalleDriver]

Moving on to other issues with my LaSalle...

At some point a previous owner decided to remove the mechanical fuel pump and run an electric one instead. Not only did they remove and dispose of the pump, but all the associated lines which connect to it, except they left the vacuum line which runs from the pump to the wipers in place (albeit disconnected).

I have now purchased the correct AC 480 pump (properly rebuilt of course), 25' of nickle/copper 3/8" fuel line, and a Weatherhead 11076 flex line to connect the fuel line to the pump. I also have yet to get some 1/4" tubing to redo the vacuum lines.

Through hours of searching around, I have pretty much come up with how everything should be routed so I should be set with that.

What I am lacking is data on, is what size and type of compression fittings I should be using on everything, and where should I get them? From what I can tell the threads on the fuel pump connections and carburetor are 7/16-24...does that sound correct? I stopped by the local auto parts store was less than impressed. Any suggestions would be appreciated because I would love to get my car back to running primarily off a mechanical pump. 

[Steve Passmore]

Never seen any compression fittings on the fuel pump. They always have a fitting which then takes flares on the tube.

[harry s]

In most cases the fitting size corresponds with the size of the tubing, inverted flare as Steve points out. A couple of suggestions, before you flare the gas line you may want to put a period looking cover or loom on to deflect heat. Also try and keep the gas line as far away from the exhaust manifold as possible.
Harry

[39LaSalleDriver]

Sorry about the terminology. I should have said flared fitting.

I've already got the insulation aspect covered. I ran across somewhere around here that the asphalt covered wire looming is what to use.

I'm still having trouble with all the fittings though. Should ALL my tubing coming from the fuel pump be 1/4"? So far as I can tell, every port on the pump and carburetor has 7/16-24 threading.

Not a problem with the vacuum lines, but it has me worried about the fuel lines. Since I'm running 3/8" line from the gas tank/electric fuel pump to the mechanical pump...won't I lose any advantage of the larger diameter line? Even if I were to use 5/16" line instead, I'd still have to have an adapter to choke it down to the 7/16-24 threaded 1/4" fitting. Or am I supposed to be running 1/4" line from the gas tank to the fuel pump? That doesn't sound right.

On top of that, I had presumed that since I was running 3/8" line into the mechanical fuel pump, I should be running 3/8" out to the carburetor to keep the flow rate the same. Am I wrong? Should I be using 1/4" line for that instead? The fitting on the carburetor is also 7/16-24 which offhand would imply that it should be 1/4" line. Any way I add it up from what I can see, if I'm running anything but 1/4" lines it will require adapters to narrow it down to that 7/16-24 fitting.

Right now I am so confused I can't see straight, and cussing whatever idiot yanked out all the original tubing and pump to begin with.

[harvey b]

my 37 has 5/16 line from the tank to the pump,seems to work fine,it has a piece of rubber line from the frame to the pump,it has the fittings already on it,all the fittings you need should be easily found,try and find a "old time " parts store,they should have lots of fittings you will need.is a pretty basic setup,it is the tubing for the wipers that is a bit complicated,at least on my car it was. Harvey

[Brad Ipsen CLC #737]

3/8"line from the tank to the fuel pump.  5/16" line out of the pump to the carb.  The threads in the pump are 1/8" NPT so need adapters to get to the flared fittings.  All this from memory and don't have the car right here to double check but 3/8" to the tank for sure. 

[tripwire]

Jon,
Here's a couple of pictures that might be helpful for you.  Brad gave you some good info regarding pipe size.  These photos show what you can use for fittings on the pump as well as at the end of the fuel pipe.

The last photo shows a rough idea of where/how to route your gas pipe from pump to carb and the routing of the vacuum pipe to the pump.

Wes in VT

[Brad Ipsen CLC #737]

Here is some further info on the hose the connects the 3/8" line to the fuel pump suction.  See attached picture.  The line on the left is an actual hose off of a 40 Cadillac as delivered from the factory.  Next to that is what I make up to closely approximate it.  The next is a period replacement hose.  It has a corrugated brass flex in the hose but I still would not trust it since formed brass can age crack.  The next picture is the fittings I use to make up the hose.  I take these fittings to an industrial hose shop and they put the hose on and crimp the sleeves on.  At the place I use this is a real loser for them since they just charge for the hose.  They make their money on the big industrial hoses.  The hose is 1/4" which closely approximates the 5/16" tubing ID on the discharge side.  For the tank line Cadillac transitioned to 5/16" inch line from the 3/8" line at some point and for sure by 1949.  They used a really odd flare fitting then on the tank which has a standard 3/8" hex flare nut and threads but is drilled for the 5/16" line.  The other problem with these sizes is you cannot buy a 3/8" female flare fitting with a 1/4" hose fitting on the end.  I make one by using a 3/8" female and a 1/4" hose fitting and silver soldering them together.  If you have a sufficient order to offset the shipping charge a good place to buy these fittings is: FittingsandAdapters.com

[39LaSalleDriver]

Thanks for all the photos and suggestions guys. I might have a handle on it now. As I mentioned I am running 3/8" line from the tank (I put in a new Tanks Inc. tank as the one I had was shot and wasn't original to the car anyway), through my Airtex pump which is located by the tank, all the way to the engine bay. I am also encasing it all in a gravel guard spring type wrapping.

It's really great the picture that Brad provided of an original flex hose, and the one he has made looks really nice. My Weatherhead flex hose that I ordered the other day hasn't arrived yet so I'll check those fittings when it gets here. I may end up having to get some other adapter fittings to make that work.

I'm running 1/4" lines for the vacuum system, and as Brad suggested, a 5/16" line from the pump to the carburetor which will be covered with asphalt coated looming material. I took my pump into a local Advance Auto Parts of all places, and surprisingly to me, we think we got all the fittings situated. It took an hour of trying this and that, but I think we finally got it.

Today I mounted the pump onto the block, which slipped right in with no troubles. I'm hoping I've got the arm inserted correctly. Then I put the lines into place by hand, bent the tubing to match the factory drawings, and marked the proper lengths to cut the tubing in preparation for reflaring the ends.

With any luck, I'll have it all put back together and running by Monday or Tuesday. Thanks again everyone, you've been an immense help, and I'll report back how it all comes out.

[39LaSalleDriver]

BTW is there anything I should worry about because my fuel pump went on so easily? I know the cam should be positioned to its lowest point with the arm riding on top of it. I decided to try putting the pump in to see if it would fit before I got into rotating anything, and to my surprise it slid right in. I didn't even have to use longer bolts as some have suggested, just positioned it and alternated tightening the bolts. Is this pretty much a go/no go type situation...either it fits right in or it doesn't? I just don't want to get in the situation of having the arm in the wrong place and turning the engine over only to bend or break it.

[Fred Pennington 25635]

You might want to give that another look. The fuel pump arm can easily slide in just to the rear of the lobe on the cam shaft. It will look like it is just a little out of line and pull up with the bolts. It is easy to break the shaft the arm rides on. Don't ask how I know this, I just do. To properly install the pump you need to rotate the engine and look through the fuel pump mounting hole to see when the lobe is at it's lowest point the hold the fuel pump square to the mounting or just a little toward the front of the engine to insure good contact. It should give you resistance most of the way. If you have not turned the motor over you might be lucky and the fuel pump may not be damaged.

Good luck

[39LaSalleDriver]

Fred, thanks for the words of caution. I was sufficiently spooked that I pulled the pump before turning the engine over to try and make sure as much as I could that everything was good to go. So far as I can tell, it is. After considerable cussing over getting the vacuum line to the wipers attached, the pump is now on my car.

I'm now waiting for two more fittings to arrive at my parts store this morning so I can complete the installation and see if it all runs correctly.

About the only problem I now have is the connection of the fuel line to the carburetor. Currently there is a barb fitting on there, and the parts store can't seem to match the threading. I don't know if someone has fouled the threads on the carburetor or what's going on, but it looks like I might have to use a 2" or so section of rubber tubing to connect the two. Not what I ideally want, but it may just have to suffice for the time being.

Can anyone confirm for me if that threading is supposed to be a standard 1/2-20 (5/16"), 7/16-24 (1/4"), or something else? I may end up having to tap it out (which I'd rather not do) to get a complete hard line connection.

[tripwire]

The pipe attaches to an adapter at the carb.  I believe it is 1/8 NPT thread into the carb.  A good ole-time parts store should have these adapters in stock. 
If the adapter bottoms out in the carb you can find or make a gasket to go between the nut and the carb to keep it from leaking.  Don't use pipe tape.
Once the adapter is in place you can use steel pipe from the pump to the carb without any rubber.

The second photo shows how it will look except your fuel pipe will go to the front of the carb if you are using the original Carter WD0.  The engine in the photo is Cadillac, they used a Stromberg  AAV or a Carter WCD.

Wes in VT

[harry s]

The fitting at the fuel pump outlet should also be NPT. If I'm understanding this correctly the need is for two brass 90* NPT male fittings that accept the fuel line with 5/16 inverted flare connections. You should be able to find those fittings at Ace Hdw or a local parts store. Good Luck,      Harry

[39LaSalleDriver]

The pipe attaches to an adapter at the carb.  I believe it is 1/8 NPT thread into the carb.  A good ole-time parts store should have these adapters in stock. 
If the adapter bottoms out in the carb you can find or make a gasket to go between the nut and the carb to keep it from leaking.  Don't use pipe tape.
Once the adapter is in place you can use steel pipe from the pump to the carb without any rubber.

The second photo shows how it will look except your fuel pipe will go to the front of the carb if you are using the original Carter WD0.  The engine in the photo is Cadillac, they used a Stromberg  AAV or a Carter WCD.

Wes in VT

Thanks Wes, that helped quite a bit. I am running the Carter WD0, no teflon tape. Even though I've tried to not be a pain about it all, I think I've about worn out my welcome at the local auto parts store with all these crazy fittings. After getting all the other fittings we tried matching up, they claimed to not have the adapter to the 1/8 NPT from a 5/16 flare (I suspect they were tired of fooling with me and didn't bother even trying), so I found an online vendor who has them. I'll go on using the rubber tube temporarily until that arrives and see what happens.

The fitting at the fuel pump outlet should also be NPT. If I'm understanding this correctly the need is for two brass 90* NPT male fittings that accept the fuel line with 5/16 inverted flare connections. You should be able to find those fittings at Ace Hdw or a local parts store. Good Luck,      Harry

I've already got the two 90* fittings so I should be good to go on that.

Hopefully in the next hour I'll have it all plumbed up and see how it all works. Will report back later.

[39LaSalleDriver]

First of all, I want to thank everyone for their comments, suggestions, and photos. They were an immense help. I am very pleased to report that after much wrangling and cussing I have finally gotten my fuel pump hard lined and working correctly.

I did however have a bit of a problem at first. After getting things hooked up I started having trouble with the engine stuttering and stalling. Fortunately, I had my electric pump installed with a switch so I could keep it running. The symptoms pointed to an obvious fuel starvation problem which could be vapor lock...or very much like the problem I had when I put in the electric pump a few months ago. At that time I was using the replacement lines which came with the car. Different sizes were mixed in from tank to carburetor. So what I did yesterday was get two barb fittings to connect a 3/8 hose from fuel line to the mechanical pump. Problem seems solved. So for future reference to anyone who uses the Weatherhead tube,  I recommend against it. It is only 1/4" diameter and seems to have been the problem causing fuel starvation.

[39LaSalleDriver]

Here we go again....

I "thought" everything was going well, and it does...until the engine has been running for a while on the 90+ degree days we've been having around these parts. Now I'm back to it bucking and jumping, stalling and/or the engine dying on me while driving down the road. Until I kick in the electric pump to get it going again and then it runs fine until a minute or so after I switch it back off.

I've been going through threads and confess the subtleties of "vapor lock" vs. "percolation" are somewhat elusive to me, but I'm thinking it is something along that vein which is my problem. I've read all the suggestions on how to prevent vapor lock from using insulation to running only non-ethanol gas, so no need to dredge all of those points back up that have been covered so thoroughly before.

Before I get to spending money on state of the art fuel line insulation, trying to locate 100% gas, adding kerosene to my fuel mix, or having the carburetor rebuilt (which is on my laundry list for the near future) I have a simple question.

With my current setup of having the electric fuel pump in series with the mechanical pump, is there any problem with running the electric pump full time (at least for now)? Will the electric being on all the time over pressurize the fuel? Will it damage the diaphragm in the mechanical pump?

I don't mind running the electric pump full time until it cools off a bit and I can see if that cures my problem. If that will work without causing any damage, so be it, I'll just run the car that way.

If it could cause problems running through the mechanical pump, I don't even mind temporarily running directly from my tank to the carburetor until cooler days prevail. But both of those options I would only consider a temporary fix. After spending a few hundred dollars to get the mechanical fuel pump in service only to not be able to use it is a finality I am not willing to accept. If after it cools off, and I still am having these problems, I will go to the next phase and seek modern insulation solutions or the other "cures" I have seen mentioned. Keep in mind, I am trying to keep my car as original looking as I can.

[Glen]

Do you know what pressure your electric pump puts out?  If it is in the 6 PSI or lower range I doubt it will cause any harm.  Electric pumps for fuel injected cars run in the 40 PSI range and that would over power the float valve in the carb and cause flooding. 

[39LaSalleDriver]

I am running an Airtex E8902 which is rated at 4-4.5 pounds (w/o regulator), so it's not an exceptionally high pressure pump. I'm wondering if anyone else has any experience with this setup and has any long term problem with the mechanical fuel pump being over pressurized. I would just as soon not ruin the internals of a newly rebuilt fuel pump within a short time of having it.

Drove mine quite a bit yesterday with the pump on and pushing through the mechanical. Car ran fine with no stalling or cutting out. However I am smelling gas when I am running it. To the point where it causes a slight burning in my eyes over time. This would imply to me that it is all pushing too much gas into the carb which isn't burning off. It doesn't do that when I am running strictly on mechanical, nor did observe it when I only had an electrical pump before a couple of weeks ago. This would also suggest to me that it isn't any of my new fuel line connections leaking (and I have been looking).

For the record, I have felt for a long while now (even before I reinstalled a mechanical) that I was running too rich. Slightly sooty plugs, bit of soot out the tail pipe on ground at idle, getting about 5-6 mpg from what I can assess. I have adjusted the carburetor with the two adjusting screws on the front of the base and haven't seen it make a lot of difference other than the expected run rougher/run smoother differences. I have not adjusted the float basically because I don't know how and haven't yet studied up on that yet to feel confident poking around in there. This is why I am plotting to have the carburetor rebuilt as I suspect it has never been worked over, or at least hasn't in a long time. Plus, I think it would benefit from having any ethanol resistant parts installed.

[Steve Passmore]

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