Won't start after running on a hot day.

[mjdunn]

I have a 1939 Ford DeLuxe Tudor that runs and starts perfectly almost all the time. It has a new fuel pump and a newly rebuilt carburator. On two occassions, one yesterday, it would not start. On both occassions it was 85 degrees outside and I had driven it 15-20 miles with no problems. While running it showed 160 degrees, I stopped for about 30 minutes and the temperature rose to 180 degrees. When I tried to start it it fired once or twice but no more, no matter what you did. It was not getting any gas. I took the gas line off the carburator and ran the starter and there was no gas coming out. I poured some gas in the carburator and it would run until it used up that gas. On both occassions after setting for two hours and the temperature going done to 140 degrees it started great and ran perfectly. I have driven the car over 200 miles in the last two weeks with no other problems. Any ideas on what would cause this?

[Vic Piano]

You car got a case of the dreaded (yet nonexistent) "Vapor Lock"... What I do when that happens is; remove the gas cap, take the air cleaner off the carb and hand choke the carb to get the vacuum to start pulling liquid gas through the fuel pump and into the carb. You can do several things to eliminate the problem in the future, first install an electric fuel pump as a primary or secondary fuel delivery. Second (and I’d do this anyway) install a known to be good coil and condenser. There are other remedies and I’m sure others will chime in with their suggestions. Have fun.

[TomT/Williamsburg]

This could be a couple things depending on your vehicle but perhaps do some simple things first. If you have never cleaned out your gas tank, you may have junk in your tank or your fuel pump needs a rebuild. If you have an electric fuel pump (I do just for start up purposes), you might want to install it and see how she runs under the same conditions. If it craps out the same way, you have tank/line issues. If not, you have fuel pump issues.

The new gas really does a number on our old cars. I put a bit of Startron in my tank (I used to use Marvel Mystery oil but have since moved away from that) at every fill up - boating guys have the same issues and they swear by this stuff to mitigate the high ethanol content, eating away at all our old seals. I get mine at ACE hardware or any boating supply shop.

I'm sure others will chime in and there are always many different ways to skin a cat - good luck!

[mjdunn]

Thanks Vic & Tom. I have cooper fuel lines to the fuel pump and from the fuel pump to the carburetor. I've seen some have a flexible line.Would that make any difference?

[Vic Piano]

The copper clad steel fuel line is fine, if you want a good conversation starter at car shows, place a few wooden clothespins on the fuel line... Tell anyone who ask "what are the clothespins for", that they relive "Vapor Lock"...

[ken ct]

Sponsored Links (Register now to hide all advertisements)

You should use a flex line from the main line at the firewall to the pump. Ford had a reason to do this. Motor moves around but body dosen't It takes up the movement of engine to body. ken ct.

[Vic Piano]

Ken is correct on using the flex line from the tank feed on the firewall to the fuel pump. I missed that when I read your post. I still recommend the clothespins though LOL

[Mike in AZ]

was wondering about the flex hose having a leak, but if you're not using one....there is someone making a flex hose that will take today's gasoline without breaking down inside.....someone hopefully will provide that info....Mike

[don's 37]

Does the clothes pin thing "really" work???

[woodypecker]

If you want to get it running take off the gas cap and blow into the tank but it usually causes a black ring around your mouth. To answer your original question it is vapor lock caused by ethanol in the fuel. Vapor pressure of modern fuels is 20 to 40 percent higher about 200 degrees. Many on this board are using electric pumps for priming and starting. There is a rare chance that it is your fuel pump or plugging at the tank pickup but I would bet against it. Let us know what happens.

[Fred A]

I had hot/warm starting problems with my '47 three of years ago. Lots of components were replaced and little changed until I replaced the resistor, new points, new coil and a high priced Echlin condenser was installed. Still can fail to start when hot, but that seldom happens. Good Luck: Fred A

[henryh]

I used to have that problem with my 36. The vapor lock is caused by too much heat which seems to be a problem with the flat head engines. I've just replaced the waterpumps with the new style that have the curved impellers. They are supposed to make the engine run cooler. I'll find out if it helps this summer. Insulating the fuel lines might also help.

[FlatheadTed]

Just add to all the good suggestions ,replace the pump with the old one test run it ,Then check the new pump and go over it ,check the push rod length ,get a vacuum tester check the out let pressure 2 Ib to 3ib and the inlet vacuum and that it hold vacuum .check all connections to the tank .Also like they say don't rule out electrical

[Vic Piano]

Originally Posted by don's 37

Does the clothes pin thing "really" work???

That depends on who you talk to...

[G.M.]

You need to put a flex hose from the main gas line at the firewall to the fuel pump.
This is important and more important if you are using a copper fuel line. The engine rocks from torque every time you increase the RPM's. Copper work hardens when flexed, becomes hard and cracks. Even the copper coated steel line will crack. The flex hose is a shock absorber for the main fuel line. Bob Shewman 1-610-933-6637
or [email protected] makes flex hoses that this new gas or any additive won't bother. He has an ad in the V/8 Times. Since you removed the fuel line and it wouldn't pump fuel it sounds like the new gas is boiling in the pump. You need to run close to 4 lbs COLD fuel pressure to HELP with this problem. As the fuel in the pump gets hotter the fuel pressure drops. If you start with 2 1/2 lbs cold when it gets hot you may have 1/2 lb or less fuel pressure which is not enough. You need to have a pressure gauge in the line between the pump and carb to see this when it gets 90 outside temp. As I said before the hotter it gets out the more posts like this will be posted. G.M.

[mjdunn]

Mac's Auto Parts has two electric pumps. One is 4-6.5 lbs. pressure and one is 2-4 lbs. pressure. Which one do I need? Should I install it right before the mechanical fuel pump or near the outlet to the gas tank, as they recommend? So,do I leave the mechanical pump, as is, and the gas just passes through it. Do I wire it so it will be on when the ignition is on?Sorry to have so many questions, I am new at this.

[russcc]

If you are going to use a push through electric pump to back up your mechanical, I would use the Facet Pump. It is made right here in the USA in NY by Purolater. The Facet pumps are used in experimental aircraft, and construction equipment among other applications. I would stay away from imported stuff at Mac's, especially an electric fuel pump. Many sad stories here on Fordbarn about that company. If you call Purolater in NY, they will put you in touch with the tech guy, can't recall his name. Great tech advice, put me on to the right Facet pump for Stromberg carbs. Pump was about $33.00.

[FlatheadTed]

Send your pump to Ken CT and get it fixed .
Recently a guy here removed a electric pump due to it over coming the needle valve /Float .
UOTE=mjdunn;661699]Mac's Auto Parts has two electric pumps. One is 4-6.5 lbs. pressure and one is 2-4 lbs. pressure. Which one do I need? Should I install it right before the mechanical fuel pump or near the outlet to the gas tank, as they recommend? So,do I leave the mechanical pump, as is, and the gas just passes through it. Do I wire it so it will be on when the ignition is on?Sorry to have so many questions, I am new at this.[/QUOTE]

[Pat/Ohio]

As recommended above...you need to install the flex line at the firewall. I would recommend installing an Airtex E8902 electric fuel pump for priming and for vapor lock situations. This pump is made for vintage vehicles that require a low volume pump. These work well with the mechanicl pump. I have these electric pumps installed on 3 of my flatheads...work great! I live about an hour & 1/2 from you. You are welcome to stop by to see where and how to install the electric pump. Good luck, Pat

[Vic Piano]

Keep in mind that, with most electric fuel pumps, you'll need to install a pressure regulator and set it between 2.5 & 3 lbs. I install the “push pumps” as close to the gas tank as possible and I put the pressure regulator as close to the fire wall as I can. If you are planning to use the electric pump as a secondary fuel delivery, place the fuel pressure regulator in line before the manual fuel pump.