Curing a Series Vapor Lock
Funny how things happen. At Safari 2010, I had someone ask me if they ever had a problem with vapor lock on my Series. I said no but I now have to change my statement. Well in this case, it is not the fuel line but the actual mechanical fuel pump. This article will go through the steps in identifying and curing this ailment.
One of the first things that needs to happen is identifying the problem. Vapor lock can be easy to identify since it essentially does not allow any fuel to the carburetor. The truck is running fine and then starts to sputter and dies. If you know your car well, it will feel like you ran out of fuel - and in fact, you did. Just not in the gas tank. It also tends to be sporadic which hampered my own diagnosis.
If you have any problems that seem fuel related, the first thing you should do is install a clear fuel filter in the fuel line right before it goes into the carburetor. This will make diagnosis very easy. Once you have that installed, drive your truck normally. If it dies, the first thing to do is open the hood and look at the fuel filter. If it is empty, no fuel is going to the carburetor. Although this does not mean that you have a vapor lock, it does narrow down a lot of possibilities of what could be wrong.
No fuel is in the line so we know it is fuel related. We can also rule out the carburetor as the problem. It was running great until the fuel stopped flowing. The next thing to check is the gas tank. Do you have fuel? This may sound stupid but check anyway. Also, ensure that the pick up tube is in the gasoline. If you are at an angle, it is possible that there is not enough fuel in the tank and you are sucking up air instead. If that is OK, you now know that the problem is somewhere after the gas tank but before the carburetor.
Next check the sediment bowl (if you have one). If the bowl is full, then you know fuel is getting to the fuel pump. You can also just disconnect the incoming line and see if fuel come out. If it does, you have the same result, gas is getting to the fuel pump.
Now disconnect the fuel line just before the carburetor. We know that this does not have any fuel since the fuel filter is empty. With the line disconnected, either manually pump the fuel pump or crank the vehicle to see if any fuel comes out of the fuel line. If nothing comes out.it is narrowed down to the fuel pump itself or a lock in the fuel line going to the carburetor.
Disconnect the outgoing fuel line from the fuel pump. Now manually pump or crank the truck over. Any fuel coming out? If not, then it is the fuel pump itself not the fuel line. If it is the fuel line, you will need to re-route the line so it does not get close to any hot objects. I know, easy said than done.
Do the fuel pump seems to be the issue. To ensure this diagnosis, put everything back together and see if it will start. If not, pour a lot of cool water on the fuel pump until it is cool to touch. Now try it. You should see fuel going to the fuel filter and the truck should start. If it does start, the problem is the fuel pump.
So how to you fix this problem? The first thing to check is that the fuel pump is working correctly. I have been told that sometimes this is caused by a fuel pump that is starting to fail. You need to test the fuel pressure and if it below the recommended PSI, you can change it and see if that fixes the issue. The other problem may be that the engine is just making the fuel pump to hot. Since the pump is connected to the engine, it can get very hot and cause this problem.
In my case, I decided to bypass the manual fuel pump and go electric. I purchased a Holley Blue fuel pump (pushes about 15 PSI) and a Holley fuel regulator. These can be purchased together as a kit for around $130 or so. These are pretty easy to install and will prevent this problem from arising again.
Find a location for the fuel pump. It should be as close the fuel tank as possible. I put mine behind the seat box right next to the tank. I mounted it in the same place as the hand brake but on the opposite side of the driver. Next you need to find a power source that works when the key is on. Using a multi-meter, just start looking. Once installed, you connect the line from the fuel tank. I was able to run my new fuel line on the same side as the carburetor which eliminated running the fuel line around or over the engine. Remember, you still need to install the fuel regulator so make sure you have enough fuel line before cutting it.
Now you install the regulator. This should be installed as close to the carburetor as you can. Some regulators have a single output and some have two. Mine has two. I run one output to the carburetor and other is connected to a fuel pressure gauge. You can just use a blanking plug as well. Once you have the regulator mounted, connect all you fuel lines. Do not forget to install a fuel filter before the carburetor.
You will also need a fuel pressure gauge to test the pressure. Go ahead turn the key on. The pump should start and you should see the fuel filter getting gas. Look at the gauge to set the PSI. I have mine at 4 PSI. Once that is set, start up the truck. Turn it off and on a few times to check that the PSI is set correctly. Once you have it set, you are done. Feel free to disconnect the gauge and use a blanking plug.
Test drive the truck. Check for leaks at all connections. If none, you are ready to ride.
One tip - you are going to need to get adaptors for you new pump and regulator. Just go to Lowes in the plumbing section and purchase what you need. The hoses will need barbeb fittings. A lot of mine were 3/8 FIP but yours may vary. Just take both the pump and regulator and test the fittings at the store. Also purchase some thread sealant (not Teflon tape) to help seal them up. All total, this project should be less than $150 with the pump, regulator, fuel line, and fittings.
If you have any questions, just ask. If you need photos, just let me know. Please comment if you have any suggestions or other ideas.