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I have a question about the mechanical fuel pump. Can the mechanical pump pump air into the line to the carb? My P-15 died on me last week going to get take out. Wouldn't start again. Primed with the electric fuel pump and hit the accelerator a couple times and it would try to start and then stumble and die. Pulled the air filter and could see the accelerator pump, pump fuel into the intakes. I sat there for about 30-40 minutes waiting for a friend and when he showed up we dinked with it some more but it would stumble and die after the start. Towed back home and trouble shot the next day. It started with no problem and ran fine. Then I noticed that the fuel filter (K&N glass) just before the carb had air going through it. Not a lot, just like the treasure chest in an aquarium, about every 40-50 seconds when running at idle or every 15-25 seconds at about 2000 rpms. Troubleshooting suggested that 1. Vapor lock from air into the line but I have an electric fuel prime pump and it still wouldn't run on the day of the shutdown. 2. crack or split fuel line sucking air into the line causing a low fuel supply at speed. Again the electric fuel pump should over come this because it is supplying fuel from back at the tank and pressurizing the fuel line. The amount of bubbles suggest a pin hole. 3. Mechanical fuel pump is going bad and pumping air into the system, but can a fuel pump do that? and at a very low amount of air, just about five to ten bubbles about 1/8" in size every 30-40 seconds. 4. I have two problems thinking I had one. Crud in the carb that blocked both the idle and run circuits and a pin hole leak some where. The crud either pushed through during the last attempt to start or fell back and broke up on the tow home. The next day I pulled the top of the carb and the inside looked good and clean. Had my grandson hit the prime pump and the carb filled normally and the float shut of the flow just as it was supposed to. I did not see anything floating around in there so I put the top back on and we started the car and presto, it started fine and ran great. Parked it as it was Easter and we had dinner to go to. The next day I put a fuel pressure gage on at the carb and started and ran the car. Gage said the Mech pump was putting out 6 psi. The prime pump when the engine was not running was at 3 psi. At this point I thought crap in the fuel line or carb had stopped the car. Started the car and then noticed the air bubbles coming through the inline filter (I hooked the pressure gage up after the filter but before the carb) I then ran the car for about 30-40 minutes and no problem except for the bubbles in the fuel filter. I'm fixing to go out and put the car up on stands and inspect the fuel line and see if there is a pinhole some where in it. While I'm doing that I just want to see what you guys think about this problem or problems. Can the mech fuel pump be going bad and introduce small amounts of air into the system to cause it to shut down or is it a crud issue and a pinhole leak at the same time? Any thoughts comments or tips are greatly appreciated. Joe Lee

Vapor lock or not, here is my story. Yesterday here in Saskatoon, Saskatchewan it was 33 degrees Celsius (about 92 F). I was driving to a car rally at the local Hot Rod club about 5 pm. My 1950 Special Deluxe has an added electric pump inline with the rebuilt mechanical pump. I have a heat shield installed. The electric pump is wired to a push button, I normally only use it to prime the engine after it has been sitting for a while. I drove about 15 minutes on the freeway and then turned off the freeway into the Industrial area where they are located. After about 5 minutes of reduced speed the car started to sputter and then die like it ran out of gas. I was pretty sure I was not out of gas but added 1 gallon from the jerry can I carry. It would start and then sputter and die, the heat gauge was normal as were all the other gauges before it died. I tried to start it with the electric pump energized and it would run longer and then quit. I took a gallon jug of water that I also carry and dumped it on the carb as I have seen discussed on here. Tried to start it with only the mechanical pump and it fired right up and I continued on the the rally. Sorry for the long winded story, but I tried to include as much information as I could.