I am fixing a older Murray with a Tecumseh OHV 125. Initially it was no start not getting fire. I replaced coil which was a quick fix but once I got it to start it would spit sputter and backfire. I checked valves and they were good. I cleaned carb and put a needle and seat and bowl gasket. It was also leaking fuel out of carb. Needle is seated correctly but still leaks. Now it will puff white smoke out of exhaust and try to start but of course is flooding out. I have rebuilt many carbs but this one is getting me. Haha. Where did I go wrong?
Either the new needle valve and seat have a piece of something stuck to it or is faulty. Check to make sure that the bowl vent isn't plugged because that can cause flooding also.
White smoke tells me you have water in you fuel. Take a Q-tip to the fuel inlet seat to make sure that there is not any dirt or small nick in the seat.
I will check seat again. I checked fuel for water in a clear jar plus it is fresh. I didnt see any but I will drain and add new. When it lets that puff of smoke out is when it tries to start and spits fuel out of the carb. Will not start at all now. Could I have a valve problem of some sort?
What color is the smoke? White would indicate water, black would be excess fuel and blue would be oil. If it just occurs during start up, I would not be to concerned as this could be just excess condensation that would burn away quickly.
If you look straight into the carb air horn, you should see a hole about 1/8" in Diameter at either the 2 or 10 o'clock position. That is the vent hole for the float bowl.
I found it and it is clear. The other end of that is under the welch plug correct?
Now if you look straight into the venturi, of course there is a passage coming straight up through the middle. But if you look just in front of that one there is another small passage in the bottom at an angle. What is that? Because that is where it is leaking from. I have been sitting here watching it to verify exactly where it is coming from.
If I were you I would take the carb to your local small engine shop and ask them to do a pressure check on your carb. The float should hold 8-9 pounds. Hopefully someone in your area has a pressure tester.
I have a pressure tester but I use it to test pressure/vac on crankcases. How exactly do I check that? Just connect it to fuel inlet? Vac or pressure? Of course vac I would have to hold it upside down.
My local small engine shop just said to adjust the float to where the fuel flow shuts off quicker. And if that doesn't work it would have to be replaced and he said good luck finding one. Which I have seen plenty on the Internet. this is why I tinker with them on my days off from the fire station. I used to work at a small engine shop and I love it but I still have a lot to learn.
Take the carb off. Remove the float bowl. Hook the pressure gage to the fuel inlet. Tip the carb outside down. Put 9 pounds of pressure on the gage. It should hold a minimum of 7 pounds without leaking down. If it leaks down you have found your problem.
Thanks for all of your help. The seat was good. But the needle was not the right fit. I noticed there are 2 different needles. One tapers down sharper than the other. I tried the other needle and tested it again and it held vacuum. But one thing I do know... Trying to find the correct setting on that carb is like trying to make a woman happy. Haha!
