1975 ezgo gas

chuck3815 · 06-05-2012, 02:50 PM

is the line coming from the engine to fuel pump suppose to have suction or it it suppose to blow. cant get mine to start and mine is blowing on hose from crankcase. also can i use a low pressure electric fuel pump and if so how many psi do I need

Dave Box · 06-05-2012, 06:01 PM

It is supposed to both suck and blow. This oscillation in pressure causes the fuel pump diaphragm to move up and down and thus pump fuel. It is somewhat hard to detect the suction cycle but if you are only feeling positive pressure this would indicate that your cylinder is worn and the blow by is causing a constant pressure in the crankcase.

For a 2 stroke engine to work it needs fuel a spark and (unlike a 4 stroke) crankcase pressure. This pressure is created by the piston moving up and down and is maintained by the crankshaft seals. This pressure powers the fuel pump but also is responsible for the transfer of fuel from the crankcase to the cylinder for burning. Thus you can see that if the cylinder is worn or if the seals have ruptured fitting an electric pump will not remedy your problem.
In the first instance I would check your compression ratio before you decide what to do. That said you should be warned that many pre 1980 parts are no longer available.

Dave

chuck3815 · 06-08-2012, 12:46 PM

thsnks so much for your help, you gave me alot of valuable info that I did not know, so if I understand you correctely it can be rings or crank seals that are bad or worn..and what kind of compression pressure should I have for desent compression.

Dave Box · 06-08-2012, 01:36 PM

Chuck,

Anything below 100 psi would be cause for concern. However should you find, for example, that your compression ratio is say 90, you have an issue. You could rebuild it and get the top end right. Then it is entirely possible that the increased power will cause the big end to let go and sadly pre 1980 crankshafts are no longer available. I mention this as a caution before you start spending serious money.

That said here is a game plan that might help you decide what to do. It's all a bit Mickey Mouse but bear with me. You will need a small squeezy bottle with a nozzle and a short length of fuel line. Remove the line from the carburetor and attach the new line. Attach the other end to the bottle. Clamp the old fuel lines either side of the pump with a vice grip or similar. (This is important as without the grips you will not build crankcase pressure and the engine will not work).
Now fill the bottle with 2 stroke fuel and give it a squeeze to ensure the carburetor bowl is full and try to start the engine. If it fires up and runs then the pump is faulty, if it does not run then we may be looking at the crankshaft seals.

Good Luck
Dave

chuck3815 · 06-09-2012, 10:43 AM

thanks Dave for staying with me on this. I will give that a try, We did a compression test and it was over 100, and I shot wd40 at both ends of engine will turning over with no rpm increase. If I do need parts, any idea who might have them. ebay or something. Also would a snowmoble engine work? I am not sure on the forward or reverse situation. THANKS A BUNCH FOR ALL YOUR HELP Chuck

chuck3815 · 06-09-2012, 06:57 PM

okay i have 115 compression. good spark cleaned out carb twice, put gas inside carb, It is like it wants to run on full to half choke. When we started to make this a model t pickup, we took off the muffler. We saw it had only like a half inch pipe going inside the muffler. We figured that was for sound. We enlarged the hole going inside the muffler to 1.25 inches. Now we are wondering if it needs back pressure to run. It is like it wants to go but not enough to engage the clutch.

chuck3815 · 06-19-2012, 07:02 PM

okay i have 115 compression. good spark cleaned out carb twice, put gas inside carb, It is like it wants to run on full to half choke. When we started to make this a model t pickup, we took off the muffler. We saw it had only like a half inch pipe going inside the muffler. We figured that was for sound. We enlarged the hole going inside the muffler to 1.25 inches. Now we are wondering if it needs back pressure to run. It is like it wants to go but not enough to engage the clutch, it is like it is a fast idle

06-05-2012, 02:50 PM	#1
chuck3815 Not Yet Wild Join Date: Apr 2012 Location: seattle, wa Posts: 44	1975 ezgo gas is the line coming from the engine to fuel pump suppose to have suction or it it suppose to blow. cant get mine to start and mine is blowing on hose from crankcase. also can i use a low pressure electric fuel pump and if so how many psi do I need

06-05-2012, 06:01 PM	#2
Dave Box Respect the Cart Join Date: May 2010 Location: Rocky Mount, Virginia Posts: 2,190	Re: 1975 ezgo gas It is supposed to both suck and blow. This oscillation in pressure causes the fuel pump diaphragm to move up and down and thus pump fuel. It is somewhat hard to detect the suction cycle but if you are only feeling positive pressure this would indicate that your cylinder is worn and the blow by is causing a constant pressure in the crankcase. For a 2 stroke engine to work it needs fuel a spark and (unlike a 4 stroke) crankcase pressure. This pressure is created by the piston moving up and down and is maintained by the crankshaft seals. This pressure powers the fuel pump but also is responsible for the transfer of fuel from the crankcase to the cylinder for burning. Thus you can see that if the cylinder is worn or if the seals have ruptured fitting an electric pump will not remedy your problem. In the first instance I would check your compression ratio before you decide what to do. That said you should be warned that many pre 1980 parts are no longer available. Dave

06-08-2012, 12:46 PM	#3
chuck3815 Not Yet Wild Join Date: Apr 2012 Location: seattle, wa Posts: 44	Re: 1975 ezgo gas thsnks so much for your help, you gave me alot of valuable info that I did not know, so if I understand you correctely it can be rings or crank seals that are bad or worn..and what kind of compression pressure should I have for desent compression.

06-08-2012, 01:36 PM	#4
Dave Box Respect the Cart Join Date: May 2010 Location: Rocky Mount, Virginia Posts: 2,190	Re: 1975 ezgo gas Chuck, Anything below 100 psi would be cause for concern. However should you find, for example, that your compression ratio is say 90, you have an issue. You could rebuild it and get the top end right. Then it is entirely possible that the increased power will cause the big end to let go and sadly pre 1980 crankshafts are no longer available. I mention this as a caution before you start spending serious money. That said here is a game plan that might help you decide what to do. It's all a bit Mickey Mouse but bear with me. You will need a small squeezy bottle with a nozzle and a short length of fuel line. Remove the line from the carburetor and attach the new line. Attach the other end to the bottle. Clamp the old fuel lines either side of the pump with a vice grip or similar. (This is important as without the grips you will not build crankcase pressure and the engine will not work). Now fill the bottle with 2 stroke fuel and give it a squeeze to ensure the carburetor bowl is full and try to start the engine. If it fires up and runs then the pump is faulty, if it does not run then we may be looking at the crankshaft seals. Good Luck Dave

06-09-2012, 10:43 AM	#5
chuck3815 Not Yet Wild Join Date: Apr 2012 Location: seattle, wa Posts: 44	Re: 1975 ezgo gas thanks Dave for staying with me on this. I will give that a try, We did a compression test and it was over 100, and I shot wd40 at both ends of engine will turning over with no rpm increase. If I do need parts, any idea who might have them. ebay or something. Also would a snowmoble engine work? I am not sure on the forward or reverse situation. THANKS A BUNCH FOR ALL YOUR HELP Chuck

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06-09-2012, 06:57 PM	#6
chuck3815 Not Yet Wild Join Date: Apr 2012 Location: seattle, wa Posts: 44	Re: 1975 ezgo gas okay i have 115 compression. good spark cleaned out carb twice, put gas inside carb, It is like it wants to run on full to half choke. When we started to make this a model t pickup, we took off the muffler. We saw it had only like a half inch pipe going inside the muffler. We figured that was for sound. We enlarged the hole going inside the muffler to 1.25 inches. Now we are wondering if it needs back pressure to run. It is like it wants to go but not enough to engage the clutch.

06-19-2012, 07:02 PM	#7
chuck3815 Not Yet Wild Join Date: Apr 2012 Location: seattle, wa Posts: 44	Re: 1975 ezgo gas okay i have 115 compression. good spark cleaned out carb twice, put gas inside carb, It is like it wants to run on full to half choke. When we started to make this a model t pickup, we took off the muffler. We saw it had only like a half inch pipe going inside the muffler. We figured that was for sound. We enlarged the hole going inside the muffler to 1.25 inches. Now we are wondering if it needs back pressure to run. It is like it wants to go but not enough to engage the clutch, it is like it is a fast idle

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