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  #1  
Old May 11th, 2011, 06:41 PM
BigNick BigNick is offline
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Default fuel pump? carb?

Hey guys... Im running into a problem. My 68 will idle fine and run in 1st. When I get up to speed usually between 2nd and 3rd it will cut out. The oil gauge drops to zero. Then it normally takes a few minutes before I can fire it back up and usually cuts out again when I take off. Seems like the carb is flooding but im not sure. Anyone run into this before or have any ideas for me.
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Old May 11th, 2011, 09:07 PM
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Default will only idle.

My M725 ran fine for about a month when I first started working on it. Then, it would only idle. I could not give it any gas or it would stall. I had the fuel pump rebuilt, same result. Had the carb rebuilt and it runs now, but rich. Mine now needs the timing adjusted, new plugs and idle mixture adj.
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Last edited by MJCougler; May 11th, 2011 at 09:08 PM. Reason: forgot a period
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Old May 11th, 2011, 10:35 PM
randygar randygar is offline
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I'd check the fuel filter, fuel pump, tank pickup sock, and the needle valve in the carb, in that order.

A fuel pressure gauge may come in handy, or you can just pop lines off and see what kind of flow you can get.

--Randy
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Old May 11th, 2011, 11:20 PM
randygar randygar is offline
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Could also be an ignition problem, such as a bad coil failing when warm.

--Randy
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Old May 12th, 2011, 09:30 AM
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Easy way to check the fuel pump is to see if it will fill up a small water bottle in less than a minute while cranking the engine. You will also see if there is any gunk in it.

The fuel tank has a plug on the bottom. You can drain the tank and put in fresh gas.
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Old May 12th, 2011, 05:41 PM
BigNick BigNick is offline
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ive replaced the fuel filter already so I think its time to play with the fuel pump. Thanks for the help fellas. I'll let you know how it goes
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Old May 14th, 2011, 08:39 PM
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Default Fuel filter placement

Many Zoners have posted to put a second see-through fuel filter on the rubber hose where the fuel comes out of the fuel tank, and before the fuel goes into the metal fuel lines on the side rail. This keeps "clean" fuel flowing through the lines and the fuel pump.

Good luck!
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'67 M725, VIN 10030, Delivery: 7/67
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Old May 15th, 2011, 05:03 AM
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Since my carburetor had rust in it and the tank is a mess, I have decided to buy a new SS tank from Mike and replace the fuel lines from the tank to the engine. They are easy to get at and not made of anything exotic. I have a double flare and tube bender so with all new parts, I hope to be ahead of the game. I will most likely replace the still original rubber fuel line that goes from the frame to the engine with conventional rubber fuel line. I also intend to use high pressure fuel line designed for fuel injection and high pressure clamps. Yes, it costs more but I hope to only do this one time.

I will let you know how it goes. I just can't see taking the time to rebuild the carburetor (I already did) and then just pump rust into it again. I am undecided as to whether I will put another filter at the tank. I think that using a new tank will eliminate that issue.

Pix of the carb before rebuild and the "nasty" tank.



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Old May 15th, 2011, 05:06 AM
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BTW, when making fuel lines, here is one trick you may want to use if you have a double flare kit. Clamp the line as per directions with the kit. Use the little metal disc that starts the double flare and make that bend. Then just use the tubing as you have just prepared it. It will put a little barb on the end of the line not unlike what the manufacturers do and help the clamp hold the rubber hose on.
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Old May 15th, 2011, 08:15 AM
randygar randygar is offline
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A filter at the tank also protects the pump from anything that might be added to the tank, not just what's from the tank... Old jerry cans, crap from gas stations' tanks, etc.

--Randy
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