Fuel problem

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Fuel problem

Postby boltman » 22 Wed Jan, 2014 12:33 am

Hi everyone:

I have a fuel problem and would be grateful for you all to weigh in on. My buggy is a Manx knock off. The fuel filler neck is on the front left side of the tank. The guy who built the buggy shortened the neck on the fuel tank omitting the vent tube. When I get the buggy up to highway speed, it acts like it's starving for fuel. When I slow down a little it seems to come back to life until I get up to 65 or so when the problem returns. The tank has a decent conventional cap with the "vw" logo stamped in it, but has a crappy gasket. This is an non vented cap. Do you guys think I should drill the cap, buy a different cap, look else where for the problem?? There is no vent in the tank. I have had the tank out and its spotless clean with a new screen inside. Blew out the steel line through the tunnel. New hose in the front between the steel line and tank and on back fastened to the fan shroud about a foot above the intake with a new filter. I have not checked the fuel pump yet. Just thought the vent issue was the logical place to start.

Thanks for all your input.

Keith
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Re: Fuel problem

Postby johber41 » 22 Wed Jan, 2014 1:22 am

Hello Keith, you might want to check the fuel pump. If you have the conventional in-the-block pump, they are known to give you that type of problem if the plastic spacer is worn or swelling with engine heat. If you pull the pump off, see if the pump push rod moves freely in the spacer. The spacer has an extension that goes all the way down inside the block and it is about the length of the push rod. Sometimes the spacer will keep the push rod from moving correctly and this is what causes the pump to stop pushing fuel. You may also have a bent push rod. Easy to check and easy to change. If you decide that this is the problem, make sure you get the right replacement part too. They are not all the same. I am running a 1961 1200 CC engine and many of the mechanics at the part stores sell me parts that fit the 1600 CC engines. They believe that those parts fit all of the engines. They do not! Youtube has a few good instructional videos that relate to this problem too.

Hope that helps.

John
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Re: Fuel problem

Postby Ken » 22 Wed Jan, 2014 7:42 am

Check your push rod for end wear. The point can get beat and cause length issues that results in poor fuel flow. There are different pumps for alternator and generator and the rods are different lengths.

Although my personal experience with pump rod wear was a more predominant failire over your described problem. Still something to check out.
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Re: Fuel problem

Postby johber41 » 22 Wed Jan, 2014 2:20 pm

If you have access to an electric pump you can put in line temporarily, it would answer the pump questions for you.
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Re: Fuel problem

Postby GregR » 22 Wed Jan, 2014 4:22 pm

I would suspect you're creating a vacuum in the tank without a vent.
Do you know if the engine loads up when the buggy sits in the sun for a time?
As the gas heats up, the vapors need someplace to go....many times it'll come out the vent.
In your case it may load up the pump and eventually the carb.

Try a vented cap or if you're brave take the cap off and use a rag to slow any spillage. Then retry your driving test.
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Re: Fuel problem

Postby Ken » 23 Thu Jan, 2014 7:32 am

GregR wrote:Try a vented cap or if you're brave take the cap off and use a rag to slow any spillage. Then retry your driving test.


X2 what GregR said. Heck for a test, get crazy with a hose and some tape. Let us know.
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Re: Fuel problem

Postby boltman » 08 Sat Mar, 2014 10:52 pm

I blew the line out through the tunnel (it was clean) and drove the car with no gas cap. It still acted like it was starving for fuel.

After a visit to Qualitat to buy an electric fuel pump, Doug suggested I would be happier with dual EMPI carbs. I had a little buggy money burning a hole in my pocket so I decided to give it a try.

Problem solved. Installed the EMPI dual carbs. Synced them and now...well I am probably going to get a speeding ticket. I am not so good with carbs, and have the Weber progressive is beyond my area of expertise. At any rate the buggy sounds and runs great now. No flat spots etc. All I want now is the weather to cooperate so I can get some windshield time!!

BTW the electric fuel pump is in my road bag for a backup.

Thanks to you guys who responded to my post and hope to meet some of you guys soon!!!

Keith
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