Carb problem

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sidewayzbaja

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Well i was running my Marder on sunday and I notice that my primer bubble was full of gas but when i run it a few minuets the primer bubble would be empty, It happen to me about 6 times, What could be the problem???????
 
i think this might be normal, haven't really paid it attention myself but i thought once you run it the fuel slowly drains out of this.

please correct me if im wrong.
 
You are running out of fuel... This is NOT normal. In fact this will burn down your motor!

It is caused by an empty tank. Got gas in it? :lol:

Or can be caused by a plugged fuel cap vent. If the gasket in the cap is jacked or plugged with crap this will happen. After the vehicle sits for awhile or if the temperature changes, the tank will build with pressure. When you open the cap you will hear a hiss. This also happens as the vehicle is ran, but the hard part is to tell if the tank is hissing from pressure (Good!) of from vacuum (bad)

Put your hand on the tank when you release the cap and see if the tank feels like it's getting smaller (from pressure, Good!) or gets bigger (from vacuum, Bad!)

I take the cap off the tank and seal my lips around it and try to suck in air, if it "Breathes" in, it's fine. If it doesn't allow air to come in OR if it allows you to blow air out, the cap is faulty and needs to be replaced.

If you are running the old style cap (Really old style) or a cheap spin on black cap (like the Firehammer), the vent line is plugged. The vent line should be running out the back of the car, check for flow by sticking the line in your mouth and blow through the line...
 
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hey trip, ill like to question your comment about the fuel tank pressure. i always hear a hiss when I remove my fuel cap, i think the pressure release might be blocked or something. even if I haven't run it on a warm/hot day it makes a hiss.

as long as its blowing out air and not suckin in should the cap be ok?
 
Pressurization will more then not expand the fuel bulb or give an erratic idle.
More then not, if you have the fuel lines backward, you will run out of gas before the tank is empty.
The fuel in the bulb flows back to the tank. How empty is empty? It will not be 100% full. GOT A PHOTO?
 
Mike1970 said:
if the bubble is full when you pump it then empty after a run you engine is too lean! it should be 1/2 full after a good thrashing.
Click to expand...

The primer bulb is filled before the fuel enters the carb... You could close the needles right off completely and the bulb would still be full. Needle settings have ZERO affect on the primer bulb.
 
sperera said:
hey trip, ill like to question your comment about the fuel tank pressure. i always hear a hiss when I remove my fuel cap, i think the pressure release might be blocked or something. even if I haven't run it on a warm/hot day it makes a hiss.

as long as its blowing out air and not suckin in should the cap be ok?
Click to expand...

Correct.

There was a big debate on that subject a few years back. The hiss should be coming out of the tank, not sucking in.

There is no pressure release on the tank or the cap that I am aware of... My tank has hissed every time I have opened it for over 50 gallons of fuel.. So do the tanks on my chainsaws and weed whackers.
 
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Trip said:
The primer bulb is filled before the fuel enters the carb... You could close the needles right off completely and the bulb would still be full. Needle settings have ZERO affect on the primer bulb.
Click to expand...

Sorry Trip but I disagree. The state of the bubble WILL dictate in most cases if the carb is set correctly.
 
Trip said:
Correct.

There was a big debate on that subject a few years back. The hiss should be coming out of the tank, not sucking in.

There is no pressure release on the tank or the cap that I am aware of... My tank has hissed every time I have opened it for over 50 gallons of fuel.. So do the tanks on my chainsaws and weed whackers.
Click to expand...

awesome, im pretty confident its blowing out and no sucking in, im guessing sucking in would be a different sound to what I get, and its always done it, since new!
 
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