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Fuel leakage from accelerator pump.


OUTFXD
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Been paying a lot of attention to the fuel system lately.  Noticed some wetness at the foot of the carb.  It seems to be where the accelerator pump linkage goes into the bottom of the float bowl.

 

Anyone have experience with this? 

 

Any suggestions on a fix?

 

Thanks in advance!

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1 hour ago, Racer-X- said:

Do those leather plungers and leather parts stand up to ethanol? 

 

On the Weber DG series carbs, the accelerator pump is one of the first things to crack and leak if you feed it ethanol blended gasoline. 

they do not like corn gas. but float adjustment seems to be at fault. thanks to professor Sniper. I plan on rebuilding a DH1 over the winter just to have a spare handy

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When reassembling the carb, you will want to set the float about 3/32" lower than the spec. New fuels, especially ethanol enhanced fuels, are less dense than the gasoline available when these carbs were built and the float will not sufficient force to the needle to fully shut off the fuel inlet. The float has to be set lower to compensate for this. One more thing, the two check balls are not the same size. The smaller one is for the accelerator pump check valve.

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So scratch that.  Today drove to the gas station.   She was doing her standard "Out-o-fuel" thing (Even though I had 3/4 of a tank).  I put a splash of gas down the throat of the carb to "encourage" the fuel pump to work and about half the fuel splashed out from under the fuel bowl and onto the manifold.

 

Now,  when I rebuilt the carb I did a pretty thorough job cleaning it.  I am pretty sure I would have noticed A crack in the body.

 

I guess I will pull the carb off one more time to see whats what.

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New thing I noticed. When I "Prime the pump" (ie splash some gas down the carburator)  with the engine hot., I hear a hiss and can observe "steam" coming from the carb.

 

This leads me to believe that, AT OPERATING TEMPERATURE, I am getting fuel boil caused by heat from the manifold.

 

Is my assumption correct and is that how our cars are supposed to work?

 

Theories? Advice? Experience? Place to source a "new" replacement carb?

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  • 2 weeks later...

Two thoughts from my reading . . .

 

How's your heat riser assembly? Could it be diverting heat all the time to your intake manifold. @keithb7 has a good video about this (just finished watching it, again) and you can search the forums. Oh. Also a good link in the reference section.

 

 

Also, there is a heat shield for the fuel pump . . .

PXL-20221127-151258666.jpg

PXL-20221127-151415705.jpg

 

I think wrapping the fuel line (picture foreground, left side) in foil tape.

 

Cheers!

 

John

Edited by JohnTeee
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2 hours ago, JohnTeee said:

How's your heat riser assembly? Could it be diverting heat all the time to your intake manifold.

On First inspection I was rusted to the point it couldnt move and the bimetal "spring" wasnt even attached.

 

I shot it with penetrating fluid, let it soak, I could get it to move but it was tight.  Then I noticed that in the video the heat riser rotated about 90degree,  Mine rotated something close to 270degree.

 

I think its safe to assume the heat riser assembly is shot.  However with Christmas coming, Pulling the manifolds is not financially viable so will have to wait until next year.

2 hours ago, JohnTeee said:

 

Also, there is a heat shield for the fuel pump . . .

 

Okay that is cool and also not present on my car.  Is this a stock piece?  Do you have a source for buying one?

 

2 hours ago, JohnTeee said:

 

 

 

I think wrapping the fuel line (picture foreground, left side) in foil tape.

 

done and done. I wrapped mine (from fuel pump to carburator) in 500degree heat sheath.

 

Thank you for all the input!

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7 hours ago, OUTFXD said:

Okay that is cool and also not present on my car.  Is this a stock piece?  Do you have a source for buying one?

Don't know the answer to the stock question or recall if mine came with it or I added on down the road. However, I did remember that it lived in Downloads and here it is:

 

John

 

 

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