Gas in Oil

[hivewax]

My '66 sat for almost a year to upgrade the suspension, wheels, and rear. I started the car maybe 5-6 times during that time frame. I also added Stabil to the fuel tank.

Oil change was done. It drives like normal, but the oil smells heavy of gas. The car doesn't stall at idle. It starts right up... no flooding of the carb. Some have suggested a bad fuel pump, which is only 2 years old. Others said it could be a stuck needle float in the 4150 carburetor (Holley 670 SA), which is also 2 years old. I bought parts cleaner and took the carb off. I found some dirt in the fuel inlet filters and cleaned that out. i haven't checked anything else yet.

What would you suggest next? I plan to clean the fuel bowls and metering blocks, check the needles, and buy a fast rebuild kit.

 

[tx65coupe]

Its either running way to rich, there is a stuck float or the needle/seat is not sealing, or its a bad fuel pump.

It could be any of these. I have seen newer parts that fail early. My car has only been running again for about a year, and recently I had stuck floats and had to replace the needles/seats. My oil smelled like gas too. Everything mechanical on mine is only a little over a year old and has 3k miles on it. I think there is something about the fuel we use today that causes some of these issues.

 

[hivewax]

Damn. I hate it when you can't pinpoint the problem. Is there a way of knowing if the fuel pump is bad like some test? Engine shop said the engine wouldn't run right with a bad pump...

 

[D.Hearne]

If it's not running bad or rich, the only place that fuel could be coming from is the mech fuel pump. The diaphram can be ruptured and still pump enough fuel to run the car.

 

[hivewax]

So, if this fuel pump diaphragm is ruptured, is this due old gas eating at it or from something else?

When the car is driven and when I get out, my clothes also smells of gas. It always has been doing this. So, the carb is running rich. Do I adjust the floats, idle screw, and/or timing?

 

[hungrymonkey]

Fuel pumps are fairly cheap, and not to hard to replace. If you pull it to check, then you might as well replace it.

I had the same issue with a pickup with a 351w. Heavy fuel smell while driving, bad gas smell in the oil.
It was the fuel pump diaphram leaking into the oil.

 

[hivewax]

I believe the Holley mechanical fuel pump on there is over $80; maybe with a dual diaphragm... hard to break I was told. I'm going to check the floats first.

 

[rbohm]

chances are that the fuel pump diaphram has a pinhole leak that is pushing fuel into the oil pan.

 

[hivewax]

I guess I'll check the fuel pump first, since it's easier than the carburetor. I'm going to call Holley and, hopefully, see if any of their diaphragm rebuild kits will work.

 

[tx65coupe]

I have a Summit brand mechanical fuel pump that has only about 3k miles on it and is about a year old. I was running it with my Edelbrock carb. I'm now running an Edelbrock pump. It should be suitable for your Holley carb. Its one of these, but I forgot which one it is. I believe its the fist link SUM-250024. If your interested, you can have it for free. Just PM me your address.

Summit Racing SUM-250024-1 - Summit Racing® Mechanical Fuel Pumps - Overview - SummitRacing.com

Summit Racing SUM-250004-1 - Summit Racing® Mechanical Fuel Pumps - Overview - SummitRacing.com

I didn't realize that Holley had diaphram rebuild kits. I believe that the Summit brand pumps are made by Holley.

D.Hearne is correct. A leaky pump can still supply enough fuel for the car to run.

 

[hivewax]

Checked the fuel pump diaphragm... no rupture or pinholes. Then, I adjusted the floats and used Chem-Dip parts cleaner for the fuel bowls and meter blocks. Hopefully, there'll be no more gas in oil...

pictures of the fuel pump - '66FB GT Upgrade Build-Up

Thanks for offering the Summit fuel pump.

 

[hivewax]

Oh, called Holley. Only the Ultra HP billet fuel pumps can be rebuilt. They have internal pins that connect the diaphragm. Regular models are cast-in-place.

 

[Az Pete]

If there is still a problem, you could have a small leak from the bowls draining into the cylinders and past the rings. Depending on how long the car sets, you might have a dry bowl. I had a Holley do this once and was hard to figure until the car sat for more then a week and was then hard to start. New gaskets fixed the problem.

My car runs rich and has side pipes but I never smell of fumes after driving it with the windows open or closed. Might have an exhaust problem too.