Mechanical fuel pump, to much psi?? - The 1947 - Present Chevrolet & GMC Truck Message Board Network

AnotherWs6 · 05-04-2016, 03:30 PM

Not to hijack, but fuel in the oil is an issue I have never had before, but I think I have now. Am I getting this straight - if the fuel pump diaphram is damaged fuel can leak into the crank case? Can fuel get in there if the carb is getting too much fuel or running way too rich?

My oil felt a bit thin when I bought the truck and brought it home. I changed it and out synthetic 10-30 in it and it looks a bit thin now too. With a total of maybe 20 miles since the change. And it had the faint odor of gas. I took the old Holley and factory-looking fuel pump off last weekend. Got the new pump installed, hoping to get the new carb setup this weekend. I'm doing this for drive-ability reasons but am also hoping to fix this gas/oil problem if it's not just my imagination.

cleszkie · 05-04-2016, 06:27 PM

Quote:

Originally Posted by AnotherWs6

Not to hijack, but fuel in the oil is an issue I have never had before, but I think I have now. Am I getting this straight - if the fuel pump diaphram is damaged fuel can leak into the crank case? Can fuel get in there if the carb is getting too much fuel or running way too rich?

Yes - bad pump can allow gas into crankcase.

Yes - gas can potentially make it past your rings if there is a lot of it, and your rings are worn. But I believe the gas would have to sit on the rings for a period of time. Excess gas while running would just get blown out the exhaust valve.

Jrainman · 05-04-2016, 07:56 PM

I think you may be on the right track , your PSI is a little on the high side , but I would also check :

Check floats for leaks

check float level , take the top half of the carb off bench it upside down, take 7/16 drill bit to check float height roll bit under the first 1/2'' of floats ,if gap is more then 7/16'' adjust by bending float arms

Check float needle and seat make sure needle is sealing in seat ,move floats open and close, use 5-6 psi air pressure if blow exists adjust or replace needle and seat.

these would be other considerations when the smell of raw fuel is present along with to high fuel pressure causing the needle and seat to have blow by.

05-04-2016, 03:30 PM	#1
AnotherWs6 Registered User Join Date: Feb 2016 Location: Westchester, NY Posts: 602	Re: Mechanical fuel pump, to much psi?? Not to hijack, but fuel in the oil is an issue I have never had before, but I think I have now. Am I getting this straight - if the fuel pump diaphram is damaged fuel can leak into the crank case? Can fuel get in there if the carb is getting too much fuel or running way too rich? My oil felt a bit thin when I bought the truck and brought it home. I changed it and out synthetic 10-30 in it and it looks a bit thin now too. With a total of maybe 20 miles since the change. And it had the faint odor of gas. I took the old Holley and factory-looking fuel pump off last weekend. Got the new pump installed, hoping to get the new carb setup this weekend. I'm doing this for drive-ability reasons but am also hoping to fix this gas/oil problem if it's not just my imagination. __________________ 1968 C-10 Suburban - Original 396/TH400 2002 Transam WS6 - M6 - Black/Black - Evil Garage Queen 2000 Silverado - DD - Small lift+Body lift+35" Duratracs+4.88's + Eaton TruTrac - Monster Truck 2010 Cadillac CTS Wagon Sport - Wife's DD and the only classy car we have.

05-04-2016, 07:56 PM	#3
Jrainman Registered User Join Date: Jul 2015 Location: North East PA Posts: 685	Re: Mechanical fuel pump, to much psi?? I think you may be on the right track , your PSI is a little on the high side , but I would also check : Check floats for leaks check float level , take the top half of the carb off bench it upside down, take 7/16 drill bit to check float height roll bit under the first 1/2'' of floats ,if gap is more then 7/16'' adjust by bending float arms Check float needle and seat make sure needle is sealing in seat ,move floats open and close, use 5-6 psi air pressure if blow exists adjust or replace needle and seat. these would be other considerations when the smell of raw fuel is present along with to high fuel pressure causing the needle and seat to have blow by.



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