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oil pressure

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It sounds like you may have a leak where the vac line connects to the oil pump.  If it is sucking any air there, it will not suck oil from the pan

The oil- pump is really an oil-vac pump.  If there is no fuel in the upper chamber of the vac-fuel tank, it could take a long time to seal and draw fuel, if at all.

Try capping the vac line to the fuel pump to see if that is the problem.  The best way is to make a sealed end with another 1/8 compression fitting and short piece of 1/8 copper tubing and solder it shut.  But, since you may not have that, you could remove the fitting and just hold something against the opening with your finger.

Do not use teflon tape - that is a compression fitting, so the tape will not help - it may actually make things worse.

As for the pickup line, you did the right thing replacing it with a compression fitting.  The original is what is known as a GM style fitting - it works great once at the factory, but is not designed to be re-used.  Sometimes they can be reused, but there is no garantee.  Best to repace with compression.

As for getting a prime going, it once took me 60 seconds twice to get a prime going.  That was a bit un-nerving.  I suspect that time it was a problem with my fuel vac pump tank.


I am leaning to a vac leak also.  I pulled the pump (total about 20) and installed a fitting to a 3/8 clear line and that to a can of oil.  I hit the starter for about 10 seconds and that lifted the oil about 6 inches.  Please note, I had no line to the fuel pump.  I had installed about 6 oz of gas in the pump at the start of all of this as I planned on a easy project.   I took all apart the fuel pump (cannister) and replaced the one gasket.  Kind of hard to screw that up.  The top of the fuel pump seems to just sit in the main housing.  Is there a gasket that goes between the top "cap" and the main body?  Would it make a difference?  I think I may just need to crank her for a true minute.  That just seems like a long time.  rusty

If there is not enough gas in the cannister, would that cause a vac leak and then "disable" the oil pump? How much gas is enough?  Should I just fit it to the top?  I had only place 6 oz or so in it currently.


I wouldn’t suspect the vacuum fuel pump.  Mine is hooked up for show only and while running the oil pump is just sucking air and has no negligible affect on the oil pressure.  With no spark plugs installed the oil pump should be able to pump up some pressure after a reasonably long crank.  Are you sure the pump gear is engaged and working properly. ?  If so you may have an air leak on the oil side or intake tubing.  If so even if the pump is working properly it would be easier to suck air then the heavy oil.

Just my thoughts,  Chet…

Did you stop when the oil drew up about 6 inches in the tube, or was that all it would do?  It is a smaller hole, but it should have drawn it all the way into the pump.

As for the fuel vac-tank, there is no need for a gasket at the top.  The vacume is formed only in the top portion - the smaller top tank the sits in the top.  This cannister must have no leaks and be airtight, both fittings on top must be sealed tight.   Also, since you took it apart, the inside is dry.  normally there is always some fuel in the top tank - but there is no way to fill  it of check it.  IF the tank is airtight, but dry, it will take a little while longer for it to draw up fuel from the gas tank.  This is the same vacume that draws the oil up from the pan.  So, it will also take longer to draw oil from the pan. 

Adding fuel to the little tank just allows you to start the engine.  It does not affect the vacume.

You seem to have ruled all other problems out.  But, not sure I understand exactly the test you did.  If it only draws about six inches and stops, perhaps the pump is not very efficient for some reason (too thick of a a gasket on the cover? It should only be the thickness of about two pieces of paper.)  But didn't yoo say you bench tested it and it was pumping oil?)  If the pump is good, I would try and seal shut the small vac port on the pump and try again.

I had stopped cranking the engine once I saw the oil coming up the tube.  I did not have a line to the fuel pump, strictly oil for this test. The pump worked fine.  I was using 3/8 clear plastic tubing of about 12 inches in lenght to a can  of oil.  I just wanted to make sure that the copper tube to screen (suction) was working with out  a air leak and it seems fine, no bubbles seen in the oil.   I think all the lines should be clear, at least you can tell is fuild is present and moving. I am starting to wonder if the problem is with me as I am not patient enought to crank the engine long enought to have the suck oil up to the pump and then in to the engine.  Since the pump works, no leaks on suction side, it seemed tight as I "pressurized the block", the fuel pump is cleaned and tight, I may just need to crank a bit longer and starter her up.  rusty

I did remove the cover and the gasket is very thin so I reinstalled it.


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