Fuel pump noise ?? help - The 1947 - Present Chevrolet & GMC Truck Message Board Network

Dylan86 · 03-11-2013, 11:26 PM

ok, just the other day we solved my leak issue, a bolt hole that was left out located next to my fuel pump. now that the bolt is in there, and now my fuel pump is very noise. i took the bolt out again and the noise stopped. put my finger over the hole while running and it is sucking in allot of air? why would it be doing this, i dont think it should be this noisy.

piecesparts · 03-12-2013, 01:51 AM

How long of a bolt are you using? All youneed is ashort bolt to plug the hole, do not have one that goes in too far and goes up against the fuelpump push rod. That would be bad for the rod and the crank, if it is.

James McClure · 03-12-2013, 02:23 AM

Bolt in question should be NO longer than 7/16". Any longer it will hit the pump push rod scoreing it deeply and damaging the eng block itself. Oil can and will leak from this hole at all times when the eng is running

Dylan86 · 03-12-2013, 07:42 PM

Its not the bolt. Even if i hold my finger over the hole while its running the pump starts making the same noise. its only when that hole is plugged that it makes any noise.

James McClure · 03-13-2013, 12:39 AM

Dylan, I might have an idea here. I've seen crankcase vacuum levels do some funny stuff you wouldn't believe so here goes. You can duplicate the problem and this is good. You say you feel a vacuum at the bolt hole, ok, remove the PCV valve and see if you can duplicate it, put it back and check again. There are only 2 passages in the fuel pump arm cavity. 1 is for the push rod, the other for oil return. The only possible way to get a vacuum in this cavity is thru the drain back hole, but I think that would be normal with the PCV installed, so mabey it isn't vacuum, but pressure caused by heat and blow by from the rings. If the PCV system is in some way compromised you can build pressure in the crankcase. I would also consider removing the pump and checking the arm for excessive looseness at the pivot and where it attaches to the diaphram and making sure it's the right pump for the application, EG,2 hose or 3 hose. Let us know what you find, jim

03-11-2013, 11:26 PM	#1
Dylan86 Registered User Join Date: Dec 2012 Location: Lloydminster, Alberta Posts: 88	Fuel pump noise ?? help ok, just the other day we solved my leak issue, a bolt hole that was left out located next to my fuel pump. now that the bolt is in there, and now my fuel pump is very noise. i took the bolt out again and the noise stopped. put my finger over the hole while running and it is sucking in allot of air? why would it be doing this, i dont think it should be this noisy. Attached Images

03-12-2013, 01:51 AM	#2
piecesparts Parts and more parts Join Date: Nov 2003 Location: Lebo, Kansas (middle of nowhere Posts: 6,821	Re: Fuel pump noise ?? help How long of a bolt are you using? All youneed is ashort bolt to plug the hole, do not have one that goes in too far and goes up against the fuelpump push rod. That would be bad for the rod and the crank, if it is. __________________ Frank

03-12-2013, 02:23 AM	#3
James McClure One shot, one kill. Join Date: Dec 2007 Location: Saratoga Springs NY Posts: 859	Re: Fuel pump noise ?? help Bolt in question should be NO longer than 7/16". Any longer it will hit the pump push rod scoreing it deeply and damaging the eng block itself. Oil can and will leak from this hole at all times when the eng is running __________________ 1984 K20 350M engine with 465,000 miles. Well, it's finally done!! Almost 2 years of work, but it was really worth the effort. Little stuff left to do is mount winch, wet sand & buff out and build belly pan\running boards. Body work takes lots and LOTS of beer!!!! God, Guts and Guns made America and God, Guts and Guns will preserve it! The worst thing you could do is get into my sights, but that don't matter, you'll never know it, cause you'll never hear the shotJim or Paladin whichever you choose.

03-12-2013, 07:42 PM	#4
Dylan86 Registered User Join Date: Dec 2012 Location: Lloydminster, Alberta Posts: 88	Re: Fuel pump noise ?? help Its not the bolt. Even if i hold my finger over the hole while its running the pump starts making the same noise. its only when that hole is plugged that it makes any noise.

03-13-2013, 12:39 AM	#5
James McClure One shot, one kill. Join Date: Dec 2007 Location: Saratoga Springs NY Posts: 859	Re: Fuel pump noise ?? help Dylan, I might have an idea here. I've seen crankcase vacuum levels do some funny stuff you wouldn't believe so here goes. You can duplicate the problem and this is good. You say you feel a vacuum at the bolt hole, ok, remove the PCV valve and see if you can duplicate it, put it back and check again. There are only 2 passages in the fuel pump arm cavity. 1 is for the push rod, the other for oil return. The only possible way to get a vacuum in this cavity is thru the drain back hole, but I think that would be normal with the PCV installed, so mabey it isn't vacuum, but pressure caused by heat and blow by from the rings. If the PCV system is in some way compromised you can build pressure in the crankcase. I would also consider removing the pump and checking the arm for excessive looseness at the pivot and where it attaches to the diaphram and making sure it's the right pump for the application, EG,2 hose or 3 hose. Let us know what you find, jim __________________ 1984 K20 350M engine with 465,000 miles. Well, it's finally done!! Almost 2 years of work, but it was really worth the effort. Little stuff left to do is mount winch, wet sand & buff out and build belly pan\running boards. Body work takes lots and LOTS of beer!!!! God, Guts and Guns made America and God, Guts and Guns will preserve it! The worst thing you could do is get into my sights, but that don't matter, you'll never know it, cause you'll never hear the shotJim or Paladin whichever you choose.



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