Fuel Pump vent holes leaking gas - The 1947 - Present Chevrolet & GMC Truck Message Board Network

tattooboy37 · 01-01-2014, 06:46 PM

63 c20 w/ 283 . I recently noticed gas leaking from what appears to be vent holes on the upper part of the fuel pump. I've been having a loss of fuel under heavier throttle unless I ease into it. It has been driving me nuts because I recently rebuilt the carb. put in a new inline fuel filter ect. I've been chasing the carb for the last couple weeks and am pissed at myself if its the damn pump all along. In the course of the project I remember cleaning all the built up crud from the fuel pump while installing the new lines. Could the holes have been plugged before and not allowed fuel to escape? If my friend puts his fingers over the holes and I work the throttle it doesn't seem to want to sputter. if he removes his fingers and I open it up you can tell the air/fuel mix is off and it wants to die. at idle it is leaking just a little and when the throttle is opened up it seems to suck air and not be delivering enough fuel.
Is the pump shot or do/can those vent holes be plugged. the replacement ones online appear to have a recessed spot like a hole, but it looks plugged up. Is that vent necessary cause everything is perfect when my friend blocked them w/ his fingers.

63burban · 01-01-2014, 06:56 PM

Pump is shot !

ncoonen · 01-01-2014, 07:43 PM

The pump diaphragm is ruptured so the pump needs to be replaced. When you put your finger over the leaky vent hole, it is able to make enough pressure to feed the carb. Covering the hole is not a fix though and you need a new pump.

...ned.

Trsmotrhed · 01-01-2014, 08:02 PM

Quote:

Originally Posted by ncoonen

The pump diaphragm is ruptured so the pump needs to be replaced. When you put your finger over the leaky vent hole, it is able to make enough pressure to feed the carb. Covering the hole is not a fix though and you need a new pump.

...ned.

X2. I wouldn't run/drive it anymore either until it's replaced. That diaphragm breaks and gas will squirt everywhere.

firemanjimtfd · 01-01-2014, 08:12 PM

I have had to replace the fuel pump on about every 66 truck I have had. The new ethanol fuel is rough on them and rubber hoses. Also check the oil to make sure its not pumping gas into the motor.

tattooboy37 · 01-02-2014, 01:27 AM

Thanks guys, I figured it was done. at least they are cheap. I'll check/change oil to make sure. I was gonna replace my water pump soon anyways since it sounds a bit rough like the bearings are shot. might as well do it all while its down.

01-01-2014, 06:46 PM	#1
tattooboy37 Registered User Join Date: Apr 2012 Location: central california Posts: 19	Fuel Pump vent holes leaking gas 63 c20 w/ 283 . I recently noticed gas leaking from what appears to be vent holes on the upper part of the fuel pump. I've been having a loss of fuel under heavier throttle unless I ease into it. It has been driving me nuts because I recently rebuilt the carb. put in a new inline fuel filter ect. I've been chasing the carb for the last couple weeks and am pissed at myself if its the damn pump all along. In the course of the project I remember cleaning all the built up crud from the fuel pump while installing the new lines. Could the holes have been plugged before and not allowed fuel to escape? If my friend puts his fingers over the holes and I work the throttle it doesn't seem to want to sputter. if he removes his fingers and I open it up you can tell the air/fuel mix is off and it wants to die. at idle it is leaking just a little and when the throttle is opened up it seems to suck air and not be delivering enough fuel. Is the pump shot or do/can those vent holes be plugged. the replacement ones online appear to have a recessed spot like a hole, but it looks plugged up. Is that vent necessary cause everything is perfect when my friend blocked them w/ his fingers.

01-01-2014, 06:56 PM	#2
63burban Chevy addict Join Date: May 2012 Location: Iron Ridge, WI Posts: 1,085	Re: Fuel Pump vent holes leaking gas Pump is shot !

01-01-2014, 07:43 PM	#3
ncoonen Registered User Join Date: Jul 2013 Location: Livermore, CO Posts: 136	Re: Fuel Pump vent holes leaking gas The pump diaphragm is ruptured so the pump needs to be replaced. When you put your finger over the leaky vent hole, it is able to make enough pressure to feed the carb. Covering the hole is not a fix though and you need a new pump. ...ned. __________________ '63 C10 long wide; '61 Corvair Lakewood; '74 BMW 2002tii; '89 BMW 325i, '49 Ford 8N

01-01-2014, 08:12 PM	#5
firemanjimtfd Registered User Join Date: Feb 2013 Location: Sapulpa Oklahoma Posts: 197	Re: Fuel Pump vent holes leaking gas I have had to replace the fuel pump on about every 66 truck I have had. The new ethanol fuel is rough on them and rubber hoses. Also check the oil to make sure its not pumping gas into the motor.

01-02-2014, 01:27 AM	#6
tattooboy37 Registered User Join Date: Apr 2012 Location: central california Posts: 19	Re: Fuel Pump vent holes leaking gas Thanks guys, I figured it was done. at least they are cheap. I'll check/change oil to make sure. I was gonna replace my water pump soon anyways since it sounds a bit rough like the bearings are shot. might as well do it all while its down.



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