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Old 08-21-2008, 05:38 PM
GMR GMR is offline
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fuel pressure questions

Could some of you fellas help me understand how to recognize when a mechanical fuel pump is putting out too much pressure. I've read about carb flooding but not sure how to recognize it. I have a sbc 350 with a Edelbrock 600 cfm carb. The motor is on a test stand so I can't put it under load.

My Summit fuel pressure gauge is showing almost 8 psi. Which brings up another question - it's still showing 8 psi even though the engine has been shut off for about 9 hours now, is that correct? Previously it had been going back to 0 after a period of time.

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Old 08-21-2008, 05:49 PM
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GMR,
In my experience a carb can only handle between 4 & 6 pounds pressure before the fuel forces its way past the shutoff valve.

Carb flooding usually happens at tickover, the enging will start to lose revs and may cut out completely at the lights because the engine is getting more fuel than it can handle.

James.
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Old 08-21-2008, 06:37 PM
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Quote:
Originally Posted by GMR
Could some of you fellas help me understand how to recognize when a mechanical fuel pump is putting out too much pressure. I've read about carb flooding but not sure how to recognize it. I have a sbc 350 with a Edelbrock 600 cfm carb. The motor is on a test stand so I can't put it under load.

My Summit fuel pressure gauge is showing almost 8 psi. Which brings up another question - it's still showing 8 psi even though the engine has been shut off for about 9 hours now, is that correct? Previously it had been going back to 0 after a period of time.
Yep to your last paragraph, that shows that the valves in the pump and the shut off in the float bowl are as Tony the Tiger says "GR-R-REAT".

8's a little high but it seems to be holding it OK. Flooding will show fuel running out the vents.

Not being able to load the motor keeps you from really testing what's going on, it's hard to open the throttle fully with no load, if not downright dangerous.

Bogie
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Old 08-21-2008, 07:14 PM
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Quote:
Originally Posted by GMR
Could some of you fellas help me understand how to recognize when a mechanical fuel pump is putting out too much pressure. I've read about carb flooding but not sure how to recognize it. I have a sbc 350 with a Edelbrock 600 cfm carb. The motor is on a test stand so I can't put it under load.

My Summit fuel pressure gauge is showing almost 8 psi. Which brings up another question - it's still showing 8 psi even though the engine has been shut off for about 9 hours now, is that correct? Previously it had been going back to 0 after a period of time.
the edelbrock carburetor requires no more than 6psi. i just had an oem fuel pump putting out 7.5psi and that was too much. so i had to get an edelbrock performer fuel pump for it. the carb manual says 5.5psi is at best.
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Old 08-22-2008, 06:38 AM
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Quote:
Originally Posted by runn141
the edelbrock carburetor requires no more than 6psi. i just had an oem fuel pump putting out 7.5psi and that was too much. so i had to get an edelbrock performer fuel pump for it. the carb manual says 5.5psi is at best.
###################################

I had the same problem with my 327. I went to a local parts store and picked up a Carter fuel pump that was factory checked to put out 6 lbs of pressure. The price was a whopping $21.00+ for the pump. When I checked Summit for a new fuel pump, they sold the same Carter pump for $43.00. You might want to check with the local parts store to see if they have something that meets your needs.

Steve
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Old 08-22-2008, 08:07 AM
GMR GMR is offline
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Thanks for the help. I'm thinking about a pressure regulator. Any recommendations as to manufacturer.

Reflog, what part number is your pump. I've got a M6624 from NAPA which is supposed to be 5.5 - 6.5 psi but my pressure gauge is showing 8 psi.
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Old 08-22-2008, 08:38 AM
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Quote:
Originally Posted by GMR
Thanks for the help. I'm thinking about a pressure regulator. Any recommendations as to manufacturer.

Reflog, what part number is your pump. I've got a M6624 from NAPA which is supposed to be 5.5 - 6.5 psi but my pressure gauge is showing 8 psi.
google mr.gasket fuel pressure regulater
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Old 08-22-2008, 08:49 AM
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Quote:
Originally Posted by GMR
Thanks for the help. I'm thinking about a pressure regulator. Any recommendations as to manufacturer.

Reflog, what part number is your pump. I've got a M6624 from NAPA which is supposed to be 5.5 - 6.5 psi but my pressure gauge is showing 8 psi.
#################################

This is the unit I am running. It only pumps 40gph but I don't need any more than that. The one you have pumps 120gph. I bought mine through Auto Value store here in my home town.

Steve

PS Summit price is $24.00+ but you have handling for that and that I believe is a flat rate of $12.95 through Summit. I thought it was $43.00+ but I was in error on that.


Brand: Carter
Product Line: Carter Muscle Car Mechanical Fuel Pumps
Part Type: Fuel Pumps, Mechanical
Part Number: CRT-M4685
Free Flow Rate: 40 gph
Maximum Pressure (psi): 5.5 to 6.5 psi
Inlet Attachment: Stock
Inlet Size: Stock
Inlet Quantity: Single
Outlet Attachment: Stock
Outlet Size: Stock
Outlet Quantity: Single
Quantity: Sold individually.

Fuel Pump, Mechanical, Muscle Car Series, Chevy, Small Block, Each
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Old 08-22-2008, 01:09 PM
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OK, thanks fellas
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