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Discussion Starter · #1 ·
I have a fuel pressure problem, it keeps dropping to "0" after about 10 minutes and dies out.
It will keep running if i drive it
I have a new holley (remauf.from Holley) 700 Dbl.Pump, new fuel pump,was a holley 130 Gph, now a Edelbrock 110Gph and a jegs regulator. AN fittings from the Russell fuel filter before the reg., just checked and cleaned.
I hooked air pressure to the line from before the pump back to the tank and "No" restriction
After i shut it down when the pressure drops, it will build pressure back again to about 5 lbs in 10 minutes.
Any Clue whats up????? Or what to check next??? Thanks Eric


Also i tried bypassing the regulator too, same thing happens.
 

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I have a fuel pressure problem, it keeps dropping to "0" after about 10 minutes and dies out.
It will keep running if i drive it
I have a new holley (remauf.from Holley) 700 Dbl.Pump, new fuel pump,was a holley 130 Gph, now a Edelbrock 110Gph and a jegs regulator. AN fittings from the Russell fuel filter before the reg., just checked and cleaned.
I hooked air pressure to the line from before the pump back to the tank and "No" restriction
After i shut it down when the pressure drops, it will build pressure back again to about 5 lbs in 10 minutes.
Any Clue whats up????? Or what to check next??? Thanks Eric


Also i tried bypassing the regulator too, same thing happens.
If you know the fuel filter is good, make sure the sock on the pickup tube isn't getting clog. Is it possilble the fuel is getting hot in the fuel line? Check the fuel pump as well.
 

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Discussion Starter · #3 ·
Just replaced the pump,filter is clean, hooked compressed air to back flush the line to the tank
Is there anything in the carb that might restrick pressure after 10 minutes?
its got me stummped.:eek:
 

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It could be a rubber line collapsing. You can blow through them no problem, but the pump drawing fuel from the tank is able to collapse old line that might have been kinked at one time or runs over a sharp edge.Like trying to drink a soda through a kinked straw. Just something to check,been there.
 

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Go to your gas tank when it is running and remove the gas cap and listen for a whoosh.....if you hear that check your vent tube.....or get a vented gas cap
 

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Discussion Starter · #6 ·
It could be a rubber line collapsing. You can blow through them no problem, but the pump drawing fuel from the tank is able to collapse old line that might have been kinked at one time or runs over a sharp edge.Like trying to drink a soda through a kinked straw. Just something to check,been there.
Im going to pull the Tank this weekend :mad: and replace the rubber lines and clean the sock. can you buy a replacement sock???

Go to your gas tank when it is running and remove the gas cap and listen for a whoosh.....if you hear that check your vent tube.....or get a vented gas cap
Tried that allready. + I have a vented (old and cracked rubber ) cap:eek:,

Any good tips on cleaning a Gas tank????
 

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Discussion Starter · #7 ·
Same problem

Ok, This weekend i pulled the tank and removed the sock, no crud there but it was split down the center. Looked in the tank and it looks very clean with no debris or rust. replaced all rubber line to the carb added a filter at the tank. Used high pressure air in all hard lines, all clear, even replaced the fuel pressure gauge. I capped off all the emmision tubes and added a vented gas cap. Even with the new fuel pump and regulator on wide open, i get 9 psi at first, then drops to 6 psi and after 10 to 15 minutes it slowly drops to"0" psi. If i drive it it sits around 1-2 psi. Im stummped. What else can it be??????? I dont want to drive it with low pressure and risk it running too lean and burning up the motor, plus I cant really tune the carb till i get a steady pressure. thanks Eric
 

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Vapor-lock (fuel lines getting too hot) or maybe the fuel pump pushrod is sticking. I'd pull it and inspect it to make sure there isn't any galling on the sides (from the bolt in the front of the block) of on the cam end.
 

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Discussion Starter · #13 ·
Sounds like it might be a heat sinc (sp?). Try a spacer under the carb and see if that works.
Got a 1 inch plastic spacer, hotest its run is 170- 180 degrees

Electric or mechanical pump?
Mechanical.

Vapor-lock (fuel lines getting too hot) or maybe the fuel pump pushrod is sticking. I'd pull it and inspect it to make sure there isn't any galling on the sides (from the bolt in the front of the block) of on the cam end.
The rod slid back and forth pretty good. had to use some grease to keep it up when i reinsalled the new pump.
I can feel the two places where lines are near any exhaust, not very hot to the touch. mine does not have the bolt, never drilled all the way thru. (grease it).:eek:
 

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I'd look at the fuel pump. Just because it's new doesn't mean it's not broken. Just out of curiosity, why the regulator? Do you need it?

Jim Smith
 

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Discussion Starter · #17 ·
I'd look at the fuel pump. Just because it's new doesn't mean it's not broken. Just out of curiosity, why the regulator? Do you need it?

Jim Smith
I thought it was the pump first, when i had a Holley 130 gph that needed a regulator.
I replaced it with the Edelbrock pump, (on sale!) and found out the problem is still there. I also bypassed the regulator with both pumps and still the same problem.
 

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Did you use any teflon tape anywhere? If you got a little "tail" that is floating inside a fitting, this could cause issues.

Another thing to check. Pull the pressure guage off of the line (cap it off) and see if you continue to have the problem.

Good Luck!
Jim Smith
 

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Discussion Starter · #19 ·
Yes i used tape, I always start it up a thead or two, I try to be careful of that.
I though it might be the gauge too, so thats a new. same problem.
 

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If it's not too difficult, put one of the cheap see through filters just before the pump (on the gas tank side). When you start to see the pressue drop, look at the filter, to see if you see anything.

Jim Smith
 
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