Fuel pressure dropping while driving and under acceleration to zero at idle runs 4 lb electric Blue

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I buy every Mallory 250 GPH pump I can find USED. They are bullet proof. I’ve found nice ones on fleabag and FB Market Place. I won’t pay over 200 bucks for one unless it’s PRISTINE.
 
flathead31coupe said:
So you would recommend the Mallory 250 for my application?
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Yes. You can use a 140 too if you can find one. But I would rather use the 250. IMO, you can’t have too much fuel pump, too much ignition and pushrods that are too big.

Either the 250 or the 140 will work.
 
Rat Bastid said:
Those pumps are junk.
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I said OLD holley blue pump. Mine is 30 yrs old works just fine. Keep a rebuild kit just in case. If you want to donate one of those Mallory 250s, I wouldn't object.
Just ran 10.66 with junk blue pump.
 
Carnut68 said:
I said OLD holley blue pump. Mine is 30 yrs old works just fine. Keep a rebuild kit just in case. If you want to donate one of those Mallory 250s, I wouldn't object.
Just ran 10.66 with junk blue pump.
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That's why I was asking early on in my early post. I had one used one that was doing the same thing as a brand new one was doing. Even after I put a 19 lb spring in the new one and deadheaded the regulator. I could only get about 11 lb max and it took about 45 to 50 seconds to get to that
 
Carnut68 said:
I said OLD holley blue pump. Mine is 30 yrs old works just fine. Keep a rebuild kit just in case. If you want to donate one of those Mallory 250s, I wouldn't object.
Just ran 10.66 with junk blue pump.
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Just so I know, what is old to you? I bought my first Holley blue pump in 1984. The second a year later (for my tunnel ram set up).

By 1986 I had to have both of them rebuilt. The company that did them said they had garbage brushes and they were made as cheap as they could be.

After he went through them they were more reliable, but the biggest thing that made them reliable was the return line.

LOL…I’m down to one 250 pump and I’m using that one. They aren’t coming up used so much any more. Pretty good swap meet coming up in January and another HUGE one in April and maybe I’ll get lucky and find a few.
 
Rat Bastid said:
Just so I know, what is old to you? I bought my first Holley blue pump in 1984. The second a year later (for my tunnel ram set up).

By 1986 I had to have both of them rebuilt. The company that did them said they had garbage brushes and they were made as cheap as they could be.

After he went through them they were more reliable, but the biggest thing that made them reliable was the return line.

LOL…I’m down to one 250 pump and I’m using that one. They aren’t coming up used so much any more. Pretty good swap meet coming up in January and another HUGE one in April and maybe I’ll get lucky and find a few.
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i found a 250 for 220$
 
I'll just keep my fingers crossed mine doesn't take a crap. I'll be on the lookout for a Mallory.
 
I have a quick question for anyone. I have a chance to buy a Mallory 250, but I noticed in the instructions that it said a minimum of- eight fuel line return and supply. I'm running a 3/8 return and a 3/8 supply. You think that will hurt this pump or should I get one that's smaller?
 
I called summit racing. They said it would work. Fantastic! Not to worry updates will follow updates will follow about it so I went ahead and purchased it. I got it for $160 bucks
 
flathead31coupe said:
I called summit racing. They said it would work. Fantastic! Not to worry updates will follow updates will follow about it so I went ahead and purchased it. I got it for $160 bucks
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Thats a smoking deal. Just remember if you can’t get the fuel pressure down with that pump it means your return line is too small for the fuel you are burning.

IOW’s, you are bypassing more fuel than the return line can support. You don’t want the return line being the restriction. Just the regulator.

If you can get the pressure where you want it then your return line size is fine and you are pooping in the tall cotton.

Keep us posted please.
 
Rat Bastid said:
Thats a smoking deal. Just remember if you can’t get the fuel pressure down with that pump it means your return line is too small for the fuel you are burning.

IOW’s, you are bypassing more fuel than the return line can support. You don’t want the return line being the restriction. Just the regulator.

If you can get the pressure where you want it then your return line size is fine and you are pooping in the tall cotton.

Keep us posted please.
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So if I do need a bigger return if I can't get the fuel pressure down can I just come off the side of the pump back to my tank with a bigger return and block the return up front at the regulator or is it better to use the regulator up by the carburetors and run a bigger line all the way back
 
flathead31coupe said:
So if I do need a bigger return if I can't get the fuel pressure down can I just come off the side of the pump back to my tank with a bigger return and block the return up front at the regulator or is it better to use the regulator up by the carburetors and run a bigger line all the way back
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Just curious....
 
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