Fuel pump

[Steven]

Not everyones made of money here. Theres a certain aspect of having real opinions that take into consideration money and economic times in this world we live in. At the same time, the stock pump is mounted way better and works much better then any after market fuel pump that has the amount of pressure required for a carb, which isnt much in itself. Using the stock pump is a cheap affordable way in utilizing a well made setup from the factory in a custom application. To declare someone to be lazy or cheap for not doing it, is not right.

 

[Paul]

Fuel pressue is regulated before the carb on carb'd applications, and after the fuel has been delivered to the injectors on EFI applications. Is there any significant downside to running an EFI pump all the while significantly restricting flow via the FPR, especially given the fact that there is no return line?

I don't know anything about carbs, this is merely for discussion purposes.

LAFENATU, explain what negative consequences there are to this setup please.

The factory pump is near 180lph

I believe the factory EFI pump is only 88 lph, if memory serves.

Paul.

 

[Steven]

either way, you need only 5-9 psi on a carb, so theres no down side to a stock pump

 

[LAFENATU]

Paul, a stock fuel pump was an 88lph up until 1994 where the stock was a 110lph.

#1 it doesn't have enough volume.

#2 it is not designed to run at low pressure/high volume so there will be unwanted strain in other places.

So why on earth would you want a fuel pump with a 1/4" outlet instead of 3/8" or 7/16"??

The minimum a stock EFI fuel pump can be put to is 35psi while running consistantly reliable. If he can get it lower and be consistant I would love to know how. For a carb setup you want all volume not pressure. Look at the difference between the carb pump and the EFI pump the carb pump has up to a 1/2" outlet where a EFI pump has a 5/16" - possibly a 3/8" outlet.

The return line probably will not beable to handle that much volume of return and if it does it won't handle it very long. The pressure variance between the lines could be larger than 10 pounds. Bottom line is, it will not be reliable and can possibly destroy the carb.

If he gets too much pressure it will destroy the carb.


.02


P.S...If I came across the wrong way, I apologize. My intentions were not to mean etc. Maybe I should have worded things different, I am not here to be a d1ck so if I came across wrong..I am sorry.

-Rob

 

[Paul]

Thanks for the input Rob. Like I said, I know nothing about carb'd setups, so the information is appreciated.

 

[Jrgunn5150]

Second of all don't come on a message board, ask questions and then get butt hurt when someone else posts their opinion.

I did not ask whether I could or not. I did not ask your opinion on whether I should or not.

Now that that's out of the way, I'll tell you how to do it, and why you should.

Paul, a stock fuel pump was an 88lph up until 1994 where the stock was a 110lph.

#1 it doesn't have enough volume.

#2 it is not designed to run at low pressure/high volume so there will be unwanted strain in other places.

So why on earth would you want a fuel pump with a 1/4" outlet instead of 3/8" or 7/16"??

The minimum a stock EFI fuel pump can be put to is 35psi while running consistantly reliable. If he can get it lower and be consistant I would love to know how. For a carb setup you want all volume not pressure. Look at the difference between the carb pump and the EFI pump the carb pump has up to a 1/2" outlet where a EFI pump has a 5/16" - possibly a 3/8" outlet.

The return line probably will not beable to handle that much volume of return and if it does it won't handle it very long. The pressure variance between the lines could be larger than 10 pounds. Bottom line is, it will not be reliable and can possibly destroy the carb.

If he gets too much pressure it will destroy the carb.


.02


P.S...If I came across the wrong way, I apologize. My intentions were not to mean etc. Maybe I should have worded things different, I am not here to be a d1ck so if I came across wrong..I am sorry.

-Rob

1. A stock pump does not have enough volume, but a 255 Walbro does.

2. Low/Pressure high volume. The key to running an EFI pump with a carb is using a BYPASS style regulator. A two port "dead head" style typically used will not work, and will over work the pump and kill, as well as not regulate it accurately enough. I believe when I tried that way I was still getting 17 psi with the regulator cranked all the way down.

The regulator used is key, if it's bypassed with a regulator like the one I posted, it will accurately be at 9 psi, and the pump won't care because it's a continuous duty pump anyway.

The return line does not care about volume, but I would run new lines anyway.

As for the why, it's not that I'm lazy, or cheap. Since a 155 dollar regulator to start is not cheaper than yanking the electric pump and installing a mechanical, or easier. An electric fuel pump gives a constant flow of fuel. No pulsing, no varying rates. Mechanical fuel pumps are just like alternators, they do not deliver the flow at idle that they do at WOT.

My own personal reason's for doing it, since the above I don't care about too much, are that putting in a carb'd 351 is merely an interim step, if I go that route. It's a big outlay to go from V6 to injected 351 up front, with this intermediate step, i can be on the road this summer, instead of next year.

 

[LAFENATU]

Learn something new everyday..

On paper I just could not see it working :dontknow:

You got me J.R. - no denying that. I was 110% sure it could not be done.. ccasion14:

 

[Jrgunn5150]

If you try to do it with Spectre shit from Vatozone, it won't, I tried it before, lol. And I'm sure lot's of other's do too, but with a good bypass regulator, it works great. Makes for easier starting on my old truck too, since the bowls leak and run dry when it sits, lol.