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A 521 in Massachusetts


Crashtd420

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The Carter gear pump is a great pump, but they tend to be noisy. I reserve them for use with side draft equipped, performance cars where a lot of fuel will be consumed.

 

3.5 psi at the pump doesn't sound right. I wonder if the pump is getting ready to let loose.

 

Holley makes a 1-4 psi regulator, which I typically recommend for use with Mikunis or Webers. https://www.holley.com/products/fuel_systems/fuel_pumps_regulators_and_filters/regulators/carbureted_regulators/parts/12-804

 

Other pumps that I would recommend -

Facet - https://www.pegasusautoracing.com/productdetails.asp?RecId=8462&utm_source=google&utm_medium=cpc&utm_campaign=FAC-480532&gclid=Cj0KCQjwytOEBhD5ARIsANnRjVhGMuEy8vc_6JscLqE_twjelyx3yaoPGBUkI2tlIaIuw_xZN6B7apYaAuBFEALw_wcB

or basically anything on this page - https://www.pegasusautoracing.com/group.asp?GroupID=FUELPUMPLOW

 

I run this one in my street driven Sprite - https://mossmotors.com/triumph-tr7-8/fuel-intake-emissions/fuel-tanks-pumps-lines-senders/universal-fuel-pump-kit-by-lucas

 

The cube pumps work well, but I usually use them as just a prime or lift pump, with the mechanical pump left in place. And obviously, any pump in this category needs to be mounted as close to the tank as possible, ideally below the tank, or you will have problems. Most cheap electric pumps are pushers, but expensive electric pumps can pull fuel.

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1 hour ago, Stoffregen Motorsports said:

The Carter gear pump is a great pump, but they tend to be noisy. I reserve them for use with side draft equipped, performance cars where a lot of fuel will be consumed.

 

3.5 psi at the pump doesn't sound right. I wonder if the pump is getting ready to let loose.

 

Holley makes a 1-4 psi regulator, which I typically recommend for use with Mikunis or Webers. https://www.holley.com/products/fuel_systems/fuel_pumps_regulators_and_filters/regulators/carbureted_regulators/parts/12-804

 

 

Im leaning towards the pump Is going to screw me soon, and I am actually using the Holley regulator.... 

I do like the Carter pump, my truck make more noise than the pump so I dont really hear it....

Maybe I'll just stick with them for simplicity, since the mount is already there, maybe just get the one with just a little more psi to keep the regulator happy... 

Then I can adjust the regulator to suit the carburetor... I already ordered a tee fitting to try and make a slight return system just to see if that might help the pump live longer....

The current pump has been there for about 4 years and 10,000 miles...

 

So i guess I'll get another Carter pump ordered up....

 

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The Carter gear rotor pumps are very sensitive to debris. Anything, and I mean any tiny spec of rubber or grit can screw with and destroy the pump.

 

I misunderstood your regulator specs. I thought you had the higher pressure regulator.

 

I forget, is you pump neat the tank and low?

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18 hours ago, Stoffregen Motorsports said:

The Carter gear rotor pumps are very sensitive to debris. Anything, and I mean any tiny spec of rubber or grit can screw with and destroy the pump.

 

I misunderstood your regulator specs. I thought you had the higher pressure regulator.

 

I forget, is you pump neat the tank and low?

I have a good wix filter before the pump and yes its lower than the tank and it's near the tank..... 

 

I actually just looked up the Holley regulator and I had some of that info wrong.... I thought it needed a minimum input pressure of atleast 7psi, that is actually the max input  pressure ... 

 

At this point I'm not sure... i am thinking the regulator might be the issue now, most listings rate the Carter p4070 at 4psi, others 4-6 , and as I stated before I installed the regulator I saw 7psi.... maybe my gauge was a piece of crap... I have since upgraded the gauge.... 

 

I might try taking the regulator apart and have a look... I'm still leaning towards deleting the regulator and using my current pump and creating that return to the tank to bleed off some pressure and allow the pump to keep circulating....

 

 

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Do you have a fuel return to the tank?  On the L20B and the 720 Z20, 22, &24 engine all have a fuel return Y pipe that the return has a metered orifice the allows about 3.5 lbs fuel pressure at the carb.

This is a late720 hard line.

 

 

First picture is L20B and the rest are Z24

Fuel Return Orifice.jpg

Fuel Supply Return Y 1.jpg

Fuel Supply Return Y 2.jpg

Fuel Supply Return Y 3.jpg

Fuel Supply Return Y 4.jpg

Fuel Supply Return Y 5.jpg

Fuel Supply Return Y 6.jpg

Edited by Charlie69
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No the 521 didnt have a return... 

I'm planning to use the 1/4 vent tube as a return input and I'm adding a vent line tee to what I believe is the filler neck overflow.... 

I'll setup a few tests and add an appropriate restrictor to the return line...

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1 hour ago, Charlie69 said:

Crashed give me a couple days I might have an extra L20B fuel pipe Y.  I will let you know.

Thanks but I already bought some stuff.... 

I'm trying to do a simpler return just between the pump and tank...

 

Doesn't that y pipe go in the engine bay?

I have no other line up there to connect to it if it does... I would have to route a new line which I was trying to avoid....

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45 minutes ago, Stoffregen Motorsports said:

Machine a small slug that slips into the hose. I've done this before to meter a teed off vacuum source. Small aluminum slug with a hole drilled through it, slid into the hose. Done.

That's my idea....

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I'm sure at some point I'll want to get the return line up near the carburetor but for now I installed a tee right after the pump....

 

20210510-181408.jpg

 

I added a restrictor to the line with a .125 diameter hole and ran It back to the vent line of the tank.....

 

20210510-181413.jpg

 

This did bring the psi down to where I wanted it without having to use a pressure regulator... 

 

To deal with venting the tank I bought one of these....

 

Screenshot-20210511-072818-Chrome.jpg

 

Added a tee to the filler neck overflow to connect....

 

20210510-181422.jpg

 

That will eventually have a different home, it needs to be as high as or higher than the filler neck....

 

 

Edited by Crashtd420
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Most fuel vapor vents are run into a charcoal canister, and those are usually mounted in the engine bay, at least on old cars. Modern cars have them mounted under the rear, but I don't know how they deal with venting at such a low height. There must be some sort of check valve built in.

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12 minutes ago, Stoffregen Motorsports said:

Most fuel vapor vents are run into a charcoal canister, and those are usually mounted in the engine bay, at least on old cars. Modern cars have them mounted under the rear, but I don't know how they deal with venting at such a low height. There must be some sort of check valve built in.

I would like to use a charcoal can for the gas smell but that's would take a bit more time to work out....

This was more of a quick fix for the moment.... 

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Well the truck seems to be running better, I have had a random misfire at times and after blaming my ignition system for the last 2 years I'm starting to thing it's been the fuel system this whole time... I have actually been able to add back a little more timing at full advance without issue.....

 

And yes I remember the old saying.. 

 

Also had to mess with my windshield washer pump, not that I think the check it but I was just making sure everything worked before I got for a sticker.....

Turns out the pump was a little corroded and just stuck... I was able to fix it, I guess i need to use it every so often so that doesnt happen..  

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Took the truck to the store for some paintbrushes,  wife has me doing house projects now.... 

 

Finding a spot to park I found another mini truck....

Not a datsun but it was still cool to see....

Extended cab, long bed, and riding on air.....

 

20210516_121847.jpg

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1 hour ago, Stoffregen Motorsports said:

I know what you're doing. You're driving around without your bed on to show off your new rear suspension. Trying to make the other guys jealous.

I have had a few people say that.... 

I am proud to show it off though....

Its actually been a good thing dealing with this fuel issue.... 

Even though it's been running better i think the pump is going to die soon .. my psi seems to have dropped to about 2.5 psi at the carburetor,  it was at 3.5 when I set it....

I have a new pump on the way, I'll probably change it out before the old one dies just to be on the safe side... 

I also bought a ball valve for the 1/4 return line, I figure it will act like a very basic regulator instead of a little pill with a drilled hole ...

 

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20 hours ago, Crashtd420 said:

I have a new pump on the way, I'll probably change it out before the old one dies just to be on the safe side... 

I also bought a ball valve for the 1/4 return line, I figure it will act like a very basic regulator instead of a little pill with a drilled hole ...

 

I bet that fixes it.

 

Overthinking it.

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