Stoffregen Motorsports Posted May 7, 2021 Report Share Posted May 7, 2021 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. 1 Quote Link to comment
Crashtd420 Posted May 7, 2021 Author Report Share Posted May 7, 2021 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.... 1 Quote Link to comment
Stoffregen Motorsports Posted May 7, 2021 Report Share Posted May 7, 2021 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? 1 Quote Link to comment
Crashtd420 Posted May 8, 2021 Author Report Share Posted May 8, 2021 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.... 2 Quote Link to comment
Charlie69 Posted May 8, 2021 Report Share Posted May 8, 2021 (edited) 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 Edited May 8, 2021 by Charlie69 1 Quote Link to comment
Crashtd420 Posted May 8, 2021 Author Report Share Posted May 8, 2021 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... 2 Quote Link to comment
Charlie69 Posted May 9, 2021 Report Share Posted May 9, 2021 You need back pressure on the return line or your fuel will head back to the tank. That is the reason for the metered orifice in the return line. 2 Quote Link to comment
Charlie69 Posted May 9, 2021 Report Share Posted May 9, 2021 Crashed give me a couple days I might have an extra L20B fuel pipe Y. I will let you know. 1 Quote Link to comment
Crashtd420 Posted May 9, 2021 Author Report Share Posted May 9, 2021 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.... 1 Quote Link to comment
Charlie69 Posted May 9, 2021 Report Share Posted May 9, 2021 (edited) It bolts to the upper intake manifold bolts, but you could install it under the bed I suppose. Edited May 9, 2021 by Charlie69 1 Quote Link to comment
Stoffregen Motorsports Posted May 9, 2021 Report Share Posted May 9, 2021 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. 1 Quote Link to comment
Crashtd420 Posted May 9, 2021 Author Report Share Posted May 9, 2021 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.... 2 Quote Link to comment
datzenmike Posted May 9, 2021 Report Share Posted May 9, 2021 I would install as close to carburetor(s) as possible. The farther from the carb the longer the line or hose is that is under pressure from the pump. 2 Quote Link to comment
Crashtd420 Posted May 11, 2021 Author Report Share Posted May 11, 2021 (edited) 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.... I added a restrictor to the line with a .125 diameter hole and ran It back to the vent line of the tank..... 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.... Added a tee to the filler neck overflow to connect.... That will eventually have a different home, it needs to be as high as or higher than the filler neck.... Edited May 11, 2021 by Crashtd420 1 Quote Link to comment
Stoffregen Motorsports Posted May 11, 2021 Report Share Posted May 11, 2021 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. 1 Quote Link to comment
Crashtd420 Posted May 11, 2021 Author Report Share Posted May 11, 2021 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.... 2 Quote Link to comment
Crashtd420 Posted May 14, 2021 Author Report Share Posted May 14, 2021 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.. 2 Quote Link to comment
Stoffregen Motorsports Posted May 15, 2021 Report Share Posted May 15, 2021 You could probably run the fuel tank vent tube to the air cleaner. This would eliminate the smell, but there are obvious dangers. None that are too worrisome, but nonetheless... 1 Quote Link to comment
datzenmike Posted May 15, 2021 Report Share Posted May 15, 2021 Stuff some steel wool in the end of the hose as a flame arrestor. 2 Quote Link to comment
Crashtd420 Posted May 16, 2021 Author Report Share Posted May 16, 2021 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..... 3 Quote Link to comment
Stoffregen Motorsports Posted May 17, 2021 Report Share Posted May 17, 2021 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. 2 Quote Link to comment
Crashtd420 Posted May 17, 2021 Author Report Share Posted May 17, 2021 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 ... 1 Quote Link to comment
wayno Posted May 17, 2021 Report Share Posted May 17, 2021 I welded a metal Tee tip closed and drilled a 1/16" hole in it then put the hose for the return line on it to hide my crappy welding, both my SUs should have the same pressure. 3 Quote Link to comment
Stoffregen Motorsports Posted May 18, 2021 Report Share Posted May 18, 2021 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. 1 Quote Link to comment
Crashtd420 Posted May 18, 2021 Author Report Share Posted May 18, 2021 3 hours ago, Stoffregen Motorsports said: Overthinking it. Probably..... I just dont like the inconsistancy I'm seeing.... Quote Link to comment
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.