JonSmith720 Posted June 18, 2016 Report Share Posted June 18, 2016 I have a 1985 Nissan 720, I'm running an aftermarket electronic fuel pump that's at 5psi, I have a brand new weber 32/36 waiting to go on. My questions are: 1. Will I need a fuel pressure regulator with a return line? 2. If so where do I hook the fuel return line from the regulator? I've been looking around on here and it seems I'll be needing the regulator with fuel pressure 5psi and higher 1 Quote Link to comment
Doctor510 Posted June 18, 2016 Report Share Posted June 18, 2016 Return line not needed, the Weber works best at 3-4 PSI, just use a low pressure regulator... 1 Quote Link to comment
bilzbobaggins Posted June 18, 2016 Report Share Posted June 18, 2016 I think the 720's have a feed line that meets up with the return line. Then there is a top to the threesome with a oriface to regulate fuel pressure. Hope this is right and helps 1 Quote Link to comment
Lockleaf Posted June 18, 2016 Report Share Posted June 18, 2016 I think the 720's have a feed line that meets up with the return line. Then there is a top to the threesome with a oriface to regulate fuel pressure. Hope this is right and helps This is accurate and how I have my 720 with a Weber set up. 1 Quote Link to comment
Charlie69 Posted June 19, 2016 Report Share Posted June 19, 2016 This is the 720 fuel "Y" pipe. You need the return line when running a Weber on a 720 with a Z20, Z22, Z24 engine. You also want to run a Facet fuel pump. You will constantly be replacing over the counter pumps on the 720. The 720 fuel pump runs continuously and does not build pressure and shut off as the over the counter pumps are designed to do. http://www.ebay.com/itm/FACET-PUROLATOR-PRO-60FEP-60SV-FUEL-PUMP-/172208651828?hash=item28186f7e34:m:mMG-tFrnaCrgJuzHgdr4AIw&vxp=mtr 1 Quote Link to comment
JonSmith720 Posted June 19, 2016 Author Report Share Posted June 19, 2016 So that facet fuel pump will run 3.5 pressure and no regulator needed? Thanks for the replies, I'm trying to get this stuff figured out before I take off the stock carb. 2 Quote Link to comment
datzenmike Posted June 20, 2016 Report Share Posted June 20, 2016 The picture above has a small restriction in the return or else all the gas would just run back to the tank. The restriction does nothing to regulate the fule pressure. It's only there to provide some resistance so that pressure can build. And that pressure is set by the pump used. If a new weber can handle 5 PSI and is probably ok but be prepared for a regulator if it starts flooding. Keep that return line as it allows fresh cool gas to circulate past the carb and displace the gas over heated by very hot under hood temperatures. 1 Quote Link to comment
paradime Posted June 20, 2016 Report Share Posted June 20, 2016 If you need to adjust for a specific pressure, Holey makes an inline fuel regulator. 1 Quote Link to comment
Charlie69 Posted June 20, 2016 Report Share Posted June 20, 2016 Like I said above you need to run the fuel return line with the Weber and with the facet fuel pump or with the stock fuel pump. Mike, the metered orifice creates back pressure in the fuel system alloying the float bowl to fill and remain full during operation. Without the metered orifice in the return line the fuel would not fill and maintain the proper float level as most of the fuel would return to the tank rather than be pushed through the needle and seat of the carburetor. Liquids will always follow the path of least resistance. Simple hydraulics. 1 Quote Link to comment
JonSmith720 Posted June 21, 2016 Author Report Share Posted June 21, 2016 Okay thanks guys, the Weber goes on in a few days. If I do get the regulator, will the "in port" on the regulator connect to the fuel line sticking up next to the carb? And will the "out port" go to the Weber? 1 Quote Link to comment
datzenmike Posted June 21, 2016 Report Share Posted June 21, 2016 .... yes that should work. 1 Quote Link to comment
JonSmith720 Posted June 21, 2016 Author Report Share Posted June 21, 2016 Thanks datzen, I'll let you guys know how it went. Quote Link to comment
Charlie69 Posted June 22, 2016 Report Share Posted June 22, 2016 Using the proper pump and the stock fuel lines there is no need for a pressure regulators. now if you are using a higher pressure pump you will need a pressure regulator. Mike is correct the pump creates the pressure and the pressure is constant. The lines do not change the pressure, the orifice creates restriction in the return line but the pressure is the same on both sides of the orifice. If you are running a pump that is not designed to run continuously the pump will overheat and fail in a short time. 1 Quote Link to comment
JonSmith720 Posted June 23, 2016 Author Report Share Posted June 23, 2016 I got the Weber in, deleted all emissions stuff, the pump does push too much pressure so I put a regulator, started the truck up and idles real nice and quiet. I need to get a hose to put the pcv port to the Weber. When I turn the truck off sometimes it will diesel really hard and keep turning the engine over for like 20-30 second, is this a timing issue or from a hole that needs plugged? 1 Quote Link to comment
JonSmith720 Posted June 23, 2016 Author Report Share Posted June 23, 2016 Thanks for your help guys I'm new to this suff 1 Quote Link to comment
datzenmike Posted June 24, 2016 Report Share Posted June 24, 2016 When ordering the Weber the idle cut solenoid and electric choke should have been added to it. No matter, Just do this... Just before shutting the engine off, place in 4th or 5th, hold the brake on firmly, and lift the clutch enough to load the idling engine. Turn ignition off and engine will stall. When fully stopped, let clutch up. For an automatic just shut off in drive. Be sure to place in PARK after. 2 Quote Link to comment
banzai510(hainz) Posted June 24, 2016 Report Share Posted June 24, 2016 you can try pusing on the gas right when you turn the key off also. this is common on open head Datsuns running a weber as the stock carb usuaully has a idle cut off selinoid. The DGEV-IC has a selinoid and is automatic elelctric choke. Uses a different size idle jet holder(bigger) However I alwasylike the manual choke 5A series carbs. 2 Quote Link to comment
Charlie69 Posted June 25, 2016 Report Share Posted June 25, 2016 Here is a idle cut solenoid. http://www.ebay.com/itm/Weber-Carburetor-Idle-Jet-Solenoid-32-36-DGEV-38-38-DGES-Carb-Jeep-Toyota-Suzuki-/361539717200?hash=item542d724850:g:HCAAAOSwlfxXFvH~&vxp=mtr 1 Quote Link to comment
JonSmith720 Posted June 25, 2016 Author Report Share Posted June 25, 2016 Oh okay, It did come with that piece, I just didn't know what it was haha. @Banzai I kinda did want the manual choke ha but electronic works. I got the pcv hose plumbed into the Weber. One of the original aircleaner bolts that holds it to the valve cover penetrated through the metal, it was over tightened haha and air was coming out, I just put the bolt back in with a few washers on it 1 Quote Link to comment
JonSmith720 Posted June 25, 2016 Author Report Share Posted June 25, 2016 What wire do I connect to the idle cut solenoid, is it on the original cannon plug? 1 Quote Link to comment
datzenmike Posted June 25, 2016 Report Share Posted June 25, 2016 There should be two wires for the original carb. One for the electric choke (usually Blue under the covering) and a Red for the idle cut solenoid. If not, then connect to any ignition switched source that is on, with the key. 1 Quote Link to comment
Charlie69 Posted June 25, 2016 Report Share Posted June 25, 2016 Mike is correct the blue wire is the automatic choke and the red wire to the fuel cut solenoid. It is good to help people that ask clear questions. Quote Link to comment
JonSmith720 Posted June 25, 2016 Author Report Share Posted June 25, 2016 Alright thanks, I'll hook it up and see what happens. 1 Quote Link to comment
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