Blocked Off Fuel Rail Return
Thread Starter
Staging Lane
Joined: Aug 2013
Posts: 63
Likes: 2
Blocked Off Fuel Rail Return Hi guys, I am putting in a 2003 5.3 Flex Fuel Vortec engine in a 1985 S10 pickup. I am working on the fuel system, well actually it's done and don't know if I did the right thing or if it's going to work. I have the stock 2 line return type fuel rail on it now and due to frame modifications and limited space I went with a single line from the fuel rail to the tank, blocked off the return line and am leaving the fuel pressure regulator vacuum line for max. flow. I hooked up a Corvette style fuel filter/regulator with a Walbro 255 fuel pump with only one line going up front and the return on the fuel filter going back to the fuel cell in the pickup bed.I know I need a PCM fuel map modification, but will this setup work? This is going to be a street rod only. Any thoughts or input would be appreciated.Thank You.
Fuel return = must Hi, SORRY this is the worst thing to do, block off the return.
The return flow volume is NOT the problem it is AIR in the lines.
The use of a small bleed line (3/16" S/S) will do the job.
When fuel is pumped, air bubbles form then go into the last cylinders fuel injector, in the rail, the highest injector(s).
When GM designed the PWM pump/tank "returnless" system, they spent years in tests at the AZ proving ground.
Lance
The return flow volume is NOT the problem it is AIR in the lines.
The use of a small bleed line (3/16" S/S) will do the job.
When fuel is pumped, air bubbles form then go into the last cylinders fuel injector, in the rail, the highest injector(s).
When GM designed the PWM pump/tank "returnless" system, they spent years in tests at the AZ proving ground.
Lance
Thread Starter
Staging Lane
Joined: Aug 2013
Posts: 63
Likes: 2
Air Bleed Hi Pantera EFI, thank you for the information. I was afraid of something like this and thought the air may bleed out through the injectors. How and where would I put the bleed off valve and where could I get one? I never saw one. How could it bleed off air without leaking fuel vapors or fuel? I should have known better to think it would be easy. Any information on where to get one and where to put it would be a lifesaver. Thanks again.
Tank Return of Fuel Hi, it would help to see a picture, to be sure.
The SMALL line should be at the rail high position, then back to the tank/make-up tank.
Mercury Marine uses a "lift pump" at the engine, then a tank that looks like ONE side of a Holley Carb, the float chamber.
The EFI pump feeds from that tank with no return/small return.
Lance
The SMALL line should be at the rail high position, then back to the tank/make-up tank.
Mercury Marine uses a "lift pump" at the engine, then a tank that looks like ONE side of a Holley Carb, the float chamber.
The EFI pump feeds from that tank with no return/small return.
Lance
Thread Starter
Staging Lane
Joined: Aug 2013
Posts: 63
Likes: 2
Fuel Rail Hi Lance, I want to thank you again for the info, you were spot on. I was skeptical from the start and because of the space issue I did it the easy way. I also want to apologize for not reading your response correctly. I better have my eyes checked, I thought you wrote bleed valve but it was bleed line. It all makes sense, but I read several other posts that guys put a Vette fuel filter/regular, blocked off the the return and used only the one line and it worked for them with the return type fuel rail, but it don't sound right. I don't want to take that chance so I think I am going to get rid of the Vette fuel filter and install a regular fuel filter and somehow run a return back to the fuel cell. Also I would have two fuel regulators in the same system if I used the stock rail and the Vette filter and I don't know how that would work out and the stress put on the stock regulator plus the danger of a leak. I'm getting sick of the fuel system for now and putting it on the back burner, while I work on the wiring harness. Thank you again. Have a nice day.
