Was currently running two fuel pumps on my SR20DE swapped roadster. A Walbro 255 and a 280ZX pump. Both external. The shop that did my swap insisted so don’t ask me why I would go with such an extreme overkill setup. I was getting a lot of fuel dumped into my engine and my oil now has a strong fuel smell to it. So, I recently took everything apart and now I only have the 280ZX pump hooked up. I am getting the pump to prime and I am pretty sure all of the wiring is correct since it was working before with the old setup. I just can’t get the car to turn over. I’m guessing its just not getting any fuel up front to the injectors. I have the feed line going from connector on the very front of the fuel tank, where the stock connector once was, going to the fuel pump and pumping fuel to the fuel rail. Then the return is going from the fuel pressure regulator to the connector on the top of the fuel tank where the fuel-level sensor is.
Anyone have any idea what I am doing wrong. I am definitely not a mechanic. Any help is appreciated.
How do you mean you got the pump to prime? When you turn on the key it makes noise for a second? I found that the motor wouldn't run unless the fuel pump was hooked up through the stock fuel pump relay and wiring. Just trying to hook the pump directly to the ignition wire didn't work.
What do you mean by it won't turn over? Do you mean that it cranks but won't start or that it won't crank?
Fuel being "dumped into the motor" should not be a problem with the fuel pump / pumps. You should have a "return" off the injector rail that will bypass the rail and send fuel back to the tank when the appropriate pressure has been reached. If that does not happen, then too much pressure will overload the injectors and that's when you get an over-rich environment.
MORE likely is that one pump is continuing to pressurize the rail after the engine is turned-off (or residual pressure remains because the bypass is not functioning) resulting in fuel bleeding into the cylinders. when this happens, it "washes" the oil off the rings and ends-up in your oil pan. (this is very bad for the cylinder walls when you go to start it back up)
What were the symptoms other than the fuel smell in the oil? Any chance you've just got a leaky injector?
Correct, the fuel pump primes, turns on for a few seconds when you turn the key. But then when I go to start, it justs cranks, doesnt turn over.
After, I disconnected the feed-hose connecting to the fuel rail and barely a little bit of fuel came out, leading me to believe that maybe fuel isnt being pushed up to the front. This lead me to believe that I had the fuel pump facing the wrong way. So I switched it around. But it still didn't work.
if your fuel rail has been open to air, which yours has, then it will be full of... well... air.
so somewhere on the end of the rail there will be some sort of purge valve. Many have a schraeder-type valve, others have a jamb-bolt or other.
here's where my disclaimer comes in: you can't sue me for anything that happens to you while follwing the procedures that "I" use.....
turn the key on so you can hear your pump. gently crack the valve with a wrench, (or depress the center, if a schraeder-type) until you get fuel coming out steady. then close the valve.
Great, I am going to try this when I get home. I’ll let you know if it works. I’ve always wondered if air in the lines was an issue but it never really occurred to me to look into it. Like I said, I’m still learning as I go along.
Can anyone else confirm what type of valve is on the SR fuel rail and where exactly it is?
Hands-on learning can be the best kind. I hope that helps.
I'm really new to the Datsun / Nissan / asian car scene..... so I can't tell ya where to look on this particular engine, or even what type.
good luck.
Cherry Blossom wrote:Great, I am going to try this when I get home. I’ll let you know if it works. I’ve always wondered if air in the lines was an issue but it never really occurred to me to look into it. Like I said, I’m still learning as I go along.
Can anyone else confirm what type of valve is on the SR fuel rail and where exactly it is?
There is no schrader valve on the fuel system. The fuel should ciculate through the rail and back through the return line. It sounds a lot like you have the fuel flow backwards through the fuel rail. It should go in to all the fuel injectors before it goes through the pressure regulator. The pressure regulator is a little vacuum diaphram that needs to be hooked up to the intake manifold with a vacuum line.
One way to make sure the pump is working is to pump gas in and back out of a gas can with a loop of hose and the fuel pump. You can also try to pump it out of the gas tank and into a gas can. I place my bets on the fuel flow being backwards through the rail.
Update: Turns out the "280ZX" pump that the shop installed was only good for 8.5-9 psi. (Which is weird because I know a few people are running these pumps). I took it out and put the Walbro in, wich is overkill but better than nothing, and the car fired right up and idled better then it ever has. I think the last setup of two pumps was too much pressure on my injector o-rings and was causing a slow leak of fuel into the pistons. That’s my guess.
Just need to change the oil now to get out the oil with gas mixed in.
I was getting a lot of fuel dumped into my engine and my oil now has a strong fuel smell to it. So, I recently took everything apart and now I only have the 280ZX pump hooked up. I am getting the pump to prime and I am pretty sure all of the wiring is correct since it was working before with the old setup. I just can’t get the car to turn over. I’m guessing its just not getting any fuel up front to the injectors. I have the feed line going from connector on the very front of the fuel tank, where the stock connector once was, going to the fuel pump and pumping fuel to the fuel rail. Then the return is going from the fuel pressure regulator to the connector on the top of the fuel tank where the fuel-level sensor is. 