PhatManBUD

Alright guys after a couple of months of messing around with this thing. I finally got the fuel pressure regulator in. Heres what i noticed about the car flooding. After turning the key to the on position, you can hear the pump (walbro 255 universal) prime, and the fuel pressure gauge goes up to 45-50 stutters then goes back down to 0 fairly quickly 2-4 seconds. When you try cranking the car the fuel pressure just bounces off the 45psi. then drops when you stop cranking.

What do you guys think could cause this.

Secondary injectors stuck open? i say this because ive swaped the primarys in and out between the 850s and the stock 550s and i still get the same prob. And the secondaries are the ones i bought off of a forum member and i havent touched them since i put them in.

Or maybe the fuel pump?

RotorJoe

I thought you had "all" your injectors tested at one point? If that’s even a thought, pull them and get them tested.

BTW, are you sure that the secondary 1600s have the correct o-rings and are seated properly? I remember some time back that you had a different o-ring configuration for the 1600s then some others.

Your fuel system should hold the idle/cranking pressure for at least a few minutes after you're done cranking. I know 45-50 is a touch high to start the car but that is where mine is set tell I hook up the vacuum/boost reference on the FPR and go for a retune. So I don't think your fuel pressure is set too high.

How's your FPD? Has that been replaced? That could cause the spikes/bounces you're seeing, but probably not the root cause. The only time I’ve seen one fail is when is starts leaking fuel, so I don’t know if yours is bad.

You really only have a few major parts that can cause something like this. Fuel Pump, Injectors, FPD and FPR. You're almost done checking them all.

The shop that tests injectors, ask and see if they’ll test the fuel pump too. I don’t think it’s the pump because it does build pressure and you are flooding the car. So that tells me the pump is working. Once it starts and is running you’ll want to monitor the fuel pressure through all RPM ranges and with boost (all in good time of course). When my pump failed it would hold pressure at idle but drop major pressure at anything else.

You know the FPR is good (new), some of your injectors are good. I would look at the few injectors you haven’t tested, the FPD and possibly even the stock FPR. With some hunting around you may be able to find a thread on how to remove the stock FPR from the rail.

FYI: After my rebuild I had a leaky primary injector (leaking from the plastic cap/electrical connector on top) and then my walbro pump failed. So a few things can go wrong at once.

Sorry a lot to digest, I hope I said everything correctly. Please correct me if I’m wrong.

PhatManBUD

hmm i am running the stock 850 cc for the secondaries and i bought them off some rx7 owner up north so im unaware if they were cleaned correctly or not

RotorJoe

oh yeah, my bad. I remember, now that I have looked at your past posts. The o-ring issue was with the 850 primaries. Sorry. And on that note I guess you already know how to remove the stock FPR and install a new one.

DaleClark

iTrader: (55)

I believe the fuel pump will "prime" the lines when you turn the key to On - that's what you're seeing with the quick spike. Something may be weird if the system isn't holding pressure and it's dropping so quickly - maybe something with the FPR, or something plumbed in backwards.

Dale

tcb100

You probably know this stuff but let me throw it out. Get some pinch-off pliers so you can pinch your fuel lines closed.

Pinch off the return line. Crank the motor briefly. Pressure ought to jump up a bunch when you crank it, a so-called "dead head test". If it does, you know your pump is putting out.

Pressurize the system and quickly pinch off the return again. If it does leakdown, then you know your regulator is not the problem because you have sealed off the return line like the regulator is supposed to do.

Pressurize the system again and and pinch off the supply line back near the gas tank or in front of the fuel rail. If it holds pressure you have a leaky fuel pump leaking back into the tank. I think they all have internal check valves.

If pinching off the supply and the return does not stop the leakdown, it's the injectors.

I have never tried it but it might be possible to get the pliers on the line between the primary and secondary rail and isolate the leak that way. If pinching off there stops the leak, then you know it's the secondary injectors. If not, it's the primaries.

There is nothing left except the fuel filter and your fuel line connections. Good luck.