timfitz63

Hey, guys!

Haven't been really active for a while, but I'm finally devoting some quality time to the 'Bird in an effort to get it running properly again. I'm in the process of replacing all the components that have been removed in order to replace the fuel injectors (at least two of which were bad), and performed a fuel pressure test to the rails. Pump runs for the prescribed period (2-3 seconds) when power is applied (engine off), good fuel pressure reading while it is running (~42 psi), and everything looks tight on the rails (no leaks around injectors or places where O-rings were replaced). But once the pump quits, the fuel pressure at the rails drops rapidly below 20 psi, with or without the return line clamped.

My neighbor, who is helping me with this job, checked a number of things that could cause this, and all signs seem to point in one direction: the check valve on the fuel pump. But I thought I'd post a query here in case we may be overlooking something simple. Thoughts?

eseibel67

Your neighbor is right. The only other possibility is that the fuel injectors are leaking, which is unlikely since they are new.

Wish I had neighbors that could give sound advice.

riche

I have just been through this with my aftermarket set up. See if you can find a spot on the return line you can clamp. and try the test again. That will help rule out the Fuel Pressure Regulator.

timfitz63

Thanks for the replies, guys!

Yeah, no leaks at the injectors or where they're installed. Everything around the fuel rail is dry.

He's pretty good and quite knowledgeable about this stuff. I'm fortunate to have his help. But he wanted me to post the masses as a 'sanity check' on his findings.

Neglected to mention in my initial post that I'd also replaced the EGR and fuel regulator diaphragm. My neighbor clamped off both the return line (which I thought was a check of the fuel pump check valve) and the supply line (which checks the fuel regulator diaphragm, I thought). Whichever way it goes, he performed both tests and the pressure regulator diaphragm checked good.

As an aside, the whole thing is back together again. The car starts with a slight bit of hesitation -- perhaps because the check valve ostensibly isn't holding -- but runs smoothly and pulls strong now!

eseibel67

What I meant by fuel injector leaking is that the injector could be leaking fuel out the nozzle and into the intake. I've had this happen with a brand new one. Of course a leak at the rail would be quite easy to detect.

timfitz63

OK. Well, like you said, a leaky new injector is not as likely as a leaky old fuel pump check valve, but I can't eliminate a leaky injector beyond the shadow of a doubt at the moment.

What would be an easy way of checking for a leaky injector without tearing everything apart again? Ohm checking the injectors?

eseibel67

Prime the pump a few times without starting the engine. Take the spark plugs out one by one. If you have a leaking injector, the fuel smell will hit you.

timfitz63

Makes sense! Thanks!