Is there a "Check Valve" on the return fuel line?

I'm trying to isolate an intermittent hard start problem on my son's 88 GT and a mechanic suggested that the check valve in the fuel return line was letting fuel pressure drop causing the occasional hard starts. Fuel pressure is 45lbs. at start up.

Is this a common problem and how difficult would it be to replace the "check valve?" Can someone post a picture of what it looks like? Thank you

No, there is the fuel pressure regulator on the injector tree but no check valve. the return line after fuel leaves the regulator is an open line back to the tank.
There is a check valve in the fuel pump but that is on the supply side.

He may have been referring to the regulator.

You have to pull the top of the intake off to get to it and it has special torque screws you have to remove.
It's not a hard job, just have to watch the parts and get a good seal.

If you put a pressure gage on it and have 45 at key on and then it drops to around 40 or so running it sounds like the regulator is good. The reg. don't normally fail off and on. It either works or not.

Think your problem is elsewhere.

[This message has been edited by Dodgerunner (edited 01-10-2010).]

The fuel return line does not have a check valve. The fuel pump itself does but that's on the feed line. The fuel pressure regulator is a sort of check valve though.

When you shut off the car does the pressure stay up for a while before slowly bleeding off or does it immediately go to zero?

The Fuel pressure stays up for awhile after the engine is switched off.

The hard start symptoms are: In the morning the engine starts and drives fine. If my son drives somewhere and parks it for 10 minutes or so, the engine will start but, dies in a few seconds. This happens about 5 times until my son gives it some gas then it'll idle and drive fine. This only happens on occasion not every restart.

I took it to a mechanic but, he said he couldn't re-create the problem so, they couldn't fix it (the engine started fine everytime). He said the fuel pressure was OK and he changed the fuel filter. There are no codes. I mentioned the Fuel Pump but, he said everything tested OK (pressure wise) and to bring it back when the problem started happening more frequently.

I also, replaced the Fuel Pump and AC Relays with new NAPA parts which seemed to help for a few weeks then the hard starts continued. This is frustrating.

Could be your IAC motor is sticking. Might give it a cleaning and see if there is any change. If you want to try there are several post of cleaning if you do a search. It screws out BTY.. don't loose the gasket.

https://www.fiero.nl/forum/A...030204-2-026449.html

[This message has been edited by Dodgerunner (edited 01-10-2010).]

I forgot to mention that the IAC motor, O2 sensor, EGR valve, new Braided EGR Tube, Spark Plugs, Wires, Cap, Rotor, Fuel Injectors and Battery were all recently replaced.

My gut feeling tells me it's a dying fuel pump but, the engine only has 50K on it. Thank you everyone for all the help.

[This message has been edited by GKK1 (edited 01-10-2010).]

I chased a "no-start when warm" issue and it turned out to be my MAP sensor.

Did the engine start and die or just not start at all?

Thanks, I'll check it out.

[This message has been edited by GKK1 (edited 01-11-2010).]

Wouldn't start at all until the car cooled off. Strangest problem. Of course I replaced my fuel pump and regulator too, but before swapping out the regulator I replaced the MAP and the dang thing worked.