My new fuerl-pressure gauge arrived last night, and by this morning, I had determined that the hard starting that I was experiencing was, indeed, due to one or more injectors leaking down - fairly rapidly. Is there a thread that will show me the steps to replace the injectors. I could probably muddle through it, but PFF is such a good source of inside information that it doesn't make any sense not to ask. So, I'm asking.

its not to bad of a job
basicly its removing the upper plenum. theres quite a few thing attached to it tho.
be VERY careful with the EGR tube. its brittle, and its expensive.
also, all the vacuum lines are attached. they can be brittle also. they hold their shape, and are easy to put back
and then, theres the AIC tube, that goes from the throttle body to the intake manifold - just note its position - its easy to forget to put back.
once the plenum is off, undo the 2 fuel lines & the cold start injector line. now, your almost there.
pullout the injector harness. might wanna mark the ends 1-2-3-4-5-6.
2 more bolts holding the fuel rail in. once they are out, start rolling the fuel rail back & forth, and it'll eventually pop out, with the injectors hanging on.
the injectors have little clips you that hold them to the fuel rail. these bend easy, so be careful. push the tab, they'll rotate over, and the injector will be free to come out. but, it wont come out easy. twisting & pulling will be required. be careful. they will be tough. make sure you dont drop/let fly the injector when it comes free - or the fuel rail. thats basicly it. while the fuel rail is out - keep it clean.

http://www.cruzinperformance.com
^ they do a good job with cleaning injectors - fast turnaround, I think its like $10-$12 per injector.

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1985 Fiero SE - Plain Red V6 Coupe
3.1 Crane 272 MSD 4.10-4spd
D.A.M.M. - Drunks Against Mad Mothers

Pyrthian,

Thank you for the information. Do I disconnect the throttle body from the plenum, or do I disconnect the water lines and keep the throttle body with the plenum?

you can leave the throttle body on the plenum. the coolant lines can be disconnected over by the thermostat housing, and come up with the plenum.

Thanks, again, for the information.

What makes you think it's the injectors?I have a friend who's a mechanic,he says GM cars dont have this problem very often,the Nisons do (spelling?).

The car cranks for quite a while before it fires and then it takes a second or two for the engine to even out, just like cars used to do when they had carburetors and were "flooded." The gas mileage has diminished. These are symptomatic of a leaky injector (although there are other possible causes of those symptoms.) I've swapped the fuel-pump relay, the air temp sensor, and the manifold pressure sensor for their counterparts from a good running 88 like mine. I disconnected the cold-start injector to see if maybe that was causing the "flooding," but none of those actions identified the cause of the problem. Finally, I bought a fuel-pressure gauge and hooked it up. When the cars is running, there is 37 pounds of fuel pressure; when it is first turned off, fuel pressure reads 44 pounds; ten minutes later, it reads 32 pounds; twenty minutes later, it reads 24 pounds; 32 minutes later, it reads 20 pounds. That leads me to believe that something in the fuel system is leaking, and since nothing is leaking outside the engine, I'm assuming that it's leaking inside the engine. That suggests to me that the fuel injectors are leaking. What does your mechanic friend think might be leaking?

That leakdown rate is a tad fast. The other place it can be leaking is the pulsator and fuel pump connections inside the tank, as well as at the regulator. Pull the fuel rail and the cold start injector with the injectors and fuel line still connected, then run the pump with the ALDL terminal jump and see if any fuel leaks out of the injector tips.

JazzMan

Jazzman, Thank you for the tip. I wa wondering how I might actually witness a leaky fuel injector, and you just told me how.

Just as JazzMan says it's either the pulsater valve and should be replaced with a ruber fuel line and hose clamps,this will also prevent the fuel pump from poping off if you hit a pot hole (might as well replace the fuel pump while your at it,unless the pump is fairly new) or it could be the fuel pressure regulater.The fuel pressure regulater "kit" is a ruber diaphram.The old one may have a hole ore tear in it causeing fuel to be pumped from one of the little vacume lines into the intake manifold,this will cause the car to run rich,poor gas milage,hard starting,poor performance and may have the ocasional backfire.Try the cheepest and easyiest fix first and go from there,I would do the injectors last.I personally would'nt pull the fuel rail and injectors,because they have a plastic tip or hat and they become very brittle from heat and age,this little tip is not avalable through parts stores.If the tip breakes this will affect the spray pattern and may affect performance,not to mention the injectors are rather expensive to replace (about $68 each or more).Save that for last.Pic of the fuel pressure regulater below....

James Bond 007,

Thanks for the information, but as I do not have poor performance, and there is no backfiring, the lack of these symptoms (which you associate with the pulsator valve and the pressure regulator) would suggest that the culprit is a leaky injector, no? Also, I've pulled the injectors out of my other 88 GT and they are the later type that do not have the cap that can crack or fall off, so I'm not too worried about pulling the injectors on my current car, which is also an 88.

I think the empirical method might be best - pull the injector rail and see if any injector is leaking. If none of them is leaking, then I'll start replacing the pressure regulator and, if necessary, the pulsator valve (which sounds like it is in the fuel tank and difficult to replace.)

Incidentally, do you know where I can get a new gasket (the metal plate with two O-rings) that goes between the fuel-line block and the fuel rail? I took my other one apart and I don't think that gasket is salvagable.

Because your fuel pressure is constantly fluctuating.It's probubly the pulsater valve,a failing fuel pump,fuel filter or it still could be the fuel presure regulater.Sorry ther is no single answer to this problem.Just remember your not really loseing any $$$ by installing these new parts
Pic of a cloged fuel filter below...

James Bond 007,

Thanks for you input. I won't get to work on my car until my "new" injectors arrive, and then I'll let you know what I find. Thanks, again, for your help.

With the engine running you should see a steady pressure. When you rev the engine you should see the pressure drop. The pressure regulator is tied to engine vacuum so that the fuel pressure across the injector tip stays the same regardless of engine condition. You can pull the vacuum line and check for fuel in the line, that would indicate a bad regulator diaphragm.

JazzMan

JazzMan,

Thanks again for the tip. I have some injectors coming, and as soon as they get here, I plan to pull the plenum.