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The damper IS missing. Here's the story.

The previous owner told me that at some point in the cars life, there was a fuel leak at "the fuel pressure regulator". So his mech replaced the "fuel pressure regulator" with this Bosch one for a BMW.

After I took possession of the car, I discovered that what was actually removed was one of two fuel dampers, not the actual FPR. The FPR is still in the car, and still original as far as I know. Here is a picture of an engine bay from the same year, same model Impulse as mine, the arrow points to the damper.



The car actually has two dampers, one on the input side and one on the output side of the fuel rail. If you look at the pic above, you can see the other one behind the arrow. You can also see the pressure regulator underneath the damper where the arrow points.

Your Piazza's from Oz do not have these dampers? I believe this is the correct info:

8944083700 198503 - 198705 + 4ZC1 ENG(LR9) DAMPER; FUEL

Now, I don't think this part is needed either, not to get the car running right, but I can't imagine it would hurt to have some of the missing factory parts replaced.

One thing that might be going on now, which is causing the fuel pressure to be high, is that I replaced tons of stuff under the hood, including my injectors. So now, I have new injectors that are squirting really well, and maybe the fuel pressure is just too high now with the new injectors, where before, the old injectors were a bit clogged and the fuel pressure was high, but working ok considering this. My plugs are black and the car spits and pops at me while running. I have a pressure gauge hooked up and the pressure is constant around 49-51 psi, which is too high.

So I think my buddy Mike is correct that I am getting too much fuel and I have to get it under control. I with there was another aftermarket pressure regulator that I could buy knowing it would work.

Bart

Replace the regulator and that should fix the over-pressure problem UNLESS the return fuel line is blocked (ie, check that first).


W do have the same plumbing on our Piazzas. but that arrowed part is listed as an Air Regulator p/n 8942171231.
Below that to its right is the fuel pressure regulator p/n 8941467750.
[FYI - the last digit in p/n's is the revision number. The first digit (8) signifies "Gemini" (I-Mark) etc.]

That "damper's" upper hose goes to the inlet manifold doesn't it? (Like ours, it's too big for fuel.)
I'm not certain of its exact function, but it is tied to the fuel system (maybe rising rate fuel pressure regulator? - where's Wedgy?).

But I still reckon check the replace the fuel return line for blockage and if that was ok, then replace the fuel pressure regulator.

My plan of attack is as follows:

Drain all fuel out of the tank
Disconnect hard lines and blow out as much old gas as I can
Replace regulator and damper
Replace any existing rubber fuel line that I might have missed from under the car
Replace the fuel filter (again, just in case there is some crap in there now)
Do a valve adjustment
Put it back together and see what I get

Hopefully I will get to this on Sunday.

Bart

That sounds good.


IMO it is well worth renewing all rubbers after an engine rebuild or decade. (The olds are kept as spares...)

That includes the old "new"fuel filter - renew after catching any repair offwash or blobs.

So, tonight I finished with the fuel system. Dropped the tank, cleaned it, replaced all remaining rubber hoses I did not replace before. Blew out the lines with my air compressor. Installed a new FPR and a new damper. Installed another new fuel filter just in case.

Put 5 gallons of fresh mid grade in. Fuel pressure is still over 40psi and I am getting the same business. Car starts, immediately dies. If I start it and give a little throttle, it will run but it runs rough and wants to die.

Could a valve adjustment be what I need? I plan on checking the valve clearance next, but if that doesn't fix it, then I have absolutely no idea what could be left to do. I am completely stumped.

Bart

A new fpr?
What psi is it rated for?

Ghost wrote:A new fpr?
What psi is it rated for?

Its new OEM from Isuzu. So it should be correct for this car. Not sure what it is rated for or how to find out.

Looking at the manual, I wonder if I have a faulty vacuum switching valve.

I need to check the valves also.

Bart

Just a quick update. I'm still stumped. Timing is good. Valve lash is good. Completely cleaned the fuel system. OEM FPR and damper installed. Changed the IAC again. Cleared the ECU. Same business. Starts, then dies right away.

I guess next I will change the coolant temperature sensor. After that, there really isn't anything I haven't touched.

This is a weird one.

Bart

Maybe power the fuel pump(s) direct in case they are not being kept on.
I assume you have the ITEC ECU (optical distributor; locked) and not the Bosch-copy JECs system (mechanical dizzy with vac advance) - not that I recall how the JECs controls the fuel pump, but Bosch were too stupid not to have the ECU control the pumps.

But you should NOT be getting an over-high fuel pressure. Either the pressure regulator is wrong, or there is a return blockage. (Or your fuel tank shares the same pressure!)
But others are more knowledgeable on that issue.


Sorry if I have repeated something from before - I have lost track, though I know you replaced the FPV,

IZU069 wrote:Maybe power the fuel pump(s) direct in case they are not being kept on.

Tried that. Wired 12v direct to the pump to keep it on. Same business.

IZU069 wrote:I assume you have the ITEC ECU (optical distributor; locked)

Correct. Could the distributor still be at fault?

IZU069 wrote:But you should NOT be getting an over-high fuel pressure. Either the pressure regulator is wrong, or there is a return blockage. (Or your fuel tank shares the same pressure!)
But others are more knowledgeable on that issue.

Well, my fuel pressure is still high, but from everything I have read, high fuel pressure should not kill the engine. It might run at high RPM and run rich, but the engine should not die. Low fuel pressure is a different story however.

I dropped the fuel tank, cleaned it out, let it dry, replaced any remaining rubber that I did not replace already, new fuel filter, pressure regulator, damper, and blew the lines out, both feed and return with my compressor. Not blockage as far as I can tell.

There is something telling the car to shut off. Its got to be an electrical issue. Something like a fail safe or something. Its the only thing that makes sense. I have not tried replacing the distributor, but my timing is good and dead on now.

Bart

Too much fuel at idle can and will stall out an engine. It's the main reason why vehicles with Faulty O2 sensors stall out, because the ECU is in a "safe" mode and staying rich.

It sucks that you are still fighting this problem...

And since rich mixtures (or petrol/fuel) are the biggest killers of O2 sensors....

impulsive wrote:After I took possession of the car, I discovered that what was actually removed was one of two fuel dampers, not the actual FPR.

I would like to inform you that I have just installed a BOSCH 0280161024 (replacement part for BMW and Alfa Romeo cars manufactured in late 70s - early 80s)

http://www.autopartoo.com/oem/bosch/0280161024.html

in place of the original fuel pulsation dampener (aka fuel damper).

Please also refer to viewtopic.php?p=13672 .

Cool! Thanks for this info!

Bart