I just bought an '82 280zx non turbo. When I got it, it would idle fine but bog down and backfire through the intake whenever given any throttle. I checked fuel pressure after the filter and I was getting 30psi at idle and around 5 when bogging. I replaced the fuel pump and got the same results. Then, after much searching I found that the end of the pressure regulator towards the firewall was nearly pinched shut. I straightened that out and it ran fine until it warmed up and began having the same issues as before. I hooked my pressure gauge up to the same end of the regulator that I found bent and I also had about a foot of extra hose between the rail, gauge, and regulator. But with the gauge hooked up that way, the car ran perfect, other than having one injector plug broken. I drove it a short distance and it performed well. I, then, disconnected my gauge and replaced the hoses on either end of the regulator. It now runs good and will rev but anything past 1/2 to 3/4 throttle, it will bog down. With the gauge hooked back up, it runs flawlessly. Kind of a long post but I wanted to give all the details. Also, timing is set around 10* advanced, so it should be good. Any ideas?

Edit: I doubt the broken injector plug is at fault because I can hold it onto the injector until the miss clears up and it still acts the same. New injector plugs come tomorrow.

 

is the FPR working?


the list goes as such for the direct fuel system (excluding fuel lines) so one (or more?) of these things is acting up.
pump>filter>FPR>injectors

other things that could be screwing with it,
your air flow meeter
cold start injector (if you have one)

www.xenonzcar.com has FSMs you can DL, itl have the timing in there
(since i cant recall off the top of my head lol)

 

What do you want for the fuel pump you replaced?

Edit: Nevermind, I figured out something better.

 

I'm not sure about the regulator. They are kinda pricey so I only want to get one if I absolutlely need it. I'm going to try to get ahold of a local guy who as a few z's and maybe borrow a known good regulator. I'm thinking about pulling the lines at the sending unit and before the filter to blow some compressed air through the lines. But that will be once the snow clears up a little, I can't get the car into the garage right now.
I can't download any manuals because I may be the last person left who's still using dial-up, but I had Advance order a haynes for me.
Last question, for now, where can I get new plugs for the injectors? Napa thought they had some but they weren't quite right. No other place can find any.

 

The free to download factory service manual covers pressure testing, as well as Bosch on their web page.(it's in a pdf file) If you can come up with a pressure gauge, shouldn't be any need to swap parts until it works.

 

Do a google search. One of the other forums has an Auto Zone part number but I can't locate it right now. worst case check with z man of washington he'll have them.

 

Tried to download the FSM, says it will take about 17 hours. I guess that's the price to pay living here, beautiful scenery... slow internet. I'm not having any luck tracking down injector plugs but I did find some info through searching about using pontiac v6 injector plugs. I guess I'll keep looking. I've searched google, zdriver, zcar, hybridz, automotiveforums, and too many others.
As for the fuel problems, I do have a pressure gauge. A very overpriced snap-on kit. But I can't find any problems when using the gauge because it runs perfect with it hooked up. About 30psi at idle and anywhere from 30-35 when rev'd/under load.
If I unplug the vacuum line from the fpr, there is no change. That seems to be a problem with the fpr. So, I thought that maybe (very tired at this point), the gauge could have somehow been regualting the fuel better than the fpr. So I hooked the gauge up where the fpr was and bypassed the fpr. Of course, it flooded and didn't run. I just don't see how my pressure gauge is fixing the problem. When the 20+ inches of snow starts melting away, I'll mess with it more.

 

Hmmm, have you run it long enough for the Catalytic converter to get hot and burn out all of the carbon? Bogging at higher RPM's was an issue for me until I examined the exhaust path and installed a new CC. Timing probably not an issue. Just a thought......

 

Heh, I hear ya on the pop off stuff, some of their stuff is pretty silly.

The way you say it's 30 psi at idle, and varies from 30-35, and then say removing the vacuum line makes no difference at idle, is a clue to me. Sounds like the extra vacuum of deceleration may be enough to open the valve, but idle vacuum won't, and it should. I don't understand your description of your gauge hookup.

FSM page EF36, Fuel pressure check"
"Connect a fuel pressure gauge between the fuel pipe and the fuel hose of the fuel filter" Pic shows "fuel pipe" as the pipe going from passenger side of valve cover to fuel injector area.
"At idling approximately 30 psi" The moment accelerator pedal is fully depressed approximately 37 psi If not as specified, replace regulator and repeat check. If below speck, check for clogged or deformed line, if necessary replace fuel pump."

Page ef55
Hesitation, stumble on acceleration

improper ignition system
Malfunctioning Aif Flow Meter

Intake air leakage at following points
pcv valve
Dipstick and oil filler cap seals
Manifold gaskets
Air Flow meter hoses.

Improper fuel pressure
improper idle co% adjustment
Improper EFI circuit.

Page ou812
Move out of crappy weather.

 

Before replacing the fuel pump, I checked pressure after the filter but before the rail. Second try, I put the gauge on the end of the fpr pointing towards the firewall. I've never payed attention to whether that is the inlet or outlet. It's supposed to get up to 42 degrees tomorrow, so I may get something done. We had a nice sunny day today but I had to replace the radiator in my 4runner after work. Thanks for posting up some of the fsm. I'll report back with my findings in a couple days.

 

Just as an update, mine flunked the first test, in 2 ways. Keep in mind that both failure in my case could cause a no run situation by themselves, much less together. First, fuel pressure was 38-44, thus easily flooded and possible cause of all the transitional weirdness. The second problem was I got a huge bunch of air or fuel vapor when I went to install the gauge. My injector cooling fan hasn't worked for who knows how long, and is gonna shortly. The other possibility is that that 31 year old externally braided cloth hose from the tank to the fuel pump that I did not replace has deteriorated to the point that it's sucking air, thus causing another possible no start. Not proceeding with diagnostics until these are cured.

 

Finally got mine fixed and I am a dumbass. Before buying the car and just hearing about the symptoms, I thought it might just have a plugged fuel filter. But when I saw the filter it looked new. So I went about my search and completely ignored it. I pulled the filter off and barely any fuel came out of the inlet. What came out was a few drips of dark brown nasty-ness. Installed the new filter and fired it up without my pressure gauge hooked up and she sounded perfect. I drove it about 2 miles and I'm happy with it. Just goes to show, even an experienced mechanic can overdiagnose a problem with expensive equipment and make things harder than they should be. Again, I was a dumbass.

 

Chickenshit! That's taking the easy way out! So now your car runs good, and mine still runs like dog snot and craps out when it wants to. Such a deal! Don't be surprised if that's only the first problem you spotted...

 

I hope it's that easy. I've put about 20 miles on it so far and still running strong. I did buy an extra filter just in case. Best of luck finding the problem with yours.