Sorry to be Redundent - Help

[bhermes]

So here is the plan.

1) Turn BCDD 1/2 turn and drive, repeat until rpm spike is reduced

2) Add pot in line with the coolant temp wires and tweak

3) Run fuel pump test to monitor flow out of return line. One question here can you be a little more specific with jumper wires on fuel pump relay? I think the fuel pump is somewhat new but with all of the tank rust issues who knows if it is good.

Thanks and this looks like a good start.

[FastWoman]

3) Your question: It depends on the year. The wiring is different for every year. I believe yours is a '76. Mine is a '78. On the '78, you can short between the two green/blue wires to fire up the pump.

I believe your '76 uses a switch in the AFM. You might be able to turn on the ignition (but not crank the engine), and prop open the flap on the AFM to fire up your pump. You can of course also "hotwire" it with a wire temporarily connected between the + post of the battery and the + post of the pump.

[Zed Head]

You can also remove the small wire from the starter solenoid (it pulls off) and turn the key to Start to run the pump. That works on any of the 280Z's. The starter won't run, but the pump will run. Don't let the end of the wire touch anything since it will have power when the key is at Start.

I would not mess with the BCDD yet. You'll just complicate things. There are many other possible causes of a high idle, like sticky throttle plates or sticky throttle linkage. Nissan actually issued a recall in 1977 to fix that type of problem.

[EuroDat]

Question 3) If its in the AFM like the 77 model, which I think it is. The easiest way I find is to use a medium sized screwdriver and insert it handle end first via the air cleaner. Turn the key to ON when you do this. You will here the pump start when you push the flap open.

Chas

[bhermes]

Couple other things before I head into the weekend.

I have never really had the car "tuned up" since I have owned it (2 years) and not sure prior to that. Could these symptoms just be caused from that. I have replaced the plugs but not really anything else. What else is part of getting a tune up for the car. Probably not a real good question.

And as mentioned before what if my injectors are clogged and that is the reason for the issues. Any chance or would the car be acting worse during most of the drive. Still to would like run some fuel injector clearner through.

Just want to have a plan of attack for the next few days since weather is going to be a little warmer here.

Right now it looks like adding the pot and running fuel to see if consistant are on the list.

[Zed Head]

Car ran ok for the majority of the trip. ......

The issue is that 3 times during the trip and I beleive at speeds over 50 mph the car acted like it was running out of gas.

I would try to break your problems down in to individual, manageable projects. The high idle may or may not be related to the engine acting like it's running out of gas. I don't think that the potentiometer or the BCDD will fix that problem, but that seems like the most important one. When you have several things happening at once it's easy to get distracted or decide to work on the one that seems easiest, but you might find that you're fixing something that doesn't need fixing. If you're not super-comfortable with how your engine works, changing several things at once is almost a guaranteed way to create new problems.

Most of these posts are suggestions for things to consider, not calls to action. If you think you have a fuel problem, the most direct way to confirm it is to connect a gauge and drive the car. See where fuel pressure is when the problem happens.

[siteunseen]

You'll need a solder gun or a wood burner and some solder for the wire on the potenometer. I guess I should've explained the BCDD high hang better. It does it when you push in the clutch at a stop- only for a few seconds then drops down on it's on. If it's staying high, pull up on the gas pedal with the top of your foot and that should pull it back down if it's the throttle plate gummed up or a missing return spring on your linkage and like Zed Head says, that's not as important now.

I've owned one Camaro, 1st car too, that had a carburetor and sold it in '88. Ever since they've been fuel injected and I've never used fuel injector cleaner. When you get it running good just run a couple of tanks of high octane fuel. What if the Lucas attacks your newly lined tank? That metal fuel filter up front is pretty damn good.

I'm a very slow typer. What Zed Head says above, suggestions and plenty of them from me.

Edited November 15, 2013 by siteunseen

[bhermes]

Let me clarify one thing. The increased rpms at stopping last only a few seconds and then returns to normal on its own.

Sorry if this was confused.

I understand chasing things and causing more problems.

I do like the idea of the pot and running fuel into a gas tank to see if I am getting consistant flow. To easy things with not to much damage.

[bhermes]

I know that there is a post somewhere on this but could someone please give me some direction on hooking up a pressure gauge so that I can monitor my fuel pressure. Also, what should the pressure be.

I think this should probably be the first step. I just that I would also look at adding the pot incase it is an issue with the car heating up a causing a problem with fuel mixture but maybe I should see the pressure issue first.

Thanks.

[FastWoman]

I went to the hardware store and bought a cheap ($10?) generic pressure gauge (for water?), a brass, 1/8" FPT "T" fitting, and 2 1/8" MPT nipples/barbs. If you imagine the "T" standing upright, like the letter, the two nipples went on the bottom and left. The gauge screwed into the right. Then I stood the T on its side with the gauge pointed up. I hooked the nipple pointing down to the outlet of the fuel filter with a very short hose. I hooked the nipple pointing horizontally to the fuel rail, using a slightly longer hose. The pressure gauge has lived under my hood ever since, ready for whenever I might need it. It's like an umbrella, I suppose, in that it insures I will never have fuel pressure problems ever again.

For a temporary test-drive setup, just put a "T" in the line between fuel filter and fuel rail, and run the third leg to a long hose tied to your windshield wiper. Make sure the hose is filled with fuel, and not air, or your fuel pressure regulation will get rather sloppy.

[siteunseen]

I had an older picture from when I was doing what you're doing. I think I ended up running it off the fuel rail somewhere around the injectors, to the windshield wiper. 5/16" stuff is what you need but not necessarily EFI rated for the long hose to the wiper, it's expensive but you'll always be able to use it if you do buy that type. It seems like I used a worm clamp around the base of the gauge, it's 1/4", to hold the hose to the gauge on that end. If it starts leaking you can see it real good because it's zip tied to your wiper blade .

Lowes would have a gauge somewhere, air compressor area or maybe plumbing, anything works for a short test. Pressure will vary but somewhere around 30psi is what you want. Hope this helps.

Thanks again Fastwoman, couldn't done it without your help.

After a cup of coffe I can honestly say the volume knob or potentometer ran inside while you drive is easier than hooking up a fuel gauge to the wiper. But I'm not trying to add to your worries, a fuel gauge is a must if you've got problems.

Edited November 17, 2013 by siteunseen

[siteunseen]

I can't edit anymore, timed out, anyway my car ran good for just a few seconds here and there. I got excited and rebuilt the whole motor. New fuel rail and fuel injectors, new Bosch fuel pump, new everything! It still had that same stumble after 3 months and $1500. I gave up and left it with a mechanic that worked on them at a Nissan dealership back in the days, he couldn't figure out the problem other than it wasn't getting enough fuel. So I did what I had read helped others and put that tweak knob in the coolant sensor wires. As soon as I did it I went and picked up that mechanic and went for a ride. He was amazed. If you have a Radio Shack close by try it, it's $5 worth of stuff and you unplug the existing wires, put the pot in between the 2 original wires and if it doesn't help you just unplug it and reattach the originals. I wished I had done that 2 years ago but I wouldn't have a new motor or the experiences.