78' 280Z stumbles under throttle application

[Virto]

Ok, - I think we found the source of the problem.

The PO had really done a bodge-job fix on the fuel pump - They'd clearly had it removed since I found the in-pump filter screen was gone, as if it had never been there. In its place was a solid chunk of rusty varnish. The pump had been struggling to pull against this the whole time since I woke the car up. They also HOT GLUED the wires to the pump - the little rubber boots were gone. I had to cut the wires, and I'll crimp on new terminals.

The tank was clean when I drained it, but I'll take another look and drop it if I really have to to wash it out.

The pump bracket screws are rusted into the bracket itself, and are impossible to turn, not unlike my fuel filter bracket. To work on it, we removed the entire mounting plate including the fuel dampner.

Vise-gripping the bracket screws just led to snapping the heads off, so I'll have to drill them out and replace them. No big deal. Because of that, though, I didn't get a new pump in, so I'll probably be waiting a week, de-scale the bracket and get all my ducks in a row.

I did manage to get the front fuel filter out and replaced - the fuel that came out of it was pretty clean, really. I was expecting it to be brown or rust-colored but it seemed fresh. It had a varnish smell, but I'm not surprised about that.

[siteunseen]

Does it look like this? Mine had that pink Bondo looking stuff on the terminals too, also without boots.

[Virto]

Might be the same stuff. Looked at least partially clear, but that makes it sound like the factory may have done different things with certain years.

Sadly, your rusty pump looks much better than mine.

[siteunseen]

Salt vs. humidity I suppose.

[FastWoman]

Glad to see you're making progress! Maybe the chunk of debris was causing cavitation, resulting in the whining? Hopefully your annoying noise will be gone.

My own fuel pump came with the pink bondo (?) terminals, like siteunseen's. My car had a 15 year history of Nissan dealer service before I bought it, so perhaps it was some sort of Nissan -endorsed material/compound. I used 5200 to seal mine when I was done.

It will be great when you get to finger the AFM counterweight. I think you'll learn a lot about your engine then.

[Virto]

I'm sure the pump was struggling against the blockage, like trying to suck water through a straw that's filled with sand, or perhaps a marble.

Hopefully I can get the pump in this weekend and give it a try.

[Virto]

eBay bucks came up today, so I ordered a new set of plug wires (NE61). I haven't swapped the PO's old generic parts store cables before, so it's a good idea and the price was right.

The holiday will delay shipping, of course, but it's not a big deal. Replacing little things like this is fairly easy and I can fit it into the budget here and there. It's the under-car stuff that's hard for me.

Tomorrow is the holiday, but with most things closed, I'll probably make little if any progress on the car. I need to run out and buy new drill bits and find replacements for those fuel pump bracket screws.

[Virto]

Hookay...new fuel pump is in, which was quite the bit of work for 85 degrees and 80% humidity. In-line filter installed between the tank and the pump - all new lines between the tank and pump, the pump and the damper and the damper to the fuel hard line.

Turn the key, pump runs for a second. Good sign. Crank the motor - nothing.

Remembered that we left our clamp on the tank to pump hose. Removed clamp, turned car over - nothing.

The tank is maybe 1/3 to half full...figure five gallons of gas, give or take. Do I need to fill the tank to the top to get fuel flowing again? I've seen several posts that say the OEM pumps are self-priming, but this is an aftermarket crap pump that's meant as a stop-gap while sorting my other issues.

[Zed Head]

Take the small wire off of the starter solenoid and turn the key to Start. If the pump is wired right you'll hear it whining and you should hear some bubbles in the fuel tank as the air is pushed out. The pitch of the pump will change when the lines get full pressure. If you have a pressure gauge you'll see what's happening.

Did you cut the ends off of the old wires? It's possible to wire these pumps backward. They'll run but they won't pump. Another possibility.

[Virto]

I'll try removing the wire and just letting the pump run. Sounds like I could hold the AFM open and get a similar effect, as well.

Before I do that, let's clarify the wires on the pump - I did snip the existing leads off, as they were encased in some kind of resin. I didn't see any polarity marks on the factory pump, but the casing is so rusted and corroded that it might simply not be possible.

I used the typical "black is ground or negative" approach to reconnecting the wires after crimping on new terminals. Watch me be wrong... I did look at a couple of wiring diagrams and at the EFI bible, but I'm apparently terrible at reading a diagram. I have no clue which is the positive wire and which isn't.

[Virto]

Pulled the wire off the solenoid and let the pump run. You can hear it clearly, but I noticed no change in pitch or tone over 15-20 seconds of "cranking" several times. Not sure how long is safe to hold the key in START. After doing this, I re-connected the solenoid and tried to start the car, but there was no change.

I have green on + and black on - but there was one thread a stumbled on where a gent with an early 280 had a green on - and a red on +. Hopefully Fastwoman can clear up the '78 wire colors for me.

[Zed Head]

Disconnect a hose and see if fuel is pumping. Or just loosen a hose clamp and see if fuel leaks or squirts out.

Your work would be so much easier if you had a fuel pressure gauge connected.