project 76 280z(s)

[Syncro]

I picked up my 76 280z a month or 2 ago and swapped out the injectors, fuel relay, and ecu, the pump is new and was replaced before I got the car. The cars runs great aside from a small backfire when the revs come down afte3r eving to 6k. It always back fire at 3k or close to it. Always when your driving it after it nice and warm when you floor it the car bobs back and forth like its running out of fuel or something, I know the car has around 3/4 of a tank, so its not running out of fuel. When the cars wrming up still and is sitting aroun 140 you can floor it and it accelerates great, its only hapens when the cars warm. Also if you reve the car up to 3k 2 or 3 times and then floor it while its warm the revs try to build up to 6k but the cars starts to act luck its running out of fuel and eventually just sits 2k-2500 with your foot slammed against the floor. Please I need to get this getting ready to register!
edit: this is an n42 car by the way,

[jalen]

Sounds like there is water in the tps or whatever its called. Just take a rag and dry off by the distributor, my car did the same thing after I washed the engine bay

[Skib]

my car did the same thing after I washed the engine bay

 

thats moisture under your dizzy cap

[Syncro]

alright I'll check both, but honestly, this car hasn't been by much if any water and has been like this since I got it, its was in an accident prior to me getting it, the passenger side got slammed into, not sure if there's anything that could screwed upo anything, I live in dry new mexico also.

[Syncro]

have yet to work on the car but on an upside I bought another 76 auto 280z today, things is rusted out but the parts it has are on the rare side, short list of what I know is there: rust, a 4 barrel holley carb and intake setup, blow thru turbo setup, a blown motor, nice seats, 4 point harnesses, decent set of shocks and great glass. really its simply a parts car for my 76, its got new tires on it so I'm sure the tranny is fine seeing as how the motor's shot. I plan on tossing the intake, turbo system, seats, couple of interior parts, suspension, and most of the body panels on my z, paying more for this z then I did for the running one. After that its a part out, not sure whats lurking beneath the valve cover, hopefully its good. but the diff, shafts, and everything that I haven't mentioned taking will be for sale, including a decent dash cap. I may be interested in selling the intake, carb and turbo kit if I got the right offer, not sure what kinda turbo its got on it yet.

[Syncro]

no moisture. :confused: Wtf could this be? I'm gonna swapp my fuel pump out and see what happens.

[Skib]

have you checked your fuel filter, injectors and AFM?

[bonvo]

when was the last time the dizzy cap was changed? sounds like a carbon track is starting to form to me either that or the ignition module is on its way out

[Syncro]

no moisture. :confused: Wtf could this be? I'm gonna swapp my fuel pump out and see what happens.

have you checked your fuel filter, injectors and AFM?

I've replaced the injectors with known good ones, have not checked the afm but I'm pretty the afm is good, I know its a long shot but it was replaced in 95 by the previous owner. I don't thinks its the filter, the problems only accure when the cares warmed up, fuel filter seems like it would be happening all the time.

 

 

when was the last time the dizzy cap was changed? sounds like a carbon track is starting to form to me either that or the ignition module is on its way out

cap was changed at least 3 months ago before I got the car.

Something stranged did happen today though, floored it and it still climbed and then just sat there at 2k, sounding like it was flooding sorta and running rouhg with my foot nailed to the floor, but for just a second I coulda sworn I heard the fuel pump stop just once, how loud is the stock pump supposed to be by the way? or atleast with the spare tire, and cover gone from the back?

[Syncro]

Didn't get around to swapping the pump yet, but here's a couple fo pics of the new car and whats gonna likely be thrown on my z.

[I'm BLUE]

Turbo 4bbl ?

 

Looks cool! Lol

[Syncro]

yeah, just gotta get a turbo motor so I don't make the same Mistake the last guy did and blow out my bottom end.

[Syncro]

Well its not the fuel pump, tested it at the local z clubs tech session today and no luck. the fuel pump pulsates, no matter waht fuel pump it is. One guy said to check the fuel lines, so I'll try doing that tomorrow, another guy though it could be my ecu, swapped my ecu for a spare I've got, din't really change anything. ecu is from another 76 so don't ask if its the wrong one. Think I'm gonna pull the fuel lines from my parts car, flush em, swap em, and see what happens. Also got the new wheels and tires on. 205's in back, otherwise stock. think I'm gonna rattle can it gloss black, would've gone flat but gloss is actually cheaper.

[ggzilla]

Timing too far advanced could cause that. Does it start hard? Like the battery can just barely crank it long enough?

[Syncro]

Timing too far advanced could cause that. Does it start hard? Like the battery can just barely crank it long enough?

Nope, thing fires right up everytime, its runs great til its warms up, or it used to, haven't floored lately while it not warmed up. the afm was swapped by the PO in 95, I've replaced everything but the fuel lines and the wires leading back to the pump. Also, I've been having trouble with the fuse for the dash lights and taillights blowing. but anyway here's what I know works good, Fuel injector, fuel relay, fuel regulator, fuel pump, and the ecu. I don't think its the filter or lines but I should probably replace both anyway I figure, my sending unit doesn't work though so no idea how much gas is in it usually, I know it not dry though. also, the fuel pump is loud on my car, if its hooked up to someone else's car its not as loud though. also the pump only pulsates with the car running, if the key is just turned on it runs like normal, but when you start it the pump pulsates, idle is stable and never jumps.

[Syncro]

Also one of the guys said he saw the car leave a bit of black smoke when I pulled the car out to try the pump, so its may also be running rich.

[ggzilla]

Instead of simply replacing parts, why not test it? The Datsun manual has all the tests to figure out what's wrong.

 

The first test I would do is fuel pressure test. If that's too high it will have good power, but run rich.

 

Is your car's fuel pump damper missing? Maybe a previous owner removed it.

[Syncro]

Damper? never heard of it, fuel filter and everything I'm used to seeing on a car is there. I haven't tested the pressure, (noob question) what do I use to test it?

[Syncro]

the problem has to do with the fuel pump. I'll blow out the lines tomorrow and swap the filter, I really don't want the problem to be with the tank. yeah throwing parts at it is a stupid way to handle things.

[TRsome]

I had the same issue on my L28 when I first got it. After the car was hot, I ran into issues where the car was sputtering, and when I would drive it uphill it would top out at 2500 rpm, or in some cases just die.

 

It ended up being an issue with my ignition coil, if that helps.

[ggzilla]

the problem has to do with the fuel pump

How do you know that? Many things can cause these symptoms.

 

 

Damper? never heard of it

You really need a service manual to keep a 35 year old car running right. The damper keeps it from pulsating while running. Look under the back of the car. It's a little round thing near the fuel pump. The hoses from the fuel pump go to it. It will run with no damper ... but will be noisy I think, also may not run quite right.

 

 

I haven't tested the pressure, (noob question) what do I use to test it?

A fuel pressure tester, specifically a medium-pressure EFI pressure gauge. This measurement is not of the fuel pump, but the Fuel Rail pressure. Set it to 33.6 psi for correct operation.

[Syncro]

alright I'll test it tomorrow and I'll check for the damper, though I think its the thing that sits on top of the fuel pump bracket that looks an awful lot like a fuel filter.

[Syncro]

I had the same issue on my L28 when I first got it. After the car was hot, I ran into issues where the car was sputtering, and when I would drive it uphill it would top out at 2500 rpm, or in some cases just die.

 

It ended up being an issue with my ignition coil, if that helps.

well I've got an extra ignition coil so might as well check if its good anyway, I'll try that too.

[Syncro]

Also got another question, the are 2 white wires that don't seem to go to anything by the ecu, there wrapped with the ecu harness, I could look it up in the manual but its late here and I'm lazy. there also and extra green wire by the fuel pump that doesn't seem to go to anything and its a hot wire, was told its for the sending unit by a friend of mine but I'm doubtful of that.

[Syncro]

well the problem with the pump pulsating was a wireing issue, got that knocked out, still didn't fix the problem though, haven't gotten around to testing the fuel pressure but I'm working at it, the pump was actually hot wired to the fuse box by the last owner. Painted the car black with a white stripe as well if that means anything to you guys, I'll have pics of that later, just a temporary bad rattle can job til my painter is done with my rx7.