76 280Z - fuel supply

[Oregon_PLG222]

I bought this Z from brother in law a couple years ago and I've never started it or heard it run. Apparently, he was driving it weekly and just parked it. I have turned it over (and over and over) but it doesn't seem to be getting any fuel. I really don't know anything about fuel injection systems and have not been able to devote any time to it thus far. My suspicion is that there is probably a relay for the fuel pump that is not allowing the pump to work.

 

My son shot some starting fluid in the air intake the other day and we heard if fire off. I did drain the gas tank last year and put a little new gas in it. That's all I've done to it. I have the PLG222, PLG223, 81 510 and now (as of yesterday) the 79 620 to keep me busy. But, I'd like to get the Z running.

 

 

I have receipts from the previous owner that he had the motor and trans overhauled along with other receipts totaling over 10k. Some of that was for glass and bumpers that are now damaged again and an alarm system that I don't car to have in it. But, despite the spots of primer and surface rust and the need for cleanup and paint, it should be a really good drivetrain.

 

Does anyone have advice on where to start on the fuel supply/ignition?

 

 

[Skib]

sitting forever wreaks havoc on those EFI systems.

[datzenmike]

Climb under the back and have someone turn the key on. The pump will be under the car close to the tank and you should hear it humming if working. If not unplug and check for power. If there is power then the pump is no good. No power then maybe the relay (if equipped, I don't know) or fuse is bad.

 

Try giving it a smack with a block of wood to get her running. It may have a dead spot from sitting so long.

[Oregon_PLG222]

When I drained the gas tank last year I'm pretty sure I did check to the wiring to the fuel pump for juice. As I recall, there was no power and that's why I was thinking it must be a relay or something. I'm pretty sure I checked all fuses. I'll have to open it back up and re-check. My hearts only half into the Z. I would much rather have a 521 to be working on. When I get it running I'll likely put it up for sale or trade. I would just like to get it startable.

[datzenmike]

Try a jumper from the battery to the pump and see if she fires up.

[Aaron Datsun]

I can't remember but do fuseable links control the FP in that year of Z?

[datzenmike]

Every thing is fusible linked one way or the other. I don't think there would be a separate link just for the pump though it would likely have it's own fuse in the fuse box.

 

Try a jumper from the battery to the pump and see if she fires up.

[I'm BLUE]

On 240z's ... to the left lower corner of the fuse box ...

is indeed a seperate fuse for the fuel pump ...

sometimes you have to take the center console off to expose/replace the fuse or check the wire.

 

Check for power to the circuit with a test light first ... ( buy one at parts store) ...

Clip ground alligator clamp to clean metal surface ...

stick probe on (+) power wire coming to...

 

Do the same procedure at fuel pump or any electrical circuit.

 

Today's gas mix is what kills and eats fuel systems as well as metal

That's why its important to run fuel preserver,

"isoheet" through fuel tank to burn out water,

 

Relays on 240's are at the kick panels ... not sure on 280's ...

check power to them...

If power to ... then replace ...

 

Go through and clean the shit/check your connections

be prepared to replace 1/3rd of them

 

Good luck

[NiiChan GT-R]

I believe that there's an oil pressure cut-off on 77-78 280zs that will prevent the pump from turning without sufficient pressure... It's different on my 75 (where the cutoff is initiated in the AFM), so I'm not quite sure where that relay is located, but that' would be where I'd start.

 

Yeah, try applying voltage directly to your fuel pump to see if it will turn, and see if there's voltage to the fuel pump while cranking...

 

Don't give up on L-Jet! :D It's fairly friendly once you work with it for a while, and make sure everything is clean.

[datzenmike]

The 720 uses something similar to the interior light delay. When you turn the ignition on it starts a timer (maybe a minute?) if the motor starts then there is an alternator and oil pressure input. As long as the alt is charging it's assumed the motor is running and needs the pump and keeps the relay on. If oil pressure drops or does not come up before the timer times out this will also turn the pump off or not allow to start.

 

 

Fuel pump relay/timer

 

[Oregon_PLG222]

I had power to the fuel pump but no gas. So, I put in a new fuel pump. The gas line at the filter was nasty so I put on a clear plastic line temporarily so I could see gas circluate. It took a little work on the fuel rail and the replacement of a couple of the small connector hoses but I got gas to circ and could see it in the return line.

 

Then we cranked it over and heard some small firing. The pos cable from the battery to the starter came loose from the starter. It post actually broke out of the solenoid. So, we slammed in a new starter. Then, we cranked it and.......nothing. After some investigation, we found that we had bumped off the wire for the EFI that attaches to the little fuse box on the fire wall. Then, holy moley, it fired up!!!! It runs a little rough but sounds pretty cool through the dual exhuast system. By pulling spark plug wires while running it seems that I have 3 cyl not firing. Most likely bad or plugged injectors.

 

Does anyone have, or know where I can get, a couple injectors to pop in. I don't really want to go drop 50+/piece for new or rebuilt ones right now. There were some on the parts forum but I can't get a response from the seller.

[Jeff G 78]

...By pulling spark plug wires while running it seems that I have 3 cyl not firing. Most likely bad or plugged injectors.

Are the three non-firing cylinders scattered, or are they the front/back three? L Jet batch fires all six injectors at the same time, but it does it through two circuits. One controls the front three and the other, the rear three.

 

Go to http://www.xenons30.com and download both the FSM and the Fuel Injection manual. BTW, from the looks of your car, it's not a '76. It's either a '77 or '78. Be sure to download the correct year FSM. Your car should have a build date on the door jam. You likely have an early '77.

 

Before you swap injectors or replace anything, unhook EVERY connection under the hood and spray both halves with Caig Deoxit which can be found at Guitar Center or online. Radio Shack also sells it, but only in tiny cans for big $$. L Jet EFI must have good connections, good grounds, and good vacuum to run right. Go through the FSM and check everything. Use a stethoscope or big screwdriver to listen for injector firing. You can hear a click when they fire.

 

Good luck and feel free to ask me for help. I've spent a lot of time around L Jet.

[Oregon_PLG222]

Are the three non-firing cylinders scattered, or are they the front/back three? L Jet batch fires all six injectors at the same time, but it does it through two circuits. On controls the front three and the other, the rear three.

 

Go to http://www.xenons30.com and download both the FSM and the Fuel Injection manual. BTW, from the looks of your car, it's not a '76. It's either a '77 or '78. Be sure to download the correct year FSM. Your car should have a build date on the door jam. You likely have an early '77.

 

Before you swap injectors or replace anything, unhook EVERY connection under the hood and spray both halves with Caig Deoxit which can be found at Guitar Center or online. Radio Shack also sells it, but only in tiny cans for big $$. L Jet EFI must have good connections, good grounds, and good vacuum to run right. Go through the FSM and check everything. Use a stethoscope or big screwdriver to listen for injector firing. You can hear a click when they fire.

 

Good luck and feel free to ask me for help. I've spent a lot of time around L Jet.

 

Thanks for the info. BTW, where's Northville, MI ? I moved here to Oregon from Detroit (Ferndale) 20 years ago.

[Jeff G 78]

Thanks for the info. BTW, where's Northville, MI ? I moved here to Oregon from Detroit (Ferndale) 20 years ago.

Northville is a NW suburb of Detroit. It's just west of 275 and south of 696 if you still remember the highway system. Not too far from Ferndale.

[Oregon_PLG222]

That's what I was thinking.....out by the Novi area.

[Jeff G 78]

Exactly. Just south of Novi.

[Z-train]

1. Drop the fuel tank and douche it out
   
2. replace ALL rubber in the fuel system
   
3. install a 60 psi guage betweeen the filter & the rail,this will confirm/debunk a whole shit pot full of issues
   
4. power to the FP is supplied ONLY when the motor is cranking or running.No oil pressure inter-connect.
   
5. Injectors can be cleaned & flowed for $17.00 a piece.Don't forget the CSI.
   
6. Deoxit on ALL connectors under the hood AND the computer
   
7. remove,clean & verify function of the thermotime switch and the coolant temp switch
   

The FSM in MANDATORY for chasing these issues.

[Z chopper]

wow just after I sent a Pm to skib about a simular issue with a 76 280z I am eyeing I run across this thread

[Oregon_PLG222]

No luck on downloading the FSM. Also, after pulling wired while running, it sounds like she's not firing on 2,3, 5 or 6. So, she's only hitting on 1 and 4. I have a manual that I downloaded and printed a couple years ago. But, it's for a 75. It shows the test for all the pins on the ECU connector. I'm not sure if they are the same for the 77.

 

I'm checking the spark plug wires first to make sure they have spark and that they're in the right order. I don't trust that someone didn't mix them up. Same for the injectors plugs but I'm not sure how the check those for order.

[Jeff G 78]

Yeah, I just read on another post that the '77 FSM PDF is corrupted. Try downloading the '78 FSM. They are very similar other than a distributor difference and I believe the fuel pump wiring. For what you need, either the '76 or '78 manual will work fine.

 

It wouldn't surprise me at all if the injectors are stuck or plugged with varnish. Use a screwdriver to listen to them. Put the blade of a large screwdriver directly on each injector and press your ear to the end of the handle. Start with he ones that you know are firing so you can hear the clicking. Then move to the others and listen to each one.

[Z-train]

CAREFULL!!!!Odds are other years are not the same.For my 77 810 there are FOUR DIFFERENT computers from the factory

[NiiChan GT-R]

Just realized that I'd referred to this car as if it were a 77-78 in my original post back there... Don't know what I was thinking.

 

The 76 should have a fuel cutoff switch in the AFM.

 

Which means the 75/6 and 77/8 ECUs ARE different.

 

One of them has two more pins, to facilitate the change in the oil/AFM fuel cut. I don't recall which at the moment.

[Jeff G 78]

Just realized that I'd referred to this car as if it were a 77-78 in my original post back there... Don't know what I was thinking.

 

The 76 should have a fuel cutoff switch in the AFM.

 

Which means the 75/6 and 77/8 ECUs ARE different.

 

One of them has two more pins, to facilitate the change in the oil/AFM fuel cut. I don't recall which at the moment.

The OP said it's a '76, but it has a '77/78 hood and '77/78 bumpers. I don't think I've ever seen anybody swap big bumpers from round to square, so I think he has an early '77 built in '76. As for the ECUs, I *think* it's only the '78 that has the fuel pump interlock in the oil pressure switch, so the '77 ECU might be the same as a '76. It's been over 20 years since I had a '77, so my memory is a bit fuzzy.

[cesar280z]

1. Drop the fuel tank and douche it out
   
2. replace ALL rubber in the fuel system
   
3. install a 60 psi guage betweeen the filter & the rail,this will confirm/debunk a whole shit pot full of issues
   
4. power to the FP is supplied ONLY when the motor is cranking or running.No oil pressure inter-connect.
   
5. Injectors can be cleaned & flowed for $17.00 a piece.Don't forget the CSI.
   
6. Deoxit on ALL connectors under the hood AND the computer
   
7. remove,clean & verify function of the thermotime switch and the coolant temp switch
   

The FSM in MANDATORY for chasing these issues.

whe do they clean the injector?

[Z-train]

Call around & find a reputable shop that cleans thems