Help if you can.

[Grungnak]

Hello everyone, I bought a 1977 280z last weekend and the owner before me said the car had a fuel problem. Since I've started working on it I've only noticed that the fuel pump is always on when the key is in the "ON" position. The car has air, fuel, spark, and compression, but she doesn't want to turn over and keep running. The longest I've had the car running is about 5-10 mins then I shut her down and she wont start back up. Has there been any other problems like this before with anyone else's car?

[SteveJ]

Did you verify the plug order? (1-5-3-6-2-4 counterclockwise)

Did you verify the fuel with a pressure gauge? If yes, what was the pressure? If not, how do you know you have fuel?

What are your compression numbers? Dry? Wet?

Have you consulted the Fuel Injection Bible? (I think Blue's tech tips has a copy and possibly XenonS30 as well.)

What do your plugs look like? What type plugs are you using?

I know...all questions & no answers. However, you'll get better suggestions by answering those questions.

[beandip]

check to see if you have fuel flowing. You said it has gas but is it being pumped to the engine. There is a difference. Also there should be pressure to feed the injectors. Check the fuel filters and it just would be good to just replace them then you will know there good. Since you have spark as you said , I would start with filters . The next thing would be to attach a timing light and see what it shows you when you spin the engine. this is all just basic stuff. Let us know what you find .

Gary

[IdahoKidd]

If the car will start and run for 5-10 minutes, the firing order and timing okay. Timing may not be perfect, but not to be fooled with yet, it creates to many variables. The fuel pump should come on when you turn the key on and pump for a few seconds and then shut off. It shouldn't come back on until the engine starts. Check to see if the wiring has been altered to the pump. There may be a rogue wire from the fuse panel back to the pump for example. I am guessing/certain that the symptoms and the information from the PO that there is a fuel delivery problem. It could be just the fuel filter. You may need to find a fuel pressure gauge to be certain. On the starter solenoid, there is a single wire wire with a spade just above the main terminal. This is the starter excite wire. Take it off temporarily. Pull the hose off of the filter on the engine side and put a short piece of hose onto it and into a container and turn the key on. You should have a good solid flow of fuel. If not, do the same thing on the tank side of the filter (actually using the fuel line, not from the filter) If you don't have fuel, you have a pump that isn't working or a clog in the intake (which is VERY likely). If you do have fuel on the engine side of the filter, pull the return line next to the filter (smaller line coming back from the injectors) and see if there is fuel coming back completing the circuit. (remember to hook the spade connector back to the starter at some point or the starter doesn't engage).

The fact that it starts and runs means the system is working. I am thinking it becomes a fuel starvation issue. I changed out 2 or three or more fuel filters before biting the bullet and took down the tank and shoveled out the crap in it. I've had to do that on all three of my running Z's as they all had sat for some time before I got them (5-16 years)

Do let us know how/if you get it going so the next guy that does a search with similar issues can find your particular solution.

Leonard

[Z-Luke]

A lot of fuel problems are electrical. I'm guess there's an electric fuel pump back there - check to make sure the wires have good continuity and there is a good connection.

My '93 civic was flaking out and wouldn't run or start hot, turned out that the fuel pump wires had un-soldered themselves somehow after 250,000km.

[Nigel1943]

As IdahoKid says the chances are that your tank is full of crap. That's probably why your pump is running all the time, trying to pump a reduced amount of fuel.

[S30Driver]

On the 77z, the fuel pump should not be on when the ignition switch is in the run position - unless the engine is running. There is a set of contacts in the afm that activate the fuel pump circuit when the flap rotates 8 degrees, this is part of the safety circuit to stop fuel flow in a crash.

It does sound like someone has modified the fuel pump wiring or bypassed the contacts.

I agree with SteveJ, you need to verify the fuel pressure with a gauge.

[Grungnak]

I was looking around on here and i found a problem similar to the one i was having i found if i unplug the cold start injector it would start, I also replaced the water temp sensor and it seems to be running a lot better. But it still pumps fuel when the key is in the on position before starting the car, and I'm sure it there's a wire somewhere that's been messed up because a lot of the wires seem to be spliced and/or rigged around to always get power. With the few things I've done so far I've managed to make her moveable for the moment, enough to move around in the driveway anyway. It'll probably take me a few days to sort all the wiring out and have her in tip-top shape.