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280z cranks, but will not stay running.


77Datz

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New to this site, I sure hope you guys can help.

I just got a 77 Datsun 280z for my first project car. The car sat for two years with no gas in the tank, and I've been trying to get it started for about a week now. I get plenty of spark, I checked the coil and plugs and they're all fine. I installed a new fuel filter, replaced blown fuses, charged up the battery and put fresh gas in the tank. It turns over fine, starts up for a few seconds then dies. I pulled all the injectors and cleaned them as best I could, new fuel line in the engine compartment as well.

If you push the flap in on the AFM all the injectors spray, so I think it might be the fuel pump, I'll be taking a trip to Harbor Freight to get a fuel pressure testor, but when it starts up it sounds like its starving for fuel. Also, the black fusible link is corroded and the wire is exposed, I know this needs to be replaced, but for the time being I took the link off and jumped the connections with a bit of wire and an alligator clips and it didn't change anything. So as far as I know, its getting spark, and I can only assume at LEAST a little bit of fuel. It'll start with starting fluid but again quickly sputter out.

I also pulled the AFM off the intake and checked it via a ohmmeter and the FSM, which I am lucky enough to have a hardcopy of (guy i bought if from gave me the book with the car) and the AFM checked out fine.

So, I'm thinking it might be the fuel pump, that nasty corroded fusible link, or some other electrical or fuel problem. Thoughts?

Thank you in advance for all your help:)

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You can disconnect the fuel pump, have a friend crank the engine and see what the voltage is at the wires going to the pump. You can also actuate the AFM to see if the contacts are closing (Pins 39 and 36) to keep fuel pump relay energized.

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replaced blown fuses,

It turns over fine, starts up for a few seconds then dies.

If you push the flap in on the AFM all the injectors spray, so I think it might be the fuel pump,

the black fusible link is corroded and the wire is exposed, I know this needs to be replaced, but for the time being I took the link off and jumped the connections with a bit of wire and an alligator clips and it didn't change anything.

It'll start with starting fluid but again quickly sputter out.

he AFM checked out fine.

So, I'm thinking it might be the fuel pump, that nasty corroded fusible link, or some other electrical or fuel problem. Thoughts?)

I would wonder why there were blown fuses in the first place. And recheck the ones you replaced. Maybe they blew again.

Starts for a few seconds then dies is typical of a dirty fuel pump contact switch.

There's no reason for the injectors to click when you push the AFM flap. That's not right and just weird.

I would put the fusible link back, even if it's corroded. If you burn the wiring you'll be even farther up the creek, in a leaky boat.

I would test the fuel pump contact switch like SteveJ said first, moving the AFM flap, while the key is On. That will show you if the fuel pump contact switch is allowing the pump to get power when you let go of the key while Start'ing.

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Well the injectors click and spray when the key is in the "ON" position. From what I've read thats normal. Also, coming out of the harness going to the driver side of the car, (the harness near the battery) coming out of it are two red wires, one goes to the positive, and one goes to the negative terminal of the battery, I can't for the life of me figure out why both of these wires are red. One has a fusible link, the other just has a male/female connection going to the negative terminal of the battery. One red wire is longer than the other, I'll have to take a pic and throw it up here in the morning so you can see what I'm talking about.

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The injectors should only click and spray when engine is turning and the coil is sparking. Or only when the coil is sparking and engine not turning for those who know how to cause that. The ECU fires all of them at every three sparks. Either way, with no spark to send a pulse to the ECU, there shouldn't be any injector firing. Maybe you're leaving out the part about the engine turning over? Or hearing a relay, not the injectors.

The red ground wires have screwed up many people. It's a Datsun thing.

Since the engine will run under the right conditions you probably don't want to mess with too many odd things. Good fuel pressure to the rail should keep the engine running. You probably are losing power to the pump or have a bad one or have a clog somewhere. I would focus on fuel supply.

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That's what I was thinking, like I said I'll be getting a fuel pressure testor tomorrow, how would I go about checking that the fuel pump is getting power when I try to start it? I've already taken the starter wire off and listened for the pump when i turn to the start position. I can hear the fuel pump run, I've taken the hose off the fuel filter, and theres a steady flow of fuel there, but I just don't think its getting enough pressure behind it. I'm just not sure, I've been stumped for a week and its probably just something stupid and simple (i hope, at least)

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  • 4 months later...

I have tested all injectors the a.f.m,. the fuel pump, the connectors to the c.s.i., water temp sensor, and the other water temp sensor thing with the single plug.

The a.f.m. is making the injectors click when you open it. the fuel pump is pumping 38 psi. the c.s.i. is getting no power turning the car over, or with the ignition on run? i have replaced the ignition switch and the water temp sensors are both getting power. would the cold start injector keep it from running. and i am getting great spark i installed an e12-80

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The a.f.m. is making the injectors click when you open it. ...

....the water temp sensors are both getting power.

These two things seem odd. The first is just wrong, the AFM vane opening should not make the injectors click. If the injectors are clicking when you open the AFM vane something weird is going on with your wiring. I don't know where 77Datz ever read that that was normal. It's not.

And the second thing is odd since there is no FSM test for power at the coolant temperature sensor, although it may get power from the ECU when the key is On. I don't know why anyone would do that test, the test is to measure resistance from the ECU connector. What was the voltage reading and how did you measure it?

So, the AFM causing the injectors to click is odd. But, the main reason for the engine to start the die immediately, is because the fuel pump contact switch is not being made in the AFM. You can test that also with an ohm-meter by measuring resistance at those two pins at the ECU connector and moving the AFM vane.

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Edited by Zed Head
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i used a test light so +12 volts, and i pulled the plastic side cover off the a.f.m. for the test. I am running a w48 intake off of a maxima with the 280z wiring harness i have already swapped the throttle body because of the electronically controlled idle control on the maxima it will run for a minute very occaisionally but when it does it just dies my initial thought is vacuum leak but the starting fluid test did othing so all vaccum ports are capped and there are no leaks.

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