Fuel Injection Woes

[pbatura]

Greetings.

I have a 1976 280z that I've been bring back from the dead.

Last real issue is the engine, which cranks, gets spark but won't start. I've tested the system according to the shop manual and the FI bible, and everything is pretty much to spec, including the fuel pump working. However, when I reconnect the harness and crank it, it doesn't start. If use starter fluid it will fire.

My thought is the ECM is history. Is there a way to test the unit? If it is shot, what abnout repair?

Any guidance is appreciated.

[webdawg1]

Couple of questions...

How long has it been sitting out in that corn field it came out of?? (I.E. - 2-3 years, 5-10 ??)

1. Old gas or new gas in the fuel tank....

2. Have you checked the condition of the fuel tank and fuel lines.... (I.E. - Fuel tank for RUST and fuel lines for blockage)

3. Have you checked all your connections for anything ECU/FI related.... (I.E. - Connections that have green stuff on them)

4. Fusible links for possible blown links...

That's just for starters...make yourself up a list and start checking off everything as you go thru it...at some point you should have a pretty good idea as to why it's not running...

webdawg1

[280z1975]

Had a somewhat similar issue ... you will need to check the wires going from the coil to the distributor, then also the coil to the ignition module ... check conductivity first, but then also borrow a scope (from an auto parts store) or go to a mechanic and check the lines. Mine were getting conductivity, but were internally messed up and corroded and it wouldn't send the correct signal to the parts needed ... a lot of pain in the rear stuff to diagnose ... and only do after looking at the much simpler points of trouble ... I wish you the best of luck ...

[DatsunZsRule]

E.C.U. is what you meant to say

Yes, you can perform tests at the harness if you have a factory service manual to follow all the step by step procedures and a good multimeter. One VERY important thing before you unhook the harness at the E.C.U. to do your tests is to make sure the battery is disconnected first. Failure to do so can result in damage to the E.C.U. Thought I'd point that fact out incase your current E.C.U. is Good and not the cause of the problem. Your FSM. will cover that too anyways

Besides checking your fuel pump, What other things have you checked so far? The more info. you can provide to us, the better we can try to help you out

[pbatura]

Thanks for the great info. I'll provide a consolidated reply:

• Car had been sitting in a garage for about 5 years with what started as 1/4 tank of gas.
  
• Completely cleaned fuel system from tank through FI rails.
  
• Dis-assembled pump, replaced O-rings and re-assembled.
  
• Connection contacts are pretty clean, with no corrosion except on thermostat housing connectors.
  
• wiring is somewhat brittle
  
• Conducted Fuel Injection Troubleshooting Steps 1 through 6 complete.
  
• verified spark on all six cylinders
  
• Fired up with starter fluid
  
• no illumination on test light with #5 and #6 injectors (didn't do all)
  

Greg, I'll track back on the ignition wiring, especially given the brittleness of wiring.

By the way, would it be a good idea to consider replacing the under-hood wiring?

Thanks for the help.

Peter

[240Z-Fan]

I don't know how a 76 compares to a 78 but, I had a 78 that wouldn't start.

To make a long story short, the power to the FI system was inadvertently left disconnected when replacing the battery cables.

This was some 12+ years ago but, I believe a pair of white wires goes from something near the relays in front of the battery to a 2nd lead at the positive battery terminal.

I figured it out when I was tracing wires and was puzzled by the paired white wires going "somewhere" below the battery.

Even if it is "connected", check to see if there is any corrosion at the battery terminal.

Al

[280z1975]

snip ...

Greg, I'll track back on the ignition wiring, especially given the brittleness of wiring.

By the way, would it be a good idea to consider replacing the under-hood wiring?

... snip

YES ... to answer simply ... but I will say that finding a wiring harness that is in good shape can be a problem sometimes. You can try Awesome Z in Houston, he is the best Z mechanic in town. (I use to live in Katy :squareeye ) They will be able to sort you out I bet ...

If you need a good general mechanic (they aren't going to be able to sort this out for you) go to P & B Auto on Hwy 6 and Clay (they are just south of there next to the hotel). VERY reliable and honest and always reasonable with their cost. I never left there with the "I just got ripped off" feeling for the work they did. Went to them for over 8 years!

Call up Awesome Z, they may have an engine bay harness that is in decent shape for you. If not start calling around. I know there is a NOS on Ebay for 409 right now (the seller paid 256 btw, cause I bid on it ... there is also one for a 1978 but I am planning on bidding on it so I can try and reproduce the 280Z wiring harness, then move onto the 240's)

[HowlerMonkey]

Microswitch in air flow meter.

[pbatura]

Thanks for the great info yet again.

I recognize the wire coming off the battery and will check it, as well as the switch in the AFM.

This is a great community of folks that are willing to help a guy who wanted to give his a son a graduation present (my first Z-car - didn't know).

It is said that adversity provides the best education. Boy, do I feel educated...