78 280z flooding when starting

[Dogariffic]

7 hours ago, Zed Head said:

I might go directly to the coolant temperature sensor circuit.  The best way to test it is at the ECU connector, since what the ECU sees is what matters.  Compare the resistance measured to the value in the chart.  If it's too high you'll get too much fuel.

This book has tests for all models up to 1980 - 

 

Appreciate the book . It will be helpful. I plan to test a bunch this weekend.

[Dogariffic]

1 hour ago, siteunseen said:

Try unplugging the cold start valve. I know it's new but it could be your problem and it's hot enough now that it shouldn't even be active.

It will be a good test.

[Dogariffic]

On 6/18/2017 at 9:52 AM, EuroDat said:

No need to go to another site, you can also download the FSM for this site too.

http://www.classiczcars.com/files/category/13-280z/

Wow. Stand back and throw money at it. I tried that once on an Escort. In the end my pockets were not deep enough and I had to resort to diagnosing the problem and then fix it. I say that jokingly now, but it cost me a lot of money for an eventual $30 fix. I can imagine you have spent a lot on the parts and the problem is disappointingly not solved.

Most people have trouble with running lean. What a lot of people call ecu drift.

You need to start diagnosing stuff and cross it of the list. The things you can check, for starters, are:

1. Is the system holding fuel pressure. You changed the injectors and the csv, but you can't be sure one or two (new or refurbished?) Injectors are not leaking or sticking. I wrote a test procedure on a thread here somewhere. Ill try to find it and post it here.

2. Check the temperature sensor resistance at the pin 13 & 5 in the ecu connector. Check that with the FSM and the 1980 efi supplement (bible) on this site.

3. Check the ignition for good spark while cranking the engine. You can do tests on the ingnition, but a faulty tiu is a process of elimination.

When you do tests, write down what you do and the test results. People like to see figures, it also helps with feedback.

 

All good suggestions thanks

[Dogariffic]

On 6/17/2017 at 5:28 PM, rcb280z said:

Was this before starting it? Im assuming it is. Strange. Hope you don't have much fuel getting past the rings.

They were wet after trying to start... fuel.

[Dogariffic]

On 6/19/2017 at 8:35 AM, Chickenman said:

A couple of things that OP may want to look at. 40 year old EFI systems are very sensitive to corrosion or electrical resistance in the wiring harness. Particularly the ECU CTS. Buy some Deoxit spray or Weicon Electrical Contact spray.  Weicon is a German company and makes a great line of Industrial products.

Carefully inspect all terminals and connections for corrosion. Spray the terminals with the Electrical Contact cleaner, wait 10 minutes and inspect. Weicon usually leaves the terminals looking like brand new. However, heavy corrosions may need a second application. Go through every single electrical connection for every single EFI component. Injectors, all sensors, AFM connections, TPS ( you can also spray the Contact cleaner directly on the TPS contacts. ) and the main ECU plug. It is amazing the improvement this can make. With really stubborn corrosion you may have to get in and pick away with Jewellers screwdrivers or a Dental pick. 

After a proper cleaning you can take some Dielectric grease and coat the terminals with it to prevent moisture from getting back in.

One other thing . It is really easy to get the terminals for the Thermal Time Switch and the ECU CTS mixed up. They are 4 bullet connectors. One pair is Black and the other pair is Dark Green. But after 40 years the Dark green turns Black!!. Peel back some of the insulation tape to reveal the true colors of these four wires. Missing them up will cause the car to run Pig Rich. 

The following picture should help identify the proper way to connect these :

 

Thanks for the photo. I think I am good here. Earlier today I found one of the 4 wires was loose and I reattached, but that did not change anything.

[Dogariffic]

8 hours ago, siteunseen said:

Not sure if I've shown you this?  If so, sorry but it has really helped me over the years with my '77.  Thanks again to @240260280

http://atlanticz.ca/zclub/techtips/     Click on "EFI and FUEL"

Another thought that has probably been said before, are you absolutely sure the vacuum hose to the Fuel Pressure Regulator is good and pulling vacuum?  40 year old rubber cracks. 

This will be helpful thanks and I replaced all of the vacuum hoses so that is good.

[Dogariffic]

2 hours ago, siteunseen said:

Try unplugging the cold start valve. I know it's new but it could be your problem and it's hot enough now that it shouldn't even be active.

I considered that and will give it a shot. I would rather find out why the valve is staying open....if that is the case..... but if unplugging it solves the problem....

[Dogariffic]

1 hour ago, JSM said:

Do this and take a pair of small vise grips and clamp the hose going to it. I've seen them fail without being turned on electrically. 

Dumb question, but If I remove the cold start valve, how do others fill the hole that remains to keep the vacuum?

[Dogariffic]

1 hour ago, siteunseen said:

Good call JSM! I'm not remembering how they work exactly, maybe some type ball valve or magnetic but they are a lot more prone to fail than a fuel injector.

Wrap some tape or slide two pieces of hose over your clamping tool, vise-grips to keep from cutting into the CSV hose.

Thanks 

[Zed Head]

59 minutes ago, Dogariffic said:

Dumb question, but If I remove the cold start valve, how do others fill the hole that remains to keep the vacuum?

You can build a simple plate with two holes in it to seal it.  

A test might be to remove it and leave it connected to the fuel hose, but disconnected from the electrical connection.  Stick the nozzle in to a small jar or cup.  Then remove the starter solenoid wire and turn the key to Start to pressurize the fuel system.  If it's leaking you'll see it.  You won't have to worry about intake vacuum with the starter disconnected, you'll only be testing the CSV when its pressurized.

[Dogariffic]

1 hour ago, Zed Head said:

You can build a simple plate with two holes in it to seal it.  

A test might be to remove it and leave it connected to the fuel hose, but disconnected from the electrical connection.  Stick the nozzle in to a small jar or cup.  Then remove the starter solenoid wire and turn the key to Start to pressurize the fuel system.  If it's leaking you'll see it.  You won't have to worry about intake vacuum with the starter disconnected, you'll only be testing the CSV when its pressurized.

I had seen that test written about before. Good suggestion to test the issue.

[Dogariffic]

I am planning to execute several tests this weekend to work and nail down the flooding issue but wanted to pass along a bit more information.  Yesterday I noticed a loose wire on the Water Temp Sensor.  I loosely connected it and started the car then pulled the wire and disconnected it. The car tried to die so I reconnected it tightly and took the car out for a spin....

I thought I was on to something but after about 20 minutes of driving on the freeway at 70 she suddenly died. No noise just dies. I popped the clutch a couple of times but nothing.

After stopping she would turn over but no spark.

After about 45 minutes she roughly kicked over but was trying to flood again.  I was able to work the fuel out of her and she fired up running smoothly and I went back to the house.

Looking forward to the results of the tests and figuring the issue out.  She runs well without this issue!