78 280z died and won't start back up

[Pochie45566]

Hi, 

I didn't drive my z for three months, so I put a car cover and tarp on it and let her set for a bit. I came back to a very moldy Z car. Lesson learned, she's going in the garage next time ?. I cleaned up the mold and started her up, started like I never left as was running great. I let her run for about 10 minutes, and then the idle started to get lumpy and it was surging. I went on a drive around the block and it had very little power and consistently wanted to die. I parked it and tried to start it back up and now she won't start at all. 

 

I have gone through the EFI bible a good bit, tested all the injector circuits, tested the water temp sensor, cold start system. I checked for spark by putting a screwdriver in the boot and holding it near the block. I have 36 PSI of fuel pressure. I checked some of my relays, I think they are working. I wasn't sure which one was responsible for what but most of them seemed to be clicking. When I hold a screwdriver on the injector I do not hear it click, so I presume they aren't firing? I also pulled the plugs and they did look like they had a good bit of carbon on them, but my z has always run a bit rich. 

 

I'm not sure what to look for next. Any ideas? 

[Zed Head]

44 minutes ago, Pochie45566 said:

I didn't drive my z for three months, so I put a car cover and tarp on it and let her set for a bit. I came back to a very moldy Z car.

?then the idle started to get lumpy and it was surging. I went on a drive around the block and it had very little power and consistently wanted to die. I parked it and tried to start it back up and now she won't start at all. 

I have gone through the EFI bible a good bit, 

I'm not sure what to look for next. Any ideas? 

Could be water in the gas, maybe.  Condensation.  Moist air can get in through the cap, if it doesn't seal well.

Or the coolant temperature sensor isn't making good contact.  You need to get resistance measurements on the coolant temperature sensor.  Can't tell if you measured that or not.

[Pochie45566]

2 minutes ago, Zed Head said:

Could be water in the gas, maybe.  Condensation.  Moist air can get in through the cap, if it doesn't seal well.

Or the coolant temperature sensor isn't making good contact.  You need to get resistance measurements on the coolant temperature sensor.  Can't tell if you measured that or not.

I filled up the tank before I left it and I put a fuel stabilizer in it. How could I go about testing? 

 

I pulled the efi harness and tested the coolant temp sensor according to the manual and it checked out. I was thinking water in the lines too. How do I go about getting it out lol

[w3wilkes]

After I sealed my tank and replaced all the rubber fuel lines I've run only ethanol free gas, the ethanol (alcohol) will attract water and it may be worse in high humidity areas. 

[Zed Head]

22 minutes ago, Pochie45566 said:

according to the manual and it checked out. I was thinking water in the lines too. How do I go about getting it out lol

What resistance value did you get?  Ohms.  "Checked out" might just mean you measured continuity.  You need the ohms.

If there's water in the fuel the filter will collect much of it.  You could remove the filter and drain it in to a glass container and see if water separates out.

You could also see if it starts using starter fluid.  If it does that will be a clue but you'll still need to do some detective work.

[Pochie45566]

1 minute ago, w3wilkes said:

After I sealed my tank and replaced all the rubber fuel lines I've run only ethanol free gas, the ethanol (alcohol) will attract water and it may be worse in high humidity areas. 

It is pretty high humidity here in Oregon. 

Just now, Zed Head said:

What resistance value did you get?  Ohms.  "Checked out" might just mean you measured continuity.  You need the ohms.

If there's water in the fuel the filter will collect much of it.  You could remove the filter and drain it in to a glass container and see if water separates out.

You could also see if it starts using starter fluid.  If it does that will be a clue but you'll still need to do some detective work.

I got like 1900 Ohms which was pretty close to what the EFI manual wanted. I tried unplugging it and starting the car but that didn't work either. 

I did try squirting some carb cleaner into the intake manifold through the line connecting the cold start air valve into the manifold but it didn't start doing that either. 

[Zed Head]

8 minutes ago, Pochie45566 said:

I did try squirting some carb cleaner into the intake manifold through the line connecting the cold start air valve into the manifold but it didn't start doing that either. 

Are you sure that you have good spark?  The ignition module is in the cabin with all of the humidity.

Not sure what you mean by the "line" connecting the cold start valve.  The CSV plugs/bolts in to a hole in the top of the manifold.  Try squirting the fluid in through one of the vacuum hose holes.

[Pochie45566]

Just now, Zed Head said:

Are you sure that you have good spark?  The ignition module is in the cabin with all of the humidity.

Not sure what you mean by the "line" connecting the cold start valve.  The CSV plugs/bolts in to a hole in the top of the manifold.  Try squirting the fluid in through one of the vacuum hose holes.

I tested the spark by pulling spark plug boots and holding screwdriver 1/8th inch from the block and it had spark there. Im not sure if that means a whole lot, but spark is present. that ignition module is under passenger size dash correct? I will try squirting fluid in through vac hose tomorrow. Im confused on why the car was running fine when it was cold.

[w3wilkes]

3 minutes ago, Pochie45566 said:

I'm confused on why the car was running fine when it was cold.

I was thinking that water is heavier than gas so it would settle to the bottom of the tank. The fuel in the lines, filter(s) and pump would be fine. When it started and ran fine cold it was burning the good fuel in the lines, filter(s) and pump. If there was water that had settled to the bottom of the tank it would be next in line after the fuel in the lines, filter(s) and pump was spent... Not sure if water would cause the filter element to swell and restrict fuel flow. Water is great for cooling, but not your friend in the fuel system.

[Pochie45566]

1 minute ago, w3wilkes said:

I was thinking that water is heavier than gas so it would settle to the bottom of the tank. The fuel in the lines, filter(s) and pump would be fine. When it started and ran fine cold it was burning the good fuel in the lines, filter(s) and pump. If there was water that had settled to the bottom of the tank it would be next in line after the fuel in the lines, filter(s) and pump was spent... Not sure if water would cause the filter element to swell and restrict fuel flow. Water is great for cooling, but not your friend in the fuel system.

Smart! There is a drain plug on bottom of gas tank I think? I will maybe drain 1/2 of the tank and fill back up. How would I get the existing gas out of the fuel lines? Maybe pull the line going to the injectors then crank it over?

[w3wilkes]

Since my car is carbed, not FI I don't know for sure. Seems like you should be able to disconnect the fuel line just before the injectors and just turn the key to start, I think this will run the pump. And oh, you want the line going into something to catch the fuel.

[EuroDat]

6 hours ago, Pochie45566 said:

Smart! There is a drain plug on bottom of gas tank I think? I will maybe drain 1/2 of the tank and fill back up. How would I get the existing gas out of the fuel lines? Maybe pull the line going to the injectors then crank it over?

Water could be your problem. I had a similar issue, but it happened after I tanked the car. If you suspect water is in the fuel system, I would take a sample close to the engine.

It is easy enough by removing the return line going from the FPR to the tank. That is the line that goes from the engine next to the fuel filter. Its very low pressure so no worries about fuel spraying everywhere when you disconnect it.

Find a 2 litre container or an extra length of hose to a bigger container. Anything bigger than 2 litre is hard to get into place to catch the fuel. Run the pump and catch 1 - 2 lires of fuel, let is settle and check for water. See photo for what came out of mine.

TIP: To run the pump without cranking the engine endlessly. Not good for your starter or battery. Unplug the wire with the spade shaped terminal on the back of the starter. Follow the big starter lead to the starter. It is located above the two big M8 terminals. See second photo.

Now if you hold the ignition key in start position the engine will not crank, but the pump will run.

Edited December 15, 2019 by EuroDat