Datsun Roadster Forum-311s.org

Out of curiosity, is the fuel pump priming when you try to start the car and it does not work?

My system has never held pressure when turned off. The injectors were replaced.
I always wait until I hear the fuel pump shut off before starting hot or cold.
Stock regulator hold at 42psi when running.

RCMike wrote: Tue Sep 01, 2020 11:38 pm Out of curiosity, is the fuel pump priming when you try to start the car and it does not work?

My fuel pump does prime when starting.

bobd wrote: Wed Sep 02, 2020 4:51 am My system has never held pressure when turned off. The injectors were replaced.
I always wait until I hear the fuel pump shut off before starting hot or cold.
Stock regulator hold at 42psi when running.

Is that 42psi running at idle with vacuume attached or not? What is full throttle then? I understood that the proper set up was to set the psi with vacuume hose off. What is the proper way to set the psi?

Mike,

Can you confirm that the "start" wire (T-eed from the EFI harness to the starter solenoid wire) is connected to the ECU (it should be orange). Basically, this is the wire that tells the ECU that you are "starting" the car. Many times, people do not connect this properly, and the car takes awhile to start mimicking the problem that you describe (thinking that the injectors are not working).

Michael

Bigtaku wrote: Wed Sep 02, 2020 7:19 am

bobd wrote: Wed Sep 02, 2020 4:51 am My system has never held pressure when turned off. The injectors were replaced.
I always wait until I hear the fuel pump shut off before starting hot or cold.
Stock regulator hold at 42psi when running.

Is that 42psi running at idle with vacuume attached or not? What is full throttle then? I understood that the proper set up was to set the psi with vacuume hose off. What is the proper way to set the psi?

My 42 psi is at idle with everything hooked up.
The gauge is under the hood, so I can't see what it is at full throttle

No change in my starting issue when the car is warmed up, only starts cold. So far I have changed the Fuel Injectors, cleaned and inspected the MAF, Spark Plugs, O2 Sensor, Throttle Body, and Fuel Rail. I have installed a ISR Adjustable Fuel Pressure Regulator. Had a wiring Mechanic inspect my wiring as Michael Spreadbury suggested. I am out of ideas. Just poured a glass of wine, it's 5:00 somewhere...

Possible temperature sensor.

https://www.plmsdevelopments.com/index. ... ps#13.misc

This site offers some good info regarding sr20 engines. FWIW Pat

bobd wrote: Sun Sep 20, 2020 3:40 am Possible temperature sensor.

I'm a total novice, but given what you're describing where it runs when cold but won't restart when hot does suggest that some sensor is telling the ECU that something is out of parameter. Can you hear the injectors firing when you're trying to start it hot? Since it's temperature related I'd start there. Does the car run fine until you shut it off hot the first time? Got to have fuel pressure, spark and compression right? So either spark is not occurring when it's supposed to or its not getting fuel/pressure. On the Microsquirt ECU the ignition system tells the ECU "the engine is moving at xyz rpm"; if it's not getting the signal it won't fire the injectors. Would assume a stock ECU wants that same info. Does it use a crank sensor, cam sensor or both for signal? Could one of those be failing due to heat? Could the temp sensor be failing when hot?

Again, total novice here, but I've been reading a lot about what EFI needs in order to fire an engine at idle with pulse widths etc, and if the ECU is not getting the data it needs it may not fire the injectors for safety reasons.

I'd check all my sensors for proper signal under different temp conditions. Again, I'm guessing here. But it may be that Nissan designed the system to ignore certain inputs while running to keep the engine running in "limp" mode, to throw a check engine code (which I assume you have no way to see or know?), then not allow the engine to restart until it's back into parameter, in this case the engine being cold.

I finally figured the issue out yesterday. It was the coolant temp sensor. I had swapped out the 2 prong OEM temp with one that would talk to my SpeedHut gauges. It didn't come up on Nissan Connect as a fault but after swapping it back it starts when warm again! I should have seen this but I forgot about swapping out the sensor. Now it is running a little off and sounds different than before changing out the sensor. I didn't do any investigating on this new problem as of yet but yippie! I still need to place the aftermaket sensor somewhere on the coolant line to talk to my gauge but that shouldn't be a big deal.

Hope that PM did you some good then.

Eye

Mothra is now a very smooth running roadster! I changed out one injector and that solved the issue of running rough. I also have my electric door and trunk locks all working and the really big news is the trunk lid monitor screen is working so I guess I better get my act together and finish "The Making of Mothra" movie I started three years ago. I also had an issue with my gas cap locking in place and I don't have the key. Lucky for me Sid Rapper gave me the instructions to get if off. (remove the trunk gas pipe to the tank and unscrew the lock from the inside of the pipe. Worked like a charm) I also installed a separate coolant temp sensor for my gauge and have the OEM sensor in it's standard plug. I wish I could go drive but we are getting a years worth of rain in one week. I did make a short drive in my neighborhood and that will have to do for now.

I still need to get a ride in that beast...

Bigtaku wrote: Mon Sep 28, 2020 4:09 pm I also installed a separate coolant temp sensor for my gauge and have the OEM sensor in it's standard plug.

Can you tell me more about this? Did you install the sensor in a different place? And have you driven it enough to get an idea of what the 'normal operating temperature" seems to be?