Questions and Answers

Nissan Sunny Won't Start Q. Hi, I'm running a 1992 Nissan Sunny GTI 20. Last night I had a problem with my fuel pump, probably, because my car was refused to start. I replace the gas filter with a new but the problem was the same. Then someone tow my car in my garage and I disassemble the fuel pump from the tank, trying to see what happens.

I powered the pump direct from the battery and was okay. No funny sound, no disability to run, everything was looked okay. I check also the voltage on the cables and was 12V when I switch the key, after three seconds was reduced to 9.3V and remaining there when the engine was running.

Eventually I put everything back, I tried and the engine starts and running well. I thought that the problem solved and I went to sleep. Next morning the car didn't start. You now something about that. I think that the problem is electrical, maybe a relay or a sorted cable.

I'm posted in a place were the local Nissan dealer has no idea about my car because never imported here. So I need to do something by myself. Fortunately I'm dealing with electrical issues because of my job and I think that if I found a proper electrical diagram for my engine I'll solve the problem.

I'm really sure that my fuel pump is working properly but I'm thinking about the voltage measurements. Could you help me please.

My car details are:
1992 Nissan Sunny GTI 20
SR20DE engine
Fuel injection

Thanks in advance,
Christos

A. The voltage drop at the fuel pump from 12 volts to 9.3 volts is normal. Nissan varies the speed of the fuel pump with voltage drops. When demand is low, the PCM slows fuel pump down. When demand goes up the PCM speeds the fuel pump up. This is to reduce noise and makes it slightly more fuel efficient.

The first thing to do is make sure it is a fuel problem. Spray some carburetor cleaner into the intake while someone cranks the engine. If it starts and runs, we've confirmed the no-fuel condition. If it doesn't run, then we're looking at an ignition problem.

They next thing to do is check the PCM for codes. If it doesn't start there's an excellent chance there is a DTC in the PCM that will get us going in the right direction.

READING DIAGNOSTIC CODES:

• The Electronic Control Unit (ECU) monitors several engine sensors and actuators. If a problem occurs the information is stored in the ECU's memory for retrieval.
• The codes are displayed by the red diode on the ECU. The codes are interpreted by the number of times and duration the diode flashes.
• The red diode (•)will flash for 0.6 of a second with 0.6 of a second delay between flashes "X" number of times, this will represent units of ten.
• Then there will be a delay 0.9 of a second and the red diode will flash for 0.3 of a second with 0.3 of a second delay between flashes "X" number of times, this will represent units of one.
• There will be a delay of 2.1 seconds between codes.
• For example, if the red diode flashes once and then flashes twice rapidly this should be interpreted as code 12. The codes are displayed in numerical order starting with the lowest and ending with the highest.

Selecting Modes

EXTRACTING DIAGNOSTIC CODES:

1. Access the ECU from below the panel under the carpet on the passenger side floor board and position it for observing the diode.
2. Turn the ignition switch on (do not start the engine).
3. Confirm that the "CHECK ENGINE" lamp in the instrument panel illuminates. If not, check the bulb and replace if faulty.
4. Turn the diagnostic mode selector on the ECU fully clockwise for at least two seconds then turn the selector fully counterclockwise. The ECCS system is now in mode 2.
5. Observe the diode and note the code(s) displayed. Note: Code 55 indicates all systems are okay.

ERASING DIAGNOSTIC CODES:

1. Turn the ignition key on.
2. Turn the diagnostic mode selector on the ECU fully clockwise and wait more than two seconds then turn the selector fully counterclockwise. The ECCS system is now in mode 2.
3. Turn the diagnostic mode selector on the ECU fully clockwise and wait more than two seconds then turn the selector fully counterclockwise. The ECCS system is now in mode 1. ECU memory is now erased.

Once you have the code(s) you can see what they are here: Diagnostic Trouble Codes