guy in a jetta

I have a 1995 accord LX that decided to ignore me for a month.

The car was (is?) showing a CEL staying ON while the key was turned to ON (II). You could hear the first relay click but no fuel pump and no second relay click. There were zero volts at the fuel pump while it was supposed to be priming. As such the car did not start. Voltage checks on the relay while installed in the car were...questionable. I could not draw any meaningful conclusions from checking them.

I reflowed the main relay solder joints. Then replaced the main relay outright. The shop had replaced the distributor for the previous owner. The engine bay grounds all look great. The fuel pump ground (in the trunk) looks fine. There are no fuses blown. There was a stored code for crank position sensor but from what I understand this can't prevent the fuel pump from priming. I do not believe it is the ignition switch as the dashboard functionality is not affected.

I give up on the thing for a few weeks and decide to get it towed to my shop. And naturally it started right up. And it has been for about a week now. There were not any stored codes in the ECU.

What gives? Do I have an ECU on the fritz? Are there some other grounds or wiring I can check? It seems like it could have been correlated with wet weather, but it's tough to say.

MAD_MIKE

Main relay when initially turning the key to II(ON) will prime the fuel pump/rail, but will then shut off, you can hear this with a buzz(pump) and a click(main relay) when the priming is complete, there will be no voltage to the pump after the main relay clicks off. When the key is turned to III(START) the main relay will turn on again and the fuel pump should have power again.

Did you test/backprobe the fuel pump connector when initially turning the key to ON?

guy in a jetta

Thanks for the reply. I did indeed put a multimeter on the fuel pump. When the key is at II (ON) there was no reading between the fuel pump power wire (black/yellow if I remember correctly) and ground.

That the CEL light does not go off after two seconds is what leads me to believe the ECU is suspect. From what I understand it's supposed to supply a ground to the main relay that primes the fuel pump.

MAD_MIKE

I'll check my '95 EX later tonight, I cannot recall if the CEL stays on until the car is started, or does when the Main Relay times off when the car is not started within a few seconds.

guy in a jetta

I was able to reproduce the problem.

If the key stays ON for long enough, the fuel pump will begin priming with each subsequent turn of the key to ON. It seems like something (a capacitor in the ECU?) needs to get charged before the fuel pump can turn on. The amount of time between turning the key to ON and hearing the fuel pump kicking on can vary, too.

It seems very similar to this
94 Accord with *almost* classic main relay symptoms, but doesn't seem to be the relay - Drive Accord Honda Forums

holmesnmanny

The ecu primes the fuel pump for two seconds. If it sees no crank signal it turns off the power to the pump. However there is still pressure. Turning the car to start causes the crank signal to tell the ecu to prime the pump again when it comes back to the on position.

The cel only turns on for a couple seconds til the ecu does a system check. It has nothing to do with the main relay.

The best thing to do to verify the issue is related to the fuel side is to hook up a fuel pressure tester from Harbor Freight. Lay the hood on it with the gauge facing you and drive til the car dies and see if the fuel pressure is dropping off.

guy in a jetta

The car has never died after starting. Starting is the only issue.

I unplugged the crank position sensor (8 pin plug on the distributor) and tried the same thing. the fuel pump will still prime, but only after the key sits at ON for about a minute.

I am still getting CKP code (four blinks of D4). I suppose my next course of action will be the CKP diagnosis flowchart.

holmesnmanny

Your diagnosing makes no sense.

Also the d4 light has to do with transmission codes.

Good luck.

MAD_MIKE

D4 code 4 is for VSS, not for CKP.

CEL and D4 do not share the same codes(numerically), although they may share same description for numerically different codes, e.g. TPS, Thermo, etc.

guy in a jetta

SOLVED: leaky ECU capacitor

drnewine

Could be a fuel issue caused by a bad MAP sensor.
To test this, unplug the wire going into the sensor. With the key on ACC (2nd position before starting the engine) plug the wire back in the sensor. You should immediately hear the sound of your fuel injectors working (priming). If not, try the steps again a couple of times, making sure the key is in the 2nd position. If you do hear the injectors come on right after you plug the wires, your car will now start. This means the MAP sensor needs to be replaced.
My 1994 honda civic engine would crank but intermittently wouldn't start. Replacing the MAP sensor (located right above the air intake manifold) solved the problem immediately.