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1998 Honda Civic LX
D16Y5 MT
USA model
Helm manual, fuses all checked and battery is healthy, has spark at plugs, CEL operates normally, no codes.
Son’s civic, misfire code recently read by Autozone though not on now. Did a valve adj. since he was going to sell it. Cranks and the first second tries to fire then just cranking. First thought I had jumped a tooth and verified it was fine (twice). Then noticed the fuel pump was not priming so there is no fuel pressure. Main relay was replaced a couple of years ago and still tests fine (twice tested). Then started testing the relay harness and it all checks out, ran through the 2 pages of harness checking and all is fine. I have 12v at the fuel pump fuse just never any voltage at the pump. Looks like testing the ignition switch is next? Trying to confirm the voltage flow, relay, fuse then ECM for the OK to power on?
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The ignition switch 7P connector has no continuity there is only flow on the 5P connector, looks like an ignition switch is next.
I agree that is why i have gone through the main relay test and the wiring into the main relay test. The switch did not fix it. I still have power at the fuel pump fuse any idea after that where the power flows? There is one connector right by the under hood fuse box and I think it flows though there though I have not located the wire yet.
Not lame at all with my son it usually is on E but is half full. The pump does run hooked up to 12 volts so it is working. Someone mentioned that the ECM controls power to it after analyzing other sensors that it is ready to start. With no codes it is hard to go from here. I have power going into and out of the relay for the pump then also at the under dash fuse there is power after that where does it go?
OK. Not a Honda man but generally this is how it works. When you turn the key on, the fuel pump will run for a few seconds to pressurize the fuel rail. If you turn the key off and back on then it will run again for a short time. When you crank and the engine starts the ECM reapplies power to the fuel pump. The pump will continue to run as long as there is power and oil pressure. The fuel pump relay would have 12 VDC through a fuse to one side of the relay coil and the other side would be grounded by the ECM. The contact side of the fuel pump relay then applies 12 VDC to the pump.
The fuel pressure once established by prime should remain primed account of the check valve in the tank and fuel pressure regulator at the fuel rail.
Hello 🙂
Here are wiring diagram..
Where did you conect power too, when you test pump?
Remeber it only prime 1-2 sec when turn ign on. And when it see a crank signal it will run as long as it see it..Thanks everyone for helping out. I am not getting the prime function so there is no power upon turning the key on to the pump for the 2 sec. prime. Then cranking yesterday I was not getting any power to the pump, did not test it today. I hooked the pump to the battery wire on the relay connector and then it ran. So it is strange that there is no prime at all.
To test the circuit from the ECM measure the voltage at the fuel pump relay socket. With the ignition on you should have 12 VDC on one contact terminal and one coil terminal. The other coil terminal would be the one coming from the ECM. Connect you negative meter lead there and the positive lead to the positive terminal of the battery. You should get a 12 VDC reading for the two seconds when you turn the ignition switch from off to on. If the reading is good then the ECM is good and you can look at the relay and toward the fuel pump. If the reading is not good you can go toward the ECM.
These cars are under a recall for ignition switches which can cause this kind of problem. You might call the dealer with your VIN and verify whether or not that recall has ever been done on this car. If not, it’s a free repair.
That leads to the sticky point of getting the car to the dealer to have the recall done because the odds of Honda paying for a tow is not very high.
I will check on it though yeah getting it there will not work easily. Don’t some recalls have time limits?
Looking at the schematic provided by ALLHAN. The power for the fuel pump originates at (Fuse 13 under the dash). This voltage is hot is start or run and is connected to the Main Relay with the YEL/GRN wire on pin 5.
The PCM provides ground to the fuel pump relay coil on the GRN/YEL wire on pin 1.
Plus power to the pump relay is provided through two sources. The Main Relay contact and BLU/WHT wire on pin 2.If the ignition is on the Main Relay should be energized / picked. Then power is provided for the fuel pump relay through fuse 44 under the hood. The remaining piece is the ground supplied by the PCM.
What has been confusing is at the main relay socket, key on I have 12v on pins 4, 5, and 7, key off 4 and 7. I should not have 12 v on pin 4 correct? That is the wire to the pump. This is of course not using the #s on the relay using the Helm #s.
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