Alright so I just had the s300installed, car sat for a little while but tried to start it and the fuel pump didnt prime. I've searches stuff and found things that and close but never fully answered what it was. I checked thermostat ground and it's good, there is only one ground right? And the plug. Anyways I checked the 3 fuses too, and fuse 31 didn't have power going to it, 13 and 44 did. I checked the main relay, clicks once when I turn the key, terminal 1-7 and 5-7 I think is what people hve said to check, if I run a wire between them them the pump kicks on. Ecu gets power considering my laptop reads it. But I cel doesn't blink or come on at all, idk if there is a plug or something I should check that the previous owner may have tweaked. Anyways ya no fuel pump coming on, didnt check or spark. Any idea what to do next? Ron j seems to know what he is doing based on every forum haha.

 

Did you even bother checking the fuel pump? Having the car sit for a period of time with gasoline in the fuel tank is NOT a good idea.

 

His quoted test above shows that the fuel pump does work.


Has the CEL bulb been removed or is it blown?

Does the oil pressure light turn on and stay on when the key is turned from off to ON(II)?

Have you tried cleaning and tightening the G101 ground on the thermostat housing.

 

When I get home I'm gonna check the cluster, I think the oil light comes on ill double check, I know the battery and srs stay on, but I've removed all the srs wiring anyways so I expect it. What should I look for dealing with the oil pump light? And thanks for the replies guys!

 

I have an oil pressure gauge hooked up if that helps any, I know I put the sensor in the block but I removed the wires that run to my gauge. Could be why I wouldn't(if I don't) have a oil pressure light

 

I had the exact same problem, it turned out to be a bad ecu, remove the ecu cover and when you turn the key to position II, there should be 2 lit green leds on the s300 board, 1 by the usb port and the other right next to the heat diffusser...

If only the led in the back next to the heat diffusser lights, your ecu is the culprit...

 

Cool I know I saw one green light through the case, ill check the other, wouldn't that be hondatas fault lol they had it last and then I get it back and it doesn't work. Bs -___-

 

But I did try my old obd2 ecu and still didnt fix it. Wouldn't that throw bad ecu out?

 

well... yes

have you tried with another main relay?

 

yes 2 from a 96 and 97 civic, little bit smaller size one but same result, unless i jump 1-7 or 5-7 furl isnt priming. been working all day everyday but hopefully today i will be able to take a look at it some more. Jut checked ecu, both lights green. It's gotta be a ground or wiring issue. If I knew why fuse 31 isn't getting power that may be the culprit. I checked plugs to fuse box and all are good. Should I check continuity somewhere?

 

Fuse 31 only gets voltage when the key is held in ON(III), and it's not your main problem because your pump doesn't prime in ON(II).

Did you clean and tighten G101?

 

Alright checked the ground and it's find had continuity. Then checked wires to the fuel pump. Terminal 2 on relay and the black wire to the pump plug gets continuity, also terminal 5 and the black wire to the plug gets it.terminal 7 gets continuity with the yellow wire on the plug. If that helps. Also checked volts at pump plug, nothing, but the other plug by it, fuel gauge I believe, had 12v at the green/white or yellow wire

 

 

Cel bulb looks good, no oil pump light, but like I said I don't have it wired since its an aftermarket gauge

 

Picture of the fuse box under dash

 

If you don't give clear answers to questions, I don't see how you can be helped.

Read carefully and give definitive answers to ALL questions.

Is the CEL bulb definitely good or is it bad but looks good?

Ground the oil pressure sending unit wire to the block. Does the cluster light turn on?

Do any of the warning lights in the cluster work?

 

Srs on, oil on when I ground the wire, cel has continuity and comes on with 12v, cluster back lights come on, brights bulb comes on, signals come on.

 

Unplug OBD1 ECU connector A. Turn key to ON(II). Ground pin A13 in the ECU connector. Does the CEL light turn on?

 

A13 ground did not turn on cel, also I have a conversion harness but I did use the a13 on the obd1 side

 

Can you give more details about exactly what you did here^


At first glance, your CEL is not working because the wire is broken between the cluster and ECU connector or there's a poor connection in the C411 connector or the conversion harness.

Given that you also can't start the engine, I'd suggest that the problem lies with the conversion harness. Is it OBD2b to OBD1?

 

I unplugged the A connector from the ecu, (which was the obd1 side of the conversion harness.) I also tried A18 from the obd2 harness. The harness that's hooked up to the motor and what not is an obd2 harness. The harness is tucked behind my dash but I can rip the dash out and remove the harness to see if I have any broke wires.

 

Seems to me my ignition switch isn't telling the main relay to cut the fuel pump on. because the relay, when I uses 12v and test it, opens the circuit for the fuel pump.

 

And I removed the cel bulb and ran the multimeter to the metal ring around the bulb housing. It beeped. Then used a small 9v battery negative and positive to the same metal ring and the bulb lit up. Sorry missed that question

 

Also I added a wire to A11 for the pwm boost control for the s300. Idk if that matters.

 

I think if you locate the problem with the CEL, you's locate many if not all of your problems.

For the pump, the test is similar to the A13 test. Unplug OBD1 ECU connector A. Turn key to ON(II), and then ground pin A7 or A8. Does the fuel pump run?