Furthestwave

I have a 1990 crx si. It is cranking but won’t start. I have spark and I have fuel pressure but the injectors aren’t firing. I thought it could be my tdc or crank sensors so I got a new dizzy but still nothing. I think it’s either a wiring thing or a ground somewhere but the only thing I can find is the blu/wht starter signal wire reads close to zero. Also when I turn the key to the second position and the fuel pump kicks on, my ecu will blink once then nothing, is that normal?

Brian Duke

Did you ever find out what the problem was? Having a similar issue

Furthestwave

Not yet still working it.

kraquepype

Its weird that 3 threads like this popped up within such a short timespan!

How did you check that the injectors are not firing? Is the engine/ecu a stock setup? (OBD0 ECUs have the integrated MIL so I assume so)

The ECU should blink, and if there are problems it will blink further to show any trouble codes. I think one blink at startup is normal.

Furthestwave

I crank it and pull the plugs and there’s no sign of fuel.

ef-ingfabulous

First thing to check is your main relay. Located left of the interior fuse panel.

When you key on (but not crank), you should hear the fuel pump behind you run for two seconds. If it doesn't, relay is your #1 suspect.

Furthestwave

Yeah my fuel pump is good it’s brand new and I have a fuel pressure gauge. It’s been reading 40 psi

ef-ingfabulous

Great. But that doesn't mean It'll run if the relay isn't switching it on. Listen and you'll hear it run for two seconds, then switch off. That is the symptom you're looking for.

Furthestwave

It does turn on you can hear it and I’ve tested the relay it operates in accordance with the repair manual.

ef-ingfabulous

Any codes on the ECU? What ECU are you running?

Furthestwave

No codes. It’s running the stock pm6 ecu.

Furthestwave

Update.
The injectors are still not firing. I've used a test light hooked from battery positive to the ecu side of the injector connector and confirmed that the injectors are pulsing when attempting to start. I have gone as far as pulling the fuel rail off with the injectors still attached and trying to start and verified no fuel is coming out of the injectors. I know for a fact I have good fuel pressure and good spark. At this point I am thinking the injectors are not getting enough current to actuate them. If anyone has any ideas whats going on they would be greatly appreciated.

kraquepype

Well that's something, you now know the ECU is sending a signal to them.

You can check your voltage when cranking with a multimeter - there will be a voltage drop when cranking, which is expected. If there's enough battery to crank, the injectors should be firing too.

Have you taken a look at the injector resistor box - it should be near the driver's side shock tower. I have to check the service manual but there may be ways to test it.

TacoCat

First, check and clean the thermostat housing ground. Next, pull the injector connector and check that you are getting 12v at the injector connector (while the fuel pump is running / main relay engaged). Note, just because the fuel pump is running, the main relay or chassis wiring can still be an issue.

Next, test the injector resistance. It should be around 2 ohms. Next, bypass the ECU entirely and using a 10 ohm 20 watt resistor in the loop, test that the injector clicks when 12v power and ground are applied manually. You can also test jumpering the 12v from the injector connector pin to the injector and grounding the signal side. Next, with the injector connector reconnected, crank over the car and using a long screwdriver held up to your ear to serve as a mechanic stethoscope, listen to see if the injector is clicking. If it isn't clicking, the signal (ground) side of the injector circuit is not allowing for enough current to flow. If it is clicking, I would send the injectors off for cleaning and flow bench testing. If after verifying the injectors are working correctly on a flow bench and the same behavior exists, I would test with a different ECU.

frank_el_tanke

iTrader: (4)

Out of curiosity, how long have you had this car and was it running before or was this a recent purchase? Also, which engine and ECU do you have?

Tha_JOKE_

have you check compression yet?

you may need to adjust one of the valves 🤷‍♂️