Jmunk

I have no fuel coming out of the injectors. I have power going to the injectors, but no ground. I know that the ECU supplies the ground which completes the circuit and fires the injectors, so with that said what would cause the injectors not to get the ground signal ? I used a noid light and nothing. The car cranks and thats it. Would a bad crank position sensor do this ? Any way to test it ? If the crank sensor is good than the only other thing that i can think of is that the ECU is bad, any other ideas or ways to test ?

JimBlake

First you should rule out breaks (open circuit) in that ground leg going back to the ECU. You could backpin the wires at the ECU, short to ground; see if you can fire the injectors that way.

Jmunk

I'm going to hook up the clip on the end of the test light to a batter source, probally a booster pack, than i'll use the probe on the tip of the test light to see if i get a circuit, so if the light goes off than i'm know that my problem is in the wiring to the injectors, if i don't get a the light to go off than i know that the problem is either the computer or the crank position sensor. Would the computer be throwing a code for the crank sensor if it was bad and i was trying to start it ? When i'm cranking it over what kinda of signal should the crank sensor be sending to the ecu ?

Chiovnidca

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Jmunk &raquo;</TD></TR><TR><TD CLASS="quote">Would a bad crank position sensor do this ? </TD></TR></TABLE>
Does it have any trouble codes stored? Does it have spark?

Jmunk

When i went to pull the codes off of the check engine light, the light stayed solid which i think means that the ecu is bad. Also when i try to get the codes with the OBDII scan tool it just keep telling me that i needed to turn the key to the on position.

Jmunk

Also both oxygen sensors aren't hooked up and neither is the oil pressue guage to the previsous owner and his deal with taking things apart. Wouldn't the computer see that these things aren't connected while i was cranking and store the codes for them ?

Chiovnidca

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Jmunk &raquo;</TD></TR><TR><TD CLASS="quote"> Also when i try to get the codes with the OBDII scan tool it just keep telling me that i needed to turn the key to the on position. </TD></TR></TABLE>
More questions: Year and model? When you turn the key to the run possition, does the cel come on for 2 seconds then go out?

Jmunk

96 Civic Ex. Yes the cel does comes on for a few seconds when you first turn the key than it goes out.

b18ccivics

check and see if you are getting spark, it sounds like you are not getting power to all of the places on the ecu you are suspose to so check that.

Jmunk

I'm back at school for the week now and the car is at home, so i can't do anymore testing till than. I did buy a ECU, just waiting on it to get here. Any bets on if it is the ECU ?

Kataku2K3

I've seen/had both go bad, but obviously most of the time was just the distributor (never had a problem with losing fuel though - just sensors getting out of phase and weird **** like that). Before connecting the new ECU, I would do a few more power checks just as b18ccivics said. Probe the hot (12V+) side of the injectors, power at the dizzy, and also retest your injector triggers at the ECU. Good luck and get back to us as soon as you test it!

Jmunk

The injectors have 12v at the hot side but no ground. I'll be sure to let you guys know.

JimBlake

They aren't supposed to have continuous ground; the ECU grounds them momentarily just to fire the injectors.

Find the wires from the injectors to the ECU. Try to fire each injector by grounding that wire from the ECU plug. That'll check whether those wires are intact...

Jmunk

I used a noid light and i didn't get anything while i was cranking on it.

JimBlake

The noid light can't tell the difference between a bad ECU vs. a loose wire.

Chiovnidca

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by JimBlake &raquo;</TD></TR><TR><TD CLASS="quote">The noid light can't tell the difference between a bad ECU vs. a loose wire.</TD></TR></TABLE>
Or an ecu that isn't firing the injectors for another reason.

Jmunk

Well what tells the ECU to fire the injectors ? The crank position sensor ? Thats all that i can think of, or am i wrong ?

Chiovnidca

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Jmunk &raquo;</TD></TR><TR><TD CLASS="quote">Well what tells the ECU to fire the injectors ? The crank position sensor ? Thats all that i can think of, or am i wrong ?</TD></TR></TABLE>
It needs an rpm signal also. That's why I asked if it had spark. (which you never answered)

Jmunk

I didn't get around to testing it before i had to come back to school for class for the week. If I get the ECU and head home this weekend, I'll get back to you on the spark deal. Thanks.

JimBlake

]<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by JimBlake &raquo;</TD></TR><TR><TD CLASS="quote">The noid light can't tell the difference between a bad ECU vs. a loose wire.
</TD></TR></TABLE><TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Chiovnidca &raquo;</TD></TR><TR><TD CLASS="quote">
Or an ecu that isn't firing the injectors for another reason.</TD></TR></TABLE>Exactly.

You've already found the injectors aren't firing. Now you have to work your way 'upstream' from there. Each component, like the ground side of the injector circuits, or the ignition signals from the distributor. You have to rule out each, by for example, grounding the wires at the ECU to fire the injectors. You want to do specific tests so you can isolate each thing, to rule it out.

I don't have a '96, but I think it's all driven from the 3 sensors in the distributor? When you ask about the crank sensor, are you talking about the CKF sensor at the front pulley? That doesn't control anything, it just measures speed fluctuations to detect misfiring.

You also mentioned the CEL staying on when you check for codes. That's good. When the ECU is bad (code zero) the light doesn't go on when you jumper the SCS connector.

Jmunk

One more thing i thought of last night in bed, weird that i think of these things. I had someone shoot intake cleaner into the throttle body when i was cranking it and it would just about run. That leads me to believe that i do have spark. Jim, i was referring to the crank sensor in the dist. Thanks you guys are a big help, I'm sure that i'll go home friday to work on this a little and report back. Thanks again.

JimBlake

If it fired with spraying that stuff, then you have spark. That means everything 'upstream' of the ignitor/coil is OK. That means your timing sensors in the distributor are OK. If they weren't, it wouldn't have spark.

The triggers from the distributor sensors go to the ECU, which then tells the ignitor to fire the coil. The distributor can't fire it's own coil without the ECU, so the ECU has to be getting a good signal from the distributor sensors...

Now we're getting somewhere. The fact that it fired on starting fluid is important. That just shows the distributor sensors and their circuits back to the ECU are OK.

b18ccivics

what is your fuel pressure at?

Sliced Beard

do me a favor before I go any farther in the electrical diagnosis. Check the ground that attaches to the thermostat housing. Is it tight or loose?

check all of your fuses.

Jmunk

It's right as are all the grounds. Fuel pressure is stock, fuel pressure doesn't have anything to do with me not getting a ground at the injectors.