Jump to content

injectors not firing ? help


nickkrmr
 Share

Recommended Posts

i have an 89 and but the stock setup back together, everything has power but im not getting the fuel injectors to squirt, they are brand new, the wires are getting power, and i double checked every wire and ground on this car and everthing is hooked up right, could there be anything else that would do this, please help, thanks
Link to comment
Share on other sites

Hook up a 9 volt battery with a wire soldered to each pole.

 

Briefly, and I MEAN BRIEFLY, touch both of the wires to the injector male connectors. Start with the primary injector. It is the one that is not firing.

 

Do you hear a clicking sound? If so the Injector is good. If not then the the injector is bad.

 

Do the same thing to the secondary injector.

 

How did you measure the power to the primary injector?

 

You might also try reversing the injector clips and put the primary clip to the secondary injector and see if she fires off. If so then the primary injector is shot.

 

Get your money back.

 

For what it's worth.

 

KEN

Edited by Starfighterpilot
Link to comment
Share on other sites

The injectors have constant 12V with the ignition on and fire by the ECU grounding out the return wire. The ECU needs a tach signal to fire off of.

Does your tach move when cranking?

Is your ignition stock or do you have a MSD?

What wires are on your coil?

Link to comment
Share on other sites

Hook up a 9 volt battery with a wire soldered to each pole.

 

Briefly, and I MEAN BRIEFLY, touch both of the wires to the injector male connectors. Start with the primary injector. It is the one that is not firing.

 

Do you hear a clicking sound? If so the Injector is good. If not then the the injector is bad.

 

Do the same thing to the secondary injector.

 

How did you measure the power to the primary injector?

 

You might also try reversing the injector clips and put the primary clip to the secondary injector and see if she fires off. If so then the primary injector is shot.

 

Get your money back.

 

For what it's worth.

 

these are not stock injectors so i cant check them lick that, i got them from tirlogy turbos, and they are delphi injectos, they told me that doing that does not work for these type of injectors, and i just bought them, im stumbed

 

KEN

Link to comment
Share on other sites

the tack does not move when i crank, it just moves alitlle when i turn it to accessary, but not while cranking, i tried changing the ignitor box but still nothing, everything is stock, it was running before, i disconected the ecu and harness then just plugged everything back in, went over everything 5 times to make sure it was all back together right, im getting power to injector clips, the coil just has one wire to the - and i believe one to the + side, could it be anything else that is making them not fire,
Link to comment
Share on other sites

if the tach is not jumping you have no spark,, try looking into why you have no spark and you may find why the injs don't spray,,

 

the inj show 12 volts on a volt meter but the power is thru a 6 ohm resistor any current load and the voltage drops to 6 volts ,,never apply 12 volts directly to an inj,, you can melt the windings in an instant

Link to comment
Share on other sites

i have spark, and i checked the lines and everything is getting the right amount of power. the tack only moves a little bit when i go to crank then doesnt move, but the injectors wont fire still, what else could it be, everything in the car is working, i riped apart every harnes looking for a short, nothing, every ground is attached, there power and spark to everything, and cant think that the injectors would be bad since there new, ?
Link to comment
Share on other sites

i have spark, and i checked the lines and everything is getting the right amount of power. the tack only moves a little bit when i go to crank then doesnt move, but the injectors wont fire still, what else could it be, everything in the car is working, i riped apart every harnes looking for a short, nothing, every ground is attached, there power and spark to everything, and cant think that the injectors would be bad since there new, ?

 

 

Is the fuel pump running?

 

try moving- wiggle the fusible links by the battery

 

 

 

Dad

Edited by Dad
Link to comment
Share on other sites

fuel pump is running, i try to change some of the fusuble links also

 

 

we're trying to help you,, saying things like i change'd some of the fuse links ,,says your guessing ,,you need to stop guessing and make spacific tests

 

i simple cheap test tool that comes in very handy if call'd an inj tester,, it's an led that plugs into the inj clip and flashes when the ecu sends a pulse to them , in this manner you can visualy see if the injs are geting a signal to fire or not,,it also helps while makeing tests on other systems to see at a glance if you fix'd the proplem or not

 

now do you know for a fact the injs are not sparying or are the plugs just wet and your filling the engine and intake full of gas while your trying to start the car ,

 

 

the indash tach has nothing to do with the ecu it is wire'd seperately , a couple quick test to verify the main relay and ecu is working,, with key on test for power to the CTS, and TPS plug , you should see aprox 5 volts,, now do the same test while cranking the engine ,, some times the ign swt can go bad and drop power durring the cranking mode , you said you already test'd batt voltage at the inj clips,, NEVER use any thing but an led to test the ground side of the inj clips wireing

 

testing for ign spark,,always do this by removeing the coil wire from dist cap,,NOT COIL, and holding it near the fender or body (1/4 " gap ) and have some one crank the engine , but make sure you remove and inspect the coil end connection for corrosen

power to the injs tests one side of the main relay,,power to the ecu can be verify'd by haveing power to the CCTS and TPS , this is a very simple system you can make it easy or as hard as you'd like

 

a couple MUST have tools are a decent volt ohm meter,, a test lamp,, an led inj tester,, a 10 ft piece of wire with clip on one end,,(for a jumper ) now arm'd with those few tools you can find the problem in 95 % of all the electronics on the car , add to that a cheap pressure gauge and hose and you can test the entire fuel inj system

Edited by Shelby
Link to comment
Share on other sites

the indash tach has nothing to do with the ecu it is wire'd seperately

 

Shelby, don't the tach and the ECU work off of the same wire that comes from the coil?

 

I ask this because I installed an MSD unit without the tach adapter thinking I would live without the tach for a couple days while I waited for the adapter to come in the mail. My injectors wouldn't fire without that adapter.

Link to comment
Share on other sites

look, this will all be ALOT easier if you go spend $5 on a noid light (injector tester)

 

here's an example.

 

http://www.midwayautosupply.com/showproduc...filiateid=10050

 

 

make sure you get one that fits bosch style connectors

 

all you do is plug that into the end of the injector connector and crank it over to see if your injector is getting a pulse

 

the noid light should flash. go get one.

Link to comment
Share on other sites

Is the tach moving too - just "having spark" isn't enough. If the tach is wiggling though then the signal wire from the ignition coil to the ECU & tach is working. Without that wire the ECU won't command fuel. It wants to verify ignition is present before it will flow fuel - this is a safety thing in case the car was in a wreck... don't want fuel being sprayed when the fuel lines, injectors, etc. could be busted wide open.

 

To command the injectors, the ECU:

* needs to see the signal from the ignition coil "-" post; this is the tach signal I just described.

 

* wants to see pulses from the airflow sensor. The airflow sensor (aka "MAS" or "AFS") is the single most important input to the ECU for the fuel calculations; all of the other engine sensors just add or subtract from the AFS based value.

 

* ECI fusible link must be intact. This powers the fuel pump, injectors, etc.

 

* ECI relay (actually 2 relays in one housing) powers the fuel system and fuel pump. The ECU "holds" the fuel pump side ON as long as the ECU sees those ignition pulses ("engine is still running, go ahead and send power to the fuel pump..."); the ignition key START position also trips this relay to power the pump while you're trying to start.

 

Some simple tests:

1: verify the tachometer wiggles. If not, find out what's wrong with the ignition system or your wiring. The wire from the coil "-" post to the tach and ECU is a skinny coax cable (skinny cable TV wire: a wire inside a braided shield, then encased in rubber) and it's possible for the inner conductor to short out to the shield if the wire is pinched, crushed, or bent tightly. Often it gets shorted right at the ECU connector. There are TWO of these shielded coax wires at the ECU - one is for the ignition, one is for the oxygen sensor. If you hook up an air/fuel guage to the wrong one you could screw things up.

 

2: Look for basic power to the injector while cranking: using a voltmeter red/positive lead probe either injector wire on the primary injector (the one closer to the fender on 87-later cars, or just pick either injector on earlier cars) and ground the voltmeter's black/negative lead. Now try starting... you should see 10 to 12 volts. No? Try the other post on that injector. Still no 12 volts? Then your ECI fusible link is shot, the ECI relay isn't ON, wiring is bad, or the ballast resistor is shot. The ballast is the silver prism-shaped thing bolted to the bulkhead between the air filter and passenger side headlight. +12volts goes in one wire, the resistor is actually two resistors that split this +12volt line... each resistor feeds one injector. Bad resistor = no power to injector.

 

3: Hook a noid light to the primary injector - the one closer to the driver side fender. It should pulse/blink if the ECU is completing the ground to fire the injector.

 

mike c.

 

Link to comment
Share on other sites

i have power to the injector clips and spark to the engine, i will check the actually voltage this weekend, and try the other things you suggested, i just dont get it, i have fuel i have spark, thanks for the help and i will let everyone know what the results are on your suggestions, thanks again , nick
Link to comment
Share on other sites

Is the tach moving too - just "having spark" isn't enough. If the tach is wiggling though then the signal wire from the ignition coil to the ECU & tach is working. Without that wire the ECU won't command fuel. It wants to verify ignition is present before it will flow fuel - this is a safety thing in case the car was in a wreck... don't want fuel being sprayed when the fuel lines, injectors, etc. could be busted wide open.

 

To command the injectors, the ECU:

* needs to see the signal from the ignition coil "-" post; this is the tach signal I just described.

 

* wants to see pulses from the airflow sensor. The airflow sensor (aka "MAS" or "AFS") is the single most important input to the ECU for the fuel calculations; all of the other engine sensors just add or subtract from the AFS based value.

 

* ECI fusible link must be intact. This powers the fuel pump, injectors, etc.

 

* ECI relay (actually 2 relays in one housing) powers the fuel system and fuel pump. The ECU "holds" the fuel pump side ON as long as the ECU sees those ignition pulses ("engine is still running, go ahead and send power to the fuel pump..."); the ignition key START position also trips this relay to power the pump while you're trying to start.

 

Some simple tests:

1: verify the tachometer wiggles. If not, find out what's wrong with the ignition system or your wiring. The wire from the coil "-" post to the tach and ECU is a skinny coax cable (skinny cable TV wire: a wire inside a braided shield, then encased in rubber) and it's possible for the inner conductor to short out to the shield if the wire is pinched, crushed, or bent tightly. Often it gets shorted right at the ECU connector. There are TWO of these shielded coax wires at the ECU - one is for the ignition, one is for the oxygen sensor. If you hook up an air/fuel guage to the wrong one you could screw things up.

 

2: Look for basic power to the injector while cranking: using a voltmeter red/positive lead probe either injector wire on the primary injector (the one closer to the fender on 87-later cars, or just pick either injector on earlier cars) and ground the voltmeter's black/negative lead. Now try starting... you should see 10 to 12 volts. No? Try the other post on that injector. Still no 12 volts? Then your ECI fusible link is shot, the ECI relay isn't ON, wiring is bad, or the ballast resistor is shot. The ballast is the silver prism-shaped thing bolted to the bulkhead between the air filter and passenger side headlight. +12volts goes in one wire, the resistor is actually two resistors that split this +12volt line... each resistor feeds one injector. Bad resistor = no power to injector.

 

3: Hook a noid light to the primary injector - the one closer to the driver side fender. It should pulse/blink if the ECU is completing the ground to fire the injector.

 

mike c.

 

:kowtow:

Link to comment
Share on other sites

ok im gettting the 12 volts to the injector clips, i didnt try the noid yet, some one told me that i should have to wires to my coil + is there a diagram somewere i can look at for that, because i only see one on my car, will be trying to switch the harness and ecu to try and rule them out. thanks nick
Link to comment
Share on other sites

tried the noid and the ecu is completing the gound circuit, got 12 while cranking, have spark have fuel , still have no guess as to why, does any one esle have any more suggestions, will be switching the ecu this week and the harnes.. cant see it being that since it was running, before, thanks
Link to comment
Share on other sites

 Share

×
×
  • Create New...