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How to test an injector in a 2m4 by alejandrissimo
Started on: 03-18-2014 02:05 AM
Replies: 13 (337 views)
Last post by: alejandrissimo on 03-20-2014 08:51 PM
alejandrissimo
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Report this Post03-18-2014 02:05 AM Click Here to See the Profile for alejandrissimoSend a Private Message to alejandrissimoEdit/Delete MessageReply w/QuoteDirect Link to This Post
Hey, well after read and read a lot of sites and forums I'm still a bit lost about this problem. Basically this happen one day, the fiero was good but the Fuel pump need to be replaced, after this the fiero don't want to start, I have crank and the Fuel pump is working but there is no spray at the injector.

Yes, the motor start if I put some gas on the tbi. So I get spark.

Now, I read somewhere the red wire is positive and blue one is grounded by ecm.

The problem here is that I get constant ground on red wire and nothing on the blue one, even at cranking.

I need help if anyone knows how to do a proper injector test. On the injector end and also on the ecm side, since maybe the problem is on the wires.

Btw is a 1986 2m4

Thanks.

[This message has been edited by alejandrissimo (edited 03-18-2014).]

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RWDPLZ
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Report this Post03-18-2014 06:19 AM Click Here to See the Profile for RWDPLZClick Here to visit RWDPLZ's HomePageSend a Private Message to RWDPLZEdit/Delete MessageReply w/QuoteDirect Link to This Post
9V battery across the two terminals. If the system is pressurized (turn key to start and hear fuel pump run, hook up fuel pressure gauge, ~14psi), it should squirt fuel.

ECM side, connect a noid light to the terminals, and crank the engine. Light should flash.
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phonedawgz
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Report this Post03-18-2014 01:14 PM Click Here to See the Profile for phonedawgzClick Here to visit phonedawgz's HomePageClick Here to Email phonedawgzSend a Private Message to phonedawgzEdit/Delete MessageReply w/QuoteDirect Link to This Post
Key on engien off do you get a check engine light? You should
Does the ECM prime the fuel system by running the fuel pump for the first two seconds after you turn the key on? It should.

If the answers of both 1 and 2 are no most likely the problem is that the ECM is not running. The most likely reason the ECM wouldn't be running is that the ECM reset connector is left unconnected. Unplugged, the ECM won't get any power.

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alejandrissimo
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Report this Post03-18-2014 09:25 PM Click Here to See the Profile for alejandrissimoSend a Private Message to alejandrissimoEdit/Delete MessageReply w/QuoteDirect Link to This Post
Hi,

Key on, engine off= I get check engine light, bridged A and B and I get 12, 12, 12....

I also tested something different, key on, red wire connected to injector, then crank while send the ground pulse manually with a spare wire, then the engine start.

So the problem seems is there is no pulse from ecm. How can I check if the emc is sending the pulse and maybe the blue wire is damaged? What is the pin number on ecm where the pulse come from?

Also, I read on the forum that maybe the distributor is not sending the signal to ecm to pulse the injector. How can I check this?

Thanks in advance for your advice.
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phonedawgz
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Report this Post03-18-2014 10:14 PM Click Here to See the Profile for phonedawgzClick Here to visit phonedawgz's HomePageClick Here to Email phonedawgzSend a Private Message to phonedawgzEdit/Delete MessageReply w/QuoteDirect Link to This Post
Turn the key to on and listen to the fuel pump run for two seconds (prime). Now just bump the starter. If the ECM is receiving the signal from the ICM it will again run the fuel pump for two seconds and then turn it off.

Note - Don't be fooled by cranking the engine. The oil pressure sender/switch also will turn on the fuel pump. That is why you just need to bump the starter for this test.

-------

 
quote
The problem here is that I get constant ground on red wire and nothing on the blue one, even at cranking.


You should have +12v on the RED injector wire at all times when the key is on. Have you checked your INJ fuse? The Red wire receives switched power from the ECM INJ Fuse directly. The wire also connects to other things that take power, so trying to read resistance backwards will only read ground since the other devices use power and are connected to ground. Reading resistance back up the wire isn't a good test.

The ECM grounds the Blue wire to fire the injector.

Note - The fuse box will swing down so you can see it without laying on your head. Reach down to the fuse box. Squeeze the two side tabs inward. Push up slightly to release the pressure and then the fuse box should swing down to a vertical position.

[This message has been edited by phonedawgz (edited 03-18-2014).]

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alejandrissimo
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Report this Post03-19-2014 02:12 AM Click Here to See the Profile for alejandrissimoSend a Private Message to alejandrissimoEdit/Delete MessageReply w/QuoteDirect Link to This Post
Yep, with key on I get power on red wire at all times, now the problem go to the fact that there is no ground pulse on blue wire, the injector is working as the Fuel pump is working as well.

I just need to check why I have no pulse on blue wire, how can I check this?

Which parts are involved on this pulse?

Also, English is not my native language, so what do you mean by pump the starter? It's just try to turn on the motor a short time?

Thanks

[This message has been edited by alejandrissimo (edited 03-19-2014).]

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phonedawgz
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Report this Post03-19-2014 02:53 AM Click Here to See the Profile for phonedawgzClick Here to visit phonedawgz's HomePageClick Here to Email phonedawgzSend a Private Message to phonedawgzEdit/Delete MessageReply w/QuoteDirect Link to This Post
Bump the starter - to turn the key to start - only enough time for the starter to begin to start working, and then release the key right away. The engine will have started to move, but just started to move. The key was turned to start for maybe 1/10 of one second of time.

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84fiero123
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Report this Post03-19-2014 09:06 AM Click Here to See the Profile for 84fiero123Click Here to Email 84fiero123Send a Private Message to 84fiero123Edit/Delete MessageReply w/QuoteDirect Link to This Post
test light between both wirers in the harness, if it is pulsing it will flash.

Old school rules. sometimes the simplest old tools can be the easiest way to test something.

Steve

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Technology is great when it works,
and one big pain in the ass when it doesn't



Detroit iron rules all the rest are just toys.

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alejandrissimo
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Report this Post03-19-2014 01:18 PM Click Here to See the Profile for alejandrissimoSend a Private Message to alejandrissimoEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by 84fiero123:

test light between both wirers in the harness, if it is pulsing it will flash.

Old school rules. sometimes the simplest old tools can be the easiest way to test something.

Steve



Already test that, and is not flashing, there is power at Red wire at all times with key on, but no ground on blue wire.

So I need to find out why I have no pulse on blue wire.

Thanks

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phonedawgz
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Report this Post03-19-2014 03:32 PM Click Here to See the Profile for phonedawgzClick Here to visit phonedawgz's HomePageClick Here to Email phonedawgzSend a Private Message to phonedawgzEdit/Delete MessageReply w/QuoteDirect Link to This Post
So do you show power on the blue lead. You should if the injector is connected and good.
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alejandrissimo
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Report this Post03-19-2014 04:14 PM Click Here to See the Profile for alejandrissimoSend a Private Message to alejandrissimoEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by phonedawgz:

So do you show power on the blue lead. You should if the injector is connected and good.


There is no power or ground on blue wire at all times, I want to check continuity on blue wire but I don't know where is the other end, if is on the ecm what is the pin number?
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Report this Post03-19-2014 10:07 PM Click Here to See the Profile for phonedawgzClick Here to visit phonedawgz's HomePageClick Here to Email phonedawgzSend a Private Message to phonedawgzEdit/Delete MessageReply w/QuoteDirect Link to This Post
The Blue wire runs to C2 (connector 2) pin 8 at the ECM. C2 is the White connector with the Red cover.
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Report this Post03-20-2014 01:21 PM Click Here to See the Profile for alejandrissimoSend a Private Message to alejandrissimoEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by phonedawgz:

The Blue wire runs to C2 (connector 2) pin 8 at the ECM. C2 is the White connector with the Red cover.


Ok, tested the blue wire at pin 8 c2 white connector and I get ground at all times with key on.

Also I did the pump test, with key on I get 2 sec fuel pump sound, then bump starter and I get nothing, no sound from fuel pump.

Btw the Fuel pump is new, at first I was thinking that was the problem so I replace it.

Also, the day after I changed the pump I was able to start the car and all was running perfect.

So, what's up if I cannot hear the pump when I bump the starter? What is the next to test.

Thanks
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alejandrissimo
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Report this Post03-20-2014 08:51 PM Click Here to See the Profile for alejandrissimoSend a Private Message to alejandrissimoEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by phonedawgz:

The Blue wire runs to C2 (connector 2) pin 8 at the ECM. C2 is the White connector with the Red cover.


Finally, I found the problem, there was a wire making a false contact on the 4 pin connector at ICM.

I now think the Fuel pump was not needed to be replaced LOL

Anyway my fiero is now running

Thanks for your support.
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