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New Speedhut Gauges - No Spark by Squeaky
Started on: 08-02-2014 10:51 PM
Replies: 6 (187 views)
Last post by: phonedawgz on 08-04-2014 08:36 PM
Squeaky
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Report this Post08-02-2014 10:51 PM Click Here to See the Profile for SqueakyClick Here to Email SqueakySend a Private Message to SqueakyEdit/Delete MessageReply w/QuoteDirect Link to This Post
Good day all, I just finished an install of new Speedhut gauges however now I don't believe I'm getting spark. My gauges illuminate and both my fuel gauge and my voltmeter are functioning (but since my engine won't fire they should be the only 2 working, so thats good news).

The gauges are installed on my 87' GT that I swapped a 3.4 DOHC into. To wire in the tachometer and get my ignition output signal I spliced into the middle white wire on the 7-pin connector that plugs into my ICM. I don't recall where that white wire gets the signal from because its been awhile and plenty beer's since I researched it.

The starter will function an turn the motor and I have 38 psi of fuel pressure in my fuel rail. Everything worked fine prior so I can only assume I must've hooked something up incorrectly. Does anyone have any idea's where I should start?

My Speedometer is wired though my VSS and my gauges are wired to my fusebox. The 12v power for my gauges are hooked up to the spare "BAT" slot with a blade connector, and my 12v keyed on ignition is connected to the spare "IGN" slot with a blade connector as well. My gauges are grounded to the frame.

Any idea's?? Wiring is not my forte, any help greatly appreciated!
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Joseph Upson
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Report this Post08-03-2014 07:22 AM Click Here to See the Profile for Joseph UpsonClick Here to Email Joseph UpsonSend a Private Message to Joseph UpsonEdit/Delete MessageReply w/QuoteDirect Link to This Post
Disconnect your tach wire and see if it will start and check your other fuses. I picked up my tach signal for an alternate tach reading from inside the car at the passenger side firewall harness behind the center console.

[This message has been edited by Joseph Upson (edited 08-03-2014).]

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Squeaky
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Report this Post08-03-2014 01:18 PM Click Here to See the Profile for SqueakyClick Here to Email SqueakySend a Private Message to SqueakyEdit/Delete MessageReply w/QuoteDirect Link to This Post
I disconnected my tach wire from the white wire on my 7-pin ICM connector and she still won't fire. I keep hearing a clicking from underneath the car after I attempt to start it.
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Squeaky
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Report this Post08-03-2014 01:25 PM Click Here to See the Profile for SqueakyClick Here to Email SqueakySend a Private Message to SqueakyEdit/Delete MessageReply w/QuoteDirect Link to This Post
The clicking sound is coming from up by the firewall, a relay perhaps?
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Squeaky
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Report this Post08-03-2014 02:49 PM Click Here to See the Profile for SqueakyClick Here to Email SqueakySend a Private Message to SqueakyEdit/Delete MessageReply w/QuoteDirect Link to This Post
The needle on my oil pressure gauge also flickers which is normal, correct?
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Squeaky
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Report this Post08-04-2014 07:25 PM Click Here to See the Profile for SqueakyClick Here to Email SqueakySend a Private Message to SqueakyEdit/Delete MessageReply w/QuoteDirect Link to This Post
I disconnected my gauges completely and tried again, still nothing.

I'm really stumped here fella's
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phonedawgz
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Report this Post08-04-2014 08:36 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
There is a dedicated tach output of the 7x ICM. You should have been using that instead of the white wire that ran from the ICM to the ECM.

I don't think that killed it however.

Does the tach rise to 200 RPM during cranking and then fall back to zero after cranking?

Does the fuel pump run when you turn the key to on, but before cranking? Does it then turn off two seconds later?

If you just barely bump the starter does the ECM turn on the fuel pump again for two seconds and then turn it off again? If you crank it more than a bump this test is not valid.

Do you have fuel pressure?

Have you tried starting fluid?

What makes you think you don't have spark?

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Key on but don't crank. The ECM should turn on the fuel pump relay for two seconds and then it should turn off again. Turn off the heater radio and cruise (it clicks too) You won't hear the first click of the fuel pump relay coming on because of the noise of turning the key. You should hear a motorized noise for two seconds. Go to youtube and search for fuel pump, or try it on a different car if you want to hear the noise. After two seconds the relay should click off and the fuel pump noise should stop.

Note - This test can be repeated but the key needs to remain off for at least 45 seconds for the test to be valid. If off shorter than that the ECM may or may not turn the fuel pump on again.

If you just bump the starter then the ECM when it sees an ignition pulse should again turn on the relay. The fuel pump should make the whirring noise. And two seconds later the fuel pump relay should click off and the fuel pump should stop. This test can be repeated immediately and should give the same results.

Cranking the engine may also turn on the fuel pump via the oil pressure switch. Fieros along with most GM cars were wired this way with the oil pressure switch being a back up to the ECM controlled relay. If you crank it for a bit do not be surprised for the fuel pump to run for maybe as long as a minute after you stop cranking when the oil is cold. It will normally continue to run even if you turn the key to off - for as long as it takes the oil pressure to drop to zero.

What the tach needle does when the key is off is meaningless. Non-powered it may do whatever. When you turn the key to on it most likely will twitch a bit - that is normal. When you crank it the tach should rise to about 200 RPM during cranking and then should fall back to zero when you release the key from start back to run (NOT TO OFF). If not that does primary ignition system suspect. This of course assumes the stock tach was working and you still have it.

If you only have your new tach, does the needle rise to 200 RPM during cranking and then fall back to zero after you release the key?

There is a twisted yellow and purple wire that runs from the ICM to the crank sensor located in the middle of the block. Any chance that connector got pulled or disconnected? Is it still plugged in at the ICM (coil pack base)?

No chance you left the crank pick up connector off or left the power connector off at the ICM?

Do you have power on the pink wire of the two wire ICM plug? Assuming so then do you also have ground on the black wire? Best way to test for these is with a 12v test light if you have one since it puts a load on the circuit. If all you have is a meter try it anyways but remember conditions may change once the circuit is under a load (like trying to start the car).

----------------------------

This is the ignition wiring for the DOHC - The tach output wire is shown - Is that the wire you used to feed your tach? The letters are in very small type on the 6 pin connector

[This message has been edited by phonedawgz (edited 08-04-2014).]

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