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Re: Sniper EFI bad injector [Re: MarkZ] #2933338
06/14/21 08:58 PM
06/14/21 08:58 PM
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I'd be double, triple, quadruple checking that wiring.
Also depending on how it's plumbed and where the filters are, a miniscule piece of anything inside the line or hose beyond the filters could have hung it open. I typically hard plumb everything, deburr the ends and blow compressed air through both lines and hose just before install. This one would make me nervous for a while unless I found the reason for it happening eek beer

Re: Sniper EFI bad injector [Re: TJP] #2933985
06/16/21 04:37 PM
06/16/21 04:37 PM
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MarkZ Offline OP
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Alright, spoke too soon I guess. That hole wasn't spewing gas because the injector wasn't firing. The first time I put it back together one of the pins didn't line up properly. The plug itself is just a couple of pins free floating - no molded plastic to keep them centered. After assembling it a second time it started spewing gas out the barrel that had the original problem. This is after swapping the injectors front to back. Has to be electrical, but I couldn't find anything glaringly wrong with it. Back to Holley it goes. Already have a return label. Thank you everyone for your help.


1987 Fifth Avenue - 512/518/D60
Re: Sniper EFI bad injector [Re: MarkZ] #2934022
06/16/21 07:14 PM
06/16/21 07:14 PM
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By doing that test you proved that it was a problem with the injector driver circuit so Holley tech support should have been willing to do an ECU swap. If you hadn't done that test then they would've played 20 questions with you. Once you are able to prove that it isn't an injector problem then it gets easier to get a swap. Bummer on the whole thing since it chews up time but that kind of stuff happens. Parts fail sometimes.

Re: Sniper EFI bad injector [Re: MarkZ] #2934064
06/16/21 09:08 PM
06/16/21 09:08 PM
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Originally Posted by MarkZ
Alright, spoke too soon I guess. That hole wasn't spewing gas because the injector wasn't firing. The first time I put it back together one of the pins didn't line up properly. The plug itself is just a couple of pins free floating - no molded plastic to keep them centered. After assembling it a second time it started spewing gas out the barrel that had the original problem. This is after swapping the injectors front to back. Has to be electrical, but I couldn't find anything glaringly wrong with it. Back to Holley it goes. Already have a return label. Thank you everyone for your help.


So I'm a bit confused ( not unusual LOL)
Quote
After assembling it a second time it started spewing gas out the barrel that had the original problem

Is that with another injector or the same one? I assuming a different Injector as you're now suspecting an electrical issue.

SNIPER earlier mentioned he believes they are fired off a ground signal. If so, just out of curiosity, I might try to disconnect the signal wire at the ECU to see if the injector shuts off. That would confirm 2 things. It is the ECU, and that you do not have a pinched wire or other erroneous problem. beer

Re: Sniper EFI bad injector [Re: MarkZ] #2934180
06/17/21 10:24 AM
06/17/21 10:24 AM
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Originally Posted by MarkZ
I've got about $1500 tied up into mine between the pump, unit and fittings. It's been on the car for three years now, so well outside warranty. What little I've been able to find it looks like the injectors are proprietary and Holley won't sell them separate. I really don't want to send this back to them for service. Car has been down long enough.


Was this the first time firing up in the 3 years you have had it?

Re: Sniper EFI bad injector [Re: mshred] #2934246
06/17/21 01:06 PM
06/17/21 01:06 PM
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Originally Posted by mshred
Originally Posted by MarkZ
I've got about $1500 tied up into mine between the pump, unit and fittings. It's been on the car for three years now, so well outside warranty. What little I've been able to find it looks like the injectors are proprietary and Holley won't sell them separate. I really don't want to send this back to them for service. Car has been down long enough.


Was this the first time firing up in the 3 years you have had it?


No, it was running in the fall. Originally took it apart to swap valve springs as the builder had the wrong ones in place. Sniper unit sat on the top of the car over the winter.


1987 Fifth Avenue - 512/518/D60
Re: Sniper EFI bad injector [Re: TJP] #2934249
06/17/21 01:13 PM
06/17/21 01:13 PM
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Originally Posted by TJP
Originally Posted by MarkZ
Alright, spoke too soon I guess. That hole wasn't spewing gas because the injector wasn't firing. The first time I put it back together one of the pins didn't line up properly. The plug itself is just a couple of pins free floating - no molded plastic to keep them centered. After assembling it a second time it started spewing gas out the barrel that had the original problem. This is after swapping the injectors front to back. Has to be electrical, but I couldn't find anything glaringly wrong with it. Back to Holley it goes. Already have a return label. Thank you everyone for your help.


So I'm a bit confused ( not unusual LOL)
Quote
After assembling it a second time it started spewing gas out the barrel that had the original problem

Is that with another injector or the same one? I assuming a different Injector as you're now suspecting an electrical issue.

SNIPER earlier mentioned he believes they are fired off a ground signal. If so, just out of curiosity, I might try to disconnect the signal wire at the ECU to see if the injector shuts off. That would confirm 2 things. It is the ECU, and that you do not have a pinched wire or other erroneous problem. beer


Had the original problem of the rear passenger barrel blowing fuel all over the place. Swapped injectors front to back on Andy's suggestion and observed it wasn't doing that anymore. Upon further inspection though I noticed the passenger rear injector wasn't firing at all. Turned out I didn't plug it in correctly (pins float and aren't held in place in a molded plug). After I corrected that mistake the original problem came back with the passenger rear barrel blowing fuel again. This was with the injectors being swapped, so I can only conclude now it's an electrical fault since the issue didn't follow the injector.


1987 Fifth Avenue - 512/518/D60
Re: Sniper EFI bad injector [Re: MarkZ] #2934258
06/17/21 01:57 PM
06/17/21 01:57 PM
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Look for short to ground on the trigger wire for that injector. Typically all the injectors share a common power feed (+). The injectors are turned-on (activated) by supplying a ground to the individual injector. Each injector has it's own driver in the control module (typically). This is the case for your set-up. Simply unplug the the offending injector and back-probe each wire in the terminal. You can front probe if you're careful to not damage the female terminal in the connector. It's really easy to permanently spread the terminal with a probe from the DVOM lead so it's best to back probe the connector. You can use a small t-pin to slip past the weather seal.

First measure for voltage at each wire at the injector connector KOEO using battery ground terminal for DVOM common. One should read source (battery) voltage, the other should read zero, or may fluctuate in mV. Probe the terminal that reads source voltage. Next, move the DVOM common lead from the battery negative to the other terminal in the injector plug. If you read anything other than zero or a floating mV then the trigger wire/terminal/driver in shorted to ground. Unplug the harness from the PCM/controller to help isolate the location of the fault and use the resistance function on the DVOM. With the harness unplugged from from the controller both leads should read OL (over limit or out of limit) when measured to battery negative. Turn the key off before you unplug the harness. You may also want to wiggle the harness to see if the problem is intermittently grounding and to help locate the location of the short.

If you don't have a dvom you can use a 12v test light or a small 12v bulb in a bulb-socket with a couple of leads. If the bulb lights-up when connected to the injector terminals then you've got a shorted trigger wire.

Chances are the wire is pinched or has melted somewhere in the harness.

Re: Sniper EFI bad injector [Re: Moparteacher] #2934357
06/17/21 08:35 PM
06/17/21 08:35 PM
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Originally Posted by Moparteacher
Look for short to ground on the trigger wire for that injector. Typically all the injectors share a common power feed (+). The injectors are turned-on (activated) by supplying a ground to the individual injector. Each injector has it's own driver in the control module (typically). This is the case for your set-up. Simply unplug the the offending injector and back-probe each wire in the terminal. You can front probe if you're careful to not damage the female terminal in the connector. It's really easy to permanently spread the terminal with a probe from the DVOM lead so it's best to back probe the connector. You can use a small t-pin to slip past the weather seal.

First measure for voltage at each wire at the injector connector KOEO using battery ground terminal for DVOM common. One should read source (battery) voltage, the other should read zero, or may fluctuate in mV. Probe the terminal that reads source voltage. Next, move the DVOM common lead from the battery negative to the other terminal in the injector plug. If you read anything other than zero or a floating mV then the trigger wire/terminal/driver in shorted to ground. Unplug the harness from the PCM/controller to help isolate the location of the fault and use the resistance function on the DVOM. With the harness unplugged from from the controller both leads should read OL (over limit or out of limit) when measured to battery negative. Turn the key off before you unplug the harness. You may also want to wiggle the harness to see if the problem is intermittently grounding and to help locate the location of the short.

If you don't have a dvom you can use a 12v test light or a small 12v bulb in a bulb-socket with a couple of leads. If the bulb lights-up when connected to the injector terminals then you've got a shorted trigger wire.

Chances are the wire is pinched or has melted somewhere in the harness.


iagree but I beat you to it LOL beer

Re: Sniper EFI bad injector [Re: TJP] #2934447
06/18/21 08:23 AM
06/18/21 08:23 AM
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Originally Posted by TJP
Originally Posted by Moparteacher
Look for short to ground on the trigger wire for that injector. Typically all the injectors share a common power feed (+). The injectors are turned-on (activated) by supplying a ground to the individual injector. Each injector has it's own driver in the control module (typically). This is the case for your set-up. Simply unplug the the offending injector and back-probe each wire in the terminal. You can front probe if you're careful to not damage the female terminal in the connector. It's really easy to permanently spread the terminal with a probe from the DVOM lead so it's best to back probe the connector. You can use a small t-pin to slip past the weather seal.

First measure for voltage at each wire at the injector connector KOEO using battery ground terminal for DVOM common. One should read source (battery) voltage, the other should read zero, or may fluctuate in mV. Probe the terminal that reads source voltage. Next, move the DVOM common lead from the battery negative to the other terminal in the injector plug. If you read anything other than zero or a floating mV then the trigger wire/terminal/driver in shorted to ground. Unplug the harness from the PCM/controller to help isolate the location of the fault and use the resistance function on the DVOM. With the harness unplugged from from the controller both leads should read OL (over limit or out of limit) when measured to battery negative. Turn the key off before you unplug the harness. You may also want to wiggle the harness to see if the problem is intermittently grounding and to help locate the location of the short.

If you don't have a dvom you can use a 12v test light or a small 12v bulb in a bulb-socket with a couple of leads. If the bulb lights-up when connected to the injector terminals then you've got a shorted trigger wire.

Chances are the wire is pinched or has melted somewhere in the harness.


iagree but I beat you to it LOL beer


I believe I beat both of you.

Re: Sniper EFI bad injector [Re: Sniper] #2934481
06/18/21 10:45 AM
06/18/21 10:45 AM
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Originally Posted by Sniper
Originally Posted by TJP
Originally Posted by Moparteacher
Look for short to ground on the trigger wire for that injector. Typically all the injectors share a common power feed (+). The injectors are turned-on (activated) by supplying a ground to the individual injector. Each injector has it's own driver in the control module (typically). This is the case for your set-up. Simply unplug the the offending injector and back-probe each wire in the terminal. You can front probe if you're careful to not damage the female terminal in the connector. It's really easy to permanently spread the terminal with a probe from the DVOM lead so it's best to back probe the connector. You can use a small t-pin to slip past the weather seal.

First measure for voltage at each wire at the injector connector KOEO using battery ground terminal for DVOM common. One should read source (battery) voltage, the other should read zero, or may fluctuate in mV. Probe the terminal that reads source voltage. Next, move the DVOM common lead from the battery negative to the other terminal in the injector plug. If you read anything other than zero or a floating mV then the trigger wire/terminal/driver in shorted to ground. Unplug the harness from the PCM/controller to help isolate the location of the fault and use the resistance function on the DVOM. With the harness unplugged from from the controller both leads should read OL (over limit or out of limit) when measured to battery negative. Turn the key off before you unplug the harness. You may also want to wiggle the harness to see if the problem is intermittently grounding and to help locate the location of the short.

If you don't have a dvom you can use a 12v test light or a small 12v bulb in a bulb-socket with a couple of leads. If the bulb lights-up when connected to the injector terminals then you've got a shorted trigger wire.

Chances are the wire is pinched or has melted somewhere in the harness.


iagree but I beat you to it LOL beer


I believe I beat both of you.


beer up

Re: Sniper EFI bad injector [Re: TJP] #2938959
07/02/21 09:38 AM
07/02/21 09:38 AM
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MarkZ Offline OP
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Just an update. Holley called yesterday and repaired the unit. Faulty injector driver. Cost me $250 seeing as how it was out of warranty. I'm happy though. Only took them a week to turn it around and they covered shipping there and back.


1987 Fifth Avenue - 512/518/D60
Re: Sniper EFI bad injector [Re: MarkZ] #2938978
07/02/21 11:03 AM
07/02/21 11:03 AM
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Glad you got it fixed.
Price seems a little high? How old is the system, and what does a new complete Sniper cost?

Re: Sniper EFI bad injector [Re: BDW] #2939093
07/02/21 06:27 PM
07/02/21 06:27 PM
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Originally Posted by BDW
Glad you got it fixed.
Price seems a little high? How old is the system, and what does a new complete Sniper cost?


New unit is $1k. Mine is three years old. The tech said they replaced the logic board too.


1987 Fifth Avenue - 512/518/D60
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