Odd thing with my Omni fuel pump... - Turbo Dodge Forums : Turbo Dodge Forum for Turbo Mopars, Shelbys, Dodge Daytona, Dodge SRT-4, Chrysler PT Cruiser, Omni and more!

Engine Management, Fuel, Spark, EGTs, and Air/Fuel Ratios This forum includes general electrical, modification, tuning, repair, replacement, identification and restoration of all components mentioned above including SMEC, SBEC, Logic Modules, aftermarket engine management, etc. Nitrous oxide posts go in here. This is the place

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post #1 of 21 Old 08-19-2019, 09:30 PM Thread Starter
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Odd thing with my Omni fuel pump...

Hey TD, good to be back with a new Omni project. However, I need some help. I already reached out to another TD'r and we both are a little confused.

I have an 86 GLH, T1. I bought it a while back from a guy who bought it from a guy who bought it from a guy. You know the deal, basically, nobody knew anything about the car when I picked it up. I charged the battery and just for giggles tired to start it. She turned over strong but never tried to kick. So I checked the fuel rail and it was dry. With a little starting fluid she started and idled pretty well. Now, fast forward to recently. I finally got around to working on her again. I checked the fuel pump for power and had 11.2 volts at the plug but the fuel pump would never start. So I figured it was a bad pump and replaced it tonight. Verified the pump works by connecting it to the battery and it checks out. Plugged it into the hanger and turned the key and I get nothing. Since the car does run with starting fluid I do not think it could be the ASD relay issue. I checked continuity on the wires in the hanger just in case and they work, in fact, I checked voltage at the pump itself (in hanger, out of tank) and it had the 11 volts mentioned above. However, I had voltage on both red and black wire at the pump? And, I had voltage for longer than the 7 seconds that the car sends voltage to prime the fuel system (I think it is suppose to be 7 seconds, either way, I never lost voltage). I thought it may be a ground but if that is the case, I wouldn't get voltage at the connector, correct?

Any ideas?
Thanks guys.
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post #2 of 21 Old 08-20-2019, 07:55 AM
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Re: Odd thing with my Omni fuel pump...

Is there fuel in the tank?

There is two fuel pumps in a stock turbo Omni. Which did you change? What type of fuel pump did you buy?
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post #3 of 21 Old 08-20-2019, 09:27 AM Thread Starter
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Re: Odd thing with my Omni fuel pump...

No fuel in the tank, I drained it since it was old and oxidized. I looked and do not have the second pump that some cars have. Unless I missed it some how. I am not trying to run the pump outside of the fuel since I know the fuel will keep it cool, I am just trying to make sure it works before I replace it.
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post #4 of 21 Old 08-20-2019, 09:54 AM
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Re: Odd thing with my Omni fuel pump...

You can manually actuate the ASD relay to be sure you have the proper voltage at the pump connector.
1)Locate the underhood diagnostic connector
2)Ground the DB/YL wire in the diagnostic connector.
3)Turn the key "on".
4)You will now have power at the + coil, injectors and fuel pump.
(This may set a Code 42 in memory, no worries, it is a false code)
Odd thing with my Omni fuel pump...-electrical-diagnostic-connector.jpg

Odd thing with my Omni fuel pump...-6-asd-manual-actuation.jpg

The fuel pump and sending unit both use and share an external body ground, is it still there and connected properly?
Check for continuity to ground (less than 5 ohms) at the fuel pump connector Gray ground wire.


Be sure the Main Controller Ground is properly connected at the fuel rail and firewall.
Odd thing with my Omni fuel pump...-electrical-main-controller-ground-84-89.jpg

Jan
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post #5 of 21 Old 08-20-2019, 10:16 AM Thread Starter
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Re: Odd thing with my Omni fuel pump...

I will check the grounds shortly. Thanks for the advice. I will post my findings later.
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post #6 of 21 Old 08-20-2019, 12:02 PM
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Re: Odd thing with my Omni fuel pump...

Running the pump without fuel will kill the pump very quickly. Don't do it for more than few seconds.
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post #7 of 21 Old 08-20-2019, 07:21 PM Thread Starter
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Re: Odd thing with my Omni fuel pump...

I may have found the issue. I did the continuity check on the GREY wire. I thought the Green was the ground so when I checked it yesterday I didn't pay much attention to it. However, when I checked it I found it as an open wire. So, to test this, I took a long wire, looped it around the grey wire terminal and connected the fuel pump connector. I then ran the wire to the negative side of the battery and then grounded the ASD relay and it kicked in. I then disconnected my ASD ground and just cycled the key and it worked. So, I think I have a bad ground wire. So can anyone give detailed instructions where that wire runs through the car? I will say that I moved the carpet on the passenger side and saw a rats nest of "stereo" wire. Something is bolted under the passenger seat and has all kinds of wires coming out of it for the aftermarket stereo that was in it. Thanks for the help so far everyone.
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post #8 of 21 Old 08-20-2019, 07:24 PM Thread Starter
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Re: Odd thing with my Omni fuel pump...

Oh, one more thing. When I had the ASD grounded, the relay(s) on the driver side shock tower clicked. I expected things to click since they were being energized, but odd thing is they cycled. They would click every few seconds even if nothing was touched. The cooling fan would spin once then shut off too, a few seconds later it would spin again. I hope this car doesn't have a lot of wire gremlins...
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post #9 of 21 Old 08-21-2019, 08:50 AM
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Re: Odd thing with my Omni fuel pump...

AFAIK only the fuel pump power feed runs from the front of the car to the rear of the car, the ground should only run from the connector to the body.

I would not worry about the other relays clicking when you manually actuated the ASD.

One thing at a time, get you pump circuit problem corrected, get the tank back in the car, add fuel and attempt to start the car and we will go from there or...
If the car starts and runs...
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post #10 of 21 Old 08-24-2019, 08:00 PM Thread Starter
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Re: Odd thing with my Omni fuel pump...

Sorry guys, I have been pretty busy this week in between rain showers so I haven't had much time to work on the Omni. However, I did tonight. I removed the interior so I could easily see the wires under the carpet. The ground wire from the fuel pump connector runs all the way up to a connector under the dash just behind the fuse block. I did a continuity check and that wire was good. So, I decided to go ahead and reinstall the pump into the tank since I knew the wires were good, and then the darn Gremlin started playing again. The fuel pump now runs when the ASD relay is grounded. Once the ground is removed the pump stops.

So since the pump was running I thought "why not, lets start it and let it run since it hasn't ran in a long time". It did run last fall, but not anymore. I have no spark now. Ugh!

Well, I am a little lost now, any ideas? I am about to look in my service manuals to try to follow the schematics but does anyone know where the ground goes to after the connector under the dash?

Any idea what to look for to get spark back?
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post #11 of 21 Old 08-24-2019, 08:37 PM Thread Starter
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Re: Odd thing with my Omni fuel pump...

I want to find the actual problem, however, would splicing into the grey ground wire and running it to its own body ground do the same thing as it running through connectors and splices to get to a ground? I would like to begin building the Shelby 2.2 T2 I have in the garage and at that time I could get better access to the wires behind the shock tower. Just curious if that could be a temporary fix.

On a side note, if I read the schematics correctly, the ground moves through multiple locations and ends at the "Panel ground (on left panel roll up panel)" Any idea where that is located?
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post #12 of 21 Old 08-25-2019, 01:07 AM
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Re: Odd thing with my Omni fuel pump...

Try a different HEP sensor.
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post #13 of 21 Old 08-26-2019, 07:18 PM Thread Starter
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Re: Odd thing with my Omni fuel pump...

Replaced the HEP and still no spark.
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post #14 of 21 Old 08-26-2019, 07:31 PM Thread Starter
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Re: Odd thing with my Omni fuel pump...

Is there anywhere on the car that the fuel pump and spark circuit are together? If not maybe a location where they have wires in a close vicinity? I ask because at one point during my tests I got the fuel pump to work correctly on it's own. I wonder if I didnt wiggle the right wire somewhere. I also wonder if I didnt wiggle something lose. My wife and I will go through NAJ's steps for locating a no spark issue. But any input would be appreciated.
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post #15 of 21 Old 08-29-2019, 08:32 AM
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Re: Odd thing with my Omni fuel pump...

The ASD circuit provides power to the Fuel Pump, + Coil and Injectors.

Here are the No Start/No Spark diagnostics.
Post back where the diagnostics lead or if you have any questions/problems/concerns.

No Start/No Spark Diagnostics
https://www.turbododge.com/forums/f4...k-84-90-a.html
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