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Resolved 1g stall - hot 12v feed to Fuel pump from relay

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AWD-Tony

Proven Member
6,801
3,735
Sep 11, 2017
Cincinnati, Ohio
I have just under 1/4 tank of e85 and I've ran it lower before on 93 no problem. Made a sharp right and the car stalled. Took a while before it started back up. Luckily this started happening in the subdivision and was able to get it home. Let it idle in the garage while taking out groceries, and it was fine. Looking at the log, it does look like low fuel as IDC shows 0 when this happens. Stalling starts at 223 mark.

Does my fuel pump look too high on the hanger?

Let me know what you think.

Thanks
Tony

646c8156-95cb-4128-b7bf-dd60d18bbc90-jpeg.594195
 

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  • Stall.2020.06.03-03.elg
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Is the bottom of the pump resting on the metal case piece that goes on the bottom of the hanger T?
I am looking at the position of the sending unit float in relation to the bottom of the pump is why I ask.
 
Is the bottom of the pump resting on the metal case piece that goes on the bottom of the hanger T?
I am looking at the position of the sending unit float in relation to the bottom of the pump is why I ask.

Yes. It’s bottomed out on it
 
I looked at the log, wouldn't the injectors still "show" their cycle even if no fuel is flowing to them as long as the key is on?
Your log reminds me of my log of when I bent all my valves and the motor was still showing that it was running since I was going down hill.
Look at my log of when that happened. It still shows injector duty but the car was dead from bent valves, still turning over though as I rolled down hill.
 

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  • log.2017.09.09-04 CAR BROKE LOG.elg
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IDC's should not be zero. Sounds like something is shorting out. Are any other signals zeroing out? I would look for a wire that could short to ground while turning.
 
Correct, your injector duty cycle should still be showing even if the fuel pickup uncovered momentarily. The wideband/afr might blip out for a second, but afaik there's no shutoff function when the pump gets uncovered.

Wondering if maybe you have a poor connection or something, worst case an injector driver? I can't look at the log currently, but I'll try to check it later.
 
Aren't the injectors switched on and off by the cas? Double check your wiring there Tony.
 
I checked all critical connectors that could make it stall, even the fuel pump (not the relay) while engine is on and it seems good. I pulled fuel pump wire at 30 seconds and IDC falls to 0 with rpms.

Don't see loss of any other signal.
 

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  • LongIdle.2020.06.03-05.elg
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  • PullFPwire.2020.06.03-05.elg
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IDC's should not be zero. Sounds like something is shorting out. Are any other signals zeroing out? I would look for a wire that could short to ground while turning.

Only other signal that looks strange is the o2 sensor. I'll check that in a little.

Aren't the injectors switched on and off by the cas? Double check your wiring there Tony.

I believe so.

Correct, your injector duty cycle should still be showing even if the fuel pickup uncovered momentarily. The wideband/afr might blip out for a second, but afaik there's no shutoff function when the pump gets uncovered.

Wondering if maybe you have a poor connection or something, worst case an injector driver? I can't look at the log currently, but I'll try to check it later.

Yup AFR's is all the way lean before it stalls. At 240 mark, AFR's go all the way lean and IDC & rpm read zero at 245 when engine turns off.

Think the easiest thing to do right now is to get some fuel before I go for a spin.
 
If the engine is allowed to stop rotating (i.e.- It runs out of fuel while stopped), then yes the IDC's will drop to zero within moments of it losing fuel from the pump.

since I can't look at the logs yet, what is the O2 sensor doing right before you lost IDC's during the turn? STFT?

What's the condition/age of your pump? I'm wondering if maybe it got hot with the low fuel level, and once it sloshed it just shut off for a minute.
 
Yup AFR's is all the way lean before it stalls. At 240 mark, AFR's go all the way lean and IDC & rpm read zero at 245 when engine turns off.

If that's the case, it's almost like the fuel pump shot completely off. A small amount of slosh shouldn't cause it to lose fuel that steadily. Was this just a right hand 90° turn, or was this like a roundabout type thing, where you were in the turn for an extended period of time?

Even if it was a ladder, I can't see the fuel pump losing fuel for that long. If it were a siphon type system, then I could possibly see it sucking a little more air.

FWIW, I usually don't let my tank get under 1/3 to 1/2, so I can't say I've had this problem with my talon. I have however have the issue in a couple of my Toyota pickups, and they were siphon systems with longitudinal mounted tanks. Once below a third of a tank, any hard or extended corner would cause loss of fuel for a moment.

Did you verify the fuel amount visually?
 
If the engine is allowed to stop rotating (i.e.- It runs out of fuel while stopped), then yes the IDC's will drop to zero within moments of it losing fuel from the pump.

since I can't look at the logs yet, what is the O2 sensor doing right before you lost IDC's during the turn? STFT?

What's the condition/age of your pump? I'm wondering if maybe it got hot with the low fuel level, and once it sloshed it just shut off for a minute.

The o2 goes all the way lean before it stalls. STFT before it stalls is -15%.
Pump is brand new about a month or so.
 
If that's the case, it's almost like the fuel pump shot completely off. A small amount of slosh shouldn't cause it to lose fuel that steadily. Was this just a right hand 90° turn, or was this like a roundabout type thing, where you were in the turn for an extended period of time?

Even if it was a ladder, I can't see the fuel pump losing fuel for that long. If it were a siphon type system, then I could possibly see it sucking a little more air.

FWIW, I usually don't let my tank get under 1/3 to 1/2, so I can't say I've had this problem with my talon. I have however have the issue in a couple of my Toyota pickups, and they were siphon systems with longitudinal mounted tanks. Once below a third of a tank, any hard or extended corner would cause loss of fuel for a moment.

Did you verify the fuel amount visually?

It's more like a looping 120*. I haven't check how much fuel is left in the tank but I'm certain my gauge is accurate.
 
Sound like your 120º turning loop is close to home. You could try filling your tank then see if it still stalls. If it does its not the fuel level. May not be the start way to go about this but at least you'll know if it's related to fuel tank.
 
Sound like your 120º turning loop is close to home. You could try filling your tank then see if it still stalls. If it does its not the fuel level. May not be the start way to go about this but at least you'll know if it's related to fuel tank.

It’s the entrance to our subdivision but I can do loops in the cal de sac to slosh the fuel. I’m going to do that first. Don’t want to go down the dsm rabbit hole if I don’t need to.

Thanks for the input guys!!
 
I put two gallon in and drive it to the gas station and filled her up, no problems. Talked to guy in a hellcat while filling up and then ran him on the highway. All is good and it was about 5 miles from home. Then it shut off again. Pulled over and didn’t see anything. I went to check the connection at the fuel pump and the 12v wire the feeds the pump off the relay is hot. I bypassed the relay and drove home without a problem.

Should I start another thread?

It pulled on the hellcat btw :hellyeah::talon::thumb:. Ironic how I have a hellcat fuel pump issue.

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Resistance = heat Tony. Is the connection corroded or in any bad condition? It is only holding the relay on, maybe swap out the relay, coil possibly going bad? IDK but my thoughts.
 
I replaced that one female spade connector and went through every connection on the relay including +12v on the battery, checked resistance for every wire and cleaned the ground. Everything looked good so it could be the relay itself.

I'm going to leave the multimeter along with a spare relay in the car so I can check when/if this happens again. Will also check fuel pressure too which I didn't think of until today and also see if I can run the pump through link.

Since it didn't happen when I eliminated the relay, I'm guessing the pump is good and something on the relay side. Sucks bc I'm going to the track today and hate to be stranded.

I'm going to swap out the relay.
 
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And take a spare with you also. Good Luck! Be Safe! Share how it goes! :thumb::thumb:
 
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