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21 Hellcat won’t hot restart

1729 Views 18 Replies 12 Participants Last post by  vrwebster
So after getting the turbo kit done and on and the 1700cc injectors installed I am having the worst hot restart issues. Starts fine on the Injector Dynamics data. Countless hours spent on getting the injectors dialed in thinking that was the issue but at this point I don’t think that it is. As soon as the fuel rail temp goes above 90* F it will not hot restart until the rail temp falls below 90 deg. When purging the rails with the pressure tester a ton of air bubbles come out and when the car does start it runs a full point leaner than stoich for the hellcat. I have timed this lean time and it varies between 20 sec and a minute, longer when the car is warm. Also, when hot the fuel pressure goes off the gauge with the car just sitting ignition off. I have read that it’s likely the passenger side fuel module or pump controller, is that my best shot at fixing this? I really do not want to have to drive the car over two hours to get to the dealership I bought it at when the car will not hot restart and I don’t have much confidence in the local dealership after they scuffed the rims just balancing tires and refused to replace. Any help would be great, this really sucks and have never had these kind of issues with a new car. Thanks.
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I hope with that have done to you motor does not void the warranty.
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I hope with that have done to you motor does not void the warranty.
Warranty is long gone.
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You “never had these kind of issues with a new car” ???
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You need to find a local performance shop and tuner. The dealer probably won’t touch a modified car like this especially with a turbo.


If I were you I’d find a performance shop first. If they cant fox or it’s a bigger problem return the car to stock and then go to dealer. As soon as that car shows up at dodge they will void your warranty.
this really sucks and have never had these kind of issues with a new car.
Okay. My post will provide nothing in terms of helping you and I hope you can get it sorted out but for some reason this statement you made stood out to me.

Any highly modified car, which it sounds like yours is, can cause "issues" no matter how new it is. That's part of the game when you start modifying anything.
This is what happens when 807 oem hp is just not enough for some ungodly reason
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Well even tho the glue is crap now goodyear still makes a tire that works pretty good with 11,500 hp

So although it is possible to make more than that, until someone comes up with a different clutch, clutch management system (a mechanical clutch management system so it’s still within the rules) or a better tire, 11,500 seems to be the magic number : )
Get HP Tuners and an MPVI2+ or the MPVI3 and the bypass cable and log it. You can see what happening.
Sounds a lot like vapor lock. Just need to narrow it down to the cause.
How about wrapping the fuel lines and rails in insulating fiber tape or those mirror-blanket things from engine compartment down to near end of engine block?

The bubbles were the first thing I guessed just reading the thread title.

Of what the bubbles are comprised is a question, for me. If it's air, then it's being introduced somewhere if the fuel tank is well full. If this is only a problem upon encountering heat, it makes me wonder if the injectors themselves are leaking when hot and air is slipping into them and making its way up into where fuel should be, but I don't know the quality of the 1700cc injectors.

If the bubbles are vaporized something in the fuel, trying some pricey racing gasoline to get rid of all fuel that may have low-vapor-temperature whatever in it is one way to diagnose. If the rail temps are supposedly 90°C, then the fuel may be over 100°C in some local zones of the fuel system, which would cause water to vaporize.

But, as I stated, (preferably mirrored) insulating sleeves over the fuel lines and rails would help allay the problem regardless, as if it is mainly a problem when hot, then helping the fuel stay cool just solves it.

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How about wrapping the fuel lines and rails in insulating fiber tape or those mirror-blanket things from engine compartment down to near end of engine block?

The bubbles were the first thing I guessed just reading the thread title.

Of what the bubbles are comprised is a question, for me. If it's air, then it's being introduced somewhere if the fuel tank is well full. If this is only a problem upon encountering heat, it makes me wonder if the injectors themselves are leaking when hot and air is slipping into them and making its way up into where fuel should be, but I don't know the quality of the 1700cc injectors.

If the bubbles are vaporized something in the fuel, trying some pricey racing gasoline to get rid of all fuel that may have low-vapor-temperature whatever in it is one way to diagnose. If the rail temps are supposedly 90°C, then the fuel may be over 100°C in some local zones of the fuel system, which would cause water to vaporize.

But, as I stated, (preferably mirrored) insulating sleeves over the fuel lines and rails would help allay the problem regardless, as if it is mainly a problem when hot, then helping the fuel stay cool just solves it.

I put some gold heat reflective foil over the fuel lines by the headers and it did seem to alleviate the issue temporarily. Long enough that it gave me false hopes. Ten minutes after that I went to log it and it wouldn’t start again until the rail temps went under 90* or I purged a mason jar of fuel out until no more bubbles. I will be putting a new fuel pump control module in it tomorrow to see if that helps at all. My question now is if the injectors are leaking which they do not seem to be doing because rail pressure stays constant with the ignition off and the car cold, how could air slip into the injector when fuel pressure is staying at 80+ psi, you would think it would leak right?
Okay. My post will provide nothing in terms of helping you and I hope you can get it sorted out but for some reason this statement you made stood out to me.

Any highly modified car, which it sounds like yours is, can cause "issues" no matter how new it is. That's part of the game when you start modifying anything.
Your telling me! I build and tune a lot of high performance cars at the shop with larger injectors and turbos the whole 9 and have never had any issues like this, one where the calibration seems to have little effect on what’s happening. I always tell my customers the same thing!
I put some gold heat reflective foil over the fuel lines by the headers and it did seem to alleviate the issue temporarily. Long enough that it gave me false hopes. Ten minutes after that I went to log it and it wouldn’t start again until the rail temps went under 90* or I purged a mason jar of fuel out until no more bubbles. I will be putting a new fuel pump control module in it tomorrow to see if that helps at all. My question now is if the injectors are leaking which they do not seem to be doing because rail pressure stays constant with the ignition off and the car cold, how could air slip into the injector when fuel pressure is staying at 80+ psi, you would think it would leak right?
Yes, if pressure is high, air is not getting IN. However, pressure is staying high and bubbles are forming. I wonder if the pressure is staying high BECAUSE some of the content of the fuel lines is turning into more-voluminous gas bubbles.

But, the foil you are putting on the rails, is it foil with insulating blanket material underneath it? If not, it is reflecting heat but not insulating. I suggest the blanket material with foil on the outside. Here's one that zips up with Velcro:

The product page I directed to has blanket with reflective surfaces, I think.

But, as I said, try a can of the super-high-zoot racing gasoline and see if it solves the problem. If so, your gas has something in it that evaporates too readily, forming bubbles. If it is E-anything gas, then water can become entrained in the fuel by being dissolved by the alcohol, but as distillers know, water can be evaporated directly from the alcohol (or vice versa) by heating the solution.

For you research-minded people, the boiling point of ethanol is only 78.23°C. That is, now that I've looked that up, my suspect for the gaseous substance you find making up the bubbles at 90°C.
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Yes, if pressure is high, air is not getting IN. However, pressure is staying high and bubbles are forming. I wonder if the pressure is staying high BECAUSE some of the content of the fuel lines is turning into more-voluminous gas bubbles.

But, the foil you are putting on the rails, is it foil with insulating blanket material underneath it? If not, it is reflecting heat but not insulating. I suggest the blanket material with foil on the outside. Here's one that zips up with Velcro:

The product page I directed to has blanket with reflective surfaces, I think.

But, as I said, try a can of the super-high-zoot racing gasoline and see if it solves the problem. If so, your gas has something in it that evaporates too readily, forming bubbles. If it is E-anything gas, then water can become entrained in the fuel by being dissolved by the alcohol, but as distillers know, water can be evaporated directly from the alcohol (or vice versa) by heating the solution.

For you research-minded people, the boiling point of ethanol is only 78.23°C. That is, now that I've looked that up, my suspect for the gaseous substance you find making up the bubbles at 90°C.
yeah the reflective foil is oriented correctly. I should have said 90* F. I think another part of the issue is the the motor appears to be closer to the passenger side inner fender which is where the fuel line comes up between the well and header. Suspecting this is the root of the issue but that is going to be a real pain to thread a fuel line line heat blanket around, may just go return style and be done with this issue.
Your telling me! I build and tune a lot of high performance cars at the shop with larger injectors and turbos the whole 9 and have never had any issues like this, one where the calibration seems to have little effect on what’s happening. I always tell my customers the same thing!
What are you using to Tune with, HPTUNERS or Diablo?
What supporting mods have you done, like a T stat the small stuff?
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but that is going to be a real pain to thread a fuel line line heat blanket around,
Hence my suggestion to use the zip-up (with Velcro) style of blanket. It is open from one end to the other, evidently, and you wrap it around, then Velcro it shut.

But, the problem, as Linda and at least one other pointed out, is odd and extremely rare.

If you keep cranking the car over, might it get past the air bubbles? I cranked an old pickup truck once for about ten minutes (it had a yellow Optima before they jumped off the quality deep end) until it actually started. I do not recommend this in any way. I, like others, am curious about what the root problem is, being that it is so unheard-of.

If you are truly fanatically scientifically minded, you can collect the gas from the bubbles over time and then analyze it to determine what the bubbles actually ARE.

We're rooting for you, in any case.
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