Help- Dies After Cold Start/Fuel Issue

b-pinkerton

b-pinkerton

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I have been having starting the Roxor for the first time of the morning when its cold (25-40F). Or more specifically, problems keeping it running. I have noticed that it takes longer for the the fuel pump to stop priming the engine than it used to. I recently installed the KMS Stage 3 and didn't have this problem before. It fires right up but dies unless I keep the RPS up around 1200+. Seems to go away after it warms up. But it has
Has anyone else had a
 
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Bhayarock

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I have been having starting the Roxor for the first time of the morning when its cold (25-40F). Or more specifically, problems keeping it running. I have noticed that it takes longer for the the fuel pump to stop priming the engine than it used to. I recently installed the KMS Stage 3 and didn't have this problem before. It fires right up but dies unless I keep the RPS up around 1200+. Seems to go away after it warms up. But it has
Has anyone else had a
I dont know..Since you are using kms, I hope you must have the factory ecu to rule out tune issue..
Based on the issue you described... the ecu will based on temperature, oxygen etc will send the fuel to injectors but looks like that the correct fuel mixure for ideal combustion is not happening as it's not reaching ideal RPM to warm up the engine and you need to press the gas pedal / increase rpm to dump more fuel for idle.

Just my theory from my experience but I can be totally wrong here.
 
b-pinkerton

b-pinkerton

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I dont know..Since you are using kms, I hope you must have the factory ecu to rule out tune issue..
Based on the issue you described... the ecu will based on temperature, oxygen etc will send the fuel to injectors but looks like that the correct fuel mixure for ideal combustion is not happening as it's not reaching ideal RPM to warm up the engine and you need to press the gas pedal / increase rpm to dump more fuel for idle.

Just my theory from my experience but I can be totally wrong here.
I have not tired swapping back to the original but plan on it to rule it out. I never have it with me when there is an issue or else I’d have tried. I called KMS to ask them about it Because it happened the next day after installing their CPU. They said they’d call me back but never did. I had wondered if fuel has been bleeding back into the tank and not staying in the line because it takes about 20-30 seconds to prime. Usually it’s just a few seconds.
 
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Bhayarock

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I have not tired swapping back to the original but plan on it to rule it out. I never have it with me when there is an issue or else I’d have tried. I called KMS to ask them about it Because it happened the next day after installing their CPU. They said they’d call me back but never did. I had wondered if fuel has been bleeding back into the tank and not staying in the line because it takes about 20-30 seconds to prime. Usually it’s just a few seconds.
It should not take more than couple of seconds... for fuel priming..something seems off, although I dont think fuel is bleeding back if its bleeding back its indicative of a leak in that case you might not have been able to start at all... Try switching the ECUs....looks like a faulty tune to me.
 
b-pinkerton

b-pinkerton

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It should not take more than couple of seconds... for fuel priming..something seems off, although I dont think fuel is bleeding back if its bleeding back its indicative of a leak in that case you might not have been able to start at all... Try switching the ECUs....looks like a faulty tune to me.
I had one of my mechanics listen to it yesterday morning. It wasn’t very cold so it stayed running, but if I revved and let off, it would die. I had about a whole 2 mins to mess with it so I didn’t get to swap CPU out. He thinks it’s definitely a fuel issue though.
I will swap out cpu Monday early when it’s still cold outside (west texas 40 degrees).
 
b-pinkerton

b-pinkerton

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Update: I swapped back and forth with original CPU and KMS CPU. I am thinking the problem is the KMS tuner, I would do a few revs and it would die like before when I let off. Original would rev just fine and stay idling when I left off. Both tuners would still take a long time to prime engines though. My mechanic is going to hook up a fuel pressure gauge on my pump to see if we are losing any pressure or where at. If not, I am going to be calling KMS back and trying to get them to help.
 
Paulson

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let us know how it goes. i am thinking about going the kms wrought.
 
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Bhayarock

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Update: I swapped back and forth with original CPU and KMS CPU. I am thinking the problem is the KMS tuner, I would do a few revs and it would die like before when I let off. Original would rev just fine and stay idling when I left off. Both tuners would still take a long time to prime engines though. My mechanic is going to hook up a fuel pressure gauge on my pump to see if we are losing any pressure or where at. If not, I am going to be calling KMS back and trying to get them to help.
Glad it was not something major ( non tune related). Regarding your fuel concerns, I hope you are talking to your dealership mechanic and not your personal mechanic for warranty reasons and also at the dealer you will have other brand new roxors for comparison and base lining with respect to fuel priming.
 
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Bhayarock

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let us know how it goes. i am thinking about going the kms wrought.
From what I have heard people have very mixed experience with KMS.
The sweet thing is that you get a new ECU but it can be a hit or miss.
However RxR performance and Diesel freaks have the best reviews and both are pretty experienced with diesel tuning, active with their support on Facebook and over call.
Followed by Vivid who were the first one to bring in the tune but looks like they lost their interest, support and never innovated further like the Diesel freaks or RxR. The only bad side is these tunes will reprogram your existing ECU and not give you a new 1.
 
Paulson

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thank you. i have delt with diesel freak in the past. great guys. but i dont like being strong armed into there clutch.
 
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Bhayarock

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thank you. i have delt with diesel freak in the past. great guys. but i dont like being strong armed into there clutch.
I dont think their stage 1 which gives you about 80 HP, they ask you for a clutch,(EGR delete is optional) in fact I have heard Wade himself from Diesel Frks saying that stock clutch is good as long as you are not planning on wheeling hard even with their stage 2 115hp.
 
sandyx

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I've never seen Wade enforcing clutch upgrade on anyone even for Stage2. In fact he's very clear about the use case & expected clutch life.
I'd suggest go with DF, RXR or Calibrated tunes. Calibrated did some neat r&d on the Stage3, whatever may the outcome be. They all seem to know what they are doing unlike that oh-so-defensive 'stage3' guy & vivid.
 
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