sc400 Engine Stall I'm Stumped
07-12-12, 02:09 PM
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sc400 Engine Stall I'm Stumped
Car is a 94 Sc400 and it will start but will immediately stall out. If i bypass the fuel pump ecu by using a jumper wire between FP and b+ the car will idle and run. But the thing is the fuel pump ecu is fine. I swapped out my fuel pump ecu with three other ecu's and i have the same stalling issue. But like i said when its bypassed and the fuel pump is running at a higher speed the engine doesn't stall. I'm stumped and I'm pretty sure its fuel related...
07-12-12, 08:30 PM
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Yes, I have replaced the fuel filter, fuel pump, fuel pulsation damper and the fuel pump ecu. The next part I am going to replace will be the fuel pressure regulator.
It just seems like its something simple, but I just can't seem to piece it together. My best guess is that its a fuel related issue and the engine isn't getting the fuel it needs to run. Possibly the fuel pressure is too low, causing the engine to stall and when trhe fuel pump ecu is bypassed it raises the fuel pressure up enough tha it keeps the engine from stalling. I'm just out of ideas and want to try as much as I can before I have to tow it to a shop,
It just seems like its something simple, but I just can't seem to piece it together. My best guess is that its a fuel related issue and the engine isn't getting the fuel it needs to run. Possibly the fuel pressure is too low, causing the engine to stall and when trhe fuel pump ecu is bypassed it raises the fuel pressure up enough tha it keeps the engine from stalling. I'm just out of ideas and want to try as much as I can before I have to tow it to a shop,
04-07-13, 10:53 PM
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Yes, I have replaced the fuel filter, fuel pump, fuel pulsation damper and the fuel pump ecu. The next part I am going to replace will be the fuel pressure regulator.
It just seems like its something simple, but I just can't seem to piece it together. My best guess is that its a fuel related issue and the engine isn't getting the fuel it needs to run. Possibly the fuel pressure is too low, causing the engine to stall and when trhe fuel pump ecu is bypassed it raises the fuel pressure up enough tha it keeps the engine from stalling. I'm just out of ideas and want to try as much as I can before I have to tow it to a shop,
It just seems like its something simple, but I just can't seem to piece it together. My best guess is that its a fuel related issue and the engine isn't getting the fuel it needs to run. Possibly the fuel pressure is too low, causing the engine to stall and when trhe fuel pump ecu is bypassed it raises the fuel pressure up enough tha it keeps the engine from stalling. I'm just out of ideas and want to try as much as I can before I have to tow it to a shop,
04-08-13, 09:38 AM
#5
Tis the curse of all message boards. Search for someone who had the same problem you face now and 99.999% of the time they never report their results or resolutions. The thread abruptly ends just like all the others you find.
If the car runs ok with the fuel ECU bypassed and it's not the ECU, I'd blame it on the pump itself. It's no spring chicken ya know. Replacing the pump isn't too hard on these cars and hell, I've got a $13 ebay pump in mine with no complaints.
If the car runs ok with the fuel ECU bypassed and it's not the ECU, I'd blame it on the pump itself. It's no spring chicken ya know. Replacing the pump isn't too hard on these cars and hell, I've got a $13 ebay pump in mine with no complaints.
07-08-14, 02:09 PM
#6
I've been chasing similar gremlins since buying my car three months ago. I just ran across a comment that the screw on top of the fuel pressure damper has to be tightened down all the way. I checked mine and it was maybe 1/4 turn from fully tight. After tightening it, the car started right up. As always with this learning ECU, it takes a few days to know if things will stick, but I would definitely suggest that anyone with fuel delivery start-up problems should check that screw.
There's very little info out there about the damper, and this is one of the threads that turned up while searching for additional tuning/testing of it.
There's very little info out there about the damper, and this is one of the threads that turned up while searching for additional tuning/testing of it.
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07-08-14, 08:11 PM
#8
As far as I've been able to find, "fuel pump relay" is a common misnomer for fuel pump ECU. The relay itself is part of the Main/EFI fuse. Which did you mean?
As for the fuel pump ECU, everyone and their mom has suggested that for you name what purpose. It doesn't fit the symptoms, and bypassing it wasn't the solution for me. My situation, and I suspect that of several others who have struggled to determine the cause of long starts, is that it frequently doesn't catch the first time the key is turned to On, at least not for ~3 seconds. However, I've recently discovered that I can bump the starter for a fraction of a second, wait, then turn the key again and it'll catch instantly every time. The pump and ECU work fine, but the system isn't maintaining fuel pressure.
My thinking has been fuel pressure regulator, and I ordered a new one recently to swap in, but the part was an inventory mismatch so I'm still waiting for the replacement. I never considered the fuel pulsation damper, though, because there's virtually no information out there as to how to test it or what symptoms it would cause when it's not operating properly. And that fits with why all the "fuel pump ECU" suggestions have failed to address the matter for those struggling with long cranking starts.
Of course, if the problem resurfaces in a couple days, I'll be editing and revising this post.
As for the fuel pump ECU, everyone and their mom has suggested that for you name what purpose. It doesn't fit the symptoms, and bypassing it wasn't the solution for me. My situation, and I suspect that of several others who have struggled to determine the cause of long starts, is that it frequently doesn't catch the first time the key is turned to On, at least not for ~3 seconds. However, I've recently discovered that I can bump the starter for a fraction of a second, wait, then turn the key again and it'll catch instantly every time. The pump and ECU work fine, but the system isn't maintaining fuel pressure.
My thinking has been fuel pressure regulator, and I ordered a new one recently to swap in, but the part was an inventory mismatch so I'm still waiting for the replacement. I never considered the fuel pulsation damper, though, because there's virtually no information out there as to how to test it or what symptoms it would cause when it's not operating properly. And that fits with why all the "fuel pump ECU" suggestions have failed to address the matter for those struggling with long cranking starts.
Of course, if the problem resurfaces in a couple days, I'll be editing and revising this post.
07-08-14, 08:40 PM
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As far as I've been able to find, "fuel pump relay" is a common misnomer for fuel pump ECU. The relay itself is part of the Main/EFI fuse. Which did you mean?
As for the fuel pump ECU, everyone and their mom has suggested that for you name what purpose. It doesn't fit the symptoms, and bypassing it wasn't the solution for me. My situation, and I suspect that of several others who have struggled to determine the cause of long starts, is that it frequently doesn't catch the first time the key is turned to On, at least not for ~3 seconds. However, I've recently discovered that I can bump the starter for a fraction of a second, wait, then turn the key again and it'll catch instantly every time. The pump and ECU work fine, but the system isn't maintaining fuel pressure.
My thinking has been fuel pressure regulator, and I ordered a new one recently to swap in, but the part was an inventory mismatch so I'm still waiting for the replacement. I never considered the fuel pulsation damper, though, because there's virtually no information out there as to how to test it or what symptoms it would cause when it's not operating properly. And that fits with why all the "fuel pump ECU" suggestions have failed to address the matter for those struggling with long cranking starts.
Of course, if the problem resurfaces in a couple days, I'll be editing and revising this post.
As for the fuel pump ECU, everyone and their mom has suggested that for you name what purpose. It doesn't fit the symptoms, and bypassing it wasn't the solution for me. My situation, and I suspect that of several others who have struggled to determine the cause of long starts, is that it frequently doesn't catch the first time the key is turned to On, at least not for ~3 seconds. However, I've recently discovered that I can bump the starter for a fraction of a second, wait, then turn the key again and it'll catch instantly every time. The pump and ECU work fine, but the system isn't maintaining fuel pressure.
My thinking has been fuel pressure regulator, and I ordered a new one recently to swap in, but the part was an inventory mismatch so I'm still waiting for the replacement. I never considered the fuel pulsation damper, though, because there's virtually no information out there as to how to test it or what symptoms it would cause when it's not operating properly. And that fits with why all the "fuel pump ECU" suggestions have failed to address the matter for those struggling with long cranking starts.
Of course, if the problem resurfaces in a couple days, I'll be editing and revising this post.
07-08-14, 10:09 PM
#10
My own experience in recent weeks with stalling is quite a bit different, actually. Mine seemed to be due to TPS and throttle stop screw settings. These things can have so many different scenarios and solutions, it's rather useless if not dangerous to throw fixes out there without sufficient supporting detail.
Otherwise, people stumble upon the threads years later and get led off in the wrong direction...
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