causes of start-up hesitation?
07-28-14, 02:38 AM
#16
It's enough to drive for 10-15min after warm-up for the trims to be almost fully collected
You can use 1Wt bulb in place of jumper to be sure you won't burn anything
Your mechanic must already know about the trims and how to read them, otherwise get rid of him )
You can use 1Wt bulb in place of jumper to be sure you won't burn anything
Your mechanic must already know about the trims and how to read them, otherwise get rid of him )
07-19-15, 10:29 PM
#17
It's only been two days, and I'm wary of jumping the gun on "fixes" with the SC's learning ECU, but I think I've finally solved this. OUChase pointed me on the right path with the fuel tank banjo bolts potentially allowing vapor leakage if missing a crush washer. I was "missing" one on the evap return line, but I think that's the factory design on earlier models for some reason.
What I did find was a return line rubber hose that was incredibly loose on the hard line. When I removed the pinch clamp -- those small clamps are light enough pressure to easily remove by hand -- the hose slid right off the barb. I can't imagine that was forming a tight seal with the clamp on.
https://www.clublexus.com/forums/per...njo-bolts.html
In addition to breathing a sigh of relief if truly fixed, I'm also looking forward to seeing if it has any impact on mpg.
What I did find was a return line rubber hose that was incredibly loose on the hard line. When I removed the pinch clamp -- those small clamps are light enough pressure to easily remove by hand -- the hose slid right off the barb. I can't imagine that was forming a tight seal with the clamp on.
https://www.clublexus.com/forums/per...njo-bolts.html
In addition to breathing a sigh of relief if truly fixed, I'm also looking forward to seeing if it has any impact on mpg.
07-25-16, 02:08 AM
#18
t2d2, I've only just now found your thread. Your SC400's symptoms sound somewhat similar to the ever-present starting issue I described in my long "Suspect My SC300 M/T ECU Needs Repair" thread. I actually still have that issue despite having solved many others.
So parts of the fuel tank feed and return lines can go bad or may need crush washers replaced? That was ultimately the cause of the strange startup hesitation for you?
Recently I've wondered if it's my original 241k mile fuel pump having issues but I have no issues while the car is driving-- just as yours did not. And I recently had a brand new FPR installed as well as a new fuel filter. And many other things as you know from my thread.
Just going out on a limb here to see if this is possibly something I have overlooked. Every other issue has been solved on my car other than this one.
So parts of the fuel tank feed and return lines can go bad or may need crush washers replaced? That was ultimately the cause of the strange startup hesitation for you?
Recently I've wondered if it's my original 241k mile fuel pump having issues but I have no issues while the car is driving-- just as yours did not. And I recently had a brand new FPR installed as well as a new fuel filter. And many other things as you know from my thread.
Just going out on a limb here to see if this is possibly something I have overlooked. Every other issue has been solved on my car other than this one.
07-25-16, 08:12 AM
#19
Yep, dry rotted return fuel line turned out to be the main culprit. FPR, fuel filter, fuel pump +12V bypass, fuel injectors, caps/rotors, O2 sensors... None of it made a dent in the problem, although replacing vacuum lines seemed to help slightly. That loss of fuel pressure at the tank, though, that was the root of it. Hasn't been an issue since replacing that short run of hose.
I only messed with the tank itself and crush washers because I was chasing down every last angle and thought something might be plugged in the tank's venting. One of the washers seemed to be missing (good luck making sense of the factory placement of washers; much like the asymmetrical use of spacers on the moon roof mount), but wasn't the cause. I found the not-even-finger-tight hose pretty much by accident.
I only messed with the tank itself and crush washers because I was chasing down every last angle and thought something might be plugged in the tank's venting. One of the washers seemed to be missing (good luck making sense of the factory placement of washers; much like the asymmetrical use of spacers on the moon roof mount), but wasn't the cause. I found the not-even-finger-tight hose pretty much by accident.
07-25-16, 09:32 AM
#20
I have discussed with Kahn this similar hesitation issue that I have in my recently purchased 92SC3 5speed. Reading your previous posts, it made me remember something: This cold start hesitation has recently been going on for a week and a half (I don't drive it much); I stopped at the station to fill up and noticed the fuel cap was hard to turn and there was an immense amount of pressure once loosened. The cold start following this fuel fill up was perfect with no hesitation, but thereafter, the it went back to hesitation after having driven a few miles. I hope this is the answer to what Kahn and I are experiencing.
I am not familiar with fuel systems. Can you explain where the rubber hoses you replaced are located?
I am not familiar with fuel systems. Can you explain where the rubber hoses you replaced are located?
Last edited by nsjuice; 07-25-16 at 09:42 AM.
07-25-16, 09:50 AM
#21
I investigated the fuel cap and tank pressure, but that's apparently normal for these cars.
The fuel line hoses are directly below the tank, tucked up into the subframe area. Best way to find them is to climb under the car and follow the hard lines from the fuel filter back to the tank. The one on the driver's side is supply and return is on the passenger side, as I recall. I think there's a second one on the passenger side for venting to the charcoal canister, but it's been a year.
The fuel line hoses are directly below the tank, tucked up into the subframe area. Best way to find them is to climb under the car and follow the hard lines from the fuel filter back to the tank. The one on the driver's side is supply and return is on the passenger side, as I recall. I think there's a second one on the passenger side for venting to the charcoal canister, but it's been a year.
07-25-16, 10:13 AM
#22
Thank you, I'll try and find a diagram and give it a shot.
I investigated the fuel cap and tank pressure, but that's apparently normal for these cars.
The fuel line hoses are directly below the tank, tucked up into the subframe area. Best way to find them is to climb under the car and follow the hard lines from the fuel filter back to the tank. The one on the driver's side is supply and return is on the passenger side, as I recall. I think there's a second one on the passenger side for venting to the charcoal canister, but it's been a year.
The fuel line hoses are directly below the tank, tucked up into the subframe area. Best way to find them is to climb under the car and follow the hard lines from the fuel filter back to the tank. The one on the driver's side is supply and return is on the passenger side, as I recall. I think there's a second one on the passenger side for venting to the charcoal canister, but it's been a year.
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