91 LS engine sputtering, no power problem
09-14-10, 03:01 PM
#33
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Hi all, I have been wrestling with this same problem on a '91 LS400 for several weeks now, would love to see this thing through to the end and post the solution on this forum. I have replaced the fuel pump resistor and relay, as well as given the car a full ignition and fluid tune up, to no avail. It runs like a million bucks now, but still experiences this sputtering/stalling problem when hot. The MAF was replaced by the owner before I started working on it with a used one (retarded), so I have no idea if it is functioning properly, but there are not now nor have there ever been any engine codes on this car. Is there any way to clean these weird MAFs, or do you just have to replace them? I'm going to replace the fuel pump next. Anybody know how I can tell which fuel pump my vehicle has (Aisin or Denso) without actually taking the thing apart to look at it? Is it in the VIN somewhere or something? Or maybe a manufacture date range?
09-14-10, 03:44 PM
#34
Lexus Test Driver
I've had the problem as well for a couple years and have tracked multiple threads on the issue, but I don't think anyone has fixed it. At least not reported a fix. Happens only when hot out and fuel level is at or below maybe 1/3 or less.
Had something interesting happen a couple of weeks ago though that's making me think about the evap system... I was at 5/8 or slightly more on the tank and decided to top it off on a 90+ degree day. I kept the car running while I undid the gas cap and swiped my credit card at the pump. By the time I got the gas nozzle in the car, the idle was going up, then down to almost a stall, then back up, down to a stall, on and on.
I started to fill the tank and by the time I got four or five gallons or so into it, the idle smoothed back out / went back to normal. So now I'm thinking about the EGR/EVAP system, the charcoal canister, and the BVSV Valve...
Also, I've seen some posts where people state they have a lot of pressure in their tanks when they take their gas cap off. I on the other hand, have never had any pressure in my tank when I take off the cap... The first thing I did when the problem started a couple years ago, was to replace the rubber gasket on the gas cap...
So, my question is, what happens when you take the gas cap off when the cars running as far as the evap system goes, and could something in that system be causing the problem? Is there a maintenance schedule on the charcoal canister (replacement)?
Attached at the very bottom is a .pdf diagram of the evap system and component locations, and below is Lexus' description on its function and a pic of some of the evap components.
EVAPORATIVE EMISSION SYSTEM
"The purpose of the Fuel Evaporative Emission Control (EVAP) system is to prevent the escape of fuel vapors (hydrocarbons) from the fuel tank into the atmosphere. In order to reduce hydrocarbons (HC) emissions, evaporated fuel from the fuel tank is routed through the charcoal canister then into the intake manifold for combustion in the cylinders. See Fig. 9 . A coolant temperature sensing Bimetallic Vacuum Switching Valve (BVSV) controls the operation of canister purge."
Had something interesting happen a couple of weeks ago though that's making me think about the evap system... I was at 5/8 or slightly more on the tank and decided to top it off on a 90+ degree day. I kept the car running while I undid the gas cap and swiped my credit card at the pump. By the time I got the gas nozzle in the car, the idle was going up, then down to almost a stall, then back up, down to a stall, on and on.
I started to fill the tank and by the time I got four or five gallons or so into it, the idle smoothed back out / went back to normal. So now I'm thinking about the EGR/EVAP system, the charcoal canister, and the BVSV Valve...
Also, I've seen some posts where people state they have a lot of pressure in their tanks when they take their gas cap off. I on the other hand, have never had any pressure in my tank when I take off the cap... The first thing I did when the problem started a couple years ago, was to replace the rubber gasket on the gas cap...
So, my question is, what happens when you take the gas cap off when the cars running as far as the evap system goes, and could something in that system be causing the problem? Is there a maintenance schedule on the charcoal canister (replacement)?
Attached at the very bottom is a .pdf diagram of the evap system and component locations, and below is Lexus' description on its function and a pic of some of the evap components.
EVAPORATIVE EMISSION SYSTEM
"The purpose of the Fuel Evaporative Emission Control (EVAP) system is to prevent the escape of fuel vapors (hydrocarbons) from the fuel tank into the atmosphere. In order to reduce hydrocarbons (HC) emissions, evaporated fuel from the fuel tank is routed through the charcoal canister then into the intake manifold for combustion in the cylinders. See Fig. 9 . A coolant temperature sensing Bimetallic Vacuum Switching Valve (BVSV) controls the operation of canister purge."
09-15-10, 05:29 AM
#35
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I do have lot's of pressure come out when I open my gas cap. I took the o-ring out of the gas cap the other day and cleaned and lubed it back up. It looked fine. There appears to be no place at all on the original gas cap or O-ring for emissions or pressure to escape from except possible up the middle. There is a small rubber diaphram in the middle of the cap. It doesn't look it can vent to anyplace though.
I'm wondering if this is a California Emissions only problem. Is anybody with a Federal and not CA car having this problem?
My car is a California car.
I'm wondering if this is a California Emissions only problem. Is anybody with a Federal and not CA car having this problem?
My car is a California car.
Last edited by Timinator; 09-15-10 at 09:58 AM.
09-15-10, 09:48 PM
#38
I have had the same problem for about 3 years now I put in a used MAF just the electronics and it worked for a while. I went ahead and got a new MAF from Lexus and no more problems it cost $1142.00 OUCH but I have the car for working as a applications engineer traveling all over So Cal putting 3k per month on the car THERE IS A PLACE IN CARSON CALIF CALL AUTO PARTS DEAL 1-888-231-5287 THEY HAVE THE MAF REFURBISHED FOR ABOUT $490.00 I THINK WITH A YEAR WARRANTY, WHEN I CLEAN MY MAF I USE CRC CLEANER FROM KRAGEN I JUST UN SCREW THE UNIT FROM THE AIR INTAKE AND CLEAN IT AND THE SCREEN AND IT WORKED FOR A WHILE THIS IS THE CHEAPEST WAY TO MAKE IT WORK. I RAN K&N FILTERS FOR 12 YEARS 220,000 MILES AND NO PROBLEMS WITH THE OIL FROM IT. AND STILL USE THEM
09-27-10, 09:14 AM
#40
Driver School Candidate
Thread Starter
Jim, is the valve in your diagram the same as in this thread? https://www.clublexus.com/forums/ls4...valve-vsv.html
Any new findings in regards to the canister? Thanks!
Any new findings in regards to the canister? Thanks!
I've had the problem as well for a couple years and have tracked multiple threads on the issue, but I don't think anyone has fixed it. At least not reported a fix. Happens only when hot out and fuel level is at or below maybe 1/3 or less.
Had something interesting happen a couple of weeks ago though that's making me think about the evap system... I was at 5/8 or slightly more on the tank and decided to top it off on a 90+ degree day. I kept the car running while I undid the gas cap and swiped my credit card at the pump. By the time I got the gas nozzle in the car, the idle was going up, then down to almost a stall, then back up, down to a stall, on and on.
I started to fill the tank and by the time I got four or five gallons or so into it, the idle smoothed back out / went back to normal. So now I'm thinking about the EGR/EVAP system, the charcoal canister, and the BVSV Valve...
Also, I've seen some posts where people state they have a lot of pressure in their tanks when they take their gas cap off. I on the other hand, have never had any pressure in my tank when I take off the cap... The first thing I did when the problem started a couple years ago, was to replace the rubber gasket on the gas cap...
So, my question is, what happens when you take the gas cap off when the cars running as far as the evap system goes, and could something in that system be causing the problem? Is there a maintenance schedule on the charcoal canister (replacement)?
Attached at the very bottom is a .pdf diagram of the evap system and component locations, and below is Lexus' description on its function and a pic of some of the evap components.
EVAPORATIVE EMISSION SYSTEM
"The purpose of the Fuel Evaporative Emission Control (EVAP) system is to prevent the escape of fuel vapors (hydrocarbons) from the fuel tank into the atmosphere. In order to reduce hydrocarbons (HC) emissions, evaporated fuel from the fuel tank is routed through the charcoal canister then into the intake manifold for combustion in the cylinders. See Fig. 9 . A coolant temperature sensing Bimetallic Vacuum Switching Valve (BVSV) controls the operation of canister purge."
Had something interesting happen a couple of weeks ago though that's making me think about the evap system... I was at 5/8 or slightly more on the tank and decided to top it off on a 90+ degree day. I kept the car running while I undid the gas cap and swiped my credit card at the pump. By the time I got the gas nozzle in the car, the idle was going up, then down to almost a stall, then back up, down to a stall, on and on.
I started to fill the tank and by the time I got four or five gallons or so into it, the idle smoothed back out / went back to normal. So now I'm thinking about the EGR/EVAP system, the charcoal canister, and the BVSV Valve...
Also, I've seen some posts where people state they have a lot of pressure in their tanks when they take their gas cap off. I on the other hand, have never had any pressure in my tank when I take off the cap... The first thing I did when the problem started a couple years ago, was to replace the rubber gasket on the gas cap...
So, my question is, what happens when you take the gas cap off when the cars running as far as the evap system goes, and could something in that system be causing the problem? Is there a maintenance schedule on the charcoal canister (replacement)?
Attached at the very bottom is a .pdf diagram of the evap system and component locations, and below is Lexus' description on its function and a pic of some of the evap components.
EVAPORATIVE EMISSION SYSTEM
"The purpose of the Fuel Evaporative Emission Control (EVAP) system is to prevent the escape of fuel vapors (hydrocarbons) from the fuel tank into the atmosphere. In order to reduce hydrocarbons (HC) emissions, evaporated fuel from the fuel tank is routed through the charcoal canister then into the intake manifold for combustion in the cylinders. See Fig. 9 . A coolant temperature sensing Bimetallic Vacuum Switching Valve (BVSV) controls the operation of canister purge."
09-27-10, 01:15 PM
#41
Lexus Test Driver
There's a BVSV and a VSV... If you go back to my post with the diagram, there's also a .pdf attachment at the bottom that shows the location of both valves...
No update / resolution on my end...
No update / resolution on my end...
10-06-10, 05:05 AM
#43
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I've had the problem as well for a couple years and have tracked multiple threads on the issue, but I don't think anyone has fixed it. At least not reported a fix. Happens only when hot out and fuel level is at or below maybe 1/3 or less.
Had something interesting happen a couple of weeks ago though that's making me think about the evap system... I was at 5/8 or slightly more on the tank and decided to top it off on a 90+ degree day. I kept the car running while I undid the gas cap and swiped my credit card at the pump. By the time I got the gas nozzle in the car, the idle was going up, then down to almost a stall, then back up, down to a stall, on and on.
I started to fill the tank and by the time I got four or five gallons or so into it, the idle smoothed back out / went back to normal. So now I'm thinking about the EGR/EVAP system, the charcoal canister, and the BVSV Valve...
Also, I've seen some posts where people state they have a lot of pressure in their tanks when they take their gas cap off. I on the other hand, have never had any pressure in my tank when I take off the cap... The first thing I did when the problem started a couple years ago, was to replace the rubber gasket on the gas cap...
So, my question is, what happens when you take the gas cap off when the cars running as far as the evap system goes, and could something in that system be causing the problem? Is there a maintenance schedule on the charcoal canister (replacement)?
Attached at the very bottom is a .pdf diagram of the evap system and component locations, and below is Lexus' description on its function and a pic of some of the evap components.
EVAPORATIVE EMISSION SYSTEM
"The purpose of the Fuel Evaporative Emission Control (EVAP) system is to prevent the escape of fuel vapors (hydrocarbons) from the fuel tank into the atmosphere. In order to reduce hydrocarbons (HC) emissions, evaporated fuel from the fuel tank is routed through the charcoal canister then into the intake manifold for combustion in the cylinders. See Fig. 9 . A coolant temperature sensing Bimetallic Vacuum Switching Valve (BVSV) controls the operation of canister purge."
Had something interesting happen a couple of weeks ago though that's making me think about the evap system... I was at 5/8 or slightly more on the tank and decided to top it off on a 90+ degree day. I kept the car running while I undid the gas cap and swiped my credit card at the pump. By the time I got the gas nozzle in the car, the idle was going up, then down to almost a stall, then back up, down to a stall, on and on.
I started to fill the tank and by the time I got four or five gallons or so into it, the idle smoothed back out / went back to normal. So now I'm thinking about the EGR/EVAP system, the charcoal canister, and the BVSV Valve...
Also, I've seen some posts where people state they have a lot of pressure in their tanks when they take their gas cap off. I on the other hand, have never had any pressure in my tank when I take off the cap... The first thing I did when the problem started a couple years ago, was to replace the rubber gasket on the gas cap...
So, my question is, what happens when you take the gas cap off when the cars running as far as the evap system goes, and could something in that system be causing the problem? Is there a maintenance schedule on the charcoal canister (replacement)?
Attached at the very bottom is a .pdf diagram of the evap system and component locations, and below is Lexus' description on its function and a pic of some of the evap components.
EVAPORATIVE EMISSION SYSTEM
"The purpose of the Fuel Evaporative Emission Control (EVAP) system is to prevent the escape of fuel vapors (hydrocarbons) from the fuel tank into the atmosphere. In order to reduce hydrocarbons (HC) emissions, evaporated fuel from the fuel tank is routed through the charcoal canister then into the intake manifold for combustion in the cylinders. See Fig. 9 . A coolant temperature sensing Bimetallic Vacuum Switching Valve (BVSV) controls the operation of canister purge."
Funny you mention that. I get sputtering when the engine is cold and it's humid out, or sometimes when the engine is at full operating temperature. I also currently have a Code 71 going on. I cleaned out tons of **** from my EGR valve but the problem persists, code 71 is still on. Maybe all of this has to do with the EGR system.
Has anyone with a blocked off EGR system encountered this problem?
10-08-10, 08:10 PM
#44
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Ok, so I finally solved this problem on my vehicle. Let me just review in case this problem relates to you:
1. Engine starts and runs fine when cold.
2. After running at full operating temperature for some time (varies), the vehicle experiences a severe power loss.
3. After driving for a period of time with the power loss (usually a matter of 2-20 minutes), the car will eventually lose power completely and stall out.
4. After waiting a period of time and allowing the car to cool, the car will generally start up normally and be driveable.
Items of note:
1. The condition was MUCH worse in hot weather
2. The condition was worse when fuel tank was below 1/3
Here's exactly what I did:
1. Replaced the fuel filter. This is always a good idea and I have no regrets. The old one was the original!
2. Replaced Fuel Pump Resistor (Solution in another thread)- Little or no change
3. Next: Replaced Fuel Pump Relay- Little or no change
4. Finally: Replaced Fuel Pump- Problem solved! Works perfectly now!
Other items of note:
The '91 LS400 came from the factory with 2 different fuel pumps, either the Aisan or the Denso. Even after removing mine, I have no idea which one my car came with. I talked with the Lexus people at length, and they told me that these fuel pumps have the exact same application and the exact same wiring. When replacing with aftermarket, IT MAKES ABSOLUTELY NO DIFFERENCE WHICH PUMP YOU HAD TO BEGIN WITH. I know that many aftermarket sources say that "This Bosch pump replaces Aisan", or "This Bosch pump replaces Denso" and so on and so forth, but it makes no difference! Just buy the cheapest one. I know all of the "Hank Hill" types on here will say, "Replace parts with genuine OEM parts, you need the Denso, my Lexus can tell what ATF I use, I swear to the Toyota God it can, blah blah blah" and so forth but in reality it doesn't matter. I got one from RockAuto that has the exact same guarantee that Denso offers for under $50 and my car is fixed. So that's my 2 cents. Hope it helps!
1. Engine starts and runs fine when cold.
2. After running at full operating temperature for some time (varies), the vehicle experiences a severe power loss.
3. After driving for a period of time with the power loss (usually a matter of 2-20 minutes), the car will eventually lose power completely and stall out.
4. After waiting a period of time and allowing the car to cool, the car will generally start up normally and be driveable.
Items of note:
1. The condition was MUCH worse in hot weather
2. The condition was worse when fuel tank was below 1/3
Here's exactly what I did:
1. Replaced the fuel filter. This is always a good idea and I have no regrets. The old one was the original!
2. Replaced Fuel Pump Resistor (Solution in another thread)- Little or no change
3. Next: Replaced Fuel Pump Relay- Little or no change
4. Finally: Replaced Fuel Pump- Problem solved! Works perfectly now!
Other items of note:
The '91 LS400 came from the factory with 2 different fuel pumps, either the Aisan or the Denso. Even after removing mine, I have no idea which one my car came with. I talked with the Lexus people at length, and they told me that these fuel pumps have the exact same application and the exact same wiring. When replacing with aftermarket, IT MAKES ABSOLUTELY NO DIFFERENCE WHICH PUMP YOU HAD TO BEGIN WITH. I know that many aftermarket sources say that "This Bosch pump replaces Aisan", or "This Bosch pump replaces Denso" and so on and so forth, but it makes no difference! Just buy the cheapest one. I know all of the "Hank Hill" types on here will say, "Replace parts with genuine OEM parts, you need the Denso, my Lexus can tell what ATF I use, I swear to the Toyota God it can, blah blah blah" and so forth but in reality it doesn't matter. I got one from RockAuto that has the exact same guarantee that Denso offers for under $50 and my car is fixed. So that's my 2 cents. Hope it helps!
Last edited by 89Reatta; 10-08-10 at 10:04 PM.
10-09-10, 03:01 AM
#45
Lexus Test Driver
Great news! How long has it been since you replaced the fuel pump? Did you do the work yourself or have someone do it? What was the cost, if you had someone do it? How many miles on your 91? What state are you from? Wondering how hot it is where you are now...
Thanks
Thanks