1431 code
Thread Starter
Le Mans Master
Joined: Dec 2005
Posts: 6,460
Likes: 16
From: hamilton alabama
1431 code
so i got the 1431 code on my 00 c5 and i had just replaced the passenger side fuel pump ac delco. so what could be causing this code and still making my fuel gauge to drop to empty? i dont know if i would run out of gas when this happens because the fuel is not being transferred from the passenger tank over to the driver tank so this concerns me. any ideas what this could be? 
Rick
Rick
Advanced
Joined: Jul 2013
Posts: 75
Likes: 1
From: Seattle Washington
so i got the 1431 code on my 00 c5 and i had just replaced the passenger side fuel pump ac delco. so what could be causing this code and still making my fuel gauge to drop to empty? i dont know if i would run out of gas when this happens because the fuel is not being transferred from the passenger tank over to the driver tank so this concerns me. any ideas what this could be?
Rick
Rick
Advanced
Joined: Jul 2013
Posts: 75
Likes: 1
From: Seattle Washington
Here is some fuel system operation I copied from another Forum post some time back:
OK, a little info may help you here .....
* There are two tanks .... each tank has a fuel sender that reports the fuel level to the PCM. The PCM calculates the fuel level based on the info from the two senders and reports that calculated "single tank" level to the IPC which displays it on the fuel gauge.
* The right tank has a "jet siphon" pump in it, the left tank has an electric pump. When the engine is running, the fuel rail is fed by the left tank electric pump. Just after the left pump pressurizes the fuel, there is a line that feeds some of that pressurized fuel into the right siphon pump. The siphon pump has a line that carries the siphoned fuel to the left tank. Both tanks are connected, at the tops of the tanks, by a large diameter "fuel crossover" line which is how the right tank gets fueled ... once the left tank is full during fueling the fuel then crosses over to the right tank, filling it.
* With the engine running more fuel is fed from the right tank than is being taken out of the left tank, so the excess fuel flows back to the right tank via the crossover pipe.
* The "normal" behaviour the PCM expects to see after the tanks are filled is as follows .... the right tank should drain while the left tank remains full. Once the right tank is empty then the left tank should drain. The PCM also knows that the fuel level in either tank should drop as the car is driven a certain distance ..... say 150 miles.
* If the PCM does not see "normal" behaviour (such as the car driving 150 miles and neither sender has moved) then it will set DTC for things like a stuck sender (no movement in 150 miles) or a bad siphon jet pump (the left tank is draining before the right tank) .... or whatever. A P1431 is an example of the codes than can be set.
OK, a little info may help you here .....
* There are two tanks .... each tank has a fuel sender that reports the fuel level to the PCM. The PCM calculates the fuel level based on the info from the two senders and reports that calculated "single tank" level to the IPC which displays it on the fuel gauge.
* The right tank has a "jet siphon" pump in it, the left tank has an electric pump. When the engine is running, the fuel rail is fed by the left tank electric pump. Just after the left pump pressurizes the fuel, there is a line that feeds some of that pressurized fuel into the right siphon pump. The siphon pump has a line that carries the siphoned fuel to the left tank. Both tanks are connected, at the tops of the tanks, by a large diameter "fuel crossover" line which is how the right tank gets fueled ... once the left tank is full during fueling the fuel then crosses over to the right tank, filling it.
* With the engine running more fuel is fed from the right tank than is being taken out of the left tank, so the excess fuel flows back to the right tank via the crossover pipe.
* The "normal" behaviour the PCM expects to see after the tanks are filled is as follows .... the right tank should drain while the left tank remains full. Once the right tank is empty then the left tank should drain. The PCM also knows that the fuel level in either tank should drop as the car is driven a certain distance ..... say 150 miles.
* If the PCM does not see "normal" behaviour (such as the car driving 150 miles and neither sender has moved) then it will set DTC for things like a stuck sender (no movement in 150 miles) or a bad siphon jet pump (the left tank is draining before the right tank) .... or whatever. A P1431 is an example of the codes than can be set.
Le Mans Master
Joined: Mar 2011
Posts: 6,835
Likes: 302
From: Columbia SC
so i got the 1431 code on my 00 c5 and i had just replaced the passenger side fuel pump ac delco. so what could be causing this code and still making my fuel gauge to drop to empty? i dont know if i would run out of gas when this happens because the fuel is not being transferred from the passenger tank over to the driver tank so this concerns me. any ideas what this could be?
Rick
Rick
Thread Starter
Le Mans Master
Joined: Dec 2005
Posts: 6,460
Likes: 16
From: hamilton alabama
Le Mans Master
Joined: Mar 2011
Posts: 6,835
Likes: 302
From: Columbia SC
I did several searches starting from my parts book. In my opinion you did get the proper unit for your car even thought the original was MU1004, everything shows MU1218 is a correct replacement. I also verified the GM number 88895126 (MU1004) cross references to MU1218.
With that said, you never exactly said why you replaced the unit. Also not clear if this code was there before you replaced the unit.
With that said, you never exactly said why you replaced the unit. Also not clear if this code was there before you replaced the unit.
Thread Starter
Le Mans Master
Joined: Dec 2005
Posts: 6,460
Likes: 16
From: hamilton alabama
I did several searches starting from my parts book. In my opinion you did get the proper unit for your car even thought the original was MU1004, everything shows MU1218 is a correct replacement. I also verified the GM number 88895126 (MU1004) cross references to MU1218.
With that said, you never exactly said why you replaced the unit. Also not clear if this code was there before you replaced the unit.
With that said, you never exactly said why you replaced the unit. Also not clear if this code was there before you replaced the unit.
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Thread Starter
Le Mans Master
Joined: Dec 2005
Posts: 6,460
Likes: 16
From: hamilton alabama
Le Mans Master
Joined: Mar 2011
Posts: 6,835
Likes: 302
From: Columbia SC
This code is based on the system not "sensing" a normal variation in fuel level. You might want to do a wiring check to make sure that is not your issue. That would just be the 3 wires. I looked in my 2001 FSM and the pin outs are the same as the 1997 above.
Have you looked at the diagnostics in the FSM yet?
Have you looked at the diagnostics in the FSM yet?
Melting Slicks
Joined: Apr 2004
Posts: 2,301
Likes: 199
From: Valencia CA
This is not the fix your looking for.
I chased that code on my 2002 for a while. Car has 100,000 miles.
Pulled both sensors cleaned the contacts. Actuated the sensors out of the tank and observed the readings on the Tech 2.
Everything works properly until you drive it continuously for about 45 minutes on the highway, then the 1431 code would pop up. You could almost set your watch by it.
The Tech 2 showed normal fuel levels in both tanks at the time of the code and never exceeded the programmed variation in the tune.
I could run continously and drain both tanks on long trips, so...................................... .
I turned the code off in the PCM with EFILive.
I chased that code on my 2002 for a while. Car has 100,000 miles.
Pulled both sensors cleaned the contacts. Actuated the sensors out of the tank and observed the readings on the Tech 2.
Everything works properly until you drive it continuously for about 45 minutes on the highway, then the 1431 code would pop up. You could almost set your watch by it.
The Tech 2 showed normal fuel levels in both tanks at the time of the code and never exceeded the programmed variation in the tune.
I could run continously and drain both tanks on long trips, so...................................... .
I turned the code off in the PCM with EFILive.
Le Mans Master
Joined: Mar 2011
Posts: 6,835
Likes: 302
From: Columbia SC
This is not the fix your looking for.
I chased that code on my 2002 for a while. Car has 100,000 miles.
Pulled both sensors cleaned the contacts. Actuated the sensors out of the tank and observed the readings on the Tech 2.
Everything works properly until you drive it continuously for about 45 minutes on the highway, then the 1431 code would pop up. You could almost set your watch by it.
The Tech 2 showed normal fuel levels in both tanks at the time of the code and never exceeded the programmed variation in the tune.
I could run continously and drain both tanks on long trips, so...................................... .
I turned the code off in the PCM with EFILive.
I chased that code on my 2002 for a while. Car has 100,000 miles.
Pulled both sensors cleaned the contacts. Actuated the sensors out of the tank and observed the readings on the Tech 2.
Everything works properly until you drive it continuously for about 45 minutes on the highway, then the 1431 code would pop up. You could almost set your watch by it.
The Tech 2 showed normal fuel levels in both tanks at the time of the code and never exceeded the programmed variation in the tune.
I could run continously and drain both tanks on long trips, so...................................... .
I turned the code off in the PCM with EFILive.
I would assume your BCM was the cause?????
Melting Slicks
Joined: Apr 2004
Posts: 2,301
Likes: 199
From: Valencia CA
Could be.
Daily driver and weekend toy. 1 year, 15,000 miles and a couple of long trips since I turned the code off.
I'll keep my eyes open for a spare BCM and give that a try.
I don't like turning off the code, I prefer to fix it correctly and have everything functional.
Daily driver and weekend toy. 1 year, 15,000 miles and a couple of long trips since I turned the code off.
I'll keep my eyes open for a spare BCM and give that a try.
I don't like turning off the code, I prefer to fix it correctly and have everything functional.
Thread Starter
Le Mans Master
Joined: Dec 2005
Posts: 6,460
Likes: 16
From: hamilton alabama
This is not the fix your looking for.
I chased that code on my 2002 for a while. Car has 100,000 miles.
Pulled both sensors cleaned the contacts. Actuated the sensors out of the tank and observed the readings on the Tech 2.
Everything works properly until you drive it continuously for about 45 minutes on the highway, then the 1431 code would pop up. You could almost set your watch by it.
The Tech 2 showed normal fuel levels in both tanks at the time of the code and never exceeded the programmed variation in the tune.
I could run continously and drain both tanks on long trips, so...................................... .
I turned the code off in the PCM with EFILive.
I chased that code on my 2002 for a while. Car has 100,000 miles.
Pulled both sensors cleaned the contacts. Actuated the sensors out of the tank and observed the readings on the Tech 2.
Everything works properly until you drive it continuously for about 45 minutes on the highway, then the 1431 code would pop up. You could almost set your watch by it.
The Tech 2 showed normal fuel levels in both tanks at the time of the code and never exceeded the programmed variation in the tune.
I could run continously and drain both tanks on long trips, so...................................... .
I turned the code off in the PCM with EFILive.
turning the code off does your fuel level still drop to empty? i am just worried that it will stp pumping fuel or something because it will say its empty
Melting Slicks
Joined: Apr 2004
Posts: 2,301
Likes: 199
From: Valencia CA
No sir. In my case turning off the code cured the problem of the gauge dropping to empty. Everything functions normally.
Thread Starter
Le Mans Master
Joined: Dec 2005
Posts: 6,460
Likes: 16
From: hamilton alabama
the worse that can happen is i run outta gas 
so i will just drive around locally 
Melting Slicks
Joined: Apr 2004
Posts: 2,301
Likes: 199
From: Valencia CA
Before I turned off the code, I logged data and verified that the right side tank was transferring fuel.
Easy to do with anything less than full tanks. When the car sits, the fuel equalizes between tanks. After starting, you can watch the right side tank level decrease as the left side increases until it is full. You don't even half to drive it.
Easy to do with anything less than full tanks. When the car sits, the fuel equalizes between tanks. After starting, you can watch the right side tank level decrease as the left side increases until it is full. You don't even half to drive it.
Racer
Joined: Mar 2011
Posts: 337
Likes: 1
From: Mechanicsville Md
I got a 2002 coupe and experiencing the same problem. Code 1431 and gage goes to zero at approximately 28 miles. Everything I read is that my jet pump is plugged and not transferring fuel from the right tank. The PCM sees that the left tank is going down but not the right tank. The PCM senses this at approximately 1 gal differential. Yep 28 miles is about 1 gal. I got my sending unit and am waiting for warmer weather. Don't want to have a kerosene heater running when I'm draining a gas tank. I also ran out of gas with just a hair over 1/4 tank. Hope this helps.