OBD-II Codes B1071 & B1049

[kstar24]

I have a 98 Tahoe, 5.7, 237000 miles
I have been having many issues with it lately, it has been throwing codes P0171 & P0174 for quite some time.
New spider unit, switch to MPI, new fuel pump (AC Delco), new filter. Have not been able to get rid of the codes.
Last month I attempted to go on a long trip. 170 miles in, the RPMs jumped from 2-3 and my cruise kicked off and I lost power. I pulled over, the truck was still running, checked gauges all looked fine. Revd it up sounded ok. put it in drive to go and it died. After that it would not start again, it would crank but not start. Towed it home, the next morning it started.
Now I am getting codes B1071 & B1049. I have not been able to find any information on these. Can anyone give me any help.

If you need more information please let me know.
Thanks in advance for any input.

[MT-2500]

http://www.troublecodes.net/OBD2/Bcodes.shtml

Your B codes are not listed under B Body codes.

What kind of scanner are you getting codes with?
Has the codes been cleared and rechecked for what comes back?

[kstar24]

It is a Genesis II.
No, they had not been cleared. They were cleared last night after the scan was done. I will be driving it today.

I was hoping to maybe get more clues as to why I continue to have the lean codes. This is the first time that it quit running on me since it started having the lean codes. (also it is the first long trip)

I have continued to try and research the codes for B1071 I found "Internal SDM Failure" but no explaination as to the cause.

Thanks again

[MT-2500]

Fuel pressure and Maf sensor is a leading cause of lean codes.
Give us your fuel presure reading when it quits or is acting up.
The only true test on a fuel pump is to check the direct fuel pressure from fuel pump.
A quick test is to block off the return line and see if fuel pressure comes up to 75-85 lbs.
But do not run the pump at full pressure very long.
Also when testing fuel pump and pressure you need to tape a gauge to outside windshield or outside mirror and drive it on the road for 20 -30 minutes
until the pump gets has run a while to check for a pump fading out after hot.

Hard to start cold or hot and fuel pressure testing guide lines.
Check cold start fuel pressure.
Check engine running fuel pressure.
Check engine running on the road fuel pressure.
Then shut it off and watch for fast leak down.
Pinch off at rubber part or block off return line and check full pressure.
If pump has full pressure with return line blocked and low pressure without it blocked most usually the fuel pressure regulator is leaking or not holding pressure.
Later V6 and V8 gm engines should have 60-66 fuel pressure.
Cold start should be 64-65 lbs of pressure.
If you do not have full fuel pressure on a cold start the injectors will not squirt fuel.
Do not leave home without it.
Engine running should be 60-66 lbs pressure depending on engine load.
Full pressure with return pinched off should be 75-85 or more.
And if it has a fast leak down after shut off you have a leak in system.
Post back fuel pressure readings.

[kstar24]

I have read thru many posts about the lean codes, the fuel pressure had dropped to 50, that is why we replaced the fuel pump. It made no change at all. I drove 40 miles and the check engine light came back on. I thought that maybe the B codes might point us to the right direction.
I have not changed the MAF or the HO2 sensors, since these are not inexpensive parts and it is not giving any codes that these are bad. I have spent quit a bit already trying to get it fixed.

New MPI spider unit so no injector restriction, had the intake gaskets changed also.
I had a smoke test done so I know there are no air or vacuum leaks.
As stated above new AC Delco fuel pump.

It was still getting me from point A to B, but now with only making it 170 miles I am hesitant to drive very far. Besides am I causing more damage if I keep driving it?

[777stickman]

The B codes are for the Air Bag system. The SDM is the Sensing and Diagnostic Module for this system.

I could not find B1049 in my '98 C/K service manual.

[kstar24]

So what is failing then??

[MT-2500]

What is the fuel pressure now?

[kstar24]

Good question, I will have to ask. When I find out I will post.

[kstar24]

Fuel pump pressure at idle is about 51psi & 53 KOEO
There is no leak after shut down
can not pinch off the return line as they are all metal

What would cause it to still be low?
As stated before just replaced the fuel pump with AC Delco pump.
Thank you

[MT-2500]

Originally Posted by kstar24

Fuel pump pressure at idle is about 51psi & 53 KOEO
There is no leak after shut down
can not pinch off the return line as they are all metal

What would cause it to still be low?
As stated before just replaced the fuel pump with AC Delco pump.
Thank you

Way to low on fuel pressure.

Go threw the complete fuel pressure testy and post back pressure readings.
What is engine cranking pressure?
What is engine running pressure?

What is pressure on the road running after getting hot?
If you can not pinch off return line plug it.

Also at fuel filter in line hook direct on to it and check fuel pump full pressure.
Should be 95 105 lbs. but on run at full pressure for a couple seconds.
if under 85 beter replace fuel pump.

Also make sure you have good 12 volts and ground to fuel pump.