Lean exhaust and other codes

[ouray19]

Just got a 1995 K1500 ext cab, 4wd, 5.7, auto transmission with 188K miles. Truck starts but runs rough and hard time accelerating unless you really stomp it. Just replaced the radiator because of a leak on driver side. Have also replaced fuel filter, plugs, cap/rotor, air filter and pcv valve. Just the basic tuneup stuff. SES light came on last night coming home and I pulled the following codes:

15 - Coolant sensor circuit
22 - TPS
44 - Lean exhaust
54 - Fuel pump relay low volt
73 - Pressure Control Solenoid

A lot of different codes and not sure how many have been stored for a while and which ones are current. Looks like the coolant sensor has been replaced recently. Not sure if these codes point to one problem or several separate problems. Have not checked the timing yet, will do that this weekend.

Would a weak fuel pump cause the lack of power when normal acceleration? I know this is not a whole lot of information but just curious where to start to get the normal acceleration. Open to all thoughts and suggestions.

 

[chipskittles]

There's lots of things that would cause the problems you are having.

if it were mine I would check the following in no particular order:
-Check the timing
- Check TPS
- Replace spark plug wires if they are ancient
- Check EGR valve. Could have a diaphragm leak.
- Check for other vacuum leaks
- doubt there is a problem here, but check compression
-Yes check fuel pump pressure if it comes down to it.

There's tons more things that could cause this, just getting you started. 188K miles is nothing for a TBI motor as long as it's not knocking on startup.

 

[ouray19]

Thanks Chip! All good ideas and appreciate the suggestions. I also have another 1995 K1500, pretty much the same truck except manual transmission. I've had it about 2 years and reworked everything when I got it including a new complete throttle body assembly. It got rear ended and there is frame damage, so didn't want to drive it much, plus the tranny went out on it right after the accident. Hoping there are some things I can use on my old truck for this new one. Radiator didn't transfer over since there were no connections for the auto transmission lines. But I was wondering, would the throttle body assembly from my old truck work on this new one?

 

[chipskittles]

I would think it would transfer over if everything on it matches up(TPS, fittings, etc). People do manual swaps all the time and don't change the TBI. It takes less than an hour to pull it, I would just try it. Sounds like you have a parts truck you can swap over things to until you fix the issue!

 

[ouray19]

I'll give it a try. The old one was easy and by the time you do all the parts, injectors, tps etc, the whole assembly was actually a little less and a whole lot easier. Hoping the ICM and other sensors will switch over since I had done them on the old truck less than a year ago. Thanks again for your input.

 

[Supercharged111]

Fuel pressure is among the first things I'd check, not if all else fails. Timing doesn't change once it's set, but fuel pressure will. Does the 95 have 2 O2 sensors? If so, which one? Bank one is left and bank 2 is right. IIRC the left injectoe feeds bank 2 and right injector bank 1. Obviously a throttle body would alleviate an injector issue. Good time to do the TBI mods.

 

[ouray19]

Thanks super, my 95 just has the one O2 sensor (OBD1) just in front of the cat. Have one on order and will replace it when it gets here. Working on the plugs, wires, cap, rotor and ICM today. Will see if that helps.

 

[Mule89]

There's lots of things that would cause the problems you are having.

if it were mine I would check the following in no particular order:
-Check the timing
- Check TPS
- Replace spark plug wires if they are ancient
- Check EGR valve. Could have a diaphragm leak.
- Check for other vacuum leaks
- doubt there is a problem here, but check compression
-Yes check fuel pump pressure if it comes down to it.

There's tons more things that could cause this, just getting you started. 188K miles is nothing for a TBI motor as long as it's not knocking on startup.

I will second that on knocking on start up. But visual checks can find simple problems or soon to be problems that can create a headache for you.

 

[ouray19]

There is no knocking on start up, engine seems to be strong. Just changed out the ICM and made a world of difference. Will continue to work on the basic stuff for now since I plan on keeping this truck.

This is my third 400Gen truck I have owned and won't have anything else. My first was an 89 SCSB w/ 5.7 and auto. I had owned it for 16 years and it had 388K miles on it when I got hit head on at 55mph. I survived but the truck didn't. My next one was a 95 SCSB w/ 5.7 and manual transmission. It got rear ended, was still driveable until the tranny went out. I got this current 95 (5.7 w/ auto) as a daily driver and using a lot of parts off my other 95. These trucks can't be beat. Can be frustrating at times, but at least I can do the majority of repairs that need to be done. Especially with help from great people on this forum. Thanks to everyone for their input. It has been a great help in the past.

 

[Dustin030]

For the lean code I would check the maf senor and make sure it's not dirty.