93 blazer random stalling

[93fsblazer]

I have a 93 blazer that will stall randomly. 5.7 tbi. It has new idle air control valve, tps, plugs, wires, cap, rotor, ignition control module, and fuel pump relay. No codes are being thrown up. I'm not sure what it is. Swapped the coil with a known good one and still the same. It doesn't give a warning usually it just dies. Sometimes it'll give a few sputters but that's it. Sometimes it starts right back up. And others it has to sit for a while. It has no particular time either, sometimes it's at idle or just running along or anywhere in between. Fuel pump has good pressure on it. All the grounds seem to be good. Only thing I could think of is maybe a faulty pcm or prom. Any one got any other ideas?

 

[SunlitComet]

can you keep the pressure gauge on and see if the pump is still going immediately following the stall?

 

[93fsblazer]

I haven't been able to yet. May as well just replace the pump, I have no idea when it was done last.

 

[SunlitComet]

well if you can keep on testing you may find out it may not need replacing. try not just throwing parts at it as it will just waste money if wrong. perhaps you can just run it in place to test. does it stall when just idle and what kind of testing equipment do you have around?

 

[93fsblazer]

It usually doesn't do it at idle. When it does it fires right back up. Its when it dies while moving that it takes longer to start back up. But not always. It's pretty sporadic. As far as test equipment I used a buddy's fuel gauge. All I have right off is a digital multi meter.

 

[SunlitComet]

can you rig the multimeter to test the fuel pump relay output? that could eliminate the fuel control circuitry as an issue. that would leave the pump itself to test further if possible or the ecm issue. when you check for codes do you get any number at all back? at least the number "12" three times?

 

[93fsblazer]

I get code 12. I was getting 43 for the knock sensor, id accidentally hit it when I was putting the starter in. Plugged it up and it went off after disconnecting the battery. Right now I can't really do much. I'm on night shift and the complex doesn't like it too much when I'm out there at 2 or 3 am making noise.

 

[SunlitComet]

yeah i hate to see you throw parts at it but the tbi are a little more hard to diagnose then the obd2's. do me a favor and put the ecm in field mode. with the engine already running short the diagnostic terminal and drive somewhere like home or work and tell me if the cel blinks 2.5 a second or about once a second.

 

[93fsblazer]

How do you do that? Is it the same as reading the codes? Last night I was just letting it idle and it would run maybe 2 minutes tops then die. Start it back up and it'd do the same, unless I held the rpms up a little above idle.

 

[SunlitComet]

same way but as i mentioned you do the connection after the engines running. And two minutes you say. interesting will be back shortly about that two minutes thing.

---------- Post added at 12:08 PM ---------- Previous post was at 11:46 AM ----------

can you plug the vacuum line to the egr and see if it stalls again please.

---------- Post added at 12:10 PM ---------- Previous post was at 12:08 PM ----------

also you put good thermal grease on the ignition control module? who made the icm you replaced?

 

[93fsblazer]

I'll get to those as soon as I can. The control is a ac Delco part number D1984A. I used the supplied grease.

 

[93fsblazer]

Could this possibly be a voltage related issue? I noticed I'm only charging around 13v with nothing on, with my a.c. and headlights it's around 12.8.

 

[SunlitComet]

should not be, the system can run on lower voltage and keep going. you would have to have a really bad connection or even corrosion on a component like the pcm or icm or coil or pump assembly. this stalling is at random times after starting correct? or a fixed amount of time after starting when it does happen continously?

 

[93fsblazer]

Yes just random times. It seems to have snapped out of it now though. I drove it around today about 15 miles and nothing. No sputter or anything.

 

[SunlitComet]

wait for it. have you check for loose or damaged connector everywhere as well?

 

[93fsblazer]

I've checked the grounds under the hood and the smells one in the rear that I assume was the fuel pump ground.

 

[SunlitComet]

well a funky funky connection that would certainly cause issues. I would like to go around all my grounds as well and loosing, clean and re-tighten them up then humiseal them all. I am sure on voltage will flow thru a little better.

---------- Post added at 10:02 AM ---------- Previous post was at 09:53 AM ----------

you will find grounds on the rear of the right cylinder head. hard to get to. can't remember the blazer but on the newer model the fuel pump ground was on the the left frame rail near the pump. it was by itself.

 

[93fsblazer]

I plan on upgrading some of my factory grounds and postives as well. I'll be using some 1/0 wire for them.

 

[SunlitComet]

any new stalls yet?

 

[93fsblazer]

No, nothing yet. It's done this in the past. It stopped on its own. But that was over a year ago.