I got an 89 blazer that will run fine for a few minutes then when the engine warms up the injectors run constant (no pulse) and the engine floods and dies. Then it won't start again and will pump enough gas that is drips from the exhaust if I try to start it vey long. I can unplug the injectors and it will start and run till the gas in the manifold runs out. I can then start and run it for a few minutes till it warms and floods again.

Now if I unplug the temp sensor or the O2 sensor it will run in open loop indefinatly. When I try to check codes the CEL flashes erraticly and the air pump recirc solenoid clicks not excactly in sync with the CEL but there is a connection. I can clear codes and then the CEL flashes 12 but after the engine has run a few seconds it does the erratic flash again.

What I have done

New fuel pump ( got the truck cheap cause the rubber in tank connection hose was rotten)
new O2 sensor
New temp sensor
tune up cap wires plugs timing ect
Map sensor (replaced from working similar truck)
TPS (replaced from working similar truck)
ECM grounds are good
Wires are all good ( visual and ohm meter tested)

This started when previous owner neglected t-case noise and the chain let go locking up t-case at speed and breaking the bellhousing which broke the o2 sensor. The wire is fine the sensor in new but I wonder if the ecm was damaged by the short to ground or whatever may have happened in the break. He had a shop fix the break but they could not fix this issue and the truck has sat for 3 years.

any help is appreciated
wayne

Hello is this thing on?

anybody

I am in the same boat as you are. There are tons of sites with this information on it, but I have done just about everything. I have even rebuilt the throttle body. I am going to check the compression over the weekend to make sure that it is good. Do you have any codes that come up? Have you changed the IAC? It is located on the throttle body. Have you checked the EGR? TO check it you can have the truck running and push up on the diaphragm, if it cuts the engine off then it should be working properly.

say pick up an ECM from the junkyard and give that a shot.

When you say SES is eratic is it flashing codes or something other? Do you know how to read the flashes for codes?....Your problem does seem strange and would be hard to explain IMHO...Maybe you're right and the ECM was damaged when the O2 shorted.

with all those new parts the ecm seems to be about all thats left. That or a REALLY good electrical shop...

I am in the same boat as you are. There are tons of sites with this information on it, but I have done just about everything. I have even rebuilt the throttle body. I am going to check the compression over the weekend to make sure that it is good. Do you have any codes that come up? Have you changed the IAC? It is located on the throttle body. Have you checked the EGR? TO check it you can have the truck running and push up on the diaphragm, if it cuts the engine off then it should be working properly.

Did not change IAC (I assume Iddle Air Control) but it is working as it should. the only thing that appeared to work during this whole thing. EGR is fine works as it should with vacume test and I dont' see it causing a rich condition. EGR works in open loop.

I can't read the codes. the CEL flashes erraticly sometmes 8 or 9 times the air recirc solenoid is clicking any time the key is on it is getting a 12 volt signal from best I can tell the ECM. the flashing of the CEL is not exactly in sync with the Air recirc solenoid but it is related. I suspect the codes are flashing but this recirc thing also causes the CEL to flash and that makes the codes impossible to read. NO impulse is sent to the recirc solenoid in open loop.
Thanks for the help

Wayne

say pick up an ECM from the junkyard and give that a shot.

Does any TBI ECM work or are there numbers that I have to match like on many OBD I systems. I would think any manual trany ECM should work right???

wayne

When you say SES is eratic is it flashing codes or something other? Do you know how to read the flashes for codes?....Your problem does seem strange and would be hard to explain IMHO...Maybe you're right and the ECM was damaged when the O2 shorted.


It flashes a clear 12 then nothing else when I have cleared codes but not run the engine. As soon as I run the engine and then try to check codes it flashes erraticly. Sometimes as many and 9 flashes but not the usual evenly spaced quick flashes from a normal ODB I. As I said earlier. The air recirc solenoid is clicking and some of the flashes maybe 60% of them are in sync with the clicking. the rest of the time the flashes are seperate of the click or the click is seperate of the flash. I suspect the ECM is sending codes but this click also tries to flash the CEL making it impossible to read codes without a reader.

I will try to find an OBD I reader form one of my friends see if that works.

wayne

Does any TBI ECM work or are there numbers that I have to match like on many OBD I systems. I would think any manual trany ECM should work right???

wayne

You have to use the right one. There is a 7 or 8 digit number code on the label along with a 4 digit letter code. Match the number code as it identifies the ECM. The letter code is the chip program. If the letter code doesn't match you will need to use the chip or chips out of you current ECM which could also be corrupt. You could still have wire issues inside the harness if it shorted out and melted them somewhere. The FAQ here (http://www.binderplanet.com/forums/forumdisplay.php?f=75) tells how to do voltage checks on your harness.

You have to use the right one. There is a 7 or 8 digit number code on the label along with a 4 digit letter code. Match the number code as it identifies the ECM. The letter code is the chip program. If the letter code doesn't match you will need to use the chip or chips out of you current ECM which could also be corrupt. You could still have wire issues inside the harness if it shorted out and melted them somewhere. The FAQ here (http://www.binderplanet.com/forums/forumdisplay.php?f=75) tells how to do voltage checks on your harness.

Thanks I will get to the JY this weekend and grab one. gotta pull the ECM and get the code first I suppose.

wayne

You have to use the right one. There is a 7 or 8 digit number code on the label along with a 4 digit letter code. Match the number code as it identifies the ECM. The letter code is the chip program. If the letter code doesn't match you will need to use the chip or chips out of you current ECM which could also be corrupt. You could still have wire issues inside the harness if it shorted out and melted them somewhere. The FAQ here (http://www.binderplanet.com/forums/forumdisplay.php?f=75) tells how to do voltage checks on your harness.

Ya what he said^ :smokin:

I know mine is like 7747 or something.
look for your truck and motor and try to get as similar as possible. because the computer may be the same but the programming might be different depending on the application.