OK, so your problem has nothing to do with the relay, wiring from the ECM to the relay or the wiring to the pump. That inexpensive pump may or may not have problems but you have no priming cycle output from the ecm to the relay, the question now is why. You are getting into rarified territory so buckle up because this is not a garden variety fuel pump issue, especially because you replaced the ECM and noted wiring connector problems. I love tough electrical problems so I'll stick with you as long as you want.

1. How sure are you that you got a functioning ECM, programmed properly to your vehicle VIN?
2. How confident are you that you have solid clean connections at all 120 connections to the ECM, especially the "broken" connectors?
3. If these two things are good then we need to start testing powers and grounds at the ECM and especially the power up pins that get energized when you turn on the ignition so the computer knows to energize the pump and prime the fuel rail for starting.

George

 

Thanks, I ordered the ecm from a company called flash masters online, I gave them my Vin number and they confirmed via email, I even double checked to make sure Vin was correct. I even called them and asked if i could send the ecm back that is might be fualty, they asked if there was a problem amd thst the ecm should be good and programmed properly, as far as the connections to the ecm, they are connected good and I even reconnected them Earlier, to make sure they were secure, even though the outer plastic broke on just the top part of the clips, honestly it could be the wiring somewhere down the line, I even cleaned and recounted some of the grounds that go to the frame , on the front of the vehicle, as far as the grounds towards the back or by the tank, that's what I'm wondering? Of there is a ground wire for the fuel pump that's mounted on the frame, back by the gas tank?

 

We don't care about the grounds at the tank and pump right now, we have to figure out why your ECM is not sending the priming signal at key on to the fuel pump relay. All your problems are under the hood. Lets start with checking if you are getting the key on voltages to the ecm. First I need to know if this is a 2.2L or a 4.3L.

George

 

It's a 4.3l vortex automatic, 2 wheel drive, 4 door, ls model.

 

The wiring diagrams for this year are giving me fits so we may have to do some sleuthing to complete this task, there are inconsistencies between pages in the set.

So there are three possibilities here. First, a bad ground(s) to the VCM. The second is a bad power input. The third is a bad or improper VCM:

1. First check the ECM B fuse then measure the always on voltage from that fuse to pin 21/C3 orange wire at the VCM (connector in place, back probed)
2. Second check the 4wd fuse and then turn the ignition to run and check the voltage from that fuse on pin 13/C4 brown wire
3. Third check the clstr fuse then turn the ignition to run and check the voltage on pin 17/C4 pink wire
4. Fourth check the ECM1 fuse and then we need to look for this wire because it labeled in two different places. Turn the ignition to run and look on pins 18/C4 and pin 19/C1 pink wire and measure the voltage
5. Check the grounds at the back of the engine block/heads
6. If all of this checks then we will have to check the quality of the grounds at the ECM connector(s) but I don't you unplugging those deteriorating connectors unless we have to. In addition, these grounds are also listed in two places at the ECM: pin 17/C3 or C2 and pin 18/C3 or C2, both blk/wht wires.

George

 

I checked the ecm b fuse and it was blown 😳, I know for a fact that I checked it before, I guess I missed it, know I just hope that was the reason the pump wasn't working. I'm not able to turn key and check becuase after installing new fuel pump, I lost one of the fuel line retaining clips, I ordered a new set. This blazer has been nothing but one problem to another, I probably should sell it after I get it running.

 

Does this help any?

 

The fuel pump circuit itself is OK, it’s the powers and grounds into the ECM. The engine control pages and the power /ground distr pages differ on the pins and connectors noted.

George

 

OK, standing by. You may have blown that fuse with all that relay socket jumpering by shorting that fuse power to ground. You have to be careful when your doing this because one of those socket pins is an output from the ECM and if your not careful you can blow the driver in the computer and brick the thing.

George

 

if that's the case, I'm not sure if I should purchase another computer, these repairs are getting expensive for a used vehicle that was suppose to be just a head gaskets replacement. So after purchasing the vehicle for $700 used , it's ot pretty good shape, new tires, clean interior, after putting everything back together with refurbished heads, and I did remember to clean and connect the grounds on both sides of the heads, I have replaced just about everything, starting with the whole ignition system, wires,plugs, distributor, all sensors, radiator, water pump, becuase the owner before me neglected to change the radiator fluid or do any maintenance at all, it was full of rust water so bad it was literally gunk that stopped up the thermostat and it was overheated driving on the texas heat, anyway, new battery, fuel pump, all new gaskets, fuses, relays. And of course the ecm. So all in all I have had trouble after getting it back together because online forums were saying the timing mark was the first mark on the crank, wich was not correct, if only I would have know from the beginning that it was the other mark, I wouldn't have been checking everything else and accidentally messing something else up. So it's in time and hopefully it will start soon.