Countrycrazy630

I bought a 2004 trailblazer an the thing just died.. I had a new crank sensor put in it, it started but ran like **** an was in limp mode.. It sat at my friend's for like 2yrs,I finally got it towed to my house, tried to start it an it tried to crank but wouldn't start idk what to do, any suggestions

Rednucleus

Tough one,especially after sitting 2 years. You need spark, fuel & air to go. Need to verify which one is missing and go from there. Report back please!

mountainmanjoe

Countrycrazy630

Ok so it's not getting fuel, the fuel pump won't turn on the fuel relay ain't even clickin

chem_man

First check the fuel pump fuse in the underhood electrical center.

If the fuse is OK, you need to check that battery voltage is getting to the fuel pump relay's power side socket in the underhood electrical center.

DO NOT FORCE THE TEST PROBE TIPS INTO THE RELAY SOCKET!!!!! USE A PIECE OF WIRE, A NEEDLE AND A CLIP LEAD, OR THE PROPER PROBE!!!!!

Measure the voltage (connect the negative test lead of a Digital Multi-Meter (DMM) to ground or the negative battery terminal) using the positive test lead of your DMM at the power side of the fuel pump relay socket.

If no voltage, then report back.for further assistance.

Countrycrazy630

Ok so I got power into the relay, and the relay is good but I got no power comin out
Tried jumping from power in to power out an nothing

chem_man

OK, now you need to check the control side of the relay for ground. One side of the control circuit will always be grounded. The wire from that pin/socket in the underhood electrical center runs to ground point G107 which is located on the lower left (driver's) side of the engine block just below the EVAP system purge valve. I'll attach a picture that shows it.

Now the other pin/socket for the fuel pump relay's control circuit goes to the ECM. It goes from Underhood Electrical Center Connector C1 pin A11 at the underhood electrical center to ECM Connector C2 Pin 3 at the ECM. I'll also attach images of all the conenctor pin outs so you can check continuity and I'll also attach the electrical schematics for the fuel pump system (pages 3 of 9 and 5 of 9).

Good Luck!

chem_man

Here is another diagram that will be helpful. It shows which ECM connector is which.