VX died Help....

[Scott Larson]

One thing you should include in your troubleshooting is the ignition switch. They can take a real beating with a heavy set of keys or oversized/heavy keyfobs. There's alot of small contacts doing alot of important things in that little buggar! Best of luck and please do keep us posted...

[bcbike]

Still dead
In short here is what I have done:
Jumped the fuel pump relay and the fuel pump tested OK, pressure at the fuel rail.
Checked all fuses.
Checked the ECM relay.
Cleaned and polished all of the ground connections that I could find.
Checked all of the connections I could find on the wiring harness.
Confirmed I had good ground circuits to the ECM.
Confirmed I had a good ignition circuit to the ECM
Confirmed I had a good battery circuit to the ECM.
Confirmed the injectors are not firing.
Jumped the check engine light to confirm the bulb is not dead.
Still will not start, I can jump the fuel relay to get the pump to work. I do not have a check engine light with the key on and no fuel gauge with a 1/2 tank of fuel.

[Triathlete]

Do you have a scan gauge or a code readee you can use to check for codes?

[Maddawg]

Ok, you've narrowed it down to either fuel or electical. Can you pour some fuel down the the injector body and see if it starts momentarily?? You might also spray some fuel or starter fluid into each cylinder, I know its a lot of trouble but maybe worth it.

[bcbike]

A shot of starting fluid and it fires. I threw a code reader on but it will not connect to read a code.

[Maddawg]

A shot of starting fluid and it fires. I threw a code reader on but it will not connect to read a code.

Ok, so now we know its not an ignition problem, you've got spark. Not compression issue either. So again its fuel. Its not getting there for a couple of reasons. The suspected fuel relay or a plugged fuel line. Disconnect the fuel line before the fuel filter (between the gas tank and the injector body). Start it and see if any fuel pumps into a jar.

[Maddawg]

Was this the procedure you used to check the fuel pump relay?

To troubleshoot a fuel pump relay, start by pulling the relay out of its socket. Use a circuit tester and check the pins in the socket for power with the ignition key off. There should be one pin that has power direct from the battery. If not, check the fuse and make sure that there is power to the fuse. If not, look for the main wire in the fuse block to be loose or open to the fuse. If the fuse is okay and the relay has power to the one pin, turn the ignition key on.

Check to see if there is power to two terminals now. This will require someone else to help because the computer will shut the power off to the relay in 2 seconds if it does not sense the engine starting. This is so that if the switch is turned on, the fuel pump does not keep running. In an accident, the pump will also shut off when the engine dies. Have someone turn the key on and off with 5-second delays while the pins are checked for power to a second terminal. If there is no power, then there is a problem with the line to the ignition switch or a security problem.



This is a problem with the key recognition or if the security system is engaged. If there was power to the second terminal, check the relay with two jumper wires. Put one wire from the positive battery terminal to the relay battery terminal. If this terminal can't be read, put it to any terminal. It won't hurt anything. Run the next lead from the negative terminal of the battery to the relay. With the positive lead attached to a pin on the relay, touch the negative lead to the other terminals. Listen for the relay to click when activated. If it does not click, move the positive lead to a different terminal and try again. If the relay will not click and activate, the relay is bad.

If the relay clicks, then the problem is elsewhere. Use a volt and ohmmeter for the next test. Put the meter on ohms. Remember which terminals have power because to check those terminals with an ohmmeter would ruin the ohmmeter. Look for the terminals without power. Check them for a good ground. If there is no good ground, take the fuse block loose and look under the fuse block for a loose wire or burnt wire. Cut the ground wire and make a new ground wire to the chassis.

If there was a good ground, then insert the relay back in and have someone turn the key on and off and the relay should click. If not, then the computer is at fault. If it clicks, then pull the electrical connector loose for the fuel pump located right behind the fuel tank. Have someone turn the key on and off again while checking for power at the fuel pump. If there is no power, there is an open (bad wire) in the wire leading to the fuel pump. If there is power, the fuel pump is bad.



Read more: Troubleshooing a Fuel Pump Relay | eHow.com http://www.ehow.com/how-does_4796259...#ixzz2D6ab8EX9

[Cris]

I also had a similar problem. Good fuel pressure at idel, but at road speed lost all pressure,check it that way if you can

[VxSport]

I had a chevy s10 a few years ago.... In that vehicle. normal operating fuel pressure is about 62 psi, however it also requires a minimal pressure of 56 psi to let the vehicle start.

[evillecutter]

i had this exact same problem lately - i thought i had a bad relay but it turned out it was the connection between the fuse box and the fuel pump relay -if you can get it to start see if your fuel pump relay gets hot - if it does it means its either bad or isnt getting a good connection - i took mine apart and it looked perfect inside so i sanded down all the contact points both on the relay and inside the fuse box (mine was the post most towards the firewall that wasnt getting good connection) that was a week ago and it hasnt got hot since and has been running much better

[tom4bren]

I threw a code reader on but it will not connect to read a code.

That's not good. The code reader should be able to connect to the computer even if the vehicle is not running.

... This will require someone else to help because the computer will shut the power off to the relay in 2 seconds if it does not sense the engine starting. This is so that if the switch is turned on, the fuel pump does not keep running. In an accident, the pump will also shut off when the engine dies. ... If there is no power, then there is a problem with the line to the ignition switch or a security problem. ... then the computer is at fault.

The fact that the code reader isn't talking to the computer and that the relay is functioning but not getting signal, I think your problem lies with the computer. Unfortunately I don't have a solution for you other than replacing the computer.

i had this exact same problem lately - i thought i had a bad relay but it turned out it was the connection between the fuse box and the fuel pump relay -if you can get it to start see if your fuel pump relay gets hot - if it does it means its either bad or isnt getting a good connection - i took mine apart and it looked perfect inside so i sanded down all the contact points both on the relay and inside the fuse box (mine was the post most towards the firewall that wasnt getting good connection) that was a week ago and it hasnt got hot since and has been running much better

This seems like the next logical step to take (short of replacing the computer).

[bcbike]

Ok. I ran out of options. Found a used computer on Ebay should be here in a few days. My fingers are crossed.

[tom4bren]

Holy crap on a cracker ... I didn't know that you were gonna jump in with both feet on my recommendation. Hope that's what the problem is.

Keep your old 'puter. There are companies online that can fix them (haven't checked specifically for the VX though).

[Maddawg]

Ok, so now we know its not an ignition problem, you've got spark. Not compression issue either. So again its fuel. Its not getting there for a couple of reasons. The suspected fuel relay or a plugged fuel line. Disconnect the fuel line before the fuel filter (between the gas tank and the injector body). Start it and see if any fuel pumps into a jar.

Thats why I was hoping to take the fuel pump out of the equation.

[tom4bren]

Fuel pump is working. He gets pressure at the fuel rail if he jumps the relay. Basically; he's getting power & ground to the relay, the relay functions if jumpered, he's just not getting signal to it from the computer.