fuel pump gone loco

[4g63tsiawd]

Here it is. The fuel pump doesn't kick on when I turn on the key, it wont prime. The relay clicks on with the key and clicks off with the key turned off. I hooked up my pda and did a fuel pump test, and wallah the fuel pump kicks on. Still no key though.

 

[Puscifer]

Have you rewired your FP? If so, check the connections and relay. Only thing I could think of. What kind of FP are you using.. Little more info boss man

 

[steve]

What makes you think it's suppost to kick on with the key?

It's designed to start when you begin cranking the starter and once the engine fires keep running.

The MPI side of the relay turns on with the key to provide main power to the ECU and turns off a few seconds after you turn off the key but the fule pump side has two inputs the starter circuit and the ECU for keeping the pump running.

Does your car start and run?

Steve

 

[4g63tsiawd]

When the car was running, I could turn the key to the on position and hear the fuel pump kick on and prime. Also I unhooked the ignition wire going to the starter, so I could turn the key like I was starting the car just not engaging the starter ( new motor never started) and I still don't get the fuel pump. Yes the fuel pump is rewired, but it works with the pda. Its is a walbro 255.

 

[steve]

When the car was running, I could turn the key to the on position and hear the fuel pump kick on and prime.

It's not intended to but some people with 1990 cars have reported it doing so. I haven't been able to isolate a reason. Either it's something in a very early ECU software or on some cars the CAS glitches when you turn the power on causing the ECU to think the engine is running and it activates the fuel pump. Either way it's not the normal behaviour for most DSMs. They don't prime the pump when you turn the ignition on.

The fact that you can trigger the pump with the logger means the ECU is able to control it.

Get the wiring diagram and start measuring voltages to figure out then it's not triggering the fuel pump from the starter circuit.

Steve

 

[4g63tsiawd]

Steve you were correct. Now to concur another problem. I still dont have a check engine light, a oil light when I turn on the ignition and now I have no spark, theres got to be a plug I missed. I already tried another ecu, and its not the problem.

 

[Puscifer]

Odd situation you have there. Have you by chance checked the coil pack and the power transitor (the plugin for the coil pack to the wiring harness) sadly my clip broke off so i've got to tie it down w/ zip ties, if not i get all kinds of funky readings, CEL flashing, loss of spark.. anything you'd expect w/ a bad connection. Have you by chance checked your balance shaft area out? there's a seperate belt our cars use to drive the oil pump (which can be eliminated for the health of our cars which is strongly suggested) easy to access to check to make sure they're lined up.

i know i'm bouncing around but i'm just giving you check points for issues til steve chips in

 

[4g63tsiawd]

Balance shafts are removed. I will check when I get home for power to the power transistor, and coil pack. I have a feeling that the no check engine light, and oil light have something to do with no spark.

 

[steve]

I have a feeling that the no check engine light, and oil light have something to do with no spark.

The CEL does.
If you don't get the CEL to turn on for five seconds and then turn off when you turn the ignition on then the ECU isn't working.
No ECU = no spark, no fuel, no run.

Steve

 

[4g63tsiawd]

Ok I did some voltage checks at the ecu. Are you suppose to have voltage @ pin 108 which is the ignition switch, cause I don't.

 

[steve]

Ok I did some voltage checks at the ecu. Are you suppose to have voltage @ pin 108 which is the ignition switch, cause I don't.

When you have the ignition switch in the START position you should have 12v at pin 108.
When the ignition switch is in the RUN or START position you should have 12v at pin 110.

You should always have 12v on pin 103.

When the ECU sees 12v on pin 110 it should pull pins 63, 66 low causing the MPI relay to activate and provide 12v to pins 102 and 107. That should cause the ECU to boot, turn on the CEL and set the boost gauge to zero. After five seconds it should turn the CEL off. If everything is normal the ECU will pulse pin 1 half second on, half second off, repeading or send out a CEL code.

The source of the signal to pin 108 is the same as what drives the fuel pump side of the MPI relay and the starter solenoid.

Steve

 

[4g63tsiawd]

I did everything you said in this link http://www.dsmtuners.com/forums/showthread.php?t=239406&highlight=ECU+power
And just checked what you said in my forum. Pin 110 is good 12volts. pin 63 and 66 are seeing 0.07 when pin 110 is charged. Is this ok if so what next. Also I've checked 2 ecus with the same results.

 

[4g63tsiawd]

Its magic. I was sitting there with my hand on my forehead, cursing to myself. And I thought just one more time, turned the key and Valhalla check engine light. Now for the new problem.
http://www.dsmtuners.com/forums/showthread.php?t=229514&highlight=90+cas
This is the cas I have now. So just cut and splice huh. Can some one tell me the colors of the wire that goes to the injector resistor pack, I know its a grey plug, but there are like2 grey plugs with the same number of wires. Also so I don't cut the wrong wire the colors of the wires for the cas. Its telling me a code of 41 injector circuit.

 

[4g63tsiawd]

Ground, ground, ground. These are very important in theses cars. I was at the point of giving up for the day, when I seen a lonely black wire laying there. Put it to a ground and bam, started right up. Now how long before these damn lifters stop ticking.