Craziest problem ever

[Mdot.]

O k so my resistor on my 1998 3.8 SC GTP went out one day and I bypass it by cuttin wires and tieing them together. Then my car is hesitant one day so I take the MAF sensor out. My car drives like this, fine, for about a year. One day car wont start so I bypass fuel pump from relay still wont start. I look in car at cluster panel I had less than a half tank of gas but it reads full. No check engine light. Also no fuel pump unless i use relay bypass. I replaced the resistor. It used to blow fuses so i replaced all blown fuses. I also installed a new pcm. Car will not start . The shop is sayin replace ignition control module and mass air flow sensor these are expensive parts to not even know if they work therefore i am stuck any help is appreciated. P.S. now this is reallly crazy i would hook a test light up to the resistor wires and sometimes it would glow and other times it would not, whenever it did glow the car would start.

[BNaylor]

There are two relays. Fuel pump and fuel pump speed control so which ones were bypassed? When you bypass the fuel pump resistor which works with the fuel pump speed control relay the fuel pump spins in high speed mode all the time. Check fuel pressure at the front fuel rail. Look for 48-55 psi. Check at fuel pump prime with ignition to ON and while idling with vacuum line at the fuel pressure regulator connected and disconnected.

And welcome to AF.

[tblake]

You are right, the ICM and MAF are both spendy to just throw at it. You can yank the ICM out and bring it to advance or autozone for testing. Have them test it a few times to get it good and hot.

[Mdot.]

Originally Posted by BNaylor

There are two relays. Fuel pump and fuel pump speed control so which ones were bypassed? When you bypass the fuel pump resistor which works with the fuel pump speed control relay the fuel pump spins in high speed mode all the time. Check fuel pressure at the front fuel rail. Look for 48-55 psi. Check at fuel pump prime with ignition to ON and while idling with vacuum line at the fuel pressure regulator connected and disconnected.

And welcome to AF.

Thanks the car wont start so i cant idle but i bypassed the resistor fuel pump then comes on at high fuel pressure i dont have a tester but when i push button it squrts hard

[Mdot.]

thanks i didnt know i could have my icm tested

[CrazyHorst]

The crank sensor is a prime target in my book. When it is bad the car won't start, and there can be some intermittent activity at the very end. Fairly inexpensive part (~$30-40) but a little creativity and thought is required when replacing it in the vehicle. My personal thoughts are it is a good maintenance item anyway given your model year. The fuel injection and ignition reference signals both come from the crank sensor.

[BNaylor]

Originally Posted by Mdot.

thanks i didnt know i could have my icm tested

Double check but most Autozones if not all cannot test our ICMs. They do not have the chart for testing and the special connector plug to adapt the ICM to the test fixture. Of the 17 Autozones in my area none will test the ICM. Even if they could the test is ineffective anyways. For one it doesn't test the ignition timing circuits....IC and bypass modes and a few other key areas.

[tblake]

Did not know that Bob. I thought if an ICM test was good than the ICM was good.