gp wont start "please help"

[hobie728]

I have a 91 gp with a 3.1 liter and right now it wont start. ive narrowed it down to a fuel problem and have changed the fuel pump, fuel pressure regulator, fuel filter, it has pressure at the fuel rail but still it just cranks and cranks and won't start i can hear the fuel pump relay clicking to. can anyone help me.

[GaryFenza]

Could it be the starter?

[hobie728]

it will turn over just wont start its not getting any fuel.

[BNaylor]

Have you checked for spark at any spark plug?

And have you checked the fuel injectors to see if you are getting a pulse from the ECM module?

[hobie728]

it does have spark. i havn't checked the fuel injectors i wasn't to sure on how to do that.

[BNaylor]

Originally Posted by hobie728

it does have spark. i havn't checked the fuel injectors i wasn't to sure on how to do that.

On the 3.1 it is not that easy because the upper intake manifold is in the way. The injectors will have 12 volts at one side of the coil when ignition is set to on/start. The ECM will send a low/ground in the form of a pulse to each injector. So one thing you can do is make sure the fuse feeding the 12 volts to the fuel injectors is not blown.

With a 12 volt test lamp you can check the pulse from the ECM module. There should be a big wiring harness with connector and from there it branches off to each of the 6 injectors. The wire to each fuel injector should be black in color code. To figure it out you may need a wiring diagram for pin outs and wiring color coding.

What type anti-theft deterrent system do you have?

[hobie728]

there is no anti theft system on the the car. all fuses are good. could it be possible for there to be a shorted wire or bad connection. would that cause them all to not work.

[BNaylor]

It is possible but you'll need a wiring diagram and multimeter to troubleshoot. See link below at Figure 12.

Click Here

Another thing you can do is check the connections to the ECM module.

Also, do the tap test on the ECM module. The 1991 models were subject to flaky ECM modules. Make sure the service number on the data label of the ECM is not 1227727.

[hobie728]

thank you for all your help. this will definately be of some use. ill try this out tomorrow and keep you posted. thanks again i really appreciate it.

[richtazz]

Welcome to AF hobie. bnaylor has you covered, and I will add that you may be able to access one of the end injectors without taking the upper plenum off, and get a noid light (I believe Auto Zone has a set in their free tool loan program), unplug the harness from one of the injectors and plug the noid light in. It should flash as the car is cranked, indicating that the car is getting an injector pulse from the ECM. Since the ECM is located under thood on your car in the passenger side fenderwell area, it is prone to water intrusion and corrosion, and the service number he referenced is the most problematic. In addition to no-starts, it can cause random stalling and bucking/hesitation while driving.

[BNaylor]

Originally Posted by richtazz

Welcome to AF hobie. bnaylor has you covered, and I will add that you may be able to access one of the end injectors without taking the upper plenum off, and get a noid light (I believe Auto Zone has a set in their free tool loan program)

May be able to or can definitely access the connector plug at the fuel injector to connect a noid light. The last time I checked any Vin "T" or "M" 3.1L that looked like a nearly impossible feat without removing the UIM.

[hobie728]

I tested the connecting for the fuel injector with a test light and it does flash when trying to start the car anyone got any other ideas.