Mechanics

3.1 VIN D NO CHECK ENG LITE.

1991 Pontiac Transport

Hi,
Like I said, The car is a 1991 Pont. Transport 3.1. The car stalled and check engine lite does not come on. When noid light is connected to the injector connector, there is no pulse(lite). Also with fuel pump(no pulse). Distributor has spark. Will ignite with carb spray.
Why is the computer not responding when I hook up scanner. When I checked computer with LED safe Tester, it is recieving two + and - at supply end.I (1)thought of a crank sensor.(But why is there no resonse from PCM?)(2) cannot find crank sensor?
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48chev
October 4, 2007.




Sorry for the delay, I was away this weekend. The first path that has to be crossed is the communication with the ECM. A fuse is a likely starting point, has it been checked?

When you first turn the key on does light illuminate breifly?

You sound experienced more than most so I will assume you have.

Those older 3.1 motors were plagued with injector problems that if caught early enough were able to be cleaned. Still the would set a misfire code.

Have you checked the fuel pressure and volume?

Hi, Thanks for answering. Yes I checked for fuel pump pressure. No volt sence at fuel pump and
no pulse at injectors.I disconnected the complete alarm system and reconnected the fuel pump wiring like it was originally. There is continuity from ECM to
fuel modual. There is + and - going to the ECM. Like I said engine will run with carb spray. ECM is not puting out injector pulse or fuel pump sence.I was told on some GM modles that if the Crank sensor
is no good or shorting I will have no communication with ECM and check engine lite will not come on.
This is my problem NO COMMUNICATION WITH ECM. Therefore I cannot scan. Also I was told by the dealer that this model does not have a crank sensor.
But if you go to online parts it lists one?I have a picture but no location of sensor? Your help is appriciated.
48chev

Tiny
48chev
Oct 14, 2007.
Does the CEL illuminate breifly when the key is turned to the on position for the bulb check?

DId you check the ecm/fuel pump power fuse?


http://www.2carpros.com/forum/automotive_pictures/30961_tr1_1.jpg



http://www.2carpros.com/forum/automotive_pictures/30961_tr2_1.jpg



http://www.2carpros.com/forum/automotive_pictures/30961_tr3_1.jpg



http://www.2carpros.com/forum/automotive_pictures/30961_mitchel_36.jpg



There is no crank sensor on this one that I can find. PArts store sometimes list things that are nor accurate. Cabin air filters are one of the best examples :x :? .

Also check this 10 amp fuse:


http://www.2carpros.com/forum/automotive_pictures/30961_tr4_1.jpg


Hi, Thank you for all the input. I replied to your request. The diagrams you sent me are very helpfull,
I am going to check all what you had listed including the bulbs in the dash for MIL iight. My problem is I need to tow the vehicle back home. It is stuck where it is very difficult to work on. This might take a couple of days. After I make all of the checks you
had mentioned, I will post the results.
Thanks Again
48chev
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Tiny
48chev
Oct 14, 2007.
I just want to make sure the bulb does illuminate. Probably does.

I'll catch up with you when your ready. Before you tow it, I would check the fuses I mentioned, it may be that simple.

Thanks I will check the bulb/fuse Car was towed today, I will be in touch and keep up my obligation
to your wonderful forum.

Thanks
48 Chev

Tiny
48chev
Oct 17, 2007.
Thanks I will check the bulb/fuse Car was towed today, I will be in touch and keep up my obligation
to your wonderful forum.

Thanks
48 Chev[/quote: c08ec2b6ba]

Hi,
The fuse you sent me a diagram to check was the first fuse that I checked from the begining.I checked the
MIL bulb(check engine light) and it is OK
This is becoming a real Ordeal! What else can you think of that would cause No communication with
ECU and no Check engine light and no fuel pulse.
What about a fuel pump relay? Where is it located?

Thanks 48 Chev.

Tiny
48chev
Oct 18, 2007.
Get an assistant to turn key On, At the fuel pump connector,do you have power at gray wire you gonna have this power just 2 secs. then its gone and should be there at all times while engine is being crank over. If power is at the gray wire you have a problem the F/Pump.

Familiarize yourself with the circuit below its gonna come up


http://www.2carpros.com/forum/automotive_pictures/12900_oil_sending_unit_and_fuel_pump_circuit_9.gif


Tiny
Rasmataz
Oct 19, 2007.
From 48 Chev
Hi, I will return to car on Sunday and will check power at fuel pump Again. That is also one of the first things I did. If the relay is under glove box which one is it. I need a diagram with pin # at ecm and exact location of fuel relay to check it properly. After I check I will answer.
Thanks
48 Chev

Tiny
48chev
Oct 19, 2007.

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