OBD II Fuel System Status Question

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Old_Timer - 31 Jul 2005 20:51 GMT

I have 96 Dakota 3.9 automatic that gives me less fuel mileage than
what I believe I should be getting.

I have ensured that the plugs are in good shape,the plug wires are
new, tires properly inflated, drive with a light foot, I have changed
both oxy sensors. The truck runs fine and the OBD II is not
generating any trouble codes. The truck recently passed the Calif
smog test and passed by a very wide margin. I have ran liquid
injector cleaner in the tank several times.

I obtained a Davis CarChip device so I could get a printed record of
what is happening in regard to OBD readings. What I found out is that
Fuel System #2 runs in open loop for a few minutes while the coolant
temp is coming up, but Fuel System #1 is staying in open mode all the
time.

Now I am an OLD shade tree hobby mech since Model A Fords were a
common sight on the streets. Until now I haven't given much effort
to understanding the OBD system but I now would like to increase my
knowledge in that area, hence putting out the bucks for the Davis
CarChip.

My guess, and correct me if I am wrong, is that Fuel System #1 refers
to the injectors on Bank #1 and Fuel System #2 refers to the injectors
on Bank 2. Can anyone confirm this.

Would a dirty or clogged injector in Bank #1 cause it to remain in
Open loop? Is now the next logical step to have a professional
cleaning of the injectors.

Old_Timer

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Coasty - 31 Jul 2005 21:13 GMT

Step 1 Use a long handle screw driver put it on each injector, you should
hear a distintive tapping as the injector fires. If one or two are week you
will notice it right away. Run a pressurized fuel rail cleaner follow the
directions. Recheck injectors if all is well thet was your problen, if an
injector does not sound right replace it. Also buy an o-righ kist and
replace all the injector o-rings while you have them pulled.

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Coasty

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>I have 96 Dakota 3.9 automatic that gives me less fuel mileage than
> what I believe I should be getting.
[quoted text clipped - 27 lines]
>
> Old_Timer

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Old_Timer - 01 Aug 2005 01:32 GMT

>Step 1 Use a long handle screw driver put it on each injector, you should
>hear a distintive tapping as the injector fires. If one or two are week you
>will notice it right away. Run a pressurized fuel rail cleaner follow the
>directions. Recheck injectors if all is well thet was your problen, if an
>injector does not sound right replace it. Also buy an o-righ kist and
>replace all the injector o-rings while you have them pulled.

Thanks Coasty, I will try and see if Ican hear a bad injector.

Old_Timer

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