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rpmdiag, Tech and Instructor
Category: Chevy
Satisfied Customers: 8151
Experience:  Since 1975
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Seems to be running a little especially just after being

Customer Question

Seems to be running a little rich especially just after being started.
JA: Will the headlights turn on? Is the battery fully charged?
Customer: Yes and yes.
JA: What is the model/year of your Chevy?
Customer: c1500 '88
JA: Are you fixing your 88 yourself? What have you tried so far?
Customer: I would most likely be doing the work myself.
JA: Anything else you want the mechanic to know before I connect you?
Customer: I haven't done much on trying to figure out why it is running rich. Right now I am in the research phase to see what things I should try. Spark plugs and wires are only a few months old. Alternator is less than 2 yrs. TBI was rebuilt near the begining of the year.
Submitted: 1 year ago.
Category: Chevy
Expert:  rpmdiag replied 1 year ago.

Hi, I'm Ron and I will be helping you today.
Stand by for a moment while I prepare your answer.

Customer: replied 1 year ago.
Customer: replied 1 year ago.
Also, a throttle body spacer is installed on the engine.
Expert:  rpmdiag replied 1 year ago.

Rich conditions include leaking injectors, bad pressure regulator, manifold vacuum line off of regulator, plugged air filter.

You should also scan the computer reading the integrator and block learn values. A bad O2 sensor biased lean will also cause it.

Thanks, Ron

Customer: replied 1 year ago.
I doubt the air filter is the plugged. It is a full dome air filter. TBI pressure regulator was recently rebuilt with the TBI rebuild.
How could I rule out or test for leaking injectors? Vacuum line?
Expert:  rpmdiag replied 1 year ago.

Your regulator is built in the the TBI unit, no vacuum line on that one.

A fuel pressure tester/leakdown tester is need to check for leaky injectors.

You can also test the O2 sensor with a scope for biased lean condition.

Thanks again and please remember to rate me 5 stars and keep this link for when you need me again later on.


Customer: replied 1 year ago.
Also about once a week, when I start the engine, it seems to have a low idling condition and will shut off. That almost seems like it is dependent on the weather though. Just in case the two conditions are related some how
Expert:  rpmdiag replied 1 year ago.

Let's concentrate on the initial issue first, by repairing this, may fix your other issues.

I need the data from your scan tool readings and scope as well. Let me know if you need any wave forms to match to.

Thanks, Ron

Expert:  rpmdiag replied 1 year ago.

If you are satisfied with my answer, I would greatly appreciate a 5
star rating now and I will still assist you after you have rated me
too if another question pops up. I don’t get credit for helping you
until you rate me.
Thanks again, Ron