96 SL with bad accelerator pump???

[Mike Swift]

Yes I know that Saturns do not have carburetors, and hence accelerator
pumps, but thats what the symptoms are. My mechanic has checked O2
sensors, thermal sensors, plugs, coils, throttle position sensor, and
nothing helps. Each time you depress the accelerator peddle the engine
stumbles like the mixture is going lean. It recovers in about 1/4
second, and runs strong until you increase the throttle setting. Then it
stumbles again. This is annoying when shifting gears.
Saturn factory manuals don't mention any troubles that fit this
description, so they are of little use in debugging this problem.
Sometimes I wish it had a carburetor so I could fix the problem.

--
Mike

Some say we must tax corporations more. What they do not understand is that
corporations do not pay taxes. One of our governments conditions for their
existence is they collect the taxes from their customers and pass them to
the government.
Mike Swift

 

[Bob Shuman]

Just wanted to suggest that the stumble on acceleration could very well also
a sign of running too rich (and not necessarily too lean). This appears to
be the first message posted in this thread from my news server so I have no
idea what other symptoms or actions you have taken.

How exactly has the mechanic "checked" the items you have listed? Is that
mechanic competent and familiar with Saturns? Are the plugs and wires new
and are they gapped correctly? Have the fuel and air filters been replaced?
Are there any obvious vacuum hose or manifold leaks? Is the EGR valve
functioning properly? Have you looked for and cleaned off corrosion on the
coil towers? Are the engine and body ground wire connections all clean and
tight? Are all the injector connectors clean and tight? When was the last
time the throttle body and AIS were properly serviced? Have you removed the
plugs and were they carbon fouled or oily?

Good luck. Post what you find?

Bob

 

[Mike Swift]

Just wanted to suggest that the stumble on acceleration could very well also
a sign of running too rich (and not necessarily too lean). This appears to
be the first message posted in this thread from my news server so I have no
idea what other symptoms or actions you have taken.

How exactly has the mechanic "checked" the items you have listed? Is that
mechanic competent and familiar with Saturns? Are the plugs and wires new
and are they gapped correctly? Have the fuel and air filters been replaced?
Are there any obvious vacuum hose or manifold leaks? Is the EGR valve
functioning properly? Have you looked for and cleaned off corrosion on the
coil towers? Are the engine and body ground wire connections all clean and
tight? Are all the injector connectors clean and tight? When was the last
time the throttle body and AIS were properly serviced? Have you removed the
plugs and were they carbon fouled or oily?

Good luck. Post what you find?

Bob

Thanks for the quick response Bob. Plugs are new and gapped, EGR valve
is working, air filter has been replaced in the last 5000 miles, plugs
are clean, engine ground wires are good and tight, and the throttle
position sensor has been replaced. Im not sure what you mean by
"throttle body and AIS were properly serviced". My mechanic, and his
other two men have had at least 20 years experience on almost every
brand of car including a hundred or more Saturns.
This morning he has found that the fuel pressure is 35 psi, and should
be, by the book, 45 psi minimum. He is going to replace it, and I hope
that was the problem.

--
Mike

Some say we must tax corporations more. What they do not understand is that
corporations do not pay taxes. One of our governments conditions for their
existence is they collect the taxes from their customers and pass them to
the government.
Mike Swift

 

[Bob Shuman]

Thanks. Here's to hoping it is the fuel filter and this solves your problem,
assuming that is the "it" that is being replaced. If not, the fuel pump
will be a bit more expensive.

Bob

 

[NapalmHeart]

Thanks for the quick response Bob. Plugs are new and gapped, EGR valve
is working, air filter has been replaced in the last 5000 miles, plugs
are clean, engine ground wires are good and tight, and the throttle
position sensor has been replaced. Im not sure what you mean by
"throttle body and AIS were properly serviced". My mechanic, and his
other two men have had at least 20 years experience on almost every
brand of car including a hundred or more Saturns.
This morning he has found that the fuel pressure is 35 psi, and should
be, by the book, 45 psi minimum. He is going to replace it, and I hope
that was the problem.

Which plug gap spec are you using? In '96 the spec was changed to .60", but
then was changed back to .40".

The throttle body plates are notorious for accumulating carbon and benefit
from a good cleaning with TB cleaner and a nylon bristle brush.

Ken
--
"A drug is neither moral nor immoral - it's a chemical compound. The
compound itself is not a menace to society until a human being treats it as
if consumption bestowed a temporary license to act like an asshole."

- Frank Zappa

 

[Mike Swift]

This saga is getting a little long, so I am going to top post this so
those knowing the tail won't have to page through all of the details.
My mechanic has replaced the fuel filter, no solution, fuel pump, no
solution, and then fuel air ratio sensor, but still no solution. I am
going on a trip of about 1400 miles starting tomorrow, and when I get
back will see if the Saturn dealer can diagnose the problem. I really
want to find the exact cause, Im an engineer if you could not guess, and
not just replace parts until it works.

Thanks. Here's to hoping it is the fuel filter and this solves your problem,
assuming that is the "it" that is being replaced. If not, the fuel pump
will be a bit more expensive.

Bob

Just wanted to suggest that the stumble on acceleration could very well
also
a sign of running too rich (and not necessarily too lean). This appears
to
be the first message posted in this thread from my news server so I have
no
idea what other symptoms or actions you have taken.

How exactly has the mechanic "checked" the items you have listed? Is
that
mechanic competent and familiar with Saturns? Are the plugs and wires
new
and are they gapped correctly? Have the fuel and air filters been
replaced?
Are there any obvious vacuum hose or manifold leaks? Is the EGR valve
functioning properly? Have you looked for and cleaned off corrosion on
the
coil towers? Are the engine and body ground wire connections all clean
and
tight? Are all the injector connectors clean and tight? When was the
last
time the throttle body and AIS were properly serviced? Have you removed
the
plugs and were they carbon fouled or oily?

Good luck. Post what you find?

Bob

news:tomswift-6EFEFE.00383713022007@[198.186.190.159]...
Yes I know that Saturns do not have carburetors, and hence accelerator
pumps, but thats what the symptoms are. My mechanic has checked O2
sensors, thermal sensors, plugs, coils, throttle position sensor, and
nothing helps. Each time you depress the accelerator peddle the engine
stumbles like the mixture is going lean. It recovers in about 1/4
second, and runs strong until you increase the throttle setting. Then
it
stumbles again. This is annoying when shifting gears.
Saturn factory manuals don't mention any troubles that fit this
description, so they are of little use in debugging this problem.
Sometimes I wish it had a carburetor so I could fix the problem.

Thanks for the quick response Bob. Plugs are new and gapped, EGR valve
is working, air filter has been replaced in the last 5000 miles, plugs
are clean, engine ground wires are good and tight, and the throttle
position sensor has been replaced. Im not sure what you mean by
"throttle body and AIS were properly serviced". My mechanic, and his
other two men have had at least 20 years experience on almost every
brand of car including a hundred or more Saturns.
This morning he has found that the fuel pressure is 35 psi, and should
be, by the book, 45 psi minimum. He is going to replace it, and I hope
that was the problem.

--
Mike

Some say we must tax corporations more. What they do not understand is that
corporations do not pay taxes. One of our governments conditions for their
existence is they collect the taxes from their customers and pass them to
the government.
Mike Swift

 

[njot]

I bet you tht this is the EGR control solenoid. It is turning on EGR
too soon, causing the stumble.
I'd start here and go from there.