95 Chevy 350 TBI acceleration problems

Have a question or want to start a discussion? Post it! No Registration Necessary.  Now with pictures!

Threaded View


Symptoms are as follows:

When first started it runs fine for a few seconds then just dies like
the switch was turned off. Cranks back up pretty easy again but idles
high (1500RPM) for a bit then comes down and may idle fine for ever
then it sometimes gets rough and dies. If I put it in gear or turn on
the AC it gets rough and dies.

Driving it has trouble accelerating at low RPM. When I step on the
throttle it bogs, grumbles and sometimes backfires (through the intake
I think) but then it takes off like a dragster. Temperature only seems
to make a slight difference but I do notice some improvement with the
Coolant Sensor disconnected (on the intake manifold).

New plugs, coil, cap, rotor and wires
New Cat. Convert
New fuel filter- Fuel pressure is roughly 10 PSI (book spec-9-12)
Removed EGR and it works nice and smooth
Checked values of the MAP, Coolant sensor, Throttle position sensor,
Idle air thingy and all seem to be with in spec (per tech manual) did
the best I could with my multimeter by myself.

On one occasion (early morning going to work) it back fired and
(slightly bigger than normal) and took off like a "Bat out of Hell"
and worked like new for a couple days.

At high speeds it fluctuates. It sometimes works right or some times to
maintain even throttle or increase speed it takes enough throttle to
drop in to passing gear.

Someone suggested rechecking the fuel pressure by pinching off the
return line to see if pressure increases by 4-6 PSI. That puzzles me.
Back when I first checked the fuel pressure, I did so with the engine
off and running and it held pretty steady at all times. What would be
different by pinching the return line?

Had a shop run diagnostics for 2 hours but never found the problem.
Sometimes I swear it acts like weak spark or fouled plugs. I have watch
the fuel spray in the TBI for long periods of time with out any
deviation, even when put under a load. It is my understanding that the
TBI pulsing is controlled by the distributer and I wonder if there
could be a problem there? In the fuse box the fuel pressure regulator
box gets hot (uncomfortable to touch but no injury). Is that a problem?
The ones surrounding it do not.

I am at the point of replacing the fuel pump and or the TBI,  but I
would like some more opinions or advise if any one has expertise or had
experienced similar problems.

Thanks in advance.


Re: 95 Chevy 350 TBI acceleration problems


you should be able to go have the codes read, no?



Quoted text here. Click to load it



Re: 95 Chevy 350 TBI acceleration problems



edgar wrote:
Quoted text here. Click to load it


Re: 95 Chevy 350 TBI acceleration problems



edgar wrote:
Quoted text here. Click to load it
back. He checked every thing he could think of for a couple hours but never
found the problem.

Reason for the different name: I have 2 e-mail accounts one at work and
one at home. I posted this question while at work as "rong". I am
replying at home as "welder"


Re: 95 Chevy 350 TBI acceleration problems


rong wrote:
Quoted text here. Click to load it
I think I would try unplugging the MAP (elect plug) and driving it to
see if it does better. The light will be on but it should run fairly
good. If it runs good with it disconnected and bad with it connected
then...well...replace it :) Also check the vac to it closely. Also, the
TPS, did you check it through its entire range? slowly? Some of those
TBIs had a bad problem with the tbi base gasket going bad too. Not sure
of the years (seams like late 80s)but it would make it do all kinds of
goofy stuff.

Re: 95 Chevy 350 TBI acceleration problems



rong wrote:
Quoted text here. Click to load it


Re: 95 Chevy 350 TBI acceleration problems



rong wrote:
Quoted text here. Click to load it


Re: 95 Chevy 350 TBI acceleration problems



rong wrote:
Quoted text here. Click to load it


Have you changed your fuel filter?
Is there any debrie in your fuel tank?
Are there any shorts in your plug wires?
Are there any shorts between the distributor and TBI?


Site Timeline