Shuddering and loss of power under acceleration

[Scooter2004]

I recently had my fuel injectors (spider) replaced as there was a serious over fueling problem.
Shuddering and hesitation was occurring or bogin out under acceleration.
I changed the plugs (AC Delco) and Terra cleaned it. For a cool $900.00 bucks.
Now this problem is back, not as bad as before, I am thinking fuel pump now?
I can hear the pump working as I prime it before starting and she fires right away.

Next there are a few secs of ok idling, and then it goes rough and is miss firing.
Ok by this point we should also know I have cleaned the throttle body out and replaced the air filter and replaced the oil and filter; have installed a clean screen EGR gasket replacement. (Catches the carbon particles and they burn off before the get into the pintle) The truck seems to do better if I let off the gas and then re-accelerated in a gradual fashion vs. pounding it.

Now it seems that the rough idling is effected more adversely with colder weather
And I am smelling fuel in the rear of the truck after I shut it off and open the gate.
I realize that the seal or gasket around the pump might be an issue for the smell, however,
Stating this as I am really suspecting a fuel pump issue or perhaps an oxygen sensor? Are the wires attached to the sending unit on the pump and issue to look for?
(This is a CPI model of truck by the way) this is the first GM product I have owned and I have read the specs and still I am coming up dry.

I have the previous owner’s service records and he complained of the same thing.

Anyhow I am a guessing now… so this is why I was so impressed with this forum as you all seem to have some really great ideas. I have found one article that I can share that sounds like what my issues are but I would rather email it to anyone that might help as it’s rather long.

Ok my novel of a post is done….. Thanks in advance.

Scott

[BlazerLT]

Remove the upper plenum and look for a fuel line leak that could have occured after the new injector was inserted.

You always replace the internal fuel lines with the injector.

Also, was the fuel filter replaced?

Look here for more information:

http://www.s10forum.com/forum/showth...pi+replacement

Also:

-Have you replaced the cap, rotor and wires?
-Have you CAT converter tested (could be clogged due to the leaking injector.
-Remove and reconnect the connections to the computer on your passenger side wheel well. Make sure they are clean and have no corrosion.
-Ever replaced the O2 sensors?
- How many miles on your truck?

[Scooter2004]

no, to my knowledge the internal fuel lines were not replaced.

yes, I did replace the fuel filter 60 days ago

cap n rotor is stock.

The Cat was tested and came back ok, but when the sniffer was doing its thing prior to the injector install it was off the chart. So that is somthing to look at

Sensors are stock as far as I know

201,455 kms


now I will look at your link

thanks man

[BlazerLT]

First off:

Replace the Cap & Rotor. My god 10 years on one cap and rotor and you don't even consider this one of the problems?

O2 sensors.

There will be two of them, one in front and one behind the cat.

Replace them with Bosch 15703.

After you reset the computer watch your fuel mileage take a leap.

My 1995 Blazer has 213,000kms.

[Scooter2004]

hahahaha never said I was a mechanic! just can read specs by the way excellent article you wrote on the replacement of CPI.

so first off cap n rotor
then 02 sensors
reset the computer, I will have to get that done for me I don't have the tools for that.

thanks man I really do appreciate your assistance

I will get back to you on the progress...

cheers man

Scott

[BlazerLT]

resetting the computer means just taking the negative battery cable off the battery and doesn't require any special tools.

Also, don't rule out the internal fuel lines leaking.

You need to check that out just to be sure.

Remove the cover plate and check for washing on the driver's side. If it is dry and dirty, they are fine.

If it is clean and fuel is puddled you found the problem.

Replace a new plenum gasket and put the cover back on.

Remember to clean the EGR port like in the write up I did.

[Scooter2004]

sure thing bro, I will do as you suggested I must sleep now.... cheers

[Scooter2004]

BlazerLT:

Well chopped the cat off, big difference there
looked at the EGR and its clean.
Cap and rotor with wire kit is bought but not installed yet.
I only have one 02 sensor its the 95 that has two.
I have it but GM says the check engine light would lit up if it was that. still going to change it anyhow.

All in all the issues I spoke of are now down by at least 50% now have to install the rest of the gear.
plenum is dry
so might be a vaccum leak ?
anyhow I will chat later. thx for your help

[BlazerLT]

Remove the upper plenum cover and check for leaking fuel lines or a possible defective injector again.

[Scooter2004]

yep all done, no fuel leak,
as you suggested.
cap n rotor with a wire set and an 02 sensor. NGK instead of the bosch
all I have to say is wow., there is a few other things but
at least GM is fixing my abs as its under recall for axle signal malfunction. Did my brakes and rotors, again wow.
there is a slight hick up in the vortec but I am to understand that its a quirk of the 4.3 L so I am told. anyhow I can live with it now. and I will slowly just add things like a gun turrent for rush hour hheeh :>
anyhow thanks again

now for new treads and its going to snow this coming sunday and tuesday we are expecting flurries in calgary!

see ya

Scott