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AutoMD ... 5/12/2014

1994 Chevrolet S10 LS 6 Cyl 4.30L

Preventive Maintenance

why does my Chevy s 10 still sputter after changing fuel filter?

i have a 1994 chevy s10 pickup, i replaced a new gas tank, and noticed that my fuel filter just gave out as i tryed to start it and it had a rough idle, with an odd gas like odor, and black substance left on the ground from my muffler(as i hit gas). i went and bought a new fuel filter, changed it and noticed a better difference, but still has a lag as a tap gas(idle)it almost wants to stall out but when i drive it goes away. except for when i push the gas pedel half way it seems like it sputters, i looked around some people said that bad gas might not of got filtered and made it to my throddle body or carb. Any ideas on whats going on? i went under to check for mis wireing or pinched lines. its all in tack.

3 Answers


CVO 5/12/2014

1. See this site and use their instructions to retrieve any fault codes may store in the engine control module ( ecm ).


2, Sputtering is the symptoms of a weak fuel pump.

1994 Chevrolet Truck S10 Blazer 2WD 4.3L CPI 6cyl
The Fuel System Pressure

58-64 PSI (Pounds per Square Inch)Position the ignition switch and the A/C system in the off position. Install a fuel pressure gauge to the vehicles fuel rail supply line. Place the ignition switch in the on position, confirm that no leaks are present, and start the engine. Visually verify the fuel pressure reading on the gauge.
If the fuel system pressure isn't in the criteria, replace the fuel pump as necessary.


AutoMD Member 5/12/2014

why would my fuel pump be bad its brand new as of a month ago


GT500Knights 5/12/2014

Your problem is a restricted exhaust, most likely cause is catalytic converter. An engine is essentially a big air pump. What goes in must come out. If the exhaust is restricted, then not enough air is able to enter the combustion chamber. Check out the egr valve as well. If it is stuck open then it will allow too much inert exhaust gasses to bypass into the combustion chamber. Both a faulty catalytic converter and stuck open egr valve will cause an odd smell coming from the exhaust.

You have almost the same vehicle as I do. I'm running a 94 s10 blazer lt Tahoe 4.3L vin w cpi

I know my vehicle like the back of my hand, and I maintain it extremely well. If you have any additional questions pertaining specifically to your s10, I can most likely answer them.

AutoMD Member

AutoMD Member 5/13/2014

what happened was as i replaced the failed fuel filter, build up already made it past the filter and into my carb and injectors and that explains sputtering and stalling out. nothing wrong with the vechile it just wasnt getting enough fuel.The black substance that came outa the muffler almost like spraypaint was not enough gas buring up to quickly. simple fix with lucas fuel carb and injector cleaner. pour specified amount into gas tank starter up and talk about instant results. problem started because i didnt change my fuel filter. i advise checking it every 10,000miles, apply some lucas once ina while..and thanks for the advise people.


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