Hi,

I have a 93 Suburban with 167,000 miles on it. I am having problems with the car hesitating and surging at parking lot speeds of 15 MPH and lower. Once I get above the 15 MPH zone the surging goes away but I can still tell the engine is running rough. The car just had a tune up done by the local dealership where they changed plugs, wires, rotor and cap. They did not change the fuel filter and I do not know when the last time the fuel filter was changed.

I also removed the airbox off of the throttle body and found that the metal shroud just under the airbox, was leaking and allowing unfiltered outside air to enter the fuel mixture. I sealed this area up but still with no luck.

I am going to get a fuel filter as soon as I post this thread but wanted to know from any of you, if this is a common sympton to a specific problem on the Chevy 350 where you could point me in the right direction.

Not sure if it matters on a vehicle this old but I do not have any check engine lights illuminated causing any codes.

Thank you in advance for any help you can give me.

 

Sounds possibly symptomatic of a fuel filter issue. Let us know how it runs afterwards. It might not throw a CEL if all the exhaust gasses are right, sounds like the fuel pressure might just be a tad low. Question is it somewhat powerless even at higher speeds? This could posibly be an O2 sensor or catalytic converter as well. Try the fuel filter first they are inexpensive, remember to re-pressurize the system before attempting to start the truck.

 

To repressurize the fuel system, would I just turn the ignition to the on position and leave it there for a few seconds while the pump works? I have the filter in hand and I'll be reporting the results soon.

 

Well I was just towing a single Axel 6X12 enclosed trailer up a pretty steep hill with the Suburban and the engine almost died on me. It was spitting and surging very badly.

If it was a clogged fuel filter wouldn't it have low flow at all throttle settings and not just idle? If that is correct then you would think that it would cut out on you at all RPM's. I have the new filter and its going in now. Hopefully this fixes the problem.

Any other ideas incase this doesn't work?

 

if the truck was only surging @ idle speed i would have suggested to change your IAC, but, since the problem seems 2 b happening at other speeds/conditions.....does your truck slowly lose power as it warms up? if this is the case, then it's a safe bet the cat's going. remember, if your cat's packed it in, b sure 2 change your O2 as well. it's also a good idea 2 flush the fuel system like Tommygunz suggested-just b sure 2 do it before the new cat is installed.

 

Well I changed the fuel filter and drove it out to Sierra Vista, AZ and it did not fix the problem. I guess I could see if I can eliminate the cat. The O2 sensor looks to be forward of the cat so I don't think that will cause any issues to remove it.

 

I would first recommend removing the O2 sensor, cleaning it thoroughly with a carb cleaner spray.. let it dry and reinstall, if performance comes back that was your issue, also remember as O2 sensors fail they will generally cause cats to get clogged. Do you have alot of black smoke coming from your exaust like it is running rich or looks like your mototr turned into a diesel? That is tell tale of an O2 failure. 99% of the time when O2's fail the PCM will register their signal as low air/fuel ratio and increase the fuel being dumped into the motor.