1994 Suburban sputtering/lugging off idle
 

My Uncle has a 94 Suburban with the original TBI 350 that he picked up to mess with on the side. (He has a Suburban fetish. He has 3 now.) The problem is it will idle fine but as soon as you give it just a little bit of throttle it will start to lug or sputter but let off and it idles fine again. He has replaced the fuel filter twice and cleaned up the throttle body as well as throw some parts towards the ignition. He also replaced the EGR valve. He is getting rather angry with it now. What do you guys think? Has anyone had a similar problem and if so how did you resolve it?

Re: 1994 Suburban sputtering/lugging off idle
 

Try the engine coolant temp sensor.

Re: 1994 Suburban sputtering/lugging off idle
 

Did he put a GM EGR on it? If he bought aftermarket that is likely the problem. I learned the hard way to listen to these guys. Factory EGR only.

EDIT: I should have said Delco or Delphi brand, not necessarily GM.

Re: 1994 Suburban sputtering/lugging off idle
 

It ended up being a fuel pump. Hooked up a gauge and it only had something like 4 psi. I cant remember how much he said. But thanks for the replies fellas.

Re: 1994 Suburban sputtering/lugging off idle
 

I've been having the same problem with my '94 k1500 lately, (past 2 months). Had fuel pump replaced like 6 months ago. I'll try the other suggestions hopefully it works out.

Re: 1994 Suburban sputtering/lugging off idle
 

Issues that cause stumbling in TBI engines are usually air/fuel related and Ive developed a decent list of about all there is that can cause these symptoms. My truck had this sort of problem and I had to go through every single thing before someone told me to pull the intake and look around. My problem was the intake gasket was crossed over pulling air from a coolant passage. It was not something I would have been able to diagnose without removing the intake so be prepared to go that far if need be. I had several other minor leaks though. I explained how to trouble shoot some items on this thread you might want to look it over. http://67-72chevytrucks.com/vboard/s...d.php?t=649234

IAC valve dirty or failed
Vacuum leaks at intake or TB gasket or interior intake gasket leaks
egr
Oxygen sensor
MAP sensor
low fuel pressure such as caused by a bad fuel pump or bad injectors in TB
CTS sensors. There are two. One near the intake one on the drivers side head.

If you unplug the IAC you need to cycle the ignition a few times to reset it. This can cause the ECU to compensate for the issues your having and might run well for a day or so before returning the hunt and stumble.