I just purchased a 1989 Chevy Suburban 2500 4x4. It drove fine the first few days but then started giving me problems starting. It still ran fine but misfires a a little while idling. The engine is running rich as I can smell the gas fumes. The previous owner said he recently replaced the fuel pump and all the sensors and was going to rebuild the throttle body injectors but had not gotten to it. While driving down the highway last night I decided I didn't need to burn that extra gas doing 70mph down the highway so I started to let off the accelerator. I hit an overpass and the engine bogged down. It seemed to be fine as long as I kept the speed up but anytime I let it get to 60mph and tried to accelerate from there it would bog down. It continued to do this all the way home but seemed to be fine once off the highway. Thoughts? Should I look at the TBI right away or could it be something else? Should I stop driving it until I address the problem to prevent damage?

 

Welcome to the forum.

My best guess is you have 1 or more bad injectors in the throttle body.

 

So I should look at replacing them or could they be clogged and need to be cleaned? Sorry for the ignorance. I can replace parts but as far as diagnostics and such my experience is limited to lawn mowers.

 

You could try running a couple of bottles of Techron to the gas and see if that helps.

 

Thanks. I won't be able to really dig into it until Tuesday. Should I stop driving it to and from work until then? Could I do damage to engine if I kept running it?

 

Too rich can ruin the cats and also tends to wash the oil off the cylinder walls. So yes, I'd get it fixed.

 

I rebuilt the throttle body and replaced the injectors. The truck is running again but it's still smells like the mixture is wrong. I can visually see both injectors spraying evenly when the truck is idling. What else could be causing the problem? According to the previous owner, he had replaced all the sensors just before selling it to me.

 

Nothing? I'm really puzzled over this. I looked at the check engine codes and I'm getting an EGR valve code as well as an "rich exhaust" code (which Haynes says could be the oxygen sensor). The previous owner recently replaced the EGR valve and O2 sensor.

Why would it only give me problems on my way home from work? It doesn't act up driving around town. So far it's only been at night and on the highway. I park on the sixth floor of a parking garage at work and it doesn't give me any trouble on the way there or on the way up to the sixth floor. After the TBI rebuild and injector replacement I took it to work and the same thing happened. It starts between 55 and 60 mph and the more I press the accelerator the more it slows down. Sometimes the engine will suddenly surge and my truck will dart forward and the check engine light comes on while the truck accelerates rapidly.

 

Check your throttle position sensor, idle air control valve, and EGR system.

 

Any EGR code means something bad in the EGR system. You might want to check the EGR solenoid that is plugged in somewhere near the ignition coil. Yes, they replaced the EGR valve... but did they replace the solenoid?? It might be worth looking into it.