87 Chevy 350 bogs down/ stalls

[87 K20]

I have a 1987 Chevy Pickup with a 350 and fuel injection.  Recently, I visited a gas station that some people had gotten bad gas from after Hurricane Sandy.  Soon after, my truck started bogging down, and stalling when I was stopped at lights.  I ended up pulling and replacing the gas tank, and changing the fuel filter...no change.  I pulled the air cleaner when it was running, and it looked like fuel was flowing pretty steadily in the throttle body.   I then put some fuel injector cleaner in and ran that through, but no help.  I did find out one of the spark plug wires was bad ( it was shocking me when i had my hand on top of the wires while the truck was running), so I replaced all the wires and plugs, including the distributor cap and rotor...set the timing, but the truck is still doing the same thing.  I'm now out of ideas as to what to look for.  When I pulled the tank, the filters on the fuel pickup tubes looked good...didn't look clogged or anything.  The truck will run fine for a while, then all of a sudden it will bog down, and when I give it gas, it will bog some more, then spring to life.  It will also idle real low when I come to a stop, and sometimes stall.  Other times, it runs great for 10-15 minutes...no issues.  Does the same thing whether the engine is cold or hot.   Any help would be greatly appreciated.

[DanInMichigan]

Maybe a bad fuel pressure regulator?  Does it ever smell like it is running rich?

Other than that maybe something with the evap system or egr?  I dont have any experience on those tbi systems so just a thought.

I did have a vehicle with a failed fuel pressure regulator once and under full throttle it would blow black smoke.  It started very soon after i ran fuel system cleaner through ....i bought a fuel pressure tester and diagnosed it with that.

[DanInMichigan]

You might try disconnecting things like the egr one at a time to see if the problem becomes continuous or if it goes away ( or has any other effect).  Use this process of elimination until you isolate a likely culprit.  Keep track of other factors like outside temp, coolant temp, fuel tank level, etc. 

Try hard to see if you can figure out any way to reproduce the problem on demand.  If you can do that it will reduce the time you spend waiting to see if the problem occurs after you make a change - you make a change and then initiate an action that would normally cause the problem.

Good luck.

[87 K20]

Thanks for the replies guys...I physically checked the egr, and the diaphragm moved up and down, but it was hard to push up...should it move pretty freely?  I disconnected the vacuum hose and plugged it, and thank God, the truck ran better than it has in a while...took it for a short drive and it didn't stall out once...idled very smooth, and felt like it had more power.  I'm hoping the EGR was the only culprit, and that it was coincidence that the problem started right after I might have gotten bad gas.  Now my other question...do I need to replace the EGR, or can I just leave it unplugged and out of use...will that have a negative effect on the engine, other than increased emissions?

[jasonw]

I would check the catalytic converter

[frotosride]

  Now my other question...do I need to replace the EGR, or can I just leave it unplugged and out of use...will that have a negative effect on the engine, other than increased emissions?
[/quote]

You may get an engine code with it plugged because the EGR controller actually changes the timing (maybe uel as well but I don't remember) based on the amount of exhaust it is allowing in the intake. Honestly you most likely won't even notice it. If it s the factory EGR from '87 you may want to change it out because a lot of the older ones had a tendency to warp slightly and cause the plunger to stick so when controller pulls timing. If you want to get it to work the best without EGR you'd have to have it detuned from the PROM. I wouldn't recommend running it like this just to prevent damage to the engine.

I think that this ever so common problem with these TBI units is actually a combination of things that have just added up over time. I say this because I took my TBI off and completely cleaned it and cleaned the IAC and IAC ports. It helped the engine out a lot but I have also noticed that depending on what fuel tank I'm using the engine runs differently. So maybe a fuel flow problem. I'm going to rebuild the TBI next, then change the pumps and pickup socks.

[Captkaos]

Check the fuel pressure and report back.  Or use Viles trick and crip off the return and see if anything changes.

Removing the EGR will set codes on a TBI and you gain nothing by removing it.