After having my 1993 S-10 4.3 W-vin Tahoe's engine replaced with a short-block approx. 3000 mi. ago, I started experiencing some "interesting" problems. I noticed that if I floored the gas pedal, the throttle would stick, usually unsticking if I jiggled the pedal a bit. Thinking I had a binding cable from the engine replacement, I decided to have it checked out after one episode. Some 20 mi. later, the blazer started bucking and popping, acting almost like a misfire. I barely made it home, 2 mi. from initial symptoms.

After reading the posts here, I have done the following:

- New fuel filter
- New fuel pump (AC Delco, IIRC) approx 1000 mi. ago.
- New rotor and cap
- Seafoamed tank and intake
- removed and cleaned EGR with carb cleaner (replaced gasket as well)
- IAC sensor replaced

Occasionally the SES light flashes on, then off. Had it reset, tech said it showed a misfire code.

I had the blazer to the garage after I replaced the rotor and cap and EGR clean, and they couldn't duplicate problem. Finally they replaced the Idle Air Control sensor, and I had them replace the intake boot between the airbox and throttle body as the old one had broken out the bottom.

A/C is non functional, occasionally the console air controls don't work (no light or function) other times a whack will render them operational.

I found that the vacuum tube at the rear of the intake plenum was broken, replaced with another section. No change.
No other obvious issues with vacuum system that I can find.

Current symptoms: Starts fine and runs fine on cold circuit as far as I can tell. AFter 30 sec. to 2 min. starts loping, then stalls out at idle. Sometimes can be made to continue running (roughly) if RPM is raised to mid-range. Other times, no amount of pedal feathering will prevent lope and stall.

Sometimes, after warm, starts and runs fine, no issue, but has abysmal gas mileage compared to prior running.

So, before I resort to more random parts replacement, any suggestions? I had removed the MAP sensor and re-installed, but I doubt this would cause the issue. After a $3K engine replacement, I'd just like to get it running right again. Help appreciated. Feel free to email or answer here. Regards,

~Ted

PS - No, I haven't done a spider check yet...

 

It's time. Pull the Vortec cover on top, pull the IMTV and look on both sides. If you see any washing, then it's time to pull the intake and replace whichever it is - the fuel pressure regulator or the nut kit.

 

UPDATE: Pulled intake valve and saw that FP reg. wasn't washed, had some carbon on it. Passenger side of plenum was relatively dry, driver's side looked "wet" all over, no obvious pooling. I'm assuming the nut kit is shot? Previous owner (10,000 mi ago?) said he replaced spider, but don't know if he did nut kit or not, and not sure if it was a new spider or used.

Is it possible that the nutkit is bad, but spider is good? I'd prefer to throw a new $40 FP reg and $50 nut kit without the $350 spider...

 

If he replaced the spider without replacing the nut kit, the nut kit is probably bad. The plastic lines really don't like being disturbed - they tend to crack.

At this point, I'd pull the plenum and pressurize the system - KOEO - and see if you can see any leaks.

 

Got a spider and nut kit, all told somewhere around $400. Replaced Spider and Installed Nut Kit. Retaining clip must have been loose, as supply line blew off and flooded a cylinder when trying to start for first time.

Removed everything from plenum again, checked connections, fixed issue, and pulled plugs. Broke darn plug #3 (or whatever that one behind the steering shaft is) and figured now I'll replace all tomorrow (Tue.) morning and try again. I'll try to pull the IMTV and check for leak while someone else cranks next time. That's the downside of working @ home, alone.

Old nut kit was brown and brittle, looked shot. Definitely not replaced with spider. Old spider looks like used unit too. Hopefully with new plugs, there will be no leaks and I'll be back to a smooth running blazer tomorrow.

 

OK...new problem. Spider and Nut Kit sealed fine, pulled plenum and was clean and dry. But I'm guessing I hydraulic'ed a cylinder and perhaps blew a head gasket? It was idling last night, then stalled. Went to crank and heard "ka-chunk" instead of turning over.

Now, after draining cylinder last night and changing all plugs today, runs fine on initial 10-45 sec. then starts blowing whitish smoke, with droplets and liquid out the exhaust. Seems to be a mix of gas and water, gel-like appearance on driveway, dries to black residue....

With cap off, no bubbles in rad,antifreeze stillnice and bright green, oil not discolored, but has slight gassy smell. Will change ASAP.(Doesn't light on fire with match test either).

This engine is still well within the warranty on the reman.I don't have a cherry picker or desire to pull the head... Thoughts?

 

Another update....Today it rained, and I decided to try again.

Droplets spread on wet ground and had gassy sheen, so I think it's gas only, not a mix. Seems to be overly rich on idle, and dies.

SES throws code 43.

Thoughts? When I pulled the connector on the rubber intake boot sensor, the metal part of the sensorseparated from the rest, and I had to push it back in... Looks like a thermocouple, but don't know. Could be bad now...

Anyone? Runs fine with no smoke on initial start.