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1994 Chevrolet Pickup with 454 CI engine, ran well until I ...

Sent to Car Experts October 21, 2006 5:23 p.m.

1994 Chevrolet Pickup with 454 CI engine, ran well until I let it sit for 18 months. When I started it the engine runs VERY rich, has a fast idle (no tach but it will do 20 mph idling).
Running temp used to be around 190F, now about 160F. The butterflies open when I open the throttle. What is wrong and what can I do?

Optional Information:
1994 Chevrolet 2500 454 ci

Customer (name blocked for privacy)

Status: Closed Value: $10

Answer
October 21, 2006 5:42 p.m. (18 minutes and 30 seconds later)

ACCEPTED

Greetings! Your throttle body may be carboned up and need to be cleaned! This can cause all sorts of idle and hesitation problems. This is caused by the throttle plate not seating properly. The First thing i would do is clean out the throttle body with some throttle plate and intake cleaner and a small brush. Another common cause would be the Idle Air Control motor. This is very common on older cars. The IAC motor gets lazy and cant keep up with the fast idle changes. Also when the IAC motor is out, I rec to check the passages for carbon build up. If they are plugged they need to be cleaned out. Also be sure to check for vacuum leaks. Mice or rodents could have chewed on your vacuum lines causing a vacuum leak. Open the hood and listen for a hissing sound when the engine is running. If it is hard to pinpoint take some break cleaner or starting fluid around the intake manifold and vacuum lines and see if the engine stumble or if the idle is affected. Be extremely careful when doing this!

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AMEDEE -- ASE MASTER TECH -- 98% Positive Feedback on 1039 Car Accepts
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Reply
Sent October 21, 2006 6:05 p.m. (23 minutes and 47 seconds later)

Relist: I prefer a second opinion.
1994 Chevrolet Pickup with 454 CI engine, ran well until I let it sit for 18 months. When I started it the engine runs VERY rich, has a fast idle (no tach but it will do 20 mph idling). Running temp used to be around 190F, now about 160F. The butterflies open when I open the throttle. What is wrong and what do I do about it?

Customer (name blocked for privacy)

Answer
October 21, 2006 6:10 p.m. (4 minutes and 9 seconds later)

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AMEDEE -- ASE MASTER TECH -- 98% Positive Feedback on 1039 Car Accepts
ADVANCED LEVEL SPECIALIST

Answer
October 21, 2006 6:19 p.m. (8 minutes and 57 seconds later)

REPLIED

There are a few things that can cause a rich condition like that.

One is a leaking fuel injecter. If one is not seating properly, it will do that.

A bad MAP sensor or broke vacuum line to it will also.

A ruptured diaphram in the fuel pressure regulator can do it too. You can check that by simply pulling the vacuum line off after the engine has just been running and see if there is a any fuel inside of it. That would indicate a bad regulator.

If you use a fuel pressure gauge and watch to see if the pressure holds well when yopu shut it off, that could point to either the injecter or the regulator if it drops at all

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Hammer Time -- L1 Master Technician -- 98% Positive Feedback on 2710 Car Accepts
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Reply to Hammer Time
Sent October 21, 2006 7:05 p.m. (46 minutes and 28 seconds later)

does not have fuel injection, has carb

Customer (name blocked for privacy)

Answer
October 21, 2006 7:16 p.m. (10 minutes and 57 seconds later)

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Hammer Time -- L1 Master Technician -- 98% Positive Feedback on 2710 Car Accepts
ASE Mastertech with Adv level Engine performance cert.

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