runs great for 6 minutes - Team Camaro Tech
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post #1 of 4 (permalink) Old Aug 10th, 08, 08:02 PM Thread Starter
 
Join Date: Aug 2008
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runs great for 6 minutes

89 iroc 305 tpi, starts and runs strong for about 6 min, then won't pull past 3400 rpm, studders and dies, will not start back till the engine is cold 48psi fuel pressure, new cap, rotor, wires, ignition module, coolant sensor at front by thermostat,coil, we just got this car, this is the reason the previous owner sold it. 175lbs compression on all cylinders, fans are wired together and don't come on. when checking power to the fans test light shows it to be a ground but when we put 12 volts to the wire the fans come on. can a wire be a ground from a relay and then after you hot wire it from the battery the fans come on. do we have a bad ground on the fans? are they trying to ground through the hot feed wire. I remember something like this happening on a fan motor on a chevelle a long time ago. Any ideas? thanks Jim
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post #2 of 4 (permalink) Old Aug 10th, 08, 09:01 PM
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Join Date: May 2001
Location: Ashby,MN, USA
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Re: runs great for 6 minutes

check the wiring to the temp sensor- if it is a two wire sensor, then it's possible for the two wires to be shorting out, which tells the ecm that it's still cold, which causes it to run pig rich like an older car with the choke stuck closed.
i've seen this happen twice- when it starts to run like crap, wiggle and twist the connector and see if it smooths out.
if it is a one wire temp sender- i don't think it is, but the one in the head for the gauge should be- check to see if there is a bunch of sealer on the threads, causing it to not get a ground.
also, a bad oxygen sensor will cause a car to run like crap once it gets up to temp and the ecm starts using it to trim the fuel.

you don't plan sincerity.
you have to make it up on the spot.

wanna hear about 20 years ago when i was too smart to know any better?
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post #3 of 4 (permalink) Old Aug 10th, 08, 09:37 PM Thread Starter
 
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Re: runs great for 6 minutes

novaderrick,it does seem to be running very rich, i'll try wiggleing the 2 wires soon.thanks Jim
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post #4 of 4 (permalink) Old Aug 10th, 08, 11:56 PM
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Join Date: May 2001
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Re: runs great for 6 minutes

Quote:
Originally Posted by jim r View Post
novaderrick,it does seem to be running very rich, i'll try wiggleing the 2 wires soon.thanks Jim
the last car i saw this happen to- an 84 Z28 with the crossfire 305- would run perfect for about the first 5 minutes, then it would just sputter and die and not restart. if it would restart, the only way to keep it running was to keep feathering the throttle. i accidentally found the shorted wires on the sender when i was leaning on the engine trying to listen for vacuum leaks and what not while my cousin feathered the throttle inside the car- i set my hand on the sender, and the idle smoothed out. a quick look at it showed me that the insulation on the wires had shrunk back a bit, exposing the copper wires and allowing them to touch.
the only reason i didn't suspect it on that particular car at first was because the car had an engine fire recently, and there was a lot of melted vacuum lines that we replaced and a few wires that we spliced just to get it to run at all.

you don't plan sincerity.
you have to make it up on the spot.

wanna hear about 20 years ago when i was too smart to know any better?
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