Fouling spark plugs

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89sportside

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My first test would be to check the ignition system. My 98 chevy ran like **** because the spark plug wires were all leaking. Smelled rich. Burned the paint off my cherry bombs. Open the hood in the dark and Have someone put it in gear and hold the brake and look for sparks. Check your rotor and cap for wear or moisture water in the cap will cause a no start/long crank


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Well, I did a full tune-up and replaced my rotor, cap, wires, and plugs. I'm pretty confident none of my brand new wires are shorting. And I did double check all of it since the problems started worsening. Today I can get a start without even holding the pedal to the floor, and whatI'm noticing is that the buzzing near my TB has stopped and my injectors dumping way too much fuel at random intervals, for a few seconds at a time. But then it idles normally for about 30 seconds, followed by dumping way too much fuel again. Does this sound like my FPR or more like a TPS or another sensor gone bad? Any way to check my sensors?
 

90halfton

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I cannot see tstat causing it to run that rich. Especially on cold start up. The engine would be ambient temperature regardless of tstat.
 

jsnow36318

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Sounds like you might want to have a shop run a diagnostic tool on it while its running and monitor the injector pulse width and sensor signals.


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90halfton

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I'd pull the air cleaner and throw your timing light on the coil wire and watch your injector spray pattern with it. If it's dribbling from an injector you could have a jnk injector. Or from both injectors a bad regulator.
 

89sportside

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Well, last night I got it to run long enough to put the timing light on it, was firing way before TDC. So I got that fixed but I haven't test drove it yet. Also, I thought code 15 was the thermostat but it turns out it could be a number of things, so I assumed it was the Coolant Temp sensor and went ahead and replaced it too. I've heard these trucks go through temp sensors and that causes it to run rich all the time. Will test drive it here in a minute and I'll post my results. Wish me luck!
 

90halfton

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Didn't know tbi's had a tstat code I guess. Temp sensor can be checked with an ohm meter. Low resistance it's cold, and resistance will increase with temperature accordingly. If it's good anyways. Somewhere there's a chart for ° and ohms.
 

Black_cirrus

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Sounds like coolant temp sensor problem, at 276k you could have enough wear that it easily washes down the rings. Combined with a skewed but not broken sensor, suspected due to the code 15, it looses compression and gets hard to start. That buzzing makes me suspect a bad fuel pump relay it's on the firewall behind the air cleaner.
 

leakers

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I would take a punt that the "shop" screwed with the distributor as well as the plugs, doing so they have screwed with your base timing.
To reset that you have to go right back to the basic timing procedure.
 

89sportside

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I would take a punt that the "shop" screwed with the distributor as well as the plugs, doing so they have screwed with your base timing.
To reset that you have to go right back to the basic timing procedure.

I think you're right on the money, leakers. My timing was way screwed up and fixing that along with replacing the Coolant Temperature Sensor made a YUGE improvement. However I'm still having a power issue at low rpm, along with a funny chugging sound when under a load and an erratic idle, which I didn't have before I got the "brake job"
Gonna replace map sensor, stat, and check my PCV tonight. I've almost checked off everything, anyone have any more suggestions?
 

runnin350

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89sportside. my truck did the same thing yours is doing right now. check the plugs on your ignition coil and make sure they are snug. when mine came loose it ran like **** - rich misfired - hesitated. got to the parts store swapped out my ignition coil and bam. problem solved. my truck is a 1995 Chevy Cheyenne ext cab 2dr with a 5.7 and a 4l60e. made in Canada ay. (trucks in the signature) :)
 
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