Fuel Pressure Regulator
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Senior User
Joined: Jan 2002
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From: Knoxville United States o
Fuel Pressure Regulator
How often do these things fail? And if it did fail on a Speed Density FI 300, would it cause the engine to run rich? I just wanna see if you guys would think that would be the problem here. If I let the truck run after installing new plugs, it fires right up but is spewing black smoke and after about an 30 minutes will foul all the plugs. The engine idles fine and revvs fine until the plugs foul though, just lots and lots of black smoke.
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Joined: May 2002
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From: Broken Arrow, OK
Regulator failure isn't that common. Even when they do fail they usually don't barf black smoke. The MAP sensor will cause black smoke if it fails. Try unplugging the vacuum line from the regulator and see if it makes it run worse or not. If it doesn't, the regulator might be the cause. If unplugging the line makes it run worse or kills it the regulator is doing its job.
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From: Knoxville United States o
hmmm. thanks. Well, i just got done putting the new regulator on. When i take the vaccum line off the MAP sensor the engine idles up really high. I have not unplugged the MAP sensor yet. Also, I had unplugged the vaccum line from the FPR and there was no change. So, MAP or FPR?
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From: Knoxville United States o
HMMM. well I put a new MAP sensor on it too as well as a new TPS. She's still running, but she is still running rich as well. I'm lost as to where to look now. I seem to be able to run at 3/4 throttle with no problems, but if I go WOT the stuttering effect happens. What else could it be? I still am getting black smoke out of the exhaust.
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Joined: Sep 2002
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From: Langhorne, PA
You must have busted a vacuum line on the plug side of the engine, those lines are brittle and can't take hits at at all. The lines run to and from both sides of the engine and control the regulator also. Double check every vacuum line by touching them and lightly tugging each end. You are barking up the right tree, if you are fouling the plugs, way too much fuel is getting in there. Be careful, you must analytically troubleshoot the problem, all sensors and components are monitored by the computer, one glitch from an overlooked problem will fool the computer into spewing too much fuel. You can circle jerk yourself right into the poor house by changing 5 wrong parts. Get a manual if you don't have one.
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From: Knoxville United States o
Well, I'm not sure about the vaccum lines, because I have checked them all, especially those lil plastic *******s that run from the plug side of the engine. I'm now thinking that there could be a problem with the ECM, as I cannot get it to pull codes at all. I know I'm doing the process correctly, and there is nothing being sent to the code reader. I'm going to be double checking the sensors/computer today with at dwell meter, just to see if there is signal getting from one part to the next. I'll tell ya'll how it turns out.
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From: Knoxville United States o
Well, looks like I have found and fixed teh problem. Just for teh sake of being sane in the head, I drove this black smoke puking truck down to my buddies autoshop and hooked it up to his SnapOn codescanner/troubleshooter. No codes were sent, the trouble shooter came back with scrambled eggs on the screen...bad ECU. Replaced it and now she's running like a top.
Lots of money spent that could've gone towards a set of gears....
Lots of money spent that could've gone towards a set of gears....
