WTF is wrong with my motor?
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14 Second Truck Club
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Joined: Sep 2002
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From: Bossier City, LA
WTF is wrong with my motor? Half the time it will crank, half the time it won't. Sometimes I can start it and it will idle rough for a few seconds and find idle. Sometimes it takes 3-4 times of turning it over before it will crank, all this happens when it's cold or has been running.
If I don't let it warm up for at least 15-20 minutes, I back out of the driveway and it bucks and revs, sometimes goes dead in reverse every now and then. Or when I get to the stop sign, it bucks and revs and goes dead either at the stop sign or turning at the stop sign.
Even when I let it warm up, it still surges slightly when coming to a stop and at sharp turns after a stop. Then I can go to the store or get some food, get in and have to turn it over 3-4 times.
-I haven't felt any power loss. It still pulls hard as hell at WOT.
-When I had it dyno-tuned last year, it never did any of this, the tune and drivability was perfect (Props to Allan!)
-I've checked for vaccum leaks, can't find anything.
-I've done the idle relearn twice and nothing.
-Fuel pump whines constantly (I'm thinking it's something to do with the pump)
Has anybody ever had this crap? Or know what it might could be? Because it seems to be getting slightly worse over time...
If I don't let it warm up for at least 15-20 minutes, I back out of the driveway and it bucks and revs, sometimes goes dead in reverse every now and then. Or when I get to the stop sign, it bucks and revs and goes dead either at the stop sign or turning at the stop sign.
Even when I let it warm up, it still surges slightly when coming to a stop and at sharp turns after a stop. Then I can go to the store or get some food, get in and have to turn it over 3-4 times.
-I haven't felt any power loss. It still pulls hard as hell at WOT.
-When I had it dyno-tuned last year, it never did any of this, the tune and drivability was perfect (Props to Allan!)
-I've checked for vaccum leaks, can't find anything.
-I've done the idle relearn twice and nothing.
-Fuel pump whines constantly (I'm thinking it's something to do with the pump)
Has anybody ever had this crap? Or know what it might could be? Because it seems to be getting slightly worse over time...
have you checked your fuel pressure? since you say the pump makes noise.
could be its intermitantly losing pressure.
pretty easy check.
and if you unplug the MAF, doesn't it go into "limp home mode"? if it runs better in that mode it tells you a sensor is going out...right?
could be its intermitantly losing pressure.
pretty easy check.
and if you unplug the MAF, doesn't it go into "limp home mode"? if it runs better in that mode it tells you a sensor is going out...right?
It could very well be inconsistent fuel pressure. The difference in pressure will reek havoc on the fuel trims and cause poor driveability. Try to get your hands on a fuel pressure gauge that you can hook up and tape to the windshield so you can monitor it while driving. Have you replaced the fuel filter lately?
I would say unplug your MAF and see if it drive better. Yes it throws a check engine code and puts the engine in limp mode but it will run fine without the MAF, you wont even notice. You'll just hear the fans running constantly.
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My buddy was having about the same problem with his lt1 car... factored out the fuel pump and all at first becuase we could here it running... so checked everything else out and everything looked fine, decided to check the fuel pressure, it had no fuel pressure, pulled the line of by the fuel filter, the fuel pump was not pumping no fuel but yet seemed to sound fine... pulled it out put power to it in a bowl of water and it operated ok but pumped nothing out, slapped a new fuel pump in and has not had a problem yet! Id def check your fuel pressure on your schrader valve since on the ls1 there verry easy to access....
Thread Starter
14 Second Truck Club
iTrader: (6)
Joined: Sep 2002
Posts: 2,343
Likes: 0
From: Bossier City, LA
Fuel Pressure:
At Idle - 50psi
5000 - 44-45 psi
So it is my fuel pump, right? Isn't pressure supposed to increase with rpm or hold steady? I changed my fuel filter a few days before checking the pressure.
At Idle - 50psi
5000 - 44-45 psi
So it is my fuel pump, right? Isn't pressure supposed to increase with rpm or hold steady? I changed my fuel filter a few days before checking the pressure.
