Car only runs for about 3 seconds.
Thread Starter
Joined: Oct 2005
Posts: 1,687
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From: Fairfax, Virginia
Car only runs for about 3 seconds. I'm helping my buddy with his ls1 swap into his third gen. We can only get the car to run for about 2-3 seconds. I assume it's VATS because I know that's what it does, but we deleted VATS.
One thing that seems odd.. his Aeromotive fuel pressure regulator doesn't bleed any fuel off for the return line. And if we bleed all the pressure in the fuel system, the fuel pump will prime. But the pump won't prime any more after like two key turns. Shouldn't it keep priming and bleed off the excess pressure out the return line? Maybe we have the regulator hooked up wrong? Inlet on the left, outlet on right, and bypass on bottom.. that right?
We're getting fuel pressure to the rails and obviously spark. Any ideas?
One thing that seems odd.. his Aeromotive fuel pressure regulator doesn't bleed any fuel off for the return line. And if we bleed all the pressure in the fuel system, the fuel pump will prime. But the pump won't prime any more after like two key turns. Shouldn't it keep priming and bleed off the excess pressure out the return line? Maybe we have the regulator hooked up wrong? Inlet on the left, outlet on right, and bypass on bottom.. that right?
We're getting fuel pressure to the rails and obviously spark. Any ideas?
Who did the tune? It could be vats, so you could try a vats bypass box. Aside from that it seems your description of fuel problems might be the cause or effect of the real issue. Could be a bad pump even. Maybe someone else can help more.
good luck
good luck
Thread Starter
Joined: Oct 2005
Posts: 1,687
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From: Fairfax, Virginia
He had some kid with ls1 tuning software delete VATS. Neither of us were there, so we can only assume he deleted the VATS like we asked.
We just did some tests with a voltmeter. We got about 3volts from the power wire going to the fuel pump when the car is running for a few seconds.
Is the FPR hooked up right?: http://i67.photobucket.com/albums/h2...ls/Iroc008.jpg
The hose on the bottom (assuming return line) is going to a jug at the moment to see if anything is coming out. No instructions and the manufacture won't answer their phone.
We just did some tests with a voltmeter. We got about 3volts from the power wire going to the fuel pump when the car is running for a few seconds.
Is the FPR hooked up right?: http://i67.photobucket.com/albums/h2...ls/Iroc008.jpg
The hose on the bottom (assuming return line) is going to a jug at the moment to see if anything is coming out. No instructions and the manufacture won't answer their phone.
Do you have your MAF hooked to the throttle body? I see in the pic its hooked to the harness, but if it's not getting air through it while it's running it won't run very long. Not sure if this is your problem or not, just thought I would mention it.
Thread Starter
Joined: Oct 2005
Posts: 1,687
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From: Fairfax, Virginia
Yeh I'm still thinking it's VATS because 3 seconds is all we get out of it. I'll give it gas and it will still cut out short. But they hooked the PCM up to another ls1 4th gen and it ran, so I'm confused on that.
Another thought would be the fuel pump isn't running when the car runs. Maybe it only primes and only runs off what pressure is in the system. Were working on getting the PCM reflashed so we know VATS is gone.
Another thought would be the fuel pump isn't running when the car runs. Maybe it only primes and only runs off what pressure is in the system. Were working on getting the PCM reflashed so we know VATS is gone.
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Verdad Gallardo Thread Starter
Joined: Oct 2005
Posts: 1,687
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From: Fairfax, Virginia
We made some more progress. We found out the pump will prime, but won't continue when the car starts. The power source will only give it power when you turn the key over the first time. It's a Speartech wiring harness. I donno if theres something not hooked up right because we did exactly what the manufacture said. Maybe someone can PM me if they dealt with this wiring before.
But to get around that for now, we jumped a 12v source to the pump and made it run with the motor running. It still cut out so it's gotta be VATS. I'm buying a VATS bypass box right now.
Joined: Sep 2004
Posts: 3,148
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From: Downers Grove, IL
I think you have too much fuel pressure. IIRC you said that the fuel pressure regulator was not bypassing fuel.....if you get too much fuel pressure the injectors will no longer open. That would explain why the engine cuts out a few seconds into running. The fuel pump should prime for 2 seconds every time you turn the key, if it only does it a couple of times it sounds like it is building up pressure till the pump can no longer turn.
Toss a fuel pressure gauge on and see what the fuel pressure looks like.
Toss a fuel pressure gauge on and see what the fuel pressure looks like.
Thread Starter
Joined: Oct 2005
Posts: 1,687
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From: Fairfax, Virginia
We have a fuel pressure gauge hooked on it. I dropped the pressure down quite a bit and it bled out the return line. But that was like 20psi. Don't I want it at 58psi? I can only get it to about 53psi. No matter where I have the regulator at, it still cuts out.
Thread Starter
Joined: Oct 2005
Posts: 1,687
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From: Fairfax, Virginia
It's an ls1 style Walbro 255 in-tank pump. I maxed out the screw on the regulator and 53psi is all I can get. I bet it's not getting enough amperage. I'll go ahead and see how much amperage it's drawing. Like I said, it's a Speartech wiring harness but we had to keep the third gen body harness which includes the fuel pump wiring. I'm not sure if there's a relay needed in the circuit or what... somethings not right.
dont know if it helps but ive seen all kinds of fuel pumps go out, a year ago i parked my 00 z28 in storage, i decided to pull it out, started it only ran for a couple seconds, after running around in circles trying to figure it out i got a pressure gauge and seen i was only getting 20 psi. I found a guy on ebay that sells the pump, took me an hour to throw it in and i got my z back running awesome. So the p.o.s pump decided to go out from just sitting.
Teching In
Joined: Jun 2007
Posts: 9
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From: midd. TN
we just got my friends 414 up and running.. he thought the base tune he got had VATS deleted but it didn't.. and also his cam sensor was bad, and from what he was told from his parts guy at the dealer there is only 3 places in the U.S. that has them haha.. good luck
If you don't have a relay operating the pump, you are getting too much voltage drop. You need a 10 AWG hot wire into and out of the relay for pump power. You can use a smaller wire to trigger the relay.
