Fuel pressure/volume for 98 ls1
Thread Starter
Teching In
Joined: May 2002
Posts: 24
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From: Stuart, Florida
Fuel pressure/volume for 98 ls1 I recently put a 98 ls1/a4 combo in my 90 Iroc and was wondering why my car doesn't seem to pull very hard in the upper rpm ranges. It has ported heads,hotcam,pulley,3000 vig and 4:10 gears. I also had the computer redone by Ed Wright. I set the pressure to 58 at idle. I'm wondering if that is sufficent and if it should go up at full throttle or remain the same. Also, I have a 255LPH pump in tank. Any help would be greatly appreciated.
Thread Starter
Teching In
Joined: May 2002
Posts: 24
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From: Stuart, Florida
Re: Fuel pressure/volume for 98 ls1 John B, I actually just got the A-tap last week and am now in the process of finding a laptop. I hope to be able to find out what the problem is then. I am just so disappointed in the SOP feel of the car for what it is-I had a bone-stock 99ss with a 6speed and 4:10's that pulled much harder than this one. I haven't been to the track yet, so I guess I can't get too upset. Thanks for your reply-I consulted your project notes many times during my conversionand it was very helpful. Sean
Joined: Nov 2001
Posts: 1,707
Likes: 33
From: Anderson, Indiana
Re: Fuel pressure/volume for 98 ls1 The fuel pressure should stay constant throughout the rpm/load range. When I suspect fuel pump related problems, I have a fuel pressure gage with a long hose on it that I feed out thru the back of the hood and tape to the windshield, and go out and hammer it. This will quickly tell you if there is a fuel system problem. You want good, steady pressure all the way.
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91 Z28 LS2 408CI, LS9 Supercharger, LPE GT7 cam, Yank3000, 3450 raceweight.
Latest numbers: 9.71 ET, 141.42 MPH, 1.40 60' , 610 RWHP Mustang Dyno
www.speartech.com
91 Z28 LS2 408CI, LS9 Supercharger, LPE GT7 cam, Yank3000, 3450 raceweight.
Latest numbers: 9.71 ET, 141.42 MPH, 1.40 60' , 610 RWHP Mustang Dyno
www.speartech.com
Thread Starter
Teching In
Joined: May 2002
Posts: 24
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From: Stuart, Florida
Re: Fuel pressure/volume for 98 ls1 Well, I finally got a fuel pressure gage long enough to be able to read while driving. The only problem was that it read 60 psi at idle, and my short gage read 58 at idle. Then I test drove the car and the pressure went down to 58 when I nailed it. So, if the pressure dropped even though it still maybe within range, Do I need a better pump? Actually, I guess I need a third gage to determine the correct reading and then the a-tap which will happen today. This is really frustrating! Sean
Joined: Nov 2001
Posts: 1,707
Likes: 33
From: Anderson, Indiana
Re: Fuel pressure/volume for 98 ls1 I would say that sounds acceptable. It would require a greater change than that to make the engine run bad. I think the problem is somewhere else.
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91 Z28 LS2 408CI, LS9 Supercharger, LPE GT7 cam, Yank3000, 3450 raceweight.
Latest numbers: 9.71 ET, 141.42 MPH, 1.40 60' , 610 RWHP Mustang Dyno
www.speartech.com
91 Z28 LS2 408CI, LS9 Supercharger, LPE GT7 cam, Yank3000, 3450 raceweight.
Latest numbers: 9.71 ET, 141.42 MPH, 1.40 60' , 610 RWHP Mustang Dyno
www.speartech.com
Re: Fuel pressure/volume for 98 ls1 I agree with John, the fuel pressure sounds fine. We really need to see the ATAP data to see if it is running lean or has enough timing. Is it possible that you have quite a bit of backpressure in your exhaust?
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Re: Fuel pressure/volume for 98 ls1 I had a dying fuel pump in Dragula, and WOT pressure was dropping to like 35lbs LOL.
Sounds like you have a different problem.
I am wondering if your AF ratio sucks... I'd shoot for 850 02's, and timing at 26 degrees.
Sounds like you have a different problem.
I am wondering if your AF ratio sucks... I'd shoot for 850 02's, and timing at 26 degrees.
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Teching In
Joined: May 2002
Posts: 24
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From: Stuart, Florida
Re: Fuel pressure/volume for 98 ls1 Well, despite the fuel pressure issues, I finally got to the track yesterday. A friend of mine loaned me some ET streets and convinced me to just see what the car would run. The first run was 12.504 at 111.89 with a sissy 1.9 short. The last run was slightly better(since I loaded it up a bit) with a 12.352 and 111.04. I was hoping 11's were possible from the very begining, so maybe with a little tweaking it'll happen. I've yet to figure out how to play back info I've recorded with atap. I know that my timing is like 36-38 (way too high right?) My o2's are 9 something-I'm going to figure this thing out soon I hope. I shouldn't have that much backpressure- I've got the lame hooker shorties with a real dual exhaust. I'm sure this is costing me HP. Any way, I'm gonna work on this a-tap deal and hopefully have some usefull info as to what is holding the car back. Thanks to all for the help. Sean
