Fuel starvation under WOT

LSxBakakos

LSxBakakos

Member
May 29, 2022
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Illinois
Few seasons ago I went a best of 11.96 on my 650 rwhp tune. After some eye issues that kept me from racing I went back out two weeks ago trying the spicy tuna tune for the first time. For a 100rwhp gain, I should've netted more than a tenth. Before I go out beating the breaks off this thing trying to log/identify it I have some ideas. My gut says fuel issue, I've launched hard enough with being non sumped, the truck has nosed over on itself on launch which leads me to believe starvation. I had 3 clean passes without breaking up, the others netted in sputtering between 2800-3200 in 5th. I was running a velocity stack too that night so I'm unsure if turbulence there could've caused that. Tune 4 didn't have this issue at all. I'm 65 overs with 2xcp3 so shortage shouldn't be an issue. Is it possible I need to sump it? Or any other restrictive areas in our fuel systems to look out for? I'm unsure what the factory draw straw will take. I know my charger is "rated" for a max of 750/800, and 42psi. One time I lost a map sensor racing and made 50 psi with the same weird break up, went new delco fixed the issue, then realized I also was collapsing the filter, hence the stack. This last time out I was making 48 psi which led made me wonder if it's either a maf or map related issue again.

Any help would be appreciated, definitely think this truck has 11.60s in it on SBE, maybe more if I get the boat anchors off all 4 corners
 
PureHybrid

PureHybrid

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Feb 15, 2012
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I would do a draw straw/ sump even if that wasn't your issue. OEM setup is super small. But without a log file we're kinda pissing in the wind here
 
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JoshH

JoshH

Daggum farm truck
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You're going to have to get a log for anyone to be able to do anything more than guess. I will say I went low 11s many years ago in my truck without a sump or any fuel pickup modifications. I don't particularly care for sumps because they tend to have issues with low fuel levels that I don't see with the stock fuel module. A few years ago, I started having trouble with my truck starving for fuel at low fuel levels and found there is a little crack pipe looking piece that sits in the bottom of the bucket and is used to create a venturi effect with the return fuel to fill the bucket on the stock pick-up assembly had fallen out. While I had it out, I did the PPE billet pickup kit and upgraded the lift pump feed line to 5/8". I have noticed none of the issues that are common with a sump, but it gave me the larger fuel line upgrade to help the pump be more efficient.
 
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2004LB7

2004LB7

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Dec 15, 2010
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JoshH said:
You're going to have to get a log for anyone to be able to do anything more than guess. I will say I went low 11s many years ago in my truck without a sump or any fuel pickup modifications. I don't particularly care for sumps because they tend to have issues with low fuel levels that I don't see with the stock fuel module. A few years ago, I started having trouble with my truck starving for fuel at low fuel levels and found there is a little crack pipe looking piece that sits in the bottom of the bucket and is used to create a venturi effect with the return fuel to fill the bucket on the stock pick-up assembly had fallen out. While I had it out, I did the PPE billet pickup kit and upgraded the lift pump feed line to 5/8". I have noticed none of the issues that are common with a sump, but it gave me the larger fuel line upgrade to help the pump be more efficient.
Click to expand...
IMAG0182.jpg
Had the same thing happen to me
 
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LSxBakakos

LSxBakakos

Member
May 29, 2022
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PureHybrid said:
And also, what were your trap speeds? That will tell hp gain, ET has more to do with truck setup and launch
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I've been contemplating either sump or that fleece sureflo sending unit, trap speed 11.96 was 112.81, 11.88 on the bent rod tune was 113.98
JoshH said:
You're going to have to get a log for anyone to be able to do anything more than guess. I will say I went low 11s many years ago in my truck without a sump or any fuel pickup modifications. I don't particularly care for sumps because they tend to have issues with low fuel levels that I don't see with the stock fuel module. A few years ago, I started having trouble with my truck starving for fuel at low fuel levels and found there is a little crack pipe looking piece that sits in the bottom of the bucket and is used to create a venturi effect with the return fuel to fill the bucket on the stock pick-up assembly had fallen out. While I had it out, I did the PPE billet pickup kit and upgraded the lift pump feed line to 5/8". I have noticed none of the issues that are common with a sump, but it gave me the larger fuel line upgrade to help the pump be more efficient.
Click to expand...
You may be onto something there sir. The last season I raced and had a downright violent launch that broke my sending unit. I'm almost willing to bet this may be part of the puzzle. I know a log would be best, I'm hesitant on that many more wot pulls on the big tune since I know the rods days are numbered. If I keep the delco sending unit, I think it'll be cheap insurance to add that to my list
 
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