High rpm tuning issue running out of ideas

[90 5.0]

Basics
2.4 200
wh-22
150ish psi
holley red pump
aeromitive reg

I have run into a weird issue @ high rpm. From a punch it will scream to right around 7k and stop pulling boat noses over, if you stay in it a second or so later it "cleans up" for lack of a better term. It will immediately pull hard to 72/300 and do the same. Stay in it 75/600 immediate strong pull again and fall over.

The same motor has pulled a 30 clean to 7800 and was still pulling when I ran out of straight on the river. So I know it has the power to do it.

With a 20p testing is where this problem has started showing its face(i have not put the 30 back on to see if it does it with it too still however)

I am thinking it's accelerating so hard it runs out of fuel with the small prop, where as with the 30 it takes longer to get there so it's not demanding the fuel as fast?
Thats where I am. Now anyway.

This problem first came up when I put race gas in it to test, I run pump gas when riding with a big wheel.

I jetted down for the gas and drag set up and thought I jetted down too far, have gone all the way back up to my pump gas riding jets a step at a time and it's still there.

I have tried the following with seemingly no difference
jetting
added float hieght
fp change(3 all the way to 7psi)

whats also weird is in testing a slight stumble off bottom has come out of no where too, used to come clean out and just fall over at 7, now fires out as hard as normal stumbles for a brief second and pulls clean to 7 the. Stumbles again.

Im leaning toward fuel dilerery but have checked everything I can think of other than swapping pumps.

Any ideas?

I had to stop testing as a carb gasket got messed up pulling them on and off checking stuff and I have a vacuum leak now and it's idling at 5k. So I'm getting more carb gaskets Monday to try again.

I pulled the fuel filter as this can have this effect at times on other applications. It had junk in it but not stopped up, cleaned and reinstalled. (10 micron kinsler filter)

since i have to get more gaskets anyway trying to think of a new plan of attack for testing/fixing etc.

the pump is new and has less than 10 hours on it but I'm thinking of swapping it anyway to eliminate a variable. I have a blue I can put on it.

Out of ideas?

Checked trigger arm, has loosened up a bit tightened it up, no change.
Everything "seems" to be mechanically in order(other than the now leaking carb gasket)

[W2F a V-King]

Basics
2.4 200
wh-22
150ish psi
holley red pump
aeromitive reg

I have run into a weird issue @ high rpm. From a punch it will scream to right around 7k and stop pulling boat noses over, if you stay in it a second or so later it "cleans up" for lack of a better term. It will immediately pull hard to 72/300 and do the same. Stay in it 75/600 immediate strong pull again and fall over. EGT would be nice to have for this....

The same motor has pulled a 30 clean to 7800 and was still pulling when I ran out of straight on the river. So I know it has the power to do it.

With a 20p testing is where this problem has started showing its face(i have not put the 30 back on to see if it does it with it too still however)

I am thinking it's accelerating so hard it runs out of fuel with the small prop, where as with the 30 it takes longer to get there so it's not demanding the fuel as fast?
Thats where I am. Now anyway.

^^^ This .... Wondering if you have a slight restriction somewhere?

This problem first came up when I put race gas in it to test, I run pump gas when riding with a big wheel.

I jetted down for the gas and drag set up and thought I jetted down too far, have gone all the way back up to my pump gas riding jets a step at a time and it's still there.

I have tried the following with seemingly no difference
jetting
added float hieght
fp change(3 all the way to 7psi)

Can you monitor fuel pressure when it noses over? 3/8" fittings and hose all the way from pickup tube to the Tee that splits to carbs?

whats also weird is in testing a slight stumble off bottom has come out of no where too, used to come clean out and just fall over at 7, now fires out as hard as normal stumbles for a brief second and pulls clean to 7 the. Stumbles again.

Im leaning toward fuel dilerery but have checked everything I can think of other than swapping pumps.

Any ideas?

I had to stop testing as a carb gasket got messed up pulling them on and off checking stuff and I have a vacuum leak now and it's idling at 5k. So I'm getting more carb gaskets Monday to try again.

I pulled the fuel filter as this can have this effect at times on other applications. It had junk in it but not stopped up, cleaned and reinstalled. (10 micron kinsler filter)

since i have to get more gaskets anyway trying to think of a new plan of attack for testing/fixing etc.

the pump is new and has less than 10 hours on it but I'm thinking of swapping it anyway to eliminate a variable. I have a blue I can put on it.

Out of ideas?

Checked trigger arm, has loosened up a bit tightened it up, no change.
Everything "seems" to be mechanically in order(other than the now leaking carb gasket)

Sorry about the blue fonts...easier to insert thoughts than retype them....

[90 5.0]

My egt is not reading right unfortunately the display died, waiting on a new one to get here.

I looked for restictions somewhere in the fuel system, can't find any that are obvious.

Had a car in the shop that would pull hard in the shop years back on the dyno, out on the street etc. take it to the track and would stop pulling right at the end of the quarter, drove us nuts fighting it. Had a loop in the fuel line that was kinking at the end of the quarter. So I looked at that immediately was thinking same thing.

5/8ths from tank to filter 3/8ths from filter to pump , pump to reg, reg to motor. Reg to tank return also.

[W2F a V-King]

Sure sounds like fuel...
The dyno is good for tuning, but only good to a fault. The 3K Lb. (or so) drum can't produce the same load and wind resistance as the track. But you already know this.

Guessing you lost no fuel pressure when it noses over? It's either fuel or spark...

You will find out more when your new EGT display arrives.

[mach351]

Pick up in the tank?

[90 5.0]

Sure sounds like fuel...
The dyno is good for tuning, but only good to a fault. The 3K Lb. (or so) drum can't produce the same load and wind resistance as the track. But you already know this.

Guessing you lost no fuel pressure when it noses over? It's either fuel or spark...

You will find out more when your new EGT display arrives.

Fuel pressure gauge is on the reg in the back. My in dash gauge is a fuel injection gauge and it's not hook d up to my carb set up. It's not even in the boat at the moment but it starts at ten psi I think. Anyway it doesn't read at this pressure I've tried it before I need to order an in dash low fp gauge.

Im leaning towards fuel too since it does it at same rpm every time seems like spark would be intermittent all over the scale.

Keep the ideas coming though I'm at a loss at this point

[90 5.0]

Pick up in the tank?

Sumped tank no pick up.

Im ordered new line today to go from tank to filter it's the only line that's not new. Could be colapsing on the inside at high fuel demand. I was thinking along those lines earlier too

[90 5.0]

Some one else mentioned it might be a problem in the tank vent and I remembered once there being a vacuum on the tank putting fuel in once.

Gonna check cap vent and maybe add another. When it was turning up before we had a different reg set up and my return line now used to be open to atmosphere with a hose coiled up from when it had efi on it.

Hoping this is it. Will replace fuel lines and mess with that and report findings.

[W2F a V-King]

Yes...forgot I have had problems with mud dobbers in the past plugging my vents with mud trying to make a nest... That boat set outside though...

Good thought !!

[90 5.0]

Tank vent was plugged up, some sea foam and some compressed air and all is good

[W2F a V-King]

That's great!!

Love a fix that doesn't involve a lot of $$.

Albeit tough to find sometimes...

Thx for the update !!

[Krazymaan]

Thats awesome.