WTH? fuel issue? weird! fuel pumps going out?
 

454 mag mpis with around 80 hours new long blocks in 2012. 2x on 98 33outlaw. 2 injectors were replaced and rest flow checked and cleaned. new exhaust, etc. Thinking stock fuel pump fuel cool crap. 576 hours on boat.

Quick history... filled up in January when prices dropped out but caused some mild vapor lock with the winter mix fuel. Had already ran fuel returns to tank. Only mild bc they still cranked unlike my previous experiences with vapor lock when engine would not crank at all.

ok, so I bought 2 holley fuel pumps and filters and installed as booster pumps to eliminate this issue.
First time out ran great, fixed the issue, didnt really run her that hard bc it was fairly rough but I thought I remembered running over 60, but didnt push wot.

Next poker run, we were running hard cruise at around 44-4500 and I pushed to wood and she fell on her face, rpms fell to 4k and then recovered. At first when I pushed to wot.. nothing, then after a few minutes, I gained rpms but woudl max at 45-4600 and loose power. Normally, I could push to 48-49 with a load.

Once I got home I dumped both fuel separator,filters and didnt notice any trash. Thought the fuel pumps werent keeping up with the 4psi 72gph rating should be fine, but wanted to test that theory. Ordered new glass fuel filters for before the boosters and took the P side fuel pump back off.

So, I ran with 1 booster on S and stock on P motor.

Ran today in lake with 69 degree temps (cool out) Ran 5k at 66 (fastest so far with these labbed props)

Everything was ok for about an hour, then as I was headed back, I tried to run WOT again and maxed at 4500. Stopped, lifted hatch to look at glass filter and clear. Took off again and ran up to 5k, turned around and only 4500 again with both engines acting the same. Stopped to try to cool off and try again and still 4500 max...

Wth?? Would water in fuel do this? Odd that I drained both filters and it ran good for and hour and then started acting up again. Thought I was haveing issues before and had checked fuel pressure on P a month ago and 38 at idle and around 2k while running on hose.

I will get some new fuel filters and try again and I put another 50 gallons of fuel in. May put some heet or seafoam to treat rest of tank.

Its got to be fuel right?? runs perfect at start up, idle, everything below 4500 rpms. Both engines are doing it. Fuel? or could fuel pumps be wore out?

runs well except wot..

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Do they have seperate tank pick ups ?

Check the fuel pressure at wide open throttle.

Yes, have 3 bungs. 1 pickup for each engine and 1 for return fuel. they are all right next to each other.

I was going to test fuel pressure at WOT, but was by my self... But, it ran like a spotted ape for about an hour, full power all the way to 5k, then after about an hour, next time I tried to go WOT, maxed at 4500..

4psi for fuel injected MPI engines? Is that right?

They are set 7psi low pressure booster pumps. The fuel injector pumps in the cool fuel is the high pressure side. 4psi is continuous at 72gph flow. All they do is pump fuel from tank to filter head and high pressure pumps pulls from there to injectors.

I thought they might be a bit low, but from what I have read, they only burn about 65 gph at WOT so they should be good,

But, that was why I pulled one of them off the P engine to see if it was restricting fuel even though it freeflow fuel through as well and run at idle and just off idle.

Ok, it's the lift pump.
Thanks

Yep

Update: Was questioned about whether coils were replaced when new long blocks added. Well, I went through my paper work and they did not change the coils? Are these symptoms of coils going bad? Get hot and cant carry wot spark?

Maybe fuel pressure regulators? I had a odd wot RPM issue that would come and go, fuel pressure would drop to zero after I cycled the pump, but you have a return so that would have to be shut off to test.

If you've done injectors and pumps, there are two more things to check out:

Fuel lines could be bad and sucking air. Could also be fuel pickups. They are relatively cheap and good peace of mind. Also as mentioned, FPRs could be plugged up.

If all this checks out, yes you're needing to check out ignition.

I have coils coming. I dont think pumps were changed, injectors just redone by mallory.

Would FPR work fine then start having issues? And its both engines.... I will look at the pickups since they are right next to each other.

Yes. I lost one this year. Started up fine one day. Ran a while, went to start again that day after anchoring and eventually found out my FPR was bad.

ok, went out today, but between buddies going to "Cruisin the Coast" and fishing, I went out by myself.

Installed new coils and fuel filter/water separators before going out.

First couple passes, she was able to spin 5k and 65mph. Did notice that I have to trim to moon to get up there. Wind was blowing pretty strong today so it was consistently..... slow. Stopping to cool off doesn really do anything.

0-4500 rpms it pulls hard and sounds good. At 4k, you run it up to 4500 and its fine, past that and it feels it bogs out and falls on its face. If I ease it to it, I can trim to moon and get more rpms, but running 45-4800 it didnt pick up any speed and I can bring it down to 4500 and it will hold that speed... around 60-61. Other times I would just nail it from 4k it woudl fall on face at 4500 and 56ish mph!

Feels like maybe fuel or running out of timing? Both engines doing it. Which is even stranger...

Since motors had only 12 hours on long blocks and it came from VA, 1100 miles north, should I have the ECU reprogrammed and timing checked? I did lose a more than your normal power when I first brought it down here.

Grasping at straws... Running out of time to run boat and trying small fixes!!

Going North to South does not change elevation. Change in elevation causes a change in elevation. Warmer and more humid weather can zap some hp.

And power/drivability issues without a computer trouble code, one should check fuel psi, ignition timing, compression, and intake vacuum + check for vacuum leaks first...before swapping parts.

Thanks, I was referring to the hot a$$ weather down here.
I havent trying spraying wd40 around intake yet as I kept forgetting to get some more. I was thinking this seemed like timing, but not too familiar with efi. My old 350 carb was a lil easier.

How can I check timing on these 454 mag mpis?

UPDATE: I got in yesterday and started checking my vacuum lines (after I reviewed how they ran from a diagram online). Both motors has loos fittings coming out of the intake to the FPR line.

The P side was loose enough at the T connector where it was just sitting there, I pushed it to the side with my finger and it slid right off. The S side has a loose fitting going into the underside of the intake. It was a hard plastic line that was barely held on by the lil barb fitting and was more that likely leaking.

Replaced both hoses and put cable ties to make sure they stayed tight.

Next up is cleaning out the pickups. Not sure how I am going to do this yet, I pulled both elbows and the pickup tubes are connected to the inside of the tank somehow?? If I blow them out, whatever, if anything, will just be in the tank. There is a small fuel sender hole right next to them, but not sure my hand will fit in there..... will see!

ok, blew out both pickups.. while in tank since they dont come out.... that was fun! pressurize tank and watch fuel jump out of other bung. lowered bow and opened gas cap and was able to hold 150psi to both pickups!

Then blew out vent line by cap.

Hope this helps with my problem!

ummmm....150 psi to the tank ? Yikes !

Never tested an aluminum tank, but steel and plastic they say not to test with more than just a few psi + or - (vacuum).

Ok, I see how that can be missleading.... Sorry, I used 150psi 3 gal air tank blow into pickup tube with other pickup tube open and gas cap off so the aire was coming right back out. So, the air was blowing at 150psi, I did NOT pressurize a sealed tank to 150psi. That would have not been a pretty sight, I am sure my fuel sender would have shot out!!

I had that happen to me. Boat with one motor and two tanks. One tank worked other tank started not going past 3500-4000rpm. Blew fuel line with 100psi. several times, replaced fuel line never fixed it. Could have been vacuum in tank i don't know? Sold boat.

The vent works, I stuck my hose in the gas inlet and the air (although slow) came back out. I will test this also next time out. If still have problem, I will remove gas cap and run it to rule out venting issue.

UPDATE: DONE!! Runs like a top! No more falling on FACE over 4k!!
 

Well, I took her out again today.

Repaired both engine vacuum lines going into plenum, blew out pickups and vent for tank. Also filled the filters half with lucas fuel injector cleaner for the hell of it even though there were cleaned and flow tested 85 hours ago.

Ran out in lake at about 4k, punched it and immediately noticed there was no bogging down above 4k.

I am going to make an assumption that it was the vacuum lines, hell, I didnt even know I had FPR or much less how they worked until I started chasing this down.

About 75 degrees, wind out of north around 15mph and 1 ft chop.
Both running 5k at 65-66mph
:bunnydance:

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Damn I got the exact same problem but mines a carb'd 509 with 35 hours on it and just started doing this! When motor was done everything was replaced new elect. Fuel pump all line after pump, all msd box, dist, coil, etc with new motor! Ran great then about 20 hour out bam can't run it from 4500-5500 where it needs to be! And I don't have vacuum lines! I quess I will check pick up now! Any ideas?