Runs great for a little while
 

My 99' 252 Boss 454 mpi will run great for about a half hour and then it just falls on its face. It never dies just starts cutting out if I let off to an idle it sounds fine. I let it idle for a couple minutes and then it will take off fine but after a few minutes it does the same thing. I have an extra holley low pres. pump added on. I checked fuel pres. while running on a garden hose, its at 40 psi.....Anyone have any ideas what is wrong?

injectors are dirty, bad fuel

I drained the fuel tank completely put in fresh gas and changed the filter numerous times,it (the filter) has never had anything in it I could see. Is there anyway to narrow it down to the injectors

Pick up in tanks clogged?

Ran it last night with a fuel press. gauge installed, when and while it was having its fit the fuel press. was solid at 42 psi. Now I'm thinking its not a fuel problem maybe a coil.

Coil would be the next thing I would check.

Switched ignition coil still have the same problem.....pulled out most of my hair and now I'm wondering what to try next?

Installed a new pickup coil and ignition module. It threw its fit in about the same amount of time. This time when I backed off the throttle it kept running bad for about 15 seconds then died. 1st time for that. I started it right back up and it was fine for about 15 or 20 minutes and then did it again. It ran bad longer this time then died. I restarted it immediantly and it ran like a charm to the ramp. Anyone know anything else I could look at or try ?

I had a simaliar issue years ago. Fought it for whole season. It ended being a chunk of crap stuck in the check valve on the tank pickup. Being that your pressure is staying up volume may be down. Next check, the screens in the injectors themself.. Pete

TAKE THE GAS CAP OFF AND RE RUN IT, tank may not venting.sucking fuel tank

I had similar issues with my 454 (its older than your's 1987) i did everythign, i thought it was losing fuel also I would have dropping revs a sometimes just loose power for periods of time.
Nothing worked until I found out my timing was off 4 deg, new distributor cap, button, and new plugs and wires. while i was working on i found out the main wiring harness was loose and realt dirty inside i cleaned it out too. made a big difference in performance.

Took the boat to the shop. They found that the longer the boat ran the less voltage there was at the dash. They ran a new 10 gauge wire power wire to the dash and it seems to be fixed. I hope to test run it for myself Sunday......Thanks for the Ideas and suggestions.

Good deal, glad you got it figured out. Let us know how she works out...

Test drove today and I believe its fixed. A very expensive piece of wire from battery shut off to the key switch....just glad its fixed......Now where did summer go?