Help! Engine stalls, fuel pressure spikes....

[mondorally]

Motor basics:
1986 Schiada with a 468 BBC with a 6/71 and twin holley 650's(I think). The carbs have not been touched. Not sure when the last rebuild was (if ever). Fuel lines run from twin tanks to a selector valve, through a Fram HP1 filter to both mechanical and electric fuel pumps. Pumps tie back together into one line running to a T that has a regulator T feeding the primaries. Fuel line continues to a second regulator that T's to feed the secondaries. Fuel pressure line is on the regulator for the primaries. Lately I've been having a hard start issue when warm. I have to crank the motor for a good 10-15 seconds before it will light off. When cold it starts immediately.
What happened:
Running on Havasu yesterday from the city to Havasu Springs. Boat is running great. Solid 20 minute run. Near the pump station it starts cutting out like its running out of gas. Both tanks are over 1/2 full. Engine stalls completely.
I start cranking it over and notice the fuel pressure is climbing. Normally at 7-8#, it climbs to 10 and 11 as I'm cranking. The boat cranks and cranks, giving the occasional sputter but never lighting off. When cranking once I mash the throttle, the pressure drops to 8 or so and quickly climbs back to 11. I checked the fuel filter - clean with no water or anything. I try adjusting the regulator but the pressure won't drop. I adjust it way out and it drops a pound or two but creeps back up. Keep cranking - same sputter but no start. Batteries getting weak - I get a tow from 05Schiada (Thanks Steve!).
This morning I turned the key to check the fuel pressure and its showing 4-5#. Looks like the adjustment from yesterday finally took hold. I haven't tried to start it yet.
So where do I start? Me thinks something is plugged/broken/stuck/worn/etc. in the carbs. Besides the carbs, anything else it could be?
Thanks!
-Justin

[mondorally]

Update:
I just tried to start it. Before cranking the pressure was at 4#'s. After cranking for a few seconds the pressure starts climbing to 6-7#'s. Boat doesn't start. No sputter, no cough, no nothing........
-Justin

[Blown 472]

You try pulling the lines off the carbs and pump into a bucket to see how the flow is?

[mondorally]

You try pulling the lines off the carbs and pump into a bucket to see how the flow is?
No. But I'll try it. If there is a blockage at the regulator would that cause a spike at the guage but not allow any fuel to the carbs?

[mondorally]

I pulled one line going to a primary. Flowed like a garden hose. But there was some crap in the fuel - sand looking sh!t. The water was pretty rough on Saturday so I could have stirred up a bunch of crap in the tank. I'll check the fuel filter again. I couldn't dump it overboard and really see what was in the bottom.
I took the top of the regulator off - looked clean. The ball moved smoothly but it could very well have been plugged with the mystery crap.....
-Justin

[Blown 472]

Might want to check the needle and seats as well, sounds like you got some stuff floating around in your system.

[DEL51]

WOW,Blown 472 had my thoughts, again,or sumthin like dat, I would look in the floats, the needle and seat, top thing on the bowl that has a hex and flat blade screw. First thing is pull the float bowl plug/screw on the side. have someone you trust bump the motor over and see if you can have fuel trickle out. do this for each bowl. If no fuel trickles out the drains the entry point of the fuel into the carb may be the problem. That could be the needle and seat, if each bowl is not getting fuel, 4 total, walk back the fuel system. There should be a blockage if pressure is building. Gumout carb cleaner will remove all the varnish in the intenals of your needle and seat and clean up your carbs real well if this the problem. I would not pay anyone until you seek this analysis of your problem. A needle and seat are simple to understand once you take a carb float apart. It is a little valve that lets fuel in based on the position of the Float.

[Blown 472]

WOW,Blown 472 had my thoughts, again,or sumthin like dat, I would look in the floats, the needle and seat, top thing on the bowl that has a hex and flat blade screw. First thing is pull the float bowl plug/screw on the side. have someone you trust bump the motor over and see if you can have fuel trickle out. do this for each bowl. If no fuel trickles out the drains the entry point of the fuel into the carb may be the problem. That could be the needle and seat, if each bowl is not getting fuel, 4 total, walk back the fuel system. There should be a blockage if pressure is building. Gumout carb cleaner will remove all the varnish in the intenals of your needle and seat and clean up your carbs real well if this the problem. I would not pay anyone until you seek this analysis of your problem. A needle and seat are simple to understand once you take a carb float apart. It is a little valve that lets fuel in based on the position of the Float.
You had your boat out yet?

[orange peel]

I have a small block with blower when i first got it back it would not hardly start after running for a while i had to invest in a timming retard from MSD this will let you change the timming for hot start. My dad had 502 with 420 blower(6-71) his was like that alittle but runs farily cool. The box i have is a BTM goes with 6AL bos but u can get the combo box. Maybe this will help u?