Lost all power at WOT

**Captain75** · 09-30-2016, 12:33 PM

Hello guys!
Sad day over here, autumn is coming so today it was time to take the boat out of the water, to let it rest during winter in the driveway.
Of course I did my best to empty the tank before it ended up on the trailer

Something strange happened at WOT: when trimming out to the max in order to fly the bow and get the last mph's, the motor died, buuhhh. When the boat stopped, I turned the key and it fired right up again, running as strong as before. What happened? Is it possible that the motor emptied the carb bowls before the pump could fill them due to the trim angle? Floats are set level with edge when held upside down. Motor is fed by a Holley blue, pressure is regulated to 5.5psi just before the fuelrail. Rpm was appx 6000 when this happened.
Motor is a 2.7 looper.

Any ideas?

**rjdubiel** · 09-30-2016, 01:50 PM

sucked in air from the tank and carbs ran dry since you stated you were running the tank down to empty?

**EMDSAPMGR** · 10-01-2016, 01:04 AM

When the tank is low on fuel, the ability of the fuel pump to suck fuel depends on how level the tank is. If you were on plane, at speed, perhaps the fuel ran to the back of the tank, when the pickup was in the front. Once the boat comes to normal rest, the engine will probably fire right back up-then do the same thing at speed again.

**Captain75** · 10-01-2016, 07:09 AM

Thanks for your replies guys!
Problem is that I've felt these tendecies with full tank aswell, only fully occurs when trimmed out to the max... Only logical conclusion I could come to was being Low float levels...

**XstreamVking** · 10-01-2016, 08:06 AM

I would look from the tank pick-up to the motor for restriction. When running at wot fuel is being restricted IMO.

**Captain75** · 10-02-2016, 12:28 PM

Now I've checked the fuel system all the way from the tank, just can't find any restriction. Still suspects the floats since the problem serms to be directly linked to the trim angle.

**EMDSAPMGR** · 10-02-2016, 01:50 PM

Did you pull the ball valve out of the anti-siphon valve on the built-in tank to check for debris? If you get a little sand in the ball valve, it will stick in the housing and cause engine running problems.

**Captain75** · 10-02-2016, 02:31 PM

Ball is removed earlier

**EMDSAPMGR** · 10-03-2016, 04:28 AM

If you've got a weak fuel pump on the engine, it won't be able to keep up fuel volumes at WOT. You'd be able to run it for a while, till the consumption of engine fuel overcomes the ability of the fuel pump to keep the bowls full. Usually it will slow down at higher rpm's. After running slow for a brief period, the pump will refill the bowls and off you will go back up to WOT. For a brief time, till the bowls run dry. YOu and do a test with this. Have a buddy constantly prime the fuel hose bulb. This will force extra fuel into the carbs. If it runs fine at WOT as long as you constantly prime the fuel hose bulb, then you have a fuel restriction, or even a weak fuel pump.

**powerabout** · 10-03-2016, 05:01 AM

put a valve on the end of the supply and regulate it to keep 5.5psi and run it into a bucket and time it to see how much fuel it flows

**Captain75** · 10-03-2016, 01:42 PM

Thanks for your inputs guys!
I'am beginning to think that the tank pick up is too small. The innerdiameter measures between 8 an 9mm, maybe because the boat and its tank originally was designed to get on plane with a small powerplant due to high fuel prices. My fuelsystem uses two inline filters aswell, they are supposed to be 3/8", but I don't think the innerdia really measures that big. One filter between tank and the Holley Blue, the other filter is situated between the pump and the fuel regulator.

Too bad the boat is out of the water for winter maintenance since yesterday, otherwise I would give it a try without the filters.
Even if the filters turns out to be restrictive, I still don't understand why it only starves when the last amount of trim is being applied?

**EMDSAPMGR** · 10-03-2016, 08:30 PM

After all you've been through, I think I'd double check your fuel supply hoses. Make sure they are all 3/8". That included brass fittings, hose barbs, etc.

**powerabout** · 10-03-2016, 09:18 PM

Are you running will fuel pressure gauge?
If not you need to do your fuel pressure flow check before you run your engine because maybe you are tight on the edge of lean and the extra rpm from the extra trim is putting it over the edge?