Fuel use/rpm’s

Hello this is my first year with “my” new 2005 290 AJ it has twin 5.0 mpi’s. I’m winding how my fuel use compares and if I have any sort of problem. Boat is running great and seems to be normal speed for rpm’s etc. at 32-3500 rpm’s I’m going around 25-28 mph. WOT I’m getting 4200-4400 rpm’s and I’m going 40 mph max.

my question is to me I seem to be using a lot of fuel just for everyday cruising etc. I very rarely run boat at full throttle. I typically stay around 3200-3500 rpm’s and cruise around 25-28 mph.

When I fill up full and if I spend a typical day or two cruising finding fishing spots etc. everything within 5-7 miles I come back and I’m at half a tank on the gauges.
Which leads me to my next question. Last time I filled up my gauges were reading LOW FUEL. I actually thought I was going to run out of gas getting to the pumps. I filled up and it only took 50-55 gal. Which means I actually had over half a tank left. I have 2 115 gal tanks.

I’ve re- calibrated the smart craft guages and when full it reads correctly etc. so my main question I guess is, do you think I’m having a fuel consumption issue or is it an issue with the gauges?

regardless if I’m full with 115 gal in each rank after 2 days of normal cruising use. Is it normal to be at half tank ?? Seems like a lot to me.

https://dicksimonyachts.com/blog/boat-reviews-brochures/sea-ray-290-amberjack-review-double-feature

Looks like at your cruising speed fuel burn is around 20 gph. Doesn't take many hours to burn half a tank.

Tim

Looks like your WOT should be between 4600 and 5000 RPM. May be a bit over propped on that boat and lugging a bit. That's a lot of boat for the 5.0's WOT depends on other factors, too, such as how clean is the hull and such.

Old rule of thumb, fuel use number should be about 10% of horsepower. Your engines are 260 hp, so fuel burn should be around 26 GPH WOT. Not a rock solid estimate, but gets in ball park, as EFI is better than carb, usually.

Also sounds like there is a fuel gauge sender calibration problem going on when there is 50% fuel left when gauge reads low fuel. Wondering if the tank sensors were replaced and not quite right, going all the way down to near bottom..

James, to see if you're running at an optimum speed/trim etc, listen to your engines. When you get up on plane, try trimming up and down with very tiny adjustments carefully and listen to the sound of the engines. There will be a "sweet spot" where things are running well and you'll hear it and feel it in the way the boat is running.

That will be the most efficient setup at the speed you are running and will use the least fuel for that speed.

I thought about the fuel sending unit. Can’t find where it is??

James Lee said:

I thought about the fuel sending unit. Can’t find where it is??

Click to expand...

In the fuel tank

Bill Curtis said:

In the fuel tank

Click to expand...

Lol I know that but I couldn’t see how or where to get into it to replace

There "should" be an access right above it, so you can pull it out. Maybe a removable panel in the deck?

I know, I know. "Should" is quite subjective.

Sea Ray in their infinite design wisdom put my water tank on top of the fuel tank, which requires removing a whole lot of wiring and halon system and perko switch mounted on a wooden bulkhead in front of the engine, to remove the wooden bulkhead, to remove the water tank, to access the fuel tank and sending unit, good luck.
I love all my SRs but sometimes I want to bitch slap them. Who designed this shat an intern?

Pirate, I don’t know if I have the same boat as you but on my 290 Amberjack. I’ve found the sending units. There is an Access panel under the helm seat for the starboard and the passenger seat for the port. Just unscrew the cap of the access port and you can stick your head in there in get to the Sending units. I’m not going to worry about it right now. But my guages are way off. Prob about 30-40 gallons. I’ve re calibrated the smartcraft to the 115gal in each tank. It reads fine until it gets below half tank then it drops. Quickly. Today I filled up with starboard tank showing 1/8 full. It only took 50 gal to fill up. So I was actually at half tank.

but now that I see where the sending units are and how to get to them. That may be a winter or rainy day project !

nope different, will try to take a picture soon. fortunately my gauge is good, but someday it will be a lot of work.