Bravo Three, 5.7 EFI RPM Loss

[AZSenza]

Hi guys...
1997 Larson 226 LXI
Bravo III with 26p props
5.7l EFI rated at 250HP

THe engine starts and runs GREAT, very smooth but, when you push it, it feels like its intermittantly loosing fuel, like a miss. (Actually, it feels more like its starving for fuel, then gets some every once in a while) It has fresh gas, I ran it on muffs and saw a nice fan spray out of the injectors, sounded fine, then back in the water and same thing, it feels like its running ok but then it will pick up RPM and MPH for just a few seconds then back down about 400-500 RPM loss at least.
I have not:
Checked plugs
filter
cap and rotor
I only did a quick visual till y'all can point me in the right direction, I am an expirienced mechanic but have never messed with EFI.

Also as I throttle up, get on plane etc, if you push the throttle to max, there is no increase in RPM or MPH, like something just wont let it push. HELP!!!!

 

[Don S]

Re: Bravo Three, 5.7 EFI RPM Loss

When was the last time it had a full tuneup? Cap, rotor, and plugs. Have you checked the fuel filter for water? Or replaced it?
It sounds a little like fuel starvation, you can check it like THIS, or run it on a remote outboard tank hooked directily to the engine and see how it works.
Did this problem just start, or did you buy a boat with the problem. Has it ever worked right for you?

 

[Bondo]

Re: Bravo Three, 5.7 EFI RPM Loss

Ayuh,.....

I'd start at the Fuel Filters,+ move on from there.....

 

[AZSenza]

Re: Bravo Three, 5.7 EFI RPM Loss

Ok, Changed the fuel filter, pulled the plugs, They MUST be original, they looked awful, a little rich and well worn, all looked the same. Cap needs replaced as well. When I get those changed I'll take her back out for a load test.
Thanks.
P.S. on an EFI engine, I only see the fuel water sep. Is there a fuel filter as well somewhere?

 

[TilliamWe]

Re: Bravo Three, 5.7 EFI RPM Loss

No, the water/fuel separator is the only filter. Unless you count the little screens in the two injectors, but I don't think you can or would want to replace them!

 

[Reel Poor]

Re: Bravo Three, 5.7 EFI RPM Loss

I only see the fuel water sep. Is there a fuel filter as well somewhere?

Thay are one in the same.

 

[AZSenza]

Re: Bravo Three, 5.7 EFI RPM Loss

Thanks, thats what I thought!

 

[Don S]

Re: Bravo Three, 5.7 EFI RPM Loss

It's imposible to say how many fuel filters you have in your system. Some owners add one "Just In Case".
I have found many boats with not only the engine (manufacturers engine mounted filter) filter, but 1 or 2 extra ones installed.
Just follow the hose from the tank to the engine and count the filters. You are right there, we aren't.

 

[AZSenza]

Re: Bravo Three, 5.7 EFI RPM Loss

Don, good advice. Yes I did follow it looking for in line filters, there were none so I'll be adding my own. I didn't know if (because of the EFI) there were some placed in silly locations like on the carbureted engines. I would like to install a glass inline just before the fuel/water sep. and a fuel pressure gauge at the TBI inlet.

 

[AZSenza]

Re: Bravo Three, 5.7 EFI RPM Loss

Ok, I replaced the plugs (carbon), cap and rotor(Cap was way corroded, the coil wire and one plug wire were not "snapped" on), cleaned the flame arrestor, replaced the fuel filter (very few water droplets), checked for loose connections and secured LOTS of wires with zip ties (i'm an aircraft mechanic-I cant help it) then gave it another once over. Once I got fuel back in the system, she started RIGHT up and idled great, sea trials this afternoon to see if my power came back. From the looks of the ignition parts-it might!
Oh yeah-MAN that Bravo III fluid is pricey!

 

[AZSenza]

Re: Bravo Three, 5.7 EFI RPM Loss

UPDATE for those interested- After 2 hours on the water yesterday, Id say the probel is SOLVED, plugs and cap/rotor replaced. Full gas and equipment, 1 passenger 5000-5100 RPM and 57MPH indicated (I forgot my GPS)
So with people on board 4600-4800 should be PERFECT!
Thanks for all the suggestions!

 

[subcrx]

Re: Bravo Three, 5.7 EFI RPM Loss

Hi I am experiencing this same problem but with a carb. Noticing white smoke coming out of the valve cover vents as well. any ideas?

 

[Don S]

Re: Bravo Three, 5.7 EFI RPM Loss

Hi I am experiencing this same problem but with a carb. Noticing white smoke coming out of the valve cover vents as well. any ideas?

Then start a new thread. Then everyone will see your post, and not someone elses.

 

[winbasic]

Re: Bravo Three, 5.7 EFI RPM Loss

UPDATE for those interested- After 2 hours on the water yesterday, Id say the probel is SOLVED, plugs and cap/rotor replaced. Full gas and equipment, 1 passenger 5000-5100 RPM and 57MPH indicated (I forgot my GPS)
So with people on board 4600-4800 should be PERFECT!
Thanks for all the suggestions!

For the uninitiated, what is the cap/rotor mentioned above? I understand EFI have spark plugs but didn't think they had a distributor as such. I'm assuming this is a similar setup to the 5.7 Gi VP I have.

 

[bruceb58]

Re: Bravo Three, 5.7 EFI RPM Loss

Yes, they still have a distributor.