Reply
 
Thread Tools Search this Thread
 
Old 11 July 2016, 02:41   #1
Trade member
 
Dry Run's Avatar
 
Country: UK - England
Town: portsmouth
Boat name: Hullabaloo
Make: Humber
Length: 8m +
Engine: 225 Optimax
Join Date: Mar 2011
Posts: 629
RIBase
What could it be?

Hi,

Just posting this in case anyone else has suffered similar symptoms and found the cure!

I have an intermittent fuel problem that seems unsolvable without cutting up the decks and removing the fuel tank (which we'd rather not do). The RIB is an 8m Cobra with a Yamaha 350hp 4-stroke.

Problem is that sometimes when cruising at mid range/high revs, the engine cuts down on revs and sometimes dies. Other times as the speed decreases, the engine comes back to life again. This seems to happen more in rougher seas., On occasions where the engine cuts completely, we have noticed that the primer bulb has been sucked flat suggesting a fuel blockage between the tank and the primer bulb. Engineer has checked fuel lines and replaced primer bulb, sea-trialed it for 40-mins and it didn't miss a beat. Next trip out - same problem!

My thinking is there could be something in the tank that is periodically blocking the outlet and then unblocking as the speed decreases and fuel moves around in the tank?

Could it be anything else that I haven't thought of?

Any advice welcome

Regards

Steve
__________________
You get what you settle for!
Dry Run is offline   Reply With Quote
Old 11 July 2016, 03:17   #2
Member
 
Country: UK - England
Town: Bristol
Make: Ribcraft
Length: 5m +
Engine: Yamaha
Join Date: May 2006
Posts: 4,149
Def sounds like a blockage from the Primer Bulb to the Fuel tank.. might be worth changing the Primer bulb.. Also make sure the fuel tap is fully open as a process of elimination.
__________________

__________________
Member of S.A.B.S. West Country Division
matt h is offline   Reply With Quote
Old 11 July 2016, 03:54   #3
Member
 
Country: UK - England
Town: Retford
Boat name: Spy-sea-one
Make: Mercury
Length: 3m +
Engine: Suzuki Outboard/25/4
MMSI: 235074042
Join Date: Oct 2011
Posts: 3,214
if you have changed all external hoses and bulb is the pick up pipe plastic or rubber which could have perished but i would say you have something floating around Steve could be anything really any chance you could get a camera in to have a look you could hire one from HSS intrinsically safe. or its empty the tank and wash out, if the pick up pipe is removable then by emptying the fuel through it you might be lucky and pick the blockage up.
or siphon out through the filler large bore pipe but you would need to have the boat positioned so the fuel went to the pipe[might not be easy]
__________________
jeffstevens763@g is offline   Reply With Quote
Old 11 July 2016, 04:09   #4
Trade member
 
Dry Run's Avatar
 
Country: UK - England
Town: portsmouth
Boat name: Hullabaloo
Make: Humber
Length: 8m +
Engine: 225 Optimax
Join Date: Mar 2011
Posts: 629
RIBase
Cheers guys

A camera is probably the next move after we've run it on a remote tank for a few trips. Problem is a 25l remote tank wont feed a 350 for very long
__________________
You get what you settle for!
Dry Run is offline   Reply With Quote
Old 11 July 2016, 04:45   #5
Member
 
Country: UK - England
Town: Retford
Boat name: Spy-sea-one
Make: Mercury
Length: 3m +
Engine: Suzuki Outboard/25/4
MMSI: 235074042
Join Date: Oct 2011
Posts: 3,214
Quote:
Originally Posted by Dry Run View Post
Cheers guys

A camera is probably the next move after we've run it on a remote tank for a few trips. Problem is a 25l remote tank wont feed a 350 for very long
yep know that i had a ride on ribquest with twin 300 hp verardo's 140.00 20 mins
__________________
jeffstevens763@g is offline   Reply With Quote
Old 11 July 2016, 05:01   #6
Administrator
 
John Kennett's Avatar
 
Country: UK - England
Town: Brighton
Length: 3m +
Join Date: May 2000
Posts: 6,774
I've had this a couple of times. Once it was a dodgy primer bulb, the other it turned out to be lumps of sealant which had been over enthusiastically applied to the fuel tank access hatch.

You've tried the primer bulb, so that suggests something in the tank. Do you have access to an inspection hatch? Is the fuel pickup accessible? As an interim fix, rather than draining the tank and cleaning out every last bit of silicone, a filter on the pickup worked for us.
__________________
John Kennett is online now   Reply With Quote
Old 11 July 2016, 05:19   #7
Member
 
Country: Ireland
Town: Donegal Bay
Make: ribtec
Length: 6m +
Engine: outboard 200hp
Join Date: Jul 2015
Posts: 46
Hi
I had the same problem after i got my boat. The engine carried on exactly the same way as yours. I found that the fuel sender had dissolved ( through electrolysis )and debris entered the tank. My tank is stainless steel and has baffles so I am not sure that a camera will help. I ended up cutting a 4" hole in the deck and a small 1 in the tank. I was careful to fill the tank with water to avoid a possible explosion with all the fumes.
The fuel line is small with a bore of the inside of a biro so I can get blocked quite easily. It runs along the floor of the tank towards the stern of the boat. After cleaning the tank I resealed it and fitted one of those small inspection hatches. The biggest problem I had was getting information on the exact location of the tank so that I could drill in the right place.
Hope this helps
__________________
Ribtec1 is offline   Reply With Quote
Old 11 July 2016, 06:48   #8
Member
 
Country: UK - England
Town: Retford
Boat name: Spy-sea-one
Make: Mercury
Length: 3m +
Engine: Suzuki Outboard/25/4
MMSI: 235074042
Join Date: Oct 2011
Posts: 3,214
if you can get the pick up out you could cut notches in it so the likely hood of all the notches sealing would be remote as a quick fix until you can sort properly
__________________
jeffstevens763@g is offline   Reply With Quote
Old 11 July 2016, 12:08   #9
Member
 
Country: UK - Wales
Town: Abersoch
Make: phantom
Length: 6m +
Engine: 150hp outboard
Join Date: Nov 2014
Posts: 156
We had a fuel tank vent hose full of water where it coiled under the deck, this caused us similar issues
__________________
whiskylee is offline   Reply With Quote
Old 11 July 2016, 12:41   #10
Member
 
Country: UK - England
Town: Cambs
Make: Scorpion
Length: 8m +
Engine: 225 Opti
Join Date: Sep 2010
Posts: 351
i had the same problem with my Scorpion and it turned out to be old fuel that had turned to varnish and then flaked off. When i stripped it down there were flakes in the fuel pick up and right up to the water separator.

i replaced all fuel pipes and filters, emptied the tank and then cleaned it. it was not a fun job!

interestingly i think i have the same problem on my current boat as after an hour running i had the same symptoms, checked and the bulb was compressed. pulled the pick up and the filter was covered in what looked like wool. I wonder if my fuel tank air vent has been a hide away for insects! No flakes though, so very happy with that!
__________________

__________________
Portholme is offline   Reply With Quote
Reply

Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off




Our Communities

Our communities encompass many different hobbies and interests, but each one is built on friendly, intelligent membership.

» More about our Communities

Automotive Communities

Our Automotive communities encompass many different makes and models. From U.S. domestics to European Saloons.

» More about our Automotive Communities

Marine Communities

Our Marine websites focus on Cruising and Sailing Vessels, including forums and the largest cruising Wiki project on the web today.

» More about our Marine Communities


Copyright 2002- Social Knowledge, LLC All Rights Reserved.

All times are GMT -5. The time now is 09:51.


Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2017, vBulletin Solutions, Inc.