Fuel Problem

genesis08 · #1 08-22-2009, 11:43 AM

Is there anybody on the site that has an Inline six on their boat?I used to have like an external fuel pump with a filter in it installed.it was Electric.I removed it but I think I should not have as I believe the engine is been a bit starved for fuel.To discribeb it,its about 5"tall,2" Diameter made of brass,inlet,outlet and 2 wires on it.

Thanks for the help,

Brian....

macojoe · #2 08-22-2009, 03:22 PM

Your motors fuel pump should be all you need.

genesis08 · #3 08-22-2009, 05:56 PM

Thanks Mac,

Problem is the engine will rev no problem when she is out of gear,but once you put the load on she is not getting up to full power.So I thought that was why there was an electric pump fitted which I had removed and as you said I did not think I needed it.Maybe I do.I think she is not getting enough fuel,,,,Brand new pump and brand new carb.Tha engine just seems starved...Any ideas?

Regards Brian

spareparts · #4 08-22-2009, 06:27 PM

use a portable outboard tank hooked to the mechanical pump on the engine to isolate the fual system. Then if it starts running bad, squeeze teh primer bulb to add fuel presure, if that fixes it, then check the fule screen on the fuel pump or replace teh pump. You could install a fuel pressure guage after teh pump and check the same thing, but it requires a special fitting, you could make one(inverted flare fitting with a t) or order one from mercury

genesis08 · #5 08-23-2009, 04:25 AM

Thanks Spareparts,Thats a good sugestion.I will try that the next day I get out.Weather here has been crapfor the last few weeks,Rain,Rain,Rain.I think I need to move back to the states.Anyway I am still trying to figure out why there was an electric pump fitted aswell to the boat when I got it?

Regards Brian

Hammerhead · #6 08-23-2009, 10:19 PM

I hava inline 6 w/o any external pump and it runs fine. It did duffer from a starvation issue but, went away when I got rid of the anti-siphon check valve. ( Those little steel balls in the fuel line inside the tanks ).

By all means,..check with others if t's OK to do that. Local boat mech said it was OK.

Hope it helps.

turbinedoctor · #7 08-25-2009, 01:03 AM

I have a Merc 90 inline 6 with out an external fuel pump, it ran fine for three years until the other day when it died on me. I was not related to not haveing an external fuel pump though.

Did yours run ok with the external pump?
Is you internal pump working ok?

Turbo

genesis08 · #8 08-25-2009, 05:47 AM

Yes ,engine pump is working fine and yes the last time,when the electric pump was fitted, it was ok.I have not used the boat in a couple of years.What are these steel balls in the tank that Hammerhead is on about?Are they in the siphon pipe?If so they would be restricting the fuel and thats why an electric pump was fitted what do you think?By the way the weather is bad here for the last week so I have not been out to the boat since the last trip.

P.s please look at the photo that I have uploaded of the pump.

Regards Brian.......

RidgeRunner · #9 08-25-2009, 07:23 AM

I had a pump like that on a airboat. Nice little lift pump, low pressure,not real noisy. The existence of one on a outboard probably indicates there was a problem at some point.
The steel ball is in the check valve either installed onto the pickup, or is built into the pickup tube on most permanent fuel tanks. Portable tanks don't have them. I refer to it as the fuel flow preventer. Not sure if it is ok to remove them, there may be an unforseen consequence but I can't fathom the need on a outboard with a primer ball. Maybe it is more critical with I/O's? They do foul up from time to time.
Primer balls have been known to fail. Just recently I had one fail on the flats boat. It would idle for a while without a problem but as soon as you tried to plane it would start to die. The only way to keep it running was to pump the primer ball. Removed the fuel pump, no problem internally. Tested the motor on the trailer in gear at 2000 RPM but he ball didn't feel right it would never get firm. Nine dollars later the problem was fixed.
I just read you haven't had the boat out in a couple years. You may need to give the entire fuel system a good once over. Pull a fuel sample and see what you have. If you layed it up right you might be ok. Fuel system problems are at an all time high. Hope it helps. Hope the weather improves too..

genesis08 · #10 08-25-2009, 09:25 AM

Thanks Ridgerunner,I had both tanks out and cleaned a ferw months ago,new fuel lines istalled aswell.My engine is actually an inline six inboard and I am beginning to believe that removing that pump was a mistake!Anybody else got any Ideas?