Fuel filter?

[Kng15012]

Hello, I've been searching the forums for some advice. I found similar post but wanted to throw this out there. I have 1991 4.3l merc. 2bbl carb. And the tb5 ignition.

First trip out boat runs great. But I noticed on the 2nd trip when you reach 4600 rpms and above it starts to surge. And occasional pop from the carb. If you throttle all the way up it will go more but surges all the way up. As soon as you back below that it clears up. I'm leaning towards fuel filter? It's got the clear style. And I don't know when the old owner replaced it.

 

[Bt Doctur]

It's got the clear style. And I don't know when the old owner replaced it.

there usually a metal spin on type, no plastic allowed on marine inboard or I/O fuel systems

 

[Kng15012]

The current filter is a mr gasket type. I only know because I found a 3 pack with an old filter left in the package. On the boat. It's between the mechanical pump and the carb.

 

[Kng15012]

I seen a post on here with the same internal filter. I beleive the part number is 869g on the package I found on the boat

 

[Bt Doctur]

if you mean the one inside the carb, that ok them. If you mean one connected to the fuel lines, that not ok
There should be a spin on located low on the post side. looks like a oil filter

 

[Alumarine]

Also, maximum Wide Open Throttle is 4400 - 4800 rpm for that motor.

 

[Kng15012]

It def doesn't have a spin on filter. And I had a feeling max throttle was about 4400 to 4800. It acts more like a rev limiter than anything.

 

[Kng15012]

I'll have to look tomorrow but the filter housing is glass and appears to have the filter inside. And it's in line about 12 inches from carb.

 

[Bt Doctur]

That will need to be changed immediatly, no glass allowed. Also sounds like its on the pressure side instead of the suction side.
People who have no clue about anything should not be allowed to own any kind of tool, period

 

[achris]

1991 will be TB-IV, not 5. 5 didn't start until mid '96. No rev limiter on the IV...

Fuel system.
There should be a hard line between the fuel pump and the carb. NO filter was or should be installed in that line. The only filter should be an in-line, spin-on cartridge type on the suction side of the pump, ie, between the tank and the pump. As BT said, definitely no glass or plastic filters inside the engine bay. Also, you'll find a filter inside the top of the fuel pump, don't forget to check that.

If you have a filter between the pump and the carb, please remove it and return the hard line to that position, lest you blow yourself, and anyone else on the boat, up. And that is not a joke. Never, ever, ever put a filter on the pressure side of a pump! Ever!

Chris.....

 

[Scott Danforth]

the pop from the carb is called a lean sneeze. most likely you need to pull your carb apart and go thru it, however it could be a fuel delivery problem

also, regarding the fuel filter, change that to the correct fuel filter.

 

[Kng15012]

Does anyone know a part number for the fuel filter and base assembly? So I can order it asap?

 

[Kng15012]

I've search he web and haven't come up with too much as of now.

 

[Bt Doctur]

This style?

 

[Bt Doctur]

Or this?

 

[Kng15012]

I'm kinda lost on what I need. Currently the fuel line runs straight to the fuel pump.(mechanical). Then between the pump and the carb is a clear filter. So I assume it would be a good idea to add a fuel/water seperator. And I should run a hard line from pump to carb. With just the filter found on the carb?

 

[Kng15012]

Also was there ever a setup like this? I seen no eveidience of any fuel/water seperator was ever in the setup?

 

[Bt Doctur]

Is there a filter in the pump? You need to remove the fuel line thats there now, get a length of steel brake line 3/8 ID and form a new one. If you need to cut the tube you need a double flaring kit

 

[Kng15012]

There's a filter inside the current mechanical pump. And in the carb Inlet. So I can just remove the clear filter someone put in before the carb, replace with a solid line. And all is good?

 

[Bt Doctur]

Do you have the engine serial number and a pic of the fuel pump too