External fuel filter recommendations......

[clearblue]

By the way I called purolator , burst pressure on that filter is 293psi

[Ghost-Geezer]

Good morning A,

Great information!  You bring up a very good point about burst strength, working pressures, etc. - I cannot say for certain that I used the Fram filter on the pressure side of the fuel pump, it's possible I had it before the pump.

That seems to me to make a "safer" alternative to a large inline after the pump.  What happens if the throttle is pinned in 4th at 4K and when the secondary injectors kick in, they take more fuel from the large filter than the stock pump can replace...........could you lean out?

Yes, I do believe if you have too much filter on a stock fuel pump there is a very good "drain" potential for a Gen II. Your additional injector package would have the demand to lower primary injector available pressure. Thus starving both groups.  That is a great point, and argument "not" to install a filter inline from pump to rail unless you are considering an upgrade in fuel supply. In this regard you keep available pressure for both groups at a respectable level


A.

It is my understanding that on a Gen II bike, once you get past 6K RPMs the secondary injectors - which are much bigger-er than the primary injectors,  provide 90% of the fuel requirements you are asking of the engine and the primary injectors drop back to 10%.  That is the area I would be concerned about with an inline post-pump filter.............that transitional point. 

[LVBUSA]

By the way I called purolator , burst pressure on that filter is 293psi

Thanks Blue,

Excellent research, and validation on the filter specs.  That out runs the Motorcraft FG800A by 143 psi. To me, either one on a stock Gen I would be sufficient if you changed it by pressure validation or preventative maintenance.

Great help ! A.

[LVBUSA]

Good morning A,

Great information!  You bring up a very good point about burst strength, working pressures, etc. - I cannot say for certain that I used the Fram filter on the pressure side of the fuel pump, it's possible I had it before the pump.

That seems to me to make a "safer" alternative to a large inline after the pump.  What happens if the throttle is pinned in 4th at 4K and when the secondary injectors kick in, they take more fuel from the large filter than the stock pump can replace...........could you lean out?

Yes, I do believe if you have too much filter on a stock fuel pump there is a very good "drain" potential for a Gen II. Your additional injector package would have the demand to lower primary injector available pressure. Thus starving both groups.  That is a great point, and argument "not" to install a filter inline from pump to rail unless you are considering an upgrade in fuel supply. In this regard you keep available pressure for both groups at a respectable level


A.

It is my understanding that on a Gen II bike, once you get past 6K RPMs the secondary injectors - which are much bigger-er than the primary injectors,  provide 90% of the fuel requirements you are asking of the engine and the primary injectors drop back to 10%.  That is the area I would be concerned about with an inline post-pump filter.............that transitional point.

Same to you Dave,

       The credibility of your input here pertaining to Gen II's is of the utmost concern. Fuel starvation could be a nasty end result when those secondaries go active. Excellent point Dave !.

Much thanks also !

A.

PS I just reread your post Dave. The secondaries pull 90% of the injector duty, and are larger capacity injectors ? That would stand to reason your concerns are absolutely accurate !.

[Ghost-Geezer]

Yes, they do, but only AFTER 6,000 RPMs has been passed.  Until then, the primary injectors do the work. 

Thanks for the kind words............information exchange is one good reason we are all here.  Would hate to see someone hurt their GEN II bike due to a lean condition.

[LVBUSA]

Good morning A,

Great information!  You bring up a very good point about burst strength, working pressures, etc. - I cannot say for certain that I used the Fram filter on the pressure side of the fuel pump, it's possible I had it before the pump.

That seems to me to make a "safer" alternative to a large inline after the pump.  What happens if the throttle is pinned in 4th at 4K and when the secondary injectors kick in, they take more fuel from the large filter than the stock pump can replace...........could you lean out?

Yes, I do believe if you have too much filter on a stock fuel pump there is a very good "drain" potential for a Gen II. Your additional injector package would have the demand to lower primary injector available pressure. Thus starving both groups.  That is a great point, and argument "not" to install a filter inline from pump to rail unless you are considering an upgrade in fuel supply. In this regard you keep available pressure for both groups at a respectable level

As far as a Gen I, though, at a stock pump pressure with an inline filter could be considered a decent upgrade. One could also consider upgrading the fuel supply and regulating back to a stock pressure range with the same filter arrangement and have the best of both worlds.

Received the Motorcraft FG800a in the mail.  Will be plumbing and testing pressure this evening. Dimensions set roughly 3"X3.25", fuel inlet/outlet length at about 5.5" with 5/16 on both ends.

A.

Morning all,

       Finally plumbed in the FG800A Motorcraft filter (3D X 3.25W X 5.6"L at tip of 5/16" inlet/outlet) and pressure gauge (homemade). Pre start primed pressure is same, with or without filter, at just shy of 50 psi. Running pressure is same. The fuel line is Gates 5/16" fuel injection line (Gates Fuel Injection Hose 5/16" (7.9mm) 225 PSI WP BARRICADE Greenshield TECHNOLOGY / Multi-Fuel and Bio-Fuel Compatible) rated at 225 psi. Heavy duty barrier fuel line. With fuel injection clamps, it makes for a cozy package. I haven't drilled out the fuel pump filter, nor am I concerned at this point. It's currently a double filter system. Runs good.

A.

[Ghost-Geezer]

Glad to hear it.  Sounds like a winner.   

[Ghost-Geezer]

I want to correct an error I made in a previous post...............on a Gen II, at less than 6K the primary injectors do, as I stated, perform all the work, after 6K the secondaries do kick in but only provide 70% of the motor's fuel demand, while the primaries drop back to 30%...........not the 90/10 I mentioned earlier, however, the additional fuel demand is still quite significant.........I found that out today after discussing the issue with Rodney in detail..........that is why he is not fond of a post-fuel-pump filter on a Gen II.  He knows his stuff...........IMO.  Just be careful.