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This is how the fuel port looks like on the engine. I mean LOOK at that thing, It's half the size of a drinking straw.
There is so much restriction on it I can barely blow through it. Screen looks clean though.
Makes me thing measuring fuel pressure on the fuel bowl is entirely pointless. Sure you can throw 75psi on the regulator spring but it won't even matter because you're getting half the flow at the same pressure.
This is probably why so many folks need to shim the FPR spring.
I left mine unshimmed during fuel bowl rebuild but got braided steel lines installed. Engine runs much quieter now.
As a matter of fact it runs so quiet what I thought was loud injectors was my torque converter Marbling around.
A fuel pressure gauge in the post filter port on the filter housing is a good indicator of restricted suction line, failing pump, clogged filter, etc. I really don't see how that can be considered useless. There are 1/8" NPT test ports on both heads if you'd rather plumb the gauge in to one of those. They just aren't a lot of fun to get to.
A fuel pressure gauge in the post filter port on the filter housing is a good indicator of restricted suction line, failing pump, clogged filter, etc. I really don't see how that can be considered useless. There are 1/8" NPT test ports on both heads if you'd rather plumb the gauge in to one of those. They just aren't a lot of fun to get to.
I did it was a royal pain.
My main reason for posting was to say I was shocked to find how restricted the ports were.
I removed mine also and did the CVD to aid the RiffRaff FPx. I think the FPx unit should be shipped with the CVD. I was going to just drill mine out but went ahead and got them from clay.
In my mind, it depends on your fuel demands and if the stock setup is not able to keep up with those demands. If you need to increase fuel flow through the heads, start looking for the restriction points or go with a partial or full regulated return. A regulated return is what many injector builders recommend when installing new injectors. They provide equal fuel pressure to all the injectors and allow air to be removed through the heads to the regulator instead of through the injector.
M-S-G, If you are concerned about the stock fuel system restrictions, have you considered gutting the Fuel Filter Check Valve? It's purpose is the make sure a filter is in place. But, if you are not worried about that, then why not remove the internals and the restriction.
In my mind, it depends on your fuel demands and if the stock setup is not able to keep up with those demands. If you need to increase fuel flow through the heads, start looking for the restriction points or go with a partial or full regulated return. A regulated return is what many injector builders recommend when installing new injectors. They provide equal fuel pressure to all the injectors and allow air to be removed through the heads to the regulator instead of through the injector. M-S-G, If you are concerned about the stock fuel system restrictions, have you considered gutting the Fuel Filter Check Valve? It's purpose is the make sure a filter is in place. But, if you are not worried about that, then why not remove the internals and the restriction.
Quite frankly I don't know that much about the fuel system.
When I gutted the fuel bowl I was wondering why on earth is that check valve in there but ended up just replacing orings and leaving it be. I even tested it per guzzles instructions.
Now, I wasn't really looking for performance improvements and I don't even have a chip.
But it didn't take much wits to look at the engine ports and see they do not belong.
Stock Bosh pump puts out (zing) 30 something gallons per hour. I just don't see how on earth do you move that amount of liquid through a damn straw
I'm throwing these things away, OBS trucks don't have them and run fine.
That's because OBS trucks have a regulated fuel return from the factory whereas SD trucks have the 'deadhead' design that makes those check valves necessary.
Of course, if you are going to a regulated return then more power to you. However, removing those check valves and keeping the 'deadhead' design might literally blow up in your face someday. Not that hard to imagine a blow back situation from a loose injector or worn o-ring.
Good ol' Navistar looking for any way to save a buck.
My feeling is they look dink, but really flow just fine. I read a member here put up north of 500RWHP squirting thru those, with just fat sticks, OBS muffler and tuning on an otherwise OEM motor. Plus the screens might be very useful some day; say your passenger side fuel line wears and leaks, and the roadside fix is cut the line and slip on some fuel hose. That little screen is the last line of defense for some fragment of the cut line getting to your injectors.
This surprises me because your signature mentions Veggie Oil use. BTW- I believe the need for a fuel pressure guage is #1 of all the gauges.
What is there to know on a deadhead? Smarter people than me have figured it out and documented everything.
On my system I'm using test ports to inject grease with diesel fuel system intact.
I would not be confident saying I know a lot about the fuel system unless I knew exactly how every component of it operates. So far I haven't been even able to find correct torque specs for the fuel bowl haha.
Anyway, the 'valves' I took off didn't do squat. I tested with compressor and the flow both ways. The term 'flow' being used generously here.
Looks like mine weren't doing anything and were just shot.
My understanding of the need for the valves on the port is that they prevent the fuel bowl from blowing up.
Now that is just a theory by smart folks I was reading here and on the veggie oil forums and no known reports of this exist as far as I was able to find.
Reportedly during startups in cold weather IF you have worn or sticking injectors spikes of 100+psi inside the bowl are not unheard off, whether that is a problem or not I don't know and I don't have that problem.
M S G< are these check valves you used bigger inside then the stock ones? I like this set up better. And you said it made your truck quitier? That would be nice in it's self.
12-28-2014, 03:02 PM
it was a royal pain.
