Irratic FDC?

[Wildchild467]

I have searched quite a bit about the FDC and got some good information. The problem i see with my deuce is sometimes it runs sluggish and sometimes it runs really good even when uncle sam bypassed the FDC. I have not touched any settings on the IP or FDC at all. I have been driving it quite a bit to streach its legs, so its not an issue of it just not being run, it sees 2100rpm down the highway quite regular. the information i got is that the FDC adjusts the throttle stop to adjust the fuel rate per what fuel is being used. Also the "defult" setting for the FDC is at the "wide open, more fuel like gasoline" position. so can the FDC still bounce around and not stay at that position? I just feel like when i put the throttle to the floor the power does not feel like its all the way to the floor and am only pushing 7.5 lbs of boost out og my d turbo at 2100rpm. I read on here somewhere where i should be around 9psi. All my fuel filters are good, just changed them and fuel system is clean. Im not looking to turn the fuel up and worry about a pyro because I dont want to risk burning anything up at all. i would just like it to run like it did on those good days i have driven it where it runs real good. So what things are there for me to check to make sure the FDC was bypassed correctly other than plumbing?

 

[Floridianson]

Go to the TM's read Trouble shooting the 465 and tune her up. Check low end boost and bring the high end boost up for shure.

 

[cranetruck]

The piston within the FDC is springloaded and will not "bounce around". There should be no fuel pressure at the FDC input when bypassed correctly.

Check your fuel system for possible air leaks.

 

[Floridianson]

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[kwiksilver]

I've been reading all the fdc posts here lately and something is confusing. The above article says to increase fuel 16 flats with the stop plate bolt, but, it also says to turn the drop screw 2 turns to decrease fuel. I could swear everybody said to turn the fuel down to cool the egt's. What gives?

This post for reference... http://www.steelsoldiers.com/deuce/37763-fdc-bypass-help-yes-again.html

BTW FWIW my truck was surging with power when it wouldn't get above 2000rpm's and the fuel filters were horrible. The advice to change the filters was the right on.

 

[doghead]

WC, are you running on diesel fuel all the time?

 

[cranetruck]

Bypassing the FDC in basic terms.
Move screw IN to REDUCE fuel delivery.

 

[Maverick1701]

top

thanks for the diagram!!!

I needed something just like that....I need to reconnect my FDC pronto!

 

[SasquatchSanta]

The droop screw only controls the low-end power. The stop plate bolt addresses high-speed power.

I've been reading all the fdc posts here lately and something is confusing. The above article says to increase fuel 16 flats with the stop plate bolt, but, it also says to turn the drop screw 2 turns to decrease fuel. I could swear everybody said to turn the fuel down to cool the egt's. What gives?

This post for reference... http://www.steelsoldiers.com/deuce/37763-fdc-bypass-help-yes-again.html

BTW FWIW my truck was surging with power when it wouldn't get above 2000rpm's and the fuel filters were horrible. The advice to change the filters was the right on.

 

[Wildchild467]

WC, are you running on diesel fuel all the time?

Yes, i have been running diesel all the time. I changed the primarys and secondary filter about 150 miles ago just to make sure, but that didnt change anything. I put abou 3500 miles on the truck this summer and changed the primary filter a lot just to make sure they wernt clogged. The truck had never skipped or power surged and fuel has always looked clean.

I checked my fuel lines and cant see where i have any leaks or kinks, intank pump works good and the hose in the tank is not cracked.

I often thought about the flex hose that gos from the IP to the line under the crossmember, if that is collapsing and restricting flow. Has that ever happened to anybody?

 

[Floridianson]

thanks for the diagram!!!

I needed something just like that....I need to reconnect my FDC pronto!

Why and worry about fuel in the oil. I would leave it disconnected.

 

[Wildchild467]

Cranetruck, in that picture, the screw on the FDC that says "after adjustmet, screw will have moved in .100 inches" That is someting somebody has to asjust,it jut does not magically happen, right? I read another post somewhere where ther was a measurement of .150 inches for something esle. on my truck there is still the brass cover over that whole adjustment. that makes me wonder if uncle sam ever adjusted that after the did the bypass plumbing or not because i dont know how many threads are exposed.

 

[Floridianson]

Wildchild If you want to tune it right go to the TM troubleshooting the 465. There you will be checking the intank pump for the 5-7psi then you will do an rpm/pressure check of the ip fuel pump from there when all is good, fuel filters airfilters pressures of fuel then you do the boost checks of 1600 and then the 2100rpm. In the tms you will find boost numbers. Low calls for 4-5 I would go 6 the top end calls for 9-10 go 11 and the truck should start fast and run good

 

[gimpyrobb]

Why and worry about fuel in the oil. I would leave it disconnected.

I agree, why do you want it hooked up?

 

[Floridianson]

Chris you having any fun????????????????

 

[gimpyrobb]

Been "under the weather", starting to feel better though. Gonna have fun at the Ga rally though, you going?

 

[Wildchild467]

I took this picture last night, sorry about the quality. I took the brass "sleeve" off the FDC adjustment to see what was under it. This "sleeve" was like a tamper proof thing. my adjustment does not look like any other adjustments i have seen in the TM's. wierd.

I checked the fuel pressure at the final fuel filters and i am getting 4psi i believe. Maybe ill have to go back to the drawing board and triple check the fuel lines. Also i believe there is a 1/8"npt port on my fuel pump i could hook a gauge on and see what its putting out there. My Air filter looks real clean, but i blew that out before just to make sure. What about a fuel pressure relief valve in the IP? could something be a little stuck there and giving me low fuel pressure also? I thought there was a fuel pressure relief valve near the hyd head.

 

[Floridianson]

That cap in the pic is not to be tampered with. The cover you are looking for is just below that straight down. Looks like a triangle remove that cover and discard. then you will see the two lock nut and the stud sticking out of the bottom of FDC. Pressures can be taken from the bleed screw that is on top of the fuel canisters with a low scale gage. 0-10 if you can find one.

 

[Wildchild467]

ok, thanks for the info on the cap. I used a gauge that was 0-80 to check the pressure at the final fuel filters, so the precision is not all there i am sure. My thought is maybe i can check the fuel pressure right at the pump AND at the final fuel filters and see if there is a difference. maybe that would clue me in if there is some restriction in my lines. I have a leaky compresser gasket that i need to change and leaky oil filter canisters, so that does not help the work enviroment for checking leaks. I will fix those soon.

 

[Floridianson]

If you intank pump is working then the leak will show up in the lines or filter. The only place that could leak and you not see it is in the tank rubber hose. Need to get fuel gage for holly carb or some thing like that for low pressure and you will need a higher scale for the RPM test of IP fuel pump. I forget what it puts out without reading the Troubleshooting TM again 35psi I think is one rpm range but there is more. If you want to check both right after tank and at the finial filters go 4 it.

And your question about is the FDC bypassed. The line from the finial fuel filters runs from there right to the HH head. The FDC can have the plastic line looped back to them self on the FDC or blocked with plugs. I also might think about capping off flame heater feed and and the return line that goes from injector to injector to flame heater. The plug for the brass connection T that is on the fuel line return for the injectors is a brake line plug 4 get the size but inverted flar plug.