how to turn up fuel...in pictures?

Scottd9990

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I by-passed my FDC last night and Wow, what a difference. Pyro and boost gauges inbound for install. I now get a quick puff of black smoke with each gear shift. Smoke clears right right away as the rev's come up. I now have some power at least!!! I will temper my fun until gauges are installed.
 

yagenrok636

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just be advised if you turn the fuel up too far the FDC will do strange things to the engine like, stuttering shuttering missing popping through the exhaust bad fuel mileage loss of power extreme amount of black smoke and high EGT's at least this happen to me not saying it would happen to you. I also do know this from experience if the FDC is still attached and working when you turn it up and if you start using waste oil for some reason it counteracts with that system and it doesn't run properly when. Now, when I bypassed it runs good and doesn't stutter doesn't miss runs excellent but I still have an issue of running straight diesel fuel, not sure why that is but that is one of the issues I'm still having. I can only run waste oil without the FDC and can only run diesel fuel with the FDC as long as its not turned up....
I'm experiencing all of these things. Exhaust pops weird. Lots of black smoke at idle. Truck takes a long time to start on a 70 degree day. I only by-passed the FDC and didn't adjust the fuel at all. I went down 10 flats on the fuel, and it still has a really hard time starting, pops out the exhaust, runs really hot (1200 degree EGT) and acts like it has no power with 10 psi.
 

RAYZER

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I'm experiencing all of these things. Exhaust pops weird. Lots of black smoke at idle. Truck takes a long time to start on a 70 degree day. I only by-passed the FDC and didn't adjust the fuel at all. I went down 10 flats on the fuel, and it still has a really hard time starting, pops out the exhaust, runs really hot (1200 degree EGT) and acts like it has no power with 10 psi.
Have you had your injectors pop tested? They may be worn out and leaking.
 

RAYZER

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I'm experiencing all of these things. Exhaust pops weird. Lots of black smoke at idle. Truck takes a long time to start on a 70 degree day. I only by-passed the FDC and didn't adjust the fuel at all. I went down 10 flats on the fuel, and it still has a really hard time starting, pops out the exhaust, runs really hot (1200 degree EGT) and acts like it has no power with 10 psi.
Were you able to resolve this issue?
 

Shane 1971 M35A2

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I did the 50 cent trick or "quarter crap" on my 1971 M35A2 with C turbo, and saw a noticible improvement in power. When I upgraded to 11-20 tires I stacked another quarter for a total of 3 in the fdc. I am pleased with the improvements in power, streetability, turbo spool sound, hill climbing improvement, overall driveability, and it has been about 2 years. Maybe turning up the fuel in other ways and bypassing the fdc would give even better results. What I can say is it worked for me and thats "my 75 cents".
Shane
 

Floridianson

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I do not understand why someone would do the quarter thing on there own truck. Best thing is to bypass the FDC and add a pyrometer. From then on we do all the fuel adjusting from the main fuel control or twin nuts under the triangle cover. When we bypass the FDC the droop screw is not changing positions because it rides on the FDC wedge stop plate that use too move. So all we can do is adjust the main fuel / twin nuts and have to deal with the extra fuel on the lower end of the RPM scale.
 
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Shane 1971 M35A2

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I did the 50 cent trick or "quarter crap" on my 1971 M35A2 with C turbo, and saw a noticible improvement in power. When I upgraded to 11-20 tires I stacked another quarter for a total of 3 in the fdc. I am pleased with the improvements in power, streetability, turbo spool sound, hill climbing improvement, overall driveability, and it has been about 2 years. Maybe turning up the fuel in other ways and bypassing the fdc would give even better results. What I can say is it worked for me and thats "my 75 cents".
Shane
Well I have since discovered I don't have a G code fuel pump that is harder to turn up than later models. I watched Tatical Repair's tutorial and learned that it is very easy to turn up a non-G code pump without the chance of the "innards" dropping into some hard to retrieve place. So I adjusted the fuel screw...and for the time being have the "fuel screw" turned up four "peaks" on the inner fuel nut. It increased performance again about the same difference as adding the 3 quarters to the FDC did. Now I still have the 3 quarters in the FDC and have turned up the fuel screw four peaks. By the way it moves out now and holds its speed going up hills, I probably should get around to getting a pyrometer installed.
Shane
 

Floridianson

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Well I have since discovered I don't have a G code fuel pump that is harder to turn up than later models. I watched Tatical Repair's tutorial and learned that it is very easy to turn up a non-G code pump without the chance of the "innards" dropping into some hard to retrieve place. So I adjusted the fuel screw...and for the time being have the "fuel screw" turned up four "peaks" on the inner fuel nut. It increased performance again about the same difference as adding the 3 quarters to the FDC did. Now I still have the 3 quarters in the FDC and have turned up the fuel screw four peaks. By the way it moves out now and holds its speed going up hills, I probably should get around to getting a pyrometer installed.
Shane
The quarter thing was done when the trucks were still under control of Uncle Sam and I bet the FDC's were still hooked up. They did it so they did not have to cut the safety wire on the tin cover and twin nuts and get caught increasing the fuel. Now that you own the truck I do not think you will get in trouble for bypassing the FDC, cutting the safety wire on the tin cover and throwing it away. Now all fuel control is the main fuel control / twin nuts and since the FDC is bypassed the smoke cam and droop screw long longer change positions when the FDC servo changes positions. So forget the quarter as you will get better control of the fuel when we adjust the main fuel / twin nuts. We mark one of the flat with a marker so we can make fine fuel adjustments. Yes the engine is going to smoke more now that we bypassed the FDC at lower rpm scale till the turbo can spool up. So bypass the FDC and just adjust the main fuel control to your altitude and terrain and put your quarters in your piggy bank.
 

Beyond Biodiesel

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Hi folks I tried speeding up my deuce using an later thread that didn't have picture or much detailed instruction and ended up breaking the bolt that the FDC innerds attach to on a replacement injector pump. It is a newer version, probably the G series. I still have the old IP. So, does anyone know if it is possible to pull the top of the FDC off an older IP and replace the broken FDC unit with it? And, is there anything in the FDC unit that needs to mesh with anything down in the innerds, or is it just a simple drop-in arrangement?
 

Floridianson

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72m35a2

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1689716634380.png this rack adjustment pic says .150" of threads showing is stock. for my own records im going over everything since putting the new 395
tires on i have adjusted my rack for more fuel when i first got it. i do have a boost and pyrometer even on heavy loads full throttle i see max 900 F 12-13 lbs boost so was going to turn it up a bit more. but i never seen this pic before. so this is saying less then 1/8" of threads showing is stock correct? im currently showing 4 threads about 1/4" or so. how many threads or how far out is max where there is no more adjustment period for my reference
thanks
 

Floridianson

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Myself I do not even worry about how many threads are showing. I mark the inner nut with a black magic marker so I can see how may flats I am turning it. While adjust fuel / temps you do not have to tighten up the outer jam nut. Just find the adjustment that keeps your Temps. down while under load. Then when done hold inner nut and tighten jam nut.
Now as far as how far well you could run the inner nut all the way in and the fuel control unit assembly with go to 9 oclock. Problem way to much fuel / EGT's will be way to high fast and waist way to much fuel. Good thing if you do not over heat first thing it would be no mosquitoes because of all the black smoke. So with correct adjustment and FDC bypassed will be nice puff of black smoke on take off but clears when you get up to full RPM and very little black smoke under load.
 
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72m35a2

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I can turn the rack with both nuts
I was just wondering what the max thread was until it pretty much fell out. I deal with diesels all day. I would rather see egts on high side. Close to 1k to 1250f sustained. As the higher temps is not a problem at those temps but keeps everything clean. Moments of higher temps are ok as in drag trucks ect Can spike to 2000f but for very short time the metal won’t heat to those temperatures that quick

trying to help those understand what the rack screw does and how far they can go. Safely
What they are doing when they turn it

the book states .150”. Thread showing I’m currently at 8 threads showing or 7/16”
Fresh air filter and all clamps tight shows 1000f
Max pedal through the floor up big hill
on A Issapro egt gauge. Hope this helps those looking for more power. I personally will stick to this setting. As I believe it’s safe
 

Floridianson

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No you cannot turn both nuts at the same time. This is where some people have messed up and you'll bust off the threaded shaft from the wedge plate. You have to use very thin wrenches and hold the inside nut so the shaft does not move and then loosen the outer jam nut. I know the TM says full rack but technically the deuce does not have a rack. The Detroit is one motor that comes to mind that has a rack and that rack controls all injectors. Best thing is to break open the tm9 on the injected system.
 
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BoxTruckMan

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I just turned up my deuce, have a question for you all. Pyrometer showed peak of 910 with stock setting and FDC bypassed. Turned it up 1 flat at a time and am now at 3 flats up. I notice an increase in power and the EGTs tend to be higher throughout but are hitting around the same peak temperature. Does this sound normal or should I suspect that my pyrometer isn't working right. On some pulls it'll hit 900 and some up to 920 so it doesn't directly look like the gauge is hitting a hard stop. I want to stay in a safe fuel range, it's a show truck not a race truck so help is appreciated.
 

BoxTruckMan

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I just turned up my deuce, have a question for you all. Pyrometer showed peak of 910 with stock setting and FDC bypassed. Turned it up 1 flat at a time and am now at 3 flats up. I notice an increase in power and the EGTs tend to be higher throughout but are hitting around the same peak temperature. Does this sound normal or should I suspect that my pyrometer isn't working right. On some pulls it'll hit 900 and some up to 920 so it doesn't directly look like the gauge is hitting a hard stop. I want to stay in a safe fuel range, it's a show truck not a race truck so help is appreciated.
To clarify my concern, if you were to graph the EGT over time I'd expect it to look more like a parabolic arc or steadily climb to its peak. What I'm seeing, it spikes really sharp to peak and hits a plateau where it kinda stays glued there. This might just be paranoia since I don't really trust the gauge from the start. It's on the cheaper end with mixed reviews but it matches the look of the military gauges really well so I took a gamble.
 
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