Fuel Density Compensator

[WarCloud]

Who can give me a clue on re-connecting my fuel density compensator on my injector pump, to keep on hand for emergency "all-fuel" operation? Mine is still on the unit and still "wet", but not hooked into the fuel system..it's bypassed with a bunch of flex tubing.
Who has a diagram on how to re-connect it?

 

[maddawg308]

The FDC is not required to be hooked up to use different fuels. The motor itself and its design makes it a multi-fuel not the FDC. The FDC only ensured that the power output of the truck stayed the same regardless of the fuel used. In other words, without the FDC hooked up, you can burn whatever, but you might not get the same power that you normally would if you were burning straight diesel.

 

[deuceman51]

Something that I have noticed with the FDC. On my 3 other deuces with FDC hooked up,they start right up in a second or two. The one truck that the military bypassed the FDC I crank on it and it sputters and dies. About the second cranking with the accellerator pedal pushed down it will start, but is kinda rough for a bit. Has anyone else had that problem with FDC bypassed trucks.

 

[sak00]

No, mine starts better the with the FDC by-passed. Of course, It starts better with WVO in it too.

 

[Boatcarpenter]

Here are a couple of diagrams. Hope they help
BC

 

[gimpyrobb]

Power and starting ability varys from truck to truck. Another member had trouble with starting and when he went to adjust the fuel delivery up, found that the jamb nut had come loose and both nuts had backed off. Try increasing fuel delivery a bit.

 

[renovate7]

My truck came with no FDC and a metal plate in it's place. Is there a way to adjust the fuel delivery without it? From what I've read it looks like the fuel delivery is a part of the FDC. I'm trying to see if I can get a bit more power. We have a lot of steep hills around here (seriously, more than 10%) and I really bog down in 4th and 5th.

 

[Floridianson]

Yes take off the plate and you will see the other nuts on the inside. So there will be one on the outside and one on the inside. Turning the inside nut clockwise to let the shaft come out farther will increase boost. What RPM do you seem to be running at in those gears? Do you have a boost gage? If you need more power at below 2000 RPM you could see how much boost you are making at 1600. The droop screw or smoke cam controls the boost up to 2000 RPM.

 

[renovate7]

On some of the hills I'm in 4th and just trying to maintain. I always shift at about 2000/2100 rpm. The engine seems to "flatten out" at 2200. I honestly don't think I've ever had it to 2400/2500, it seems to scream enough at the lower RPM. I don't have a boost gauge but know to adjust in small increments. Thanks

 

[renovate7]

Here are a few pics. I don't see a screw. All I have is a big threaded plug on the back facing the firewall.

 

[FormerNewMVGuy]

Its inside ,Under the cover!
TM 9-2910-226-34
page 3-105

 

[DanMartin]

As Scott said above, it's under that cover..you have a newer style IP. It looks like someone's already been in there, because the safety wire is missing from the 4 bolts that hold the cover down...

 

[kaiser2help]

FDC

Deuceman 51 I have a LDS 4651A with the same cranking symptoms. I recently had to turn my IP back. I was running 1250 or more on my pyro gauge on a decent climb so I backed it off. Know its like 1050 to 1150. But even before adjustment I hade to burry the pedal to get it started. Even know after I backed it off its a little harder too start. I will post my results when I hook up my FDC to operational status to see how she starts then.

 

[kaiser2help]

FDC

I need a copy of fonix.

 

[Floridianson]

I corrected my post to read nuts. Sorry for the confusion 7.

 

[SasquatchSanta]

Floridaiason Wrote:

The droop screw controls the boost up to 2000 RPM.

Is the droop screw accessed by removing the back cover or is it the screw (bolt) that faces forward and has the two locking nuts?

The FDC on my LDS-1A is bypassed as was the FDC on my old LDT-D engine. Both engines are/were hard starters and like to go through a shuttering ritual upon start-up. I've never felt the FDC had anything to do with the hard starting. After the first start-up of the day all is well so I give a quick shot of ether on the first start of the day. I call it (ether) Tequila Sunrise --- Rosie likes it.

I was under the impression that depressing the fuel pedal made little to no difference when starting???

I recently turned my pump down by three flats. The LDS-1A, at the stock setting produces way more power than I need --- hopefully turning down the pump a bit will get me back up into the 12 MPG fuel economy that I enjoyed with the old LDT engine.

I agree with maddawg about not needing the FDC to run multi-fuels. Without the FDC you will find more pedal when running gas and less when running a WMO. So far, I've ran very little WMO but I like the way is "powers" the truck. There must be more BTUs in WVO. With it I don't seem to have to put my foot in the pump quite as hard to get the same results. I wish I could run WMO in the winter.

I don't run gas --- it's hard to start and hard on the IP pump. Perhaps with WMO it would be OK but I stay away from it.

 

[Floridianson]

If you look at the second pic 7 posted it is behind the hex head plug right above the round governor cover that has the two bolts on the end of the unit. Inside there you use a allen wrench. The droop is adjusted by finding out how boost you are makeing at 1600rpm with a load on the motor then eather raise or lower.When ever the main fuel adjustement ( the two lock nuts or under the top cover without FDC) is changed up or down the droop must be reset. The TM calls for 8.84 to 9.82 psi boost on the main and the droop 3.93 to 4.91 psi on the droop. Seems like you would get the best milage by setting the to the low side of the numbers. If you are looking to burn more and need more boost because of a load in the truck then use the high end. PS or MORE

 

[SasquatchSanta]

Thanks for the input Floridianson however I'm still confused.

Are you saying the droop screw is behind the round cover (the one with two bolts holding it on) on the end of the pump? I don't see a hex plug in the picture.

Perhaps I'm dense but I'm puzzled as to how you can get two different ranges of boost readings at the same RPM:

The TM calls for 8.84 to 9.82 psi boost on the main and the droop 3.93 to 4.91 psi on the droop.

I've always felt there are fine tuning secrets that one could perform to get optinum fuel economy from the Milti. Considering lightly loaded bobbed deuces with free running front hubs are a lot lighter and have a lot less rolling resistance one would think some more mileage could be squeezed out.

The IP pump has always been a "black-box" mystery to me. I'd like to learn how to properly (cautiously) experiment with the pump forthe best fuel economy.

Do you know the TM that covers this?

Thanks.

 

[gimpyrobb]

Earnie, look for the "LDS TROUBLE SHOOTING GUIDE" here on SS. It will tell you step by step.

 

[Floridianson]

Hard to see. Yes the 465 troubleshooting manual second page 4th line I think. It also shows the most consistent way of putting a load on the motor using the brakes.