Fuel Pressures | Lack of Power Issue

[bottleworks]

From the day I drove the Deuce home from Georgia, the truck has been suffering from a higher RPM range loss of power (About 1800 RPM+). For sometime I wasn't sure that there was an issue (Being that this is the only Deuce I have driven). It can barely reach 55 MPH on flat road. If you start heading up a slight hill, the engine begins to quickly bog down. After I got it home last May, I changed oil and fuel filters. The fuel filter cans were horrible. All had 1/2" of mud at the bottom. New filters installed and everything clean made no difference. I pulled the drain on the fuel tank and drain out a gallon. I found no contamination other then a stainless steel nut loose in the tank.

I didn't get around to working on the power issue again until today. I connected my fuel pressure gauge to the secondary fuel filter assembly. At idle I was getting an average of 35 PSI. At WOT, I was getting about 65-75 PSI. The problem is the nettle is bouncing almost faster then you can see! At idle, it would flicker with a 10 PSI range and at times 20 PSI. At WOT, it would flicker with a 15-25 PSI range. I checked the fuel return pressure valve in the secondary filter assembly and to my disappoint, there was no apparent trash build up or damage.

This truck starts within 2 seconds almost every start and is firing on all six instantly. The rapid pressure sweep concerns me a lot. I am worried that my boost pump on the side of the injection pump is failing. I work on gasoline powered cars. Diesel trucks and systems are new to me. Thoughts, comments, ideas, hints?

 

[cranetruck]

Noticed that you run on 100% "homemade biodiesel". I found that when full power was needed from the engine during my 8x8 tow, the use of veggie oil/bio diesel reduced the power somewhat. It was especially noticable in the hills.
How about draining the system and trying 100% petro diesel for a while?

 

[bottleworks]

On the drive home from picking it up, I ran on 100% pump diesel. The performance was the same. Before I got the Biodiesel "refinery" completed, (I got excited and made it more elaborate then the typical setup), the deuce was running on pump diesel with the same performance issue.

 

[houdel]

If you are hitting 55mph at 1800 prm, there is something more gone askew than a fuel pump. According to most Deuce data plates ( and they do NOT all agree), you r max speed in 5th gear should be around 54 mph at around 2600 rpm. If I misinterperted what you said, and your problem is a lack of balls above 1800 rpm but you can get to 55mph at 2600 rpm or so, then you have another problem.

Since the truck starts fairly quickly (although 2 seonds is a bit slow in fairly warm temps for your climate), I'd suggest turning up the fuel delivery rate VERY slightly (1/6th turn, one flat of the adjusting nut) to see if that helps. I wouldn't go much further untill you install a pyrometer to measure exhaust gas temperature.

When I got my truck from the DRMO it was slow starting and suffered a severe loss of balls above 1800 rpm in 4th and 5th speeds. I turned the fuel up 1/2 turn (3 flats of the adjusting nut), starting was near instantaneous and power was greatly improved. Once I installed my Pyro, I decided my EGTs on a long, steep hill were uncomfortably high, so I backed off 1/6th turn (one flat of the nut). Some folks are comfortable with an EGT of 1250F, I decided to keep mine at 1150-1200F to keep from trashing my turbo.

See my thread at http://www.steelsoldiers.com/index.php?name=PNphpBB2&file=viewtopic&t=6629 to adjust the fuel delivery rate. Not this is a very SENSITIVE adjustment, I wouldn't go more than 1/3rd turn (two flats of the adjusting nut) without installing a pyrometer to make sure your EGTs are within a safe range.

As for the fuel pressure issues, I'd go to the TM section and download the inection pump manuals to see what they have to say.

I have a couple of spare engines coming from Columbus if the EUCs ever get approved, I may be able to help you out with a IP or hydraulic head if either of those turn out to be a problem.

I'd try the fuel delivery adjustment first though, that may be your problem. It seems that the military turned down the fuel delivery on a lot of engines to save wear and tear with the "rodeo" drivers in the military!

 

[bottleworks]

Re: RE: Fuel Pressures | Lack of Power Issue

...and your problem is a lack of balls above 1800 rpm but you can get to 55mph at 2600 rpm or so, then you have another problem.

I'd suggest turning up the fuel delivery rate VERY slightly (1/6th turn, one flat of the adjusting nut) to see if that helps. I wouldn't go much further untill you install a pyrometer to measure exhaust gas temperature.

Right. It reaches ~2600 RPM at 55 MPH. At 1800 RPM and up seems to be the down fall of the power.

I forgot to add: I did up the fuel rate in an attempt to fix this before I checked the fuel pressures. I was thinking that it was simply the "max" setting was just too low. I turned it up three flats, I believe. The difference was very minimal. I didn't want to go past that because of all the posts I had read on there. (I don't have a pyrometer yet). I have been reading the LDS-465 trouble shooting manual. Isn't the fuel adjustment just adjusting the maximum potential that the injection pump can inject? If so, it would seem to be my issue, but there appears to be something more?

 

[Djfreema]

RE: Re: RE: Fuel Pressures | Lack of Power Issue

I had the same problem on one of my dueces, turned out to be a crushed copper fuel line under the radiator where the GL guy picked it up with a forklift. Check all your copper fuel lines for kinks in case you havent already done so.

 

[Jones]

RE: Re: RE: Fuel Pressures | Lack of Power Issue

Something to consider is that when these trucks are deadlined prior to being sent to DRMO they become; test vehicles for driver's training classes, guinea pigs for mechanics in training, parts-piles-on-wheels to keep the other trucks running, or objects of abuse, i.e." let's see what it takes to blow one up, after all it's going to scrap anyway". When everybody drives a truck but nobody owns it, it's a wonder any of them survive to old age. If motor pool mechanics have to steal a part, they're only required to put the broken part back on in it's place. You may have accidentally ended up with a collection of problems.
Somewhere along the line, get your injectors checked at an injector shop too. We had a bad batch that were unloading too soon. The IP builds line pressure but a spring inside the injector holds off until peak pressure is reached; with lower unload pressure the fuel doesn't get atomized sufficiently to give complete combustion with an end result of low power.

 

[emmado22]

RE: Re: RE: Fuel Pressures | Lack of Power Issue

And sometimes, they dont even put the bad part back on the truck...... Trust me.... Seen it done, might even ordered it to be done back in the day....

 

[westfolk]

RE: Re: RE: Fuel Pressures | Lack of Power Issue

Just as an easy check. Is your in tank pump working? I have one that kills every pump I put in it. It has the same perfromance as you describe. On the low end it does it all, starts right up, runs fine, top end forget about it. Side note, when it does have an in tank pump that is working I get to have fun on the top end also. Hence why I question if that is it.

 

[jwaller]

Re: RE: Re: RE: Fuel Pressures | Lack of Power Issue

Just as an easy check. Is your in tank pump working? I have one that kills every pump I put in it. It has the same perfromance as you describe. On the low end it does it all, starts right up, runs fine, top end forget about it. Side note, when it does have an in tank pump that is working I get to have fun on the top end also. Hence why I question if that is it.

.



I'm sure you've checked to be sure your not over volting the pumps? I wonder why it's doin that. klinda makes me think twice about replaceing mine. BTW do you have a source for that pump. memphis wants about 450 for a rebuilt one.

 

[Stretch44875]

I just did an "enema" on my deuce. It was acting all kinds of weird, from a bad batch of used oil I ran thru it. Drained the tank, and filled it with straight gasoline. Unhooked the return line to the fuel tank and turned on the pump. The return line was plugged somehow, and after a while the gas forced itself thru. I also drained all the filters while the pump was running, and bleed the filters. Filled the tank back up with regular fuel, and it has run great since.

Dennis

 

[bottleworks]

The in-tank pump does work. I have not checked its pressure output with the gauge. It will produce a strong stream of fuel when priming the fuel system. I will check the engine off-pump on pressure.

Has anyone actually had to check their fuel pressures before? I hope my truck didn't act as a parts truck before I got it. The engine is an '89. There doesn't appear to be signs of swapped parts. I just think it was abused and neglected...A fair bit... Would poor injectors cause my odd fuel pressure results?

 

[westfolk]

I'm sure you've checked to be sure your not over volting the pumps? I wonder why it's doin that. klinda makes me think twice about replaceing mine. BTW do you have a source for that pump. memphis wants about 450 for a rebuilt one.

The truck has seen alot of use. It has assorted issues. Every now and then I try to track down different problems. Yeah I can get pumps. Shoot a few weeks ago I sold one to a guy up in Mass for $30 plus $10 to ship it.
Currently I have about 20 parts trucks sitting all over the place. There are days that I think about getting into "used parts" business. That is why I say if someone is looking for something I probably have it or can get it. Don't get me wrong I am no professional with these trucks. Just been playing with them for the last 15-20 years.

 

[wpzimmer]

Loss of power or roll-off above 1700-1800 RPM is usually the result of fuel starvation. You have already checked filters,fuel lines etc. One gotcha that I missed and seems to be a fairly common problem is the fuel shut off cable at the injector pump. Because of misadjustment, binding linkages or a bending cable core wire the pump fuel shut off lever may not be returning to the full "ON" position. It has the same effect as squashed fuel llines and clogged filters- fuel starvation and lack of power. Check the cheap stuff first. Good luck.

WZ

 

[cranetruck]

To check the fuel cut-off mechanism, remove the cover (first image). The control cable comes with it and you will be able to check the movement of the lever with your fingers.
Had a problem with just this thing on my cross country trip after we replaced the hydraulic head. The lever was to tight, come to think about it, never did install the safety wire again..Hmm...

 

[bottleworks]

That's a great idea guys. I will investigate the fuel cut off. I am a bit under the weather, so I'm not going to work on Wednesday. Hopefully I will feel well enough to continue checking the system Wednesday afternoon!

 

[bottleworks]

I checked the fuel cut off. The lever moves with little resistance forward and back. The normal/"fuel on" position seems to be slightly more forward then the picture shows. A potential issue?

 

[lavarok]

was this problem ever solved? what was the solution?

 

[Recovry4x4]

Ian, since you brought this back to the top, I forgot to tell you to check that copper line going from the primary to the IP. I've seen many crushed.