possible pump fdc H.h. failure help

[dmetalmiki]

Well today I TRIED to get my M54a2, 5 Ton LDS 465 1A multifuel running right as The biggest event of the year looms and yes..Murphy is now in full attendance!. Last week came back from a run and the 5 ton was idling outside then 'stopped' uh uh..started with prime (heater pump) and it would run over 1000rpms. managed to get it to reverse into the shop in "bursts" .
Changed all the filters and cleaned the twiddly one. Replaced the rubber hoses to the pump. Ran better but stalls out after about 30 seconds although fuel is spurting from the pipe into the pump if loosened a bit. Seems to keep going above 1500 rpm (starting on the pre heater pump) but even then stalls out completely after about 20 seconds or so. Anyone with a resolution from a similar problem please step in. Could this be the fuel density compensator?..or does it have to be the hydraulic head. I'm Not looking forward to the next few days.

 

[gimpyrobb]

No not the FDC. All the FDC does is limit the amount of fuel available to the hydraulic head.

 

[red]

Not likely to be the HH either. Sounds like either one of the fuel delivery hoses is plugged up or the in tank pump has a blockage.

Install a pressure gauge at the tank then flip on the electrical. Need to have at least 5 psi there with just the in tank pump running (3psi minimum with the engine running). If the pressure is good then one of your metal fuel lines is probably plugged up.

If the pressure is low, pull the in tank pump to check the pickup and it's hose.

 

[dmetalmiki]

Thank you both, The pressure squirt is enormous though..(slackening connections while running) I will drop the tank to check if it plugs on running. (as) that radio body blocks the in tank pump!....But the pressure seems so high from everywhere while running when it just simply quits..

 

[dmetalmiki]

I just tried again. It starts promptly with pre heater squirt,, will rev up fine but after 20 or so seconds cuts out promptly! but picks up and revs again if the pre heater squirts fuel in. It does not 'run' on just the squirt though..keep the revs up and it keeps going...for a while and the revs drop and it quits. Fuel jets from any 'cracked' line while this is going on. I was sorta hoping it was the F.D.C....I am going out to check some more..the show attendance is looking grim..

 

[dmetalmiki]

Blew out every pipe fitted the new type pipe to the pump underneath the pump..bled it 21,568 times...It stated and ran without lumps and bumps for 30 minutes..I'm going to the dentist now..I shal give it run when I return...I really do SO Hope....But I do rather prefer when I actually find something " for the fix..." that was 'wrong'. still.......

 

[silverstate55]

A friend of mine had similar problem, turned out to be bad "bow tie" clip on HH plunger.

 

[red]

Blew out every pipe fitted the new type pipe to the pump underneath the pump..bled it 21,568 times...It stated and ran without lumps and bumps for 30 minutes..I'm going to the dentist now..I shal give it run when I return...I really do SO Hope....But I do rather prefer when I actually find something " for the fix..." that was 'wrong'. still.......

Glad that it ran solid for 30 minutes, looking like a restriction in the lines was a problem. Did you purge the hard line that runs into the fuel tank as well or just the other ones?

 

[dmetalmiki]

Every line but that one as everyone I cracked gushed with pressure. H.H. Pump, F.D.C. I did note however, that if any one thing leaks at all the engine rpm drops. Seems this is a characteristic of the LDS (type) engine, A deuce will run with or without the in tank pump, and seems more forgiving in a lot of ways. I knelt in front of the truck..Kissed a tire! tomorrow I will take it for a run.

 

[red]

The pumps on these move a fairly high volume but not alot of pressure. Basically there are 3 pumps in the LDT/LDS system. In tank pump, booster pump, then the main injection pump (hydraulic head).

The truck needs the volume and the pressure from each pump to run right. With the truck running it needs:
3psi from the in tank pump. Measured either at the tank or just before the first fuel filter (since your radio shelter body is in the way).
32psi from the booster pump measured after the final fuel filter.
About 1600psi from the hydraulic head (no need to measure that one, other ways to diagnose it).

Just because there is a good volume of fuel moving at each fitting when you loosen them does not mean it has the necessary pressure.

Since it's starting/running again after purging the lines then it was just a blockage, nothing mechanically wrong. Considering that the truck is at least 60 years old no real surprise that gunk has built up over the years. Take a look inside the fuel tank if the truck acts up again, might need to be cleaned.


The LDS needs more fuel than the LDT going through the injection pump (larger diameter plungers, moves more fuel) so it's more picky about having enough fuel delivered to it.

 

[Floridianson]

I like putting the gage between the secondary and final filter canisters. That way I can see the in tank pressure when engine off and when started the idle around 30 and high idle pressure 60. Thought the injectors popped at 3500psi so the head would have to make at least that.

 

[red]

I like putting the gage between the secondary and final filter canisters. That way I can see the in tank pressure when engine off and when started the idle around 30 and high idle pressure 60. Thought the injectors popped at 3500psi so the head would have to make at least that.

I might be wrong on the HH psi, been awhile since I've looked that up.

 

[dmetalmiki]

Thanks all for the information. Ok. up date, changed all the filters (again) checked the tank and rebuilt the in tank pump, which was not too dirty as it happens. Removed the 'twiddle' filter and substituted a new Golden Rod water dirt trap filter. Started it up, ran fine, revved up to 2000rpm, ran for 28 seconds and died. I immediately opened the bleeders on top of the fuel filters, with the pump running..and, NOTHING! after 30 seconds, here comes the fuel!, slow at first then a good flow.
The 'War and peace' show is only 2 weeks away...

 

[dmetalmiki]

Bled it about 10 times...left it runn9ng 30 minutes..stopped it, started it, Took it for a drive..albeit a short one..ran fine. Rick followed in our other deuce..which promptly dumped a load of fuel and oil from the sump! The problems aren't going away.

 

[red]

What's your fuel pressures between the in tank pump/before first fuel filter, and the pressure after the final filter/before the injection pump?

 

[dmetalmiki]

possibe H.H. failure The FIX

News update. We wanted to, and did attend the War and Peace show. (two whole weeks). As I did not 'trust the 5 ton camper, It was low loaded to the show. It only just got on and off both ways!. So, Back home took off the Hydraulic Head, Replace it with a new unit in the original packaging and fitted it. Bled and cranked. ? ? ? NOWT!! (nothing nada not a squirt of fuel.) Disappointing frustrating? Yes in the extreme. Took it all apart again, and replaced it with another used unit (purported when bought to be good). ? ? ? NOWT! (nothing nada not a squirt of fuel). Sat down REALLY feeling p. Now. Had a 'Perla'...hunted around for another unit..Found a scrap engine in the back of a parts truck, Which had a complete engine in..Took a gamble and went for the unit on the engine in the back body which had been (literally) kicking around and(dropped, left in mud and rain!) for 12 Years..Hammered the 'thing' on the quill shaft free with hammer and chisel and plenty of squirty oil..blew all the c...(dust cobwebs and hay out of the injector holes..Re fitted everything...Bled the system, Pushed the go button, Wham, fired right up. It was after midnight!, finished the 'perla' and went to bed. Took it for a long drive today, runs great, smokes less than it ever did, (which is quite some statement for an L.D.S. unit.)
I know details have been posted before. But here is my Method for the replacement.
Two Pictures show the 'CUT' 17mm spanner,(wrench) held by mole grips.
Remove side inspection covers. (small aperture? so what!)
With the modified 17MM ring key (No other U.S. wrench fit. the injector fittings are not 3/4 and not 11/16 (but around 21/32!
So, hammer on the cut 17MM wrench (and being tight the cut key will spread!? NO, clamp it with the mole wrench.
remove them starting at the front (I called it number one..and work anticlockwise round the head. Easy.)
Remove injector line clamps and from the injectors. AFTER labelling them. Mine would read labels as ONE at head SIX at injector and so on.
Remove shut off cover and de-wire and remove the link carefully.
Undo the four holding nuts and spacers. holding in the head.
Place transfer in neutral and turn the Propshaft whilst (in my case the lad) Holds upward pressure on the head and the it 'pops out'. Which will be when the 'dreaded' red line appears.
Replace another head holding it down and if necessary turn propshaft back and forth until the head 'pops'! back in. the (dreaded) red line was off a tooth or more at this point (So?) bolt it in, refit the control and wire it, refit the shut-off and cover.
Finished.
At NO point did the the 'red mark' line up as discussed in many forums! and the head would not go in!
I turned the prop until the hydraulic head came out easily and did the same in reverse.
Bear in mind I was more than a little aggrieved and fed up by this point and just wanted the 'Thing' out and swapped. (3 times in our case).
If 'things' refuse to work out, or make mechanical sense, I mek' em WORK OUT.
I'm please and relieved now (as) there are more shows we can now attend. My 7/8 pence worth folks for the ist timers attemting this. Harder to get at on the 5 ton. a breeze on a deuce.
Time each to swap out the hydraulic heads, 2 hours Max.

 

[gimpyrobb]

Well, I'm glad to hear you got her running.

I wonder what the "thing" you hammered off the quill shaft was! Was it the gear guard on top? Did you inspect the quill shaft on the original IP? If none of the hydraulic heads worked, I wonder if the original quill was snapped.

 

[red]

Glad it's operational again.

With the zero fuel squirting after replacing the hydraulic head, was the button and it's retaining clip still attached? Don't see it in the pic.

The timing mark sits off about 1/2 a tooth when replacing the hydraulic head.

 

[dmetalmiki]

Yes, sorry to be vague..I had read the T.M. and it rabbits on without giving the exact detail of what the fuel plunger does. When the throttle lifts that brass? oblong part with the slot in it it should run up and down the 'quill' freely, and drop under it's own weight? Well That one certainly did not. Neither did the other two spare ones, they were stuck solid. After two faulty ones and the process of fitting them I was tired sore and rather fed up in the extreme. The third one worked fine after freeing it up, a thorough cleaning, and priming after fitting. I trusted the sellers of these components as to the description.."they work fine". (Good take off's).

 

[dmetalmiki]

Thank you for addressing that point. I am still 'Miffed' as to WHY a engineering component would not align to actual timing marks..Why the heck not Place the flipp'in marks Exactly where they are supposed to be. just my 11.7 penn'eth. Also the button was present all three and that 3 legged little washer.
(Another) GLUM point of the day. One of the cadets drove out with the fork truck..without noticing a spare hydraulic Head sitting on the rear.....Yep..it fell of and snapped the quill!... Just what to say?.. try.."Tut Tut".."clumsy".....He already felt bad..No need to add to it. My fault I'm the 'boss'.