Need some diagnostic help

All,
been some good advice on here in the past. Let me know what you think is my problem on this one...


I bought a mid 70's ford 4500 TLB. It ran ok but was hard to crank. I have changed all the fluids, had the injectors pulled/cleaned/rebuilt. It cranks up ok with a shot of starter fluid and the pre-heat system is not connected (later project)


Anyway, now to the problem. Run the backhoe for about 45min - 1 hour with no issues then it just quits like you have pulled out the fuel stop. I checked and the stop lever is not moving. Next I put a new fuel filter on it, it ran great but again 45 min later it died without warning. Do these have any kind of filter or screen in the tank that might be the problem? Could it be some kind of heat/vapor lock scenario? I didn't think diesels did that... Water/cooling appears all normal, it doesn't seem to be overly hot when it quits...before I go chasing rabbits I thought I would get some thoughts here...

Any thoughts or advice would be appreciated.

I'm not familiar with that machine at all but check your battery voltage when it quits and clean terminals, check earths etc. It may well be an idle stop solenoid cutting you out because of power problems.

Older fords have rubber fuel lines, after changing filters etc, they collapse causinga similiar situation, check that first, swap out the fuel lines from tank to pump then pump to filter then filter to pump make sure they are all good.

Pecord Exc said:

Older fords have rubber fuel lines, after changing filters etc, they collapse causinga similiar situation, check that first, swap out the fuel lines from tank to pump then pump to filter then filter to pump make sure they are all good.

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I would have to agree and would look for a fuel supply problem.

Once it has cut out, does it fire straight up again when you hit the key, or does it just crank, or is it completely dead ??????

I suspect it fires straight up again.!

It's possible that the vents for the fuel tank are stopped up. That happened to my tractor once and that is about how long it would run. I chased the dirt dobbers outta the vents and never had another problem.

Galute said:

It's possible that the vents for the fuel tank are stopped up. That happened to my tractor once and that is about how long it would run. I chased the dirt dobbers outta the vents and never had another problem.

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Galute, beat me by about an hour. 2 votes for the vents being clogged!!! Most likely and easiest fix there is.

The advice above is all good . If it is not one of these you may need to put a drum of Diesel on the machine and run the pickup and return lines to it . If it runs fine after doing that , you have narrowed your search area from the drum back . If it doesn't , you have narrowed the search area from the drum forward .

Hmmm, curious we haven't heard from GA4500 since he asked his question. :beatsme
Man it's been a long time since I've worked on one of those old Fords, especially mid 70's. If I remember them right, the tank was above the engine and they used gravity flow to feed the injection pump, and they used a manual shut down. I'm thinking they didn't even use a lift pump, just gravity. Seems like I remember when changing the fuel filter, those Lucas/CAV filters that had the removable bowl on the bottom, that they were a PITA to prime to the injection pump because there was no lift pump. I could be all wet about this, but if that's what he has, it doesn't take much of a restriction to shut it down. I think they also used those fuel line fittings that used a rubber lathe cut ring to seal the nut where it connects to the male thread fitting. That rubber seal gets hard in time and it can suck air under the vacuum of drawing fuel, but not leak a bit when it's not running. Just a couple of (wow, very old) thoughts.

Sounds like a fuel venting problem to me too. Next time, as the 45 minutes draws near, open the tank cap and see if it runs well beyond the 45 minutes. That would be a pretty clear indicator.

running problem

I alyays start at the tank,from experience it has saved time and labor.First shut off tank valve.If the valve is the plastic kind sometimes it will twist off and break,bummer,replace with valve that has the brass shut off,they are available.Pull the line from the fuel filter that comes from the tank valve.Open tank valve and there should be a good stream of fuel coming from the line.If not sometimes the filter gets clogged that is on top of the tank valve,or it gets knocked off and ends up rolling around in the bottom of the fuel tank.I've seen this happen many times on the Fords,then debris will collect in the valve and fuel will just trickle out.If this is the case drain tank and remove valve.If filter has fallen off fish it out with a piece of stiff wire.Anymore even when I install a new valve I JB weld the filter to it.Iv'e also seen people replace the fuel filter and put the O ring in the top of the filter and not in groove of the upper filter housing,but tractor won't run because it can't get any fuel.I had a customer that took his Kubota M4950 to the dealer because it would run for a little while and shutoff.They ended up putting on a brand new injection pump,mucho dinero.It was still doing the same thing and then told him that the engine needed to be rebuilt.He brought the tractor to me and I drained the fuel tank.Lying in the bottom was a yellow plastic cap from a fuel jug that would float around and block off the fuel pick up causing the tractor to shut down,then float away after the suction dropped.Hope this helped

Those girls have a filter in the tank and are notorious for blocking.


Stock

alanstr said:

Lying in the bottom was a yellow plastic cap that would float around and block off the fuel pick up causing the tractor to shut down,then float away after the suction dropped.

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I can believe that. A very experienced fitter told me he was sent to sort out an intermittent fault on a not very old ADT. For no apparent reason it would come to a stop and cutout just as though it had run out of fuel, but when you turned the key it would fire straight up again.
The problem was you could not make the machine do it, sometimes it would run a complete shift, other days it would cut out several times.
The final outcome was exactly as described above, ( not too sure of the colour though ) :drinkup