Don't let firetruck diesel fuel run out. Why?


#1

Was told there would be very expensive damage if fuel runs completely out.

Can anyone explain why?

Thank you,


#2

You don’t say what type of truck, but running diesels dry used to be a bad idea.

The pressurized fuel system becomes airlocked after you refill and needs the fuel system bleeding like a brake system to get rid of the air…fuel filter, injection pump and sometimes even the injectors themselves.

Time consuming at best, if you don’t know how to do this I can foresee some wallet damage, particularly if you’re stuck on the highway.

But engine damage I’ve never heard of. Commercial diesels and their fuel systems are very industrial and robust.

Though I may be corrected here.


#3
There are several possible issues, but the first one that comes to mind are the fuel pumps and injectors.  Diesel is a lubricant and if these parts are not getting lubricated they are damaged. They are not designed to run dry.

A less expensive issue, but rather important at the time is running out of fuel mean re-priming the pump(s) and you don't want the fire truck stuck along side the road waiting for fuel and someone who knows how to re-prime the truck to arrive while the house burns.

#4

I can understand your point about seals and lubrication but it would take weeks for a diesel pump to dry out. Diesel is far less evaporative than gas, plus in a sealed fuel system there is no evaporative potential.

Injection pumps are still mostly full of fuel when you run out of fuel, they just have enough air to airlock them.

So far I’ve never seen physical damage (other than monetary and reputational) from running out of diesel.

I’m discounting the use of Aerostart to get the engine fired up while bleeding the system here. Stuff like that is always bad, diesels get addicted to it.


#5

i haven’t heard of damage when you run a diesel out of fuel.

what does happen (from experience) is that you have to bleed each injector and all while cranking the engine. so typically the battery goes dead.

some boats i have worked on have a back up fuel pump to pressurize the fuel system, so it is ALOT easier, but you still have to bleed each injector.


#6

When I worked for a heavy construction rental house, just about every unit was diesel powered and the customers were continually running the engines dry, mainly air compressors.

They’d refill the tanks and then call us to complain the engine wouldn’t start.

So out we go, 1/2" box-end wrench in hand.

Crack open the bleeder nut, crank the engine over until it fired up and close the bleeder nut.

Nothing more than a PITA.


#7

I can see where you are coming from. You are fighting a fire and must do so until you can’t. I have not heard either of damage to an injection pump by running out of fuel. There should be enough residual diesel fuel inside the pump to keep it lubed, especially at idle speeds when full injection is not required.

My long gone Chevette diesel car had a hand operated primer pump under the hood for when needed. You might want to ask around to see if this feature is available for your firetruck and if not, why not?


#8

actually i would be really surprised if a piece of equipment like a fire truck didn’t have a priming pump included, since they are SO critical. (the fire pump, not the priming pump!)