81 olds diesel out of fuel
June 2nd, 2011, 07:33 PM
#4
Connoisseur d'Junque
Join Date: Sep 2010
Location: The Hudson Valley
Posts: 21,183
But seriously...
You've run the fuel out, which means you've run air in.
Mechanical fuel injection pumps like on your diesel, and on the early '70's fuel injected Porsches, run on the principle of the non-compressibility of liquids, like your brake system does. The idea is that if the pump pushes fuel in at one end of the fuel line, the same amount of fuel will be instantaneously pushed out the other end (through the injector) at the same pressure. This works because liquids are non-compressible. In order to maintain fast opening and closing, the fuel in the lines is maintained under pressure by fuel injector nozzles that only open at high pressures (usually about 300psi). No pressure, no open.
In your case, you have replaced the liquid fuel in the lines with gaseous air, which is compressible, so that when the pump pumps in a tiny bit of fuel, it can't get up enough pressure to open up the valve on the other end and let the air out, so that fuel can fill up the line. In practice, if you cranked the motor over for an interminable (and starter-destroying) amount of time, you could get enough fuel into the lines, but it ain't gonna happen.
What to do?
You've got to bleed the lines.
Crack all of the fittings where the lines connect to the injectors and crank 'er over until you've got fuel coming out the fittings. Then, tighten them up, crank 'er over, and you should be good to go!
- Eric
You've run the fuel out, which means you've run air in.
Mechanical fuel injection pumps like on your diesel, and on the early '70's fuel injected Porsches, run on the principle of the non-compressibility of liquids, like your brake system does. The idea is that if the pump pushes fuel in at one end of the fuel line, the same amount of fuel will be instantaneously pushed out the other end (through the injector) at the same pressure. This works because liquids are non-compressible. In order to maintain fast opening and closing, the fuel in the lines is maintained under pressure by fuel injector nozzles that only open at high pressures (usually about 300psi). No pressure, no open.
In your case, you have replaced the liquid fuel in the lines with gaseous air, which is compressible, so that when the pump pumps in a tiny bit of fuel, it can't get up enough pressure to open up the valve on the other end and let the air out, so that fuel can fill up the line. In practice, if you cranked the motor over for an interminable (and starter-destroying) amount of time, you could get enough fuel into the lines, but it ain't gonna happen.
What to do?
You've got to bleed the lines.
Crack all of the fittings where the lines connect to the injectors and crank 'er over until you've got fuel coming out the fittings. Then, tighten them up, crank 'er over, and you should be good to go!
- Eric
June 3rd, 2011, 01:23 AM
#6
'87 Delta 88 Royale
Join Date: Dec 2010
Location: Margate, England
Posts: 2,513
Diesel fuel systems normally have bleed vents at the filters and on the injection pump itself.
I would start by replacing the primary fuel filter, as I recall my '79 Olds diesel had two filters, and it's likely you will have sucked up some gunk from the bottom of the tank.
Then vent the filters by cranking until air free fuel comes out of the bleed screws, next vent the fuel pump, then crack open the injector lines as Eric said.
Have a good spare battery standing by or better still another car you can run jumper cables from, it is a long winded process that makes big demands of the battery and starter motor. Avoid extended cranking, this can kill a good battery and starter motor.
Be prepared to clean up spilt fuel both round the engine and on the floor afterwards, it a messy process as well as long winded.
Good luck!.
Roger.
I would start by replacing the primary fuel filter, as I recall my '79 Olds diesel had two filters, and it's likely you will have sucked up some gunk from the bottom of the tank.
Then vent the filters by cranking until air free fuel comes out of the bleed screws, next vent the fuel pump, then crack open the injector lines as Eric said.
Have a good spare battery standing by or better still another car you can run jumper cables from, it is a long winded process that makes big demands of the battery and starter motor. Avoid extended cranking, this can kill a good battery and starter motor.
Be prepared to clean up spilt fuel both round the engine and on the floor afterwards, it a messy process as well as long winded.
Good luck!.
Roger.
June 4th, 2011, 03:02 AM
#9
Registered User
Join Date: Feb 2009
Location: Brazil Indiana
Posts: 11,515
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