air in my fuel system

[scott s]

Hi,
I have a nh.tc35 d. I am getting air in my fuel system,tractor will run rough then die bleed the injection pump and get air out ..over and over..pulled the bleader screw all the way out and turned the fuel on air bubbles come out turn fuel off and back on more air..I have drained the tank and blew the line out, replaced filter, checked lines...kinda at a loss what to do next ..thanks

 

[Tx Jim]

Is fuel tank vent open IE not plugged???????????? Do you have good fuel flow from tank to inj pump????

 

[scott s]

Hmmm good question how do you tell if plugged

 

[Gordon Gould]

One thing you can do to isolate the problem is set up a temporary fuel line. Just get a piece of fuel line and stick it in your 5 gal fuel container and connect it up at or near the pump. Put the 5 gal container about the same height as your fuel tank. You will have to prime the new line. If the air goes away relace your fuel line. Could be cracked

Also check that the fuel filter is on correctly with good gaskets.

 

[Tx Jim]

Hmmm good question how do you tell if plugged

Remove fuel cap and if engine runs correctly then tank vent is PLUGGED

 

[Gary Fowler]

Remove fuel cap and if engine runs correctly then tank vent is PLUGGED

That would be a first check if engine just stalled but the OP says he keeps getting air bubble coming out of the bleed vent at the pump. Air has to be sucking in from some where OR he didn't bleed the fuel filters properly when changing them or they have a bad gasket or improperly installed gasket. If fuel lines were cracked/ broken they would leak fuel when the engine wasn't running. Assuming that they aren't leaking, I would take out the fuel filters and look at that area for a problem. A very slight pressurizing of the fuel tank to about 2 psi or so should show up any leak by forcing out the fuel (engine not running) Then it is just a matter of fixing the leaking part.

 

[Jerry/MT]

Hi,
I have a nh.tc35 d. I am getting air in my fuel system,tractor will run rough then die bleed the injection pump and get air out ..over and over..pulled the bleader screw all the way out and turned the fuel on air bubbles come out turn fuel off and back on more air..I have drained the tank and blew the line out, replaced filter, checked lines...kinda at a loss what to do next ..thanks

Heres some general info a couple of us put together for bleeding a diesel fuel system.

Bleeding a Diesel Fuel SystemStart at the fuel outlet of the tank (inlet to the filter). Shut the tank valve, remove the line at the filter inlet and holding a suitable container to catch the diesel fuel, open the valve. You should have a CONTINUOUS rush/flow of fuel out of the line. If it dribbles or is intermittent, check the fuel cap for a blockage of the fuel vent or the strainer upstream of the valve for clogging. The strainer/screen is attached to the shut-off valve, and is positioned up inside the tank. You will have to drain the tank and pull the valve to clean the screen.
If you have good fuel flow at that point, reconnect the line and open the bleeder screw at the top of the filter. Turn on the tank valve and wait till you have a steady flow of fuel with no bubbles at the top of the filter, then close the bleeder screw.
Your pump may have a bleeder screw. If so, open that until fuel streams out with no bubbles, then close it. If you cannot identify the bleeder screw, loosen the inlet connection at the pump and purge air at that point.
Go back and make sure ALL the fittings in the fuel delivery system are tight so they cannot suck air.
Make sure the battery is fully charged. Loosen the fuel fittings at the injectors, either one at a time or all at once. Crank the engine till you see all fuel at the injector fittings and then tighten the fittings. If you do indvidual fittings, the engine will usually start before you get to the last fitting.
Alternatively, you can "tow-start" it to save wear and tear on your starter. Leave the injector lines cracked open at the injectors at first to purge the lines. Then tighten them up and she should start.
Your injection pump puts out a very small amount of fuel (high pressure/low volume). BE PATIENT. If the lines are totally empty, it takes a lot of cranking to fill them up.
sixbales & Jerry/MT

 

[jimmysisson]

Also check make sure you don't have two oring

 

[jimmysisson]

Sorry sent too soon make sure there's only one oring at the filter base- sometimes leaks there.
Jim

 

[Tx Jim]

That would be a first check if engine just stalled but the OP says he keeps getting air bubble coming out of the bleed vent at the pump.

Tank vent restriction will cause a vacuum which can appear as an air bubble in clear filter housing. Plus I was taught while performing diagnostics to always check simple things first and removing fuel cap is simple.