Air bubbles. And hard starting

[DEUCEBIGALOW]

After I shut off the truck I can see air bubbles running through the fuel lines and then the truck is hard starting. Any ideas would be great. I'm new to the MV but not new to diesels. But I don't know where to start.

 

[deathrowdave]

I see air bubbles after the engine has been shut down in mine also .I think that is normal drain back to tank.

 

[DEUCEBIGALOW]

The only way I can get mine to start is to stick it on the floor. And it takes several several cranks prob 30 secs at least. The only time it starts rite up is prob 5 secs after I shut it off.

 

[gimpyrobb]

Turn on the trucks power and see if fuel comes out of the bleeder on your secondary fuel filter bleeder. Sounds to me like your in-tank pump isn't working.

 

[DEUCEBIGALOW]

In tank pump works good. You can hear it running and you can turn it on and watch the air bubbles run away. I dunno. Can u guys start yours without giving it fuel. I have to floor mine unless I just shut it off 5 secs ago.

 

[gimpyrobb]

Mine is rough to start if it has sat overnight, but I run alternate fuels. If it has run at all within a day, she fires right up.

 

[gimpyrobb]

If the in-tank pump is working good, might have a return fuel line letting air in.

 

[DieselBob]

In tank pump works good. You can hear it running and you can turn it on and watch the air bubbles run away.

Do you get a good flow of fuel from the bleeder valve on the secondary fuel filters when you open it with the in tank pump running ?

 

[DEUCEBIGALOW]

As I type this i have it idled up and the rear filter has the line going to the injection pump and about every 7 secs a group of bubbles gp from the back line on that rear filter to the IP and that's obviously when it runs a Lil ruff then runs good till the next batch of air comes.

 

[Floridianson]

With just the intank running if there was a leak in the delivery system it should show it's self so check all connectors from tank to IP. The intank pump rubber hose has been knowen to go bad and removal and replacing line is the fix.
Have you turned up the main fuel on you truck. You could try upping the main and see if that helps cold starts.

 

[DEUCEBIGALOW]

I opened the bleeder and got a few bubbles and then straight fuel. But if the truck isn't running and the intank pump is air runs through the lines from the back filter to the IP and then through it to the first filter and it will keep pushing bubbles as long as you have the pump running.

 

[DEUCEBIGALOW]

And now that the truck has ran for about ten mins the air is gone. But as soon as I shut it off it'll come back.

 

[Floridianson]

How many inches of fuel do you have in the tank?

 

[DEUCEBIGALOW]

I'll check the hose in a few. How do I turn up the fuel. Lol I have a 650 hp dodge but it's all electronic. Dang ole technology of this 68 has me lost lol.

 

[DEUCEBIGALOW]

Have about 3-4 inches of fuel. It runs fine once all the air leaves the system but it keeps comic back.

 

[DieselBob]

I opened the bleeder and got a few bubbles and then straight fuel.

Did it just dribble out or do an imitation of old faithful.

 

[Floridianson]

To turn up fuel it would be easer to do a search as there is many threads with pics. The proper way to check intank pump is with a pressure gage that has a low scale myabe 0 to 10 and you should have at least 4lb but 5 to 7 is great. I might put more fuel in her and see if that helps.

 

[DEUCEBIGALOW]

It was like old faithful,,, I was expecting it to be slow it was deff not slow.

 

[Floridianson]

So you checked all the lines from tank to primary filter passenger side to the IP. A small leak here might let a little air in when you shut it down and then the fuel line will drain back into the tank. Then when you first start intank there might be a little air charge first. Double check all lines and fittings with wrench. There also could be a splice some where in the lines you must use light and look real well at the whole line in the frame work. Check primary filter for leakage real well maybe on top where the bolt is.

 

[DieselBob]

It was like old faithful,,, I was expecting it to be slow it was deff not slow.

Sounds like the in tank pump is at least working. I agree with Floridianson that adding more fuel to the tank and doing a pressure test would be good.