Air Intrusion ..... Stumped!

[jax1463]

I have replaced my return lines, injector O-rings and the line to the injector pump. Checked all of the fuel lines back to the tanks.

Can't find any seeping or loose connections. Anyone here have any possible idea where to look next?

 

[franklin2]

What exactly are the symptoms? Some people think they have air intrusion problems when they really don't.

 

[jax1463]

I'll bleed off the air out the fuel head schrader valve and after I keep cranking It'll finely start.

Once I get it started and come back a couple of hours later it'll start right up.

Now, when I let sit over night it will not start even after bleeding the head off again.

So now in the mean time I've got the batteries charging. I'll go out later this evening to try again.

 

[Jesus Freak]

If you're using the mechanical fuel pump on the engine, there's a check valve in it that can fail and let the fuel drain back. I've had that happen.

 

[ROCK HARVEY]

Have you checked the fuel heater in the filter head? It can fail and leak out of the electrical connector.

 

[IDIBRONCO]

If you're using the mechanical fuel pump on the engine, there's a check valve in it that can fail and let the fuel drain back. I've had that happen.

Have you checked the fuel heater in the filter head? It can fail and leak out of the electrical connector.

Both are good suggestions. How about your water separator? I that hasn't been bypassed, it could be causing your issue.
Not to mention that this is fuel drain back and not air intrusion. Air intrusion affects the way that the engine runs.

 

[Jesus Freak]

Both are good suggestions. How about your water separator? I that hasn't been bypassed, it could be causing your issue.
Not to mention that this is fuel drain back and not air intrusion. Air intrusion affects the way that the engine runs.

I forgot about that thing.

 

[Austin86250]

I’ve had nasty air Intrusion from my firewall fuel water serperator, I just took it apart and put it back together and it worked liked new again
Another time it came from my fuel selector valve diag both by running a clear hose before the mech fuel pump

 

[WrenchWhore]

Hears my Hail Mary. How much fuel is in it? Hows the shower head in the tank looking?

 

[jax1463]

I’ve had nasty air Intrusion from my firewall fuel water serperator, I just took it apart and put it back together and it worked liked new again
Another time it came from my fuel selector valve diag both by running a clear hose before the mech fuel pump

Hears my Hail Mary. How much fuel is in it? Hows the shower head in the tank looking?

I will look for the fuel/water separator. The 7.3 that's in my '84 swapped out the 6.9 that it came with.

Full tank! When I bleed the fuel head it starts out with a little air and then I get good fuel flow out of the schrader valve.

My 7.3 is definitely an earlier one. Does anyone one know where to look for manufacture date?
Going to get a new fuel pump for it and the supply house always ask me what year it is and I always guess around 1990.
Did the fuel pumps change over the years?

I appreciate all yall's help with this!

 

[Jesus Freak]

Manufacturing date is in the door jamb sticker. Fuel/water separator is a can looking thingy between the brake booster and fender wall, right in front of the driver on the firewall, it might not be there as it is common to bypass them. All the mechanical fuel pumps should be the same on 6.9, 7.3, and turbo 7.3.

 

[IDIBRONCO]

Manufacturing date is in the door jamb sticker.

Except he was asking about the engine serial number. I think that there's an engine serial number breakdown in the stickies section. That won't give you an exact manufactured date, but it will get you close enough. I'm not sure that there's a lot of differences between the N/A 7.3, but I may be wrong on that.

 

[Brian VT]

Fuel/water separator is a can looking thingy between the brake booster and fender wall, right in front of the driver on the firewall...

Are you talking about the thing that looks like a black coffee can? I think it IS an actual coffee can.
I was wondering what the heck that was. I guess I need to look at mine a bit more as to condition and if it needs to be drained or replaced or removed now that I know what it is.

 

[chillman88]

Are you talking about the thing that looks like a black coffee can? I think it IS an actual coffee can.
I was wondering what the heck that was. I guess I need to look at mine a bit more as to condition and if it needs to be drained or replaced or removed now that I know what it is.

That's a vacuum canister/reservoir.

The water separator was only on the 6.9 trucks I believe. On the 7.3 it's integrated into the fuel filter.

 

[Brian VT]

I have a 6.9 but haven't run into a water separator yet.
Thanks for the clarification on the coffee can.