6.9l Hesitation, Revving Engine

[mankypro]

6.9l Hesitation & Intermittent Rough Idle? Stumped

So today I checked my water separator for water, by draining a bit of fuel from it - I have the type that's in front of the driver side firewall.

Tonight I went for a quick drive and the truck started easy as always, but after idling for a while went in a cycle of revving up/down- like it wasn't getting enough fuel? Or like an o2 sensor was malfunctioning? Pah-****, pah-****, pah-****. Never died. And would stop doing it for minutes at a time. Revved on the pushof the pedal fine. Only hesitated once under power while driving.

Clogged fuel filter? I put a new one in like 500 miles ago?! I don't have a spare fuel filter so I can't just swap it now to figger if that's the source of the problem.

Does this have to do with me having bled diesel from the separator? Did I need to burp the system with the schrader valve after doing this?

I'm running 100% dino diesel.

 

[Diesel JD]

You've gone and done it now! People often seem to have trouble getting that thing to reseal after it has been drained. I'm not sure what to tell you. I bypassed mine, but running without a water sep can be risky and aftermarket can be expensive. You could also swap to a 7.3 style filter/seperator, but you'll need a header from a 7.3 diesel.

 

[mankypro]

I actually have a 7.3 separator - at least what I think is one. The one mounted now is the pull ring type. So we think that I have air in the lines as a result of my messing with the damned thing? The guy that sold me the truck gave me boxes and boxes of spare parts - even a brand new complete exhaust

Amazing what you get for $250.00 sometimes

You've gone and done it now! People often seem to have trouble getting that thing to reseal after it has been drained. I'm not sure what to tell you. I bypassed mine, but running without a water sep can be risky and aftermarket can be expensive. You could also swap to a 7.3 style filter/seperator, but you'll need a header from a 7.3 diesel.

 

[mankypro]

Ok think I may have solved the issue. I drained a bit of fuel from the separator again, then made sure the pin was seated well. Bled the schrader - lots of air came out. Cranked like a madman for about 30 seconds twice and it fired - then idled smoothly until I turned it off.

Any comments?

 

[NCheek]

Not uncommon for the factory pull ring separator to leak air; sounds like you got your problem solved though!

 

[leftcoastjeff]

Air inlet

As you can see from my sig. I ripped that out after dinking around with it for 2 weeks, not sure what to replace it with.
Glad I had 2 good batteries.

LCjeff

 

[mankypro]

Can anyone tell me the years that will have the superior fuel separator? I'm going to hit a pick -n-pull for one.

To bypass the factory fuel separator, do I just replumb the fuel lines to bypass it? Or should I do something with the "water in fuel sensor" to get it to fire with the 7.3 filter setup? Is there an FAQ somewhere on how to do this?

 

[hesutton]

Can anyone tell me the years that will have the superior fuel separator? I'm going to hit a pick -n-pull for one.

Any 7.3 IDI....'88-'94

Heath