[Spencnaz]

Hello all,

It's been a frustrating weekend. After months of trouble free service, my truck is stalling a dying from a persistent air leak. I was stuck on the highway a few times on Saturday getting down to Puyallup here in the Seattle area.

Here's the situation:

1. You all know what it's like when your truck runs out of fuel, starts slowing down, no power and it dies. Same happens here.

2. I installed a clear fuel filter for a gasser with the element removed to watch for any air bubbles. It's installed on the line where the water/fuel separator would be. When the engine is running, I can see a steady stream of bubbles being made from the side that sucks from the front fuel tank (i've not used the rear tank due to it getting filled with gunk it will be drained and cleaned this summer). I put in a new section of fuel line since biodiesel degrades rubber compounds with re-tightened fuel hose clamps.

3. I looked over the fuel lines coming from the tank and there are no apparent fuel leaks, I checked the connections at the tank and their tight as well, I put in new retaining clips a few months ago. I put in new fuel injector return caps and hoses last summer. A new fuel pump and IP were installed last September as well (sure hope the IP isn't going on me, but with the amount of air coming into that clear fuel filter, I think the IP is just fine.)

With that out of the way, my question is this:

Could this be a problem with the fuel selector valve? Does this valve contain any rubber parts such as o-rings that would be attacked by ULSD or biodiesel?

Sorry for the long post guys, I like to keep things short and to the point but I want to be as detailed as possible to narrow what the hell is going on here.

 

[Spencnaz]

Would a leaking o-ring in the FSV be enough to burp that much air into the fuel system?

I pretty certain it's on the fuel inlet side of the system, the line that comes from the tank to where the fuel water separator was. I've since bypassed that pain-in-the-neck.

Just had another thought:

I have a 50 gallon extra fuel tank in the bed of the truck that wasn't cleaned out by biodiesel. It drains by gravity into the forward tank keeping it full until the 50 gallon tank drains completely. I pulled the fuel filter this morning when I was stuck on the side of the road and noticed some brown liquid (obviously not biodiesel or diesel fuel ) come out of it. Could it be that I loosened a bunch of crap from that 50 gallon tank and it made it's way to the fuel filter?

It still doesn't explain the bubbles in the fuel system but it's a start I guess.

 

[RickHredf250]

[ QUOTE ]
I pulled the fuel filter this morning when I was stuck on the side of the road and noticed some brown liquid (obviously not biodiesel or diesel fuel ) come out of it. Could it be that I loosened a bunch of crap from that 50 gallon tank and it made it's way to the fuel filter?

It still doesn't explain the bubbles in the fuel system but it's a start I guess.

[/ QUOTE ]

Glycerol maybe? Batches passing the 23/7?
I got a light brown/redish color stuff out of my 96, thinking it was crud or rust from the petrol diesel. Dont know though.
Rick H...

 

[Spencnaz]

Well I didn't do the 3/27 test on these last batches of bio. Problem is that doesn't solve the air bubbles showing up in the fuel system.

I just got some new fuel line from Parker that's BD resistant and meets the ASTM D6751 requirements. At only 1.20 a foot, I got 20' of the stuff to have handy.

I've run glycerol laden (aka unwashed bio) fuel through my truck before, aside from alot of smoke when it's cold it seems to run fine.

I know I know, I need to wash the batches but sometimes I dont have the time to get it done.

 

[arthurgoboom]

The FSV line connectors have O-rings inside the fitting just like the connectors on the tanks do. It's entirely possible that those O-rings are allowing you to suck air in. Since the fuel isn't under pressure you may not see any fuel leaks. Each of those line connections has 2 o-rings in it, might be time to change all of them.

 

[Spencnaz]

Anyone have the proceedure and o-ring sizes for that? I pulled off the line from the tank and looked at the o rings as best I could, then I pushed and rotate the connection a bit before replacing the retaining clip.

I still have a stream of little bubbles, less than 1/16" in diameter which I found on Dieselmann to be normal. We'll see tomorrow morning how well it does.

I drove home tonight ok but at the end there it was surging again as air was likely getting into the system causing a lean condition.

 

[DevoK12RS]

If the orings are bad inside the FSV, I think you'd be drawing from and returning to both tanks to some extent. If the rear tank is MT, that could be part of the problem.

If the orings are bad on the slip connections to the FSV, you could be pulling air there.

A simple, temporary fix would be to bypass the FSV and hook directly to the front tank- because you aren't using the rear anyhow. This will tell you if it's the FSV but not which orings to worry about.

The inside of the FSV is not readily servicable. You'll need to drill out some rivets and then find away to seal it back up. Shouldn't be too hard, though.

Best of luck,
Devo

 

[Spencnaz]

I can get a new FSV for about 65 bucks from a local parts store, it would be much easier just to replace the unit rather than try to repair it.

 

[cdnsarguy]

Try disconnecting the timing advance solenoid wire once the engine is warm and running good...... there have been reports of the Engine temp switch going bad and causing timing advance to operate when the engine is warm.This in turn causes surging.........

Did you replace the seals on the lift pump to filter header steel line and filter header to IP line..... under the cap nuts.

 

[Spencnaz]

No I have not replaced those seals. I should probably head to a NAPA and have new one's made.

Would that explain the air bubbles I'm seeing at the clear fuel filter section that I've put where the fuel/water separator used to be?

 

[cdnsarguy]

If your getting air in the line at the firewall W/S point, I would suggest there is a bad oring seal in one of the fuel inlet line connections or a rusted through line.

 

[Spencnaz]

Update:

I checked the tank inlet connection that goes to the W/S sep. point and reseated it.

Truck's been running fine for the past couple of days. I did notice however that the retaining clip that I had put in this last winter was rather soft. Perhaps biodiesel attacks that type of plastic whatever it is.

 

[redpowerd]

[ QUOTE ]
No I have not replaced those seals. I should probably head to a NAPA and have new one's made.

Would that explain the air bubbles I'm seeing at the clear fuel filter section that I've put where the fuel/water separator used to be?

[/ QUOTE ]

well your clear filter is before the pump, witch would lead me to beleive your connection at the pump and filter head wouldnt show bubbles at your filter.

in order to test your connections from filter on out, you would need one after the point in question.

am i correct in my statements?