She just... died....

[IDIBRONCO]

But I thought the purpose in the plunger was that the water would come out not just the fuel

Yes water and diesel don't mix, water is more dense so it sinks. When you open that valve it lets anything inside out, the idea is that you'd drain it just enough to get any water out and close it again. In my experience the water separator almost never needs to be drained. Our work trucks are class B shred trucks, we put a lot of hours on them and we won't have any water in the separators like, ever. I don't know if I've ever seen any water in them. I drain them from time to time but can't remember any water.

The separator is there for bad fuel and leaving your tank sitting mostly empty through hot/cold cycles where the inside of the tank might dew up and get water that way. Another way is if you're burning un-separated WMO as I do sometimes in my rig.

To finish this out, yes, the water drains out first. If you continue to hold the plunger open, the fuel will run out because there's no water left to run out. Gravity doesn't care whether it's water or fuel that runs out. If there's no water, then only fuel will come out when you open the plunger. Simple.

 

[RSchanz]

I figured this thing couldn’t be that complex. I’ve taken it apart and cleaned it before. So in order to find out if it was water I should have captured what first came out, haha. Good news I guess is that there didn’t appear to be water in the fuel that I did capture.

 

[IDIBRONCO]

I don't drain mine as often as I'm "supposed to". That's because I've never seen any signs of water in mine. Maybe I'm, lucky? Maybe I drive mine enough for water to not collect? Maybe the Opti Lube I run emulsifies the water so it doesn't settle out? I don't know. There's only two or three gas stations that I use around home. I'm not too picky when I'm out on the road. I also don't bother to pull up to a pump when there's a fuel truck there. Whatever it is, it works for me.

 

[Cubey]

But I thought the purpose in the plunger was that the water would come out not just the fuel

No. It just opens the bottom. Water rests is at the bottom because it's denser than diesel. It's also denser than gasoline, so you can use a W/S on a gas vehicle.

Below is a photo from when I was getting the water from my bug gas tank last winter. The gas station pumped 3.3 gallons of water, so a W/S wouldn't have helped.

The bottom portion is water, upper is gasoline. I'm pointing to the line between the two.

Imagine that to be your water separator, and you pull the drain, the water will come out first, followed by diesel. If there's no water, only diesel will come out.

You must be registered for see images attach

 

[RSchanz]

I went back into it and noticed a small leak on the return line from the last injector back up the fuel filter. I replaced this and also replaced the fuel filter. So far it seems good, drove it around just for like 10 mins. Seems like it must be some kind of air intrusion or issue with fuel delivery. Fingers crossed

 

[Nero]

Forgot to mention this yesterday.
Replaced the regulator on my old mans truck, g1 alt, started randomly going full field. New regulator now it's calmy sitting at 14.3 when running.

Edit... Wait this isn't what did I do to my truck thread... How did I get here?

 

[Old Goat]

Any type water separator filter, you open the drain c ock
till you see fuel coming out. You don`t drain the whole
thing.
As mentioned water is heavier, and drops to the bottom
of the unit.
The one on my 86 when I bought it was already disconnected
and the 2 hoses connected together.
I deep 6`d the separator and installed a Racor 500FG Filter/
separator, and installed it on the Fender where if you have
Cruise Control (I don`t) . It has an inner paper Filter 2, 10 or
15 micron Filter. I use the 2 Micron. I want the best filtration
I can get. I also have a hand Primer Pump I installed
I change the paper one about every 15K miles. after 2 years
drained the Pet C ock and little bit of water and some other
gunk came out.

If you connect the 2 hoses together, then you just have the
spin on filter that is a 10 micron. some of those have a drain
on the bottom.

I used the smaller 200FG Racor on my 82 Datsun KC Diesel for
400K miles and 30 years. Also have one on my 80 Mercedes 240D.
Amazing the krap they collect.

Racor 500fg10 fg fuel filter/water separator

Turbine Series filter assemblies are designed to be installed on the vacuum side of the fuel transfer pump for best efficiency and protect precision engine components from dirt, rust, algae, asphaltines, varnishes, and especially water, which is prevalent in engine fuels. They remove...

www.racorstore.com

Goat

 

[RSchanz]

Despite the small changes I made it didn't help. It still idles a little rough and on the first start fires up for a sec then dies. Based on my knowledge it's an air intrusion happening somewhere. What are some of the main causes of this? I'm going to try bypassing the water separator with a straight connector probably today or tomorrow and see if that helps.

 

[The_Josh_Bear]

Despite the small changes I made it didn't help. It still idles a little rough and on the first start fires up for a sec then dies. Based on my knowledge it's an air intrusion happening somewhere. What are some of the main causes of this? I'm going to try bypassing the water separator with a straight connector probably today or tomorrow and see if that helps.

I like to think of air intrusion in two categories:
1. Fuel drainback. This happens becsuse of a back check valve in the stock fuel header or a tiny pinhole leak that lets the fuel in the filter drain back to the tank. Causes hard/no start in the mornings like you mentioned. Especially the "starts, dies, hard to start again" thing. (This is just a type of air intrusion, but different symptoms because it's on the return side)
2. Air intrusion. This is on the supply side, somehow air bubbles are getting into the IP and it runs poorly at idle and tends to go WOT under load because the timing is all goofy from the IP housing pressure going all over the place with air.

Fixing that fuel heater is a great start! Other common spots are:
1. Tank selector valve(can leak at connectors or internally)
2. At the tank quick-connects(turns out there are little o-rings that can get sketchy inside the female end)
3. Anywhere along the hard line can rub through if it's been touching frame or other hard metal. Not too common unless salt belt.
4. Anywhere there is soft line that wasn't fuel rated or somehow got a rub/cut in it.

I personally have deleted the stock fuel filter setup, but before I did I had a leak at the fuel heater. It let air in over night and took me a long time to find. Eventually I tapped a pipe plug into the spot where the heater was and used JB Weld, worked well.

I've experienced the air intrusion from especially my midship tank when I have WMO mixed in it in the winter. That took me a while to figure out, too, and I've yet to fix the darn thing.

Another thing that's very helpful is to either delete the return line from the filter to #1 or even better, install a proper check valve between filter and #1 return. (The stock one generally stinks.) We install the valve so fuel can flow away from the filter. The reason it helps is that check valves take about 2psi to open so your fuel pump will still drive air out but it won't let air back up the line overnight causing the fuel drainback issue.
Just deleting the line is fine and was a TSB by Ford, but makes for hard starts when you stitch tanks late or run out of fuel and need to re-prime. Been there, done that!

Hope that helps,
Joshua

 

[RSchanz]

So I bought a 3/8 adaptor thinking that would work especially based off this from another thread

Just get a 3/8th barb to barb coupler and a pair of small hose clamps.cut or pull the 2 hoses off the water sep and just connect them via the barb thingy.As for the filter......

Napa-FIL 3217 without drain or sensor $42
Napa-FIL 3417 with drain $31
Napa-FIL 3617 with drain and sensor $33

Mine appears to be 7/16in. though. I'm wondering why it's bigger and if this is a problem too like someone put fuel line on the metal lines that was too big...

 

[RSchanz]

Update:

I couldn't find a coupler at the parts store or west marine (odd) near me that was 7/16 to 7/16 so I just removed the "in" fuel line and looped the "out" fuel line from the metal line to the "in" metal line. Fired it up, started pretty good, used some pliers to push the schrader valve on the fuel filter until only diesel came out and everything seems fine. Im going to see if the next start tomorrow is smooth and then I'll assume it was the water separator. If this proves to be the issue, next thing I need to do is get a 7.3 filter head and start using the filters with the drain at the bottom.

 

[RSchanz]

Reviving this because:

1.I hate to leave things without an answer/solution (sorry)
2.The problem came back

I drove it quite a bit after bypassing the water separator and everything was fine but it sat for several weeks maybe a month and I drove it yesterday and it died again. Last time it died it just kinda shut off while the clutch was in, when it died this time it was bucking like revving up and down. I get that this could be air intrusion but it seemed kinda weird that it seemed like it was kinda accelerating too not just dying. Could this be fuel delivery issue etc?

 

[Nero]

Revving up and surging then dying is classic signs of air intrusion

 

[RSchanz]

Revving up and surging then dying is classic signs of air intrusion

I found a video where this guy attached clear fuel lines from the lift pump to the fuel filter and the return line from the injectors so he could see if there were air bubbles. I like this idea and will probably do it. Can't seem to figure out where or why this suddenly started happening.

 

[david85]

I did the clear line trick on my truck for troubleshooting. It's been several years and I still haven't taken it off.

I agree this is likely an air intrusion issue. A relatively easy way to prove this is to remove the fuel filter after the engine has been been sitting for a while. Say, a day or a few. If the fuel level is down about 1/3 from the top, you know for sure diesel is draining back to the tank (or fuel simply ran out).

There was a time when I had hard starting and it turned out to be a weak lift pump. I figure one of the internal valves failed, which allows fuel to drain back, but also made it nearly impossible to prime after the truck was shut off for any length of time. Worse still, if parked pointing uphill. Once I got it running it was usually fine until the next cold start.