Suggestions/help with clear line test

[pickupman]

So I finally had some time today to start working on my truck. My initial goal was to do some clear line tests and see if any air is getting in the fuel lines. I didn't feel like taking the square banks air filter box off today, so I was just going to run a clear line from the lift pump to the fuel filter and from the fuel filter to the #1 cap. As soon as I took the steel line off going from the lift pump to the filter, I realized the clear line I bought won't fit on the metal thread, so I was wondering if anyone knows what size fitting I need that I could attach to the filter housing that would enable me to attach a hose to it temporarily?

What I did end up doing today was just to run a clear line from the filter to the #1 cap. My impression was that this line is to allow allow air to bleed out of the filter, so I wasn't sure whether it would be normal for a lot of air to be coming out of that line. I made 2 videos, one with the engine running, and the 2nd video shows what happens right after the engine is shut off. It would be a good idea to try to view these videos using the highest quality setting possible, it will be much easier to see what's going on.

In the first video with the engine running, you can see lots of air coming out of the filter. It is hard to see in the video, but I have the line from the filter to #1 cap with a big loop in the middle. In the second video, after the engine is shut off you can see the fuel moving in the lines a little bit. I am not sure what to think. When I have time I will add to this thread with results of a clear line test from the lift pump to filter, filter to IP, and IP return line. Does anyone have thoughts so far on what may be my issue or what area of the fuel system to focus on?

With engine running
http://www.youtube.com/watch?v=Z_BniwPi-NE

Video 2 will follow shortly

 

[pickupman]

With engine shut off
http://www.youtube.com/watch?v=IuJCa9uj0WM

 

[gandalf]

I don't think I'd run a clear line from the filter to the IP. The fittings on both ends of that line are not too friendly to line attachment. Both ends have an olive, and are more like a plumbing compression fitting.

You do seem to have an excess of air in those lines.

I used two clear lines, as shown in the picture attached.

You must be registered for see images attach

This is a '92 engine, 7.3.

 

[towcat]

So I finally had some time today to start working on my truck. My initial goal was to do some clear line tests and see if any air is getting in the fuel lines. I didn't feel like taking the square banks air filter box off today, so I was just going to run a clear line from the lift pump to the fuel filter and from the fuel filter to the #1 cap. As soon as I took the steel line off going from the lift pump to the filter, I realized the clear line I bought won't fit on the metal thread, so I was wondering if anyone knows what size fitting I need that I could attach to the filter housing that would enable me to attach a hose to it temporarily?

What I did end up doing today was just to run a clear line from the filter to the #1 cap. My impression was that this line is to allow allow air to bleed out of the filter, so I wasn't sure whether it would be normal for a lot of air to be coming out of that line. I made 2 videos, one with the engine running, and the 2nd video shows what happens right after the engine is shut off. It would be a good idea to try to view these videos using the highest quality setting possible, it will be much easier to see what's going on.

In the first video with the engine running, you can see lots of air coming out of the filter. It is hard to see in the video, but I have the line from the filter to #1 cap with a big loop in the middle. In the second video, after the engine is shut off you can see the fuel moving in the lines a little bit. I am not sure what to think. When I have time I will add to this thread with results of a clear line test from the lift pump to filter, filter to IP, and IP return line. Does anyone have thoughts so far on what may be my issue or what area of the fuel system to focus on?

With engine running


Video 2 will follow shortly

bypass the water separator on the firewall and show the results.

 

[pickupman]

bypass the water separator on the firewall and show the results.

The factory water separator was replaced with a Racor separator long before I bought the truck. I do need to replace the hose going to and from it though, so I can do a still do a vid if you think bypassing it would provide and useful info.

 

[pickupman]

bypass the water separator on the firewall and show the results.

So as requested, I did a video of a clear line test with the water separator bypassed. This video was taken right after a cold start. About halfway through, the fast idle switches off, and at that point there is a small stream of bubbles that come out of the line from the filter head, but then it goes away pretty quickly. Everything else appears to be normal, there are some tiny bubbles in the lines, but from what I understand, those are okay. I think the important thing is that the stream of bubbles every 10 secs or so in the video from last week went away after bypassing the water separator. The other change is that after I shut the engine off, there was no movement of fuel in the lines, neither in the filter return line or the supply line where the water separator was bypassed.

I currently have an old Racor separator. It is using a 2 micron element and it seems to plug up pretty quickly. The last time I changed it was about 4 months ago. I feel a little skeptical that the whole issue could be that it's just that is clogging up quickly. I remember after I last changed the element, I started to have some rough idle maybe a month after I changed it. Since the Racor unit is so old, I am wondering if air might have been leaking in somewhere. I never had any issues with the engine stalling, my problems have been an occasional rough idle, and more recently having the engine acting like it's being starved of fuel at freeway speeds.

http://www.youtube.com/watch?v=pYvUjevnp9c

 

[pickupman]

One thing I forgot to mention yesterday is that after I took the video, while the engine was running, I switched tanks while the engine was running to make sure that the FSV is operating correctly. I saw a few air bubbles after it started drawing fuel from the other tank(I haven't used the rear tank in a year or so), but after that it was fine, it appears that it will run off of both tanks without any issues. The thing that concerned me is today I just noticed some black particles in the clear bowl of the Racor filter. I was reading the thread that just popped up today about the FSV and I realized that I may have a deteriorating shower head in the tank, thus the sediment that I saw in the Racor bowl.

Since I don't want whatever particles I saw clogging up the fuel system, what I want to try is to put these clear filters inline before the FSV, one for each tank: http://www.jegs.com/i/Fram/410/G3/10002/-1?parentProductId=1045095
If I start having symptoms of the truck running rough or being starved of fuel, then it should just be a matter of switching tanks, because it would mean that the filter before the FSV would be clogging up. What do you guys think?

 

[icanfixall]

I'm not a fan of running extra filters on our fuel systems. Look at it this way. You have a lift pump on the engine sucking fuel. Now add some filters and its going to suck the chrome off a bumper hitch trying to suck fuel to the engine. Thats going to suck air in from the smallest leaks in the fuel system. Believe it or not air will leak into our fuel systems long before you see a wet spot where fuel is leaking out. Its the size of the moliques. My guess is you have some bad areas on the suction side of the fuel system because your not going to have air leaking in when the system is under pressure like after the lift pump. So the air is getting in before the lift pump and its being pumped thru the filter and the rest of the fuel system. Now as our fuel systems shut down any air leaks will cause the fuel to flow. Prof of this is the straw trick. Place a straw in some fluid like a drink. Place your finger over the end of it and pull it out of the fluid. Nothing drops out but let that finger off the end of the straw and its gone quickly. Our fuel systems needs to be that tight to function correctly. An electric lift pump will band aid this problem and some times repairs it but.. Its really just masking the problem and it will return to bite you.