My 1969 Datsun 521 kingcab

[waynosworld]

Did you cut open your old main filter ?

Never actually thought about doing that, so I did it just to see what it looked like inside, not what I expected.
I don't have a clue if it looks bad or not, but that rusty spring on the bottom makes me think there was water in the filter for a long time, but the bottom of the inside of the filter wasn't that bad.
It still lost power after I changed both filters Sunday, I lost power on the way there(5 miles) and I lost power again when I had almost made it home(50 miles), I have had no issues since, but I have not been on the hiway/freeway since either.
Here are the photos.

[plenzen]

You can cut the medium top and bottom against the plates and stretch it out to have a closer look. But I'm betting it plugged with water etc.
I be thinking you got yourself a tank of funky fuel. Maybe their in ground tank was near empty and you got the dregs, rust, water and .... well,, troubles.
Is there anyway you can pump some out of your tank into a glass jar and have a look ?

[waynosworld]

You can cut the medium top and bottom against the plates and stretch it out to have a closer look. But I'm betting it plugged with water etc.
I be thinking you got yourself a tank of funky fuel. Maybe their in ground tank was near empty and you got the dregs, rust, water and .... well,, troubles.
Is there anyway you can pump some out of your tank into a glass jar and have a look ?

My tank has a drain plug, I can empty the rest of the tank, but I drove today without issues, but I didn't drive it on the freeway/hiway, just to the bank, 2 stores, Riteaid, the L&I building and then back home without a hiccup.
That filter had been on the truck a very long time, sometimes I quit driving my rigs when another one has my attention, this one sat for a long time when the 720 had my attention, it also had a bad battery and the sitting not using it made it worse, so the fuel filter was forgotten about.
The rust colored specks on top of the filter element are loose grains of whatever they are, rust chunks maybe, but it kept missing/losing power exactly the same way when I changed the filters, so maybe one of those rust grains got in the banjo fitting, I don't know, I was planning on removing the banjo fitting and looking it over real close tomorrow, and then possibly replacing it with the new one I have on that NOS complete filter assembly I have, if nothing changes I can put it back to the way it was, I just want to figure it out changing one thing at a time till I figure it out and know exactly what it is next time.
I have always run a pre-filter on both my diesel trucks, and the pre-filter element had been sucked flat 3 tanks before this issue, so maybe that filter got a hole in it when it got sucked flat and let debris thru and it finally caused an issue, the only reason I use pre-filters is because I want to protect the fuel pump from contaminants that could ruin it as they were not readily available on ebay 7 years ago like they are now.
Maybe if it is not raining I will lift the truck up and drain the tank instead, but it runs so good around here that I don't think it is a bad fuel issue, I only have issues on the hiway/freeway when the fuel requirement is steady, I think the banjo fitting should be the next thing to look at.

[waynosworld]

I don't know what water looks like, but the whole thing has a shiny light brown film on it, no chunks like rust grains on it though.
The back is darker and not shiny, drier looking.
What baffles me is that I drove over 110 miles before I started losing power on that tank, when I think of water I think it will settle to the bottom and screw things up right away, but when it starts messing up if I pull over and let it idle for a while and I am good to go again, at least around town.

[handcannon]

I appreciate the pics you put up. Just now I remembered an incident that I dealt with few years back. I have very little experience with water in the fuel, but my 94 Chevy pickup has a water in fuel light on the dash. I put a 5 gallon jug of diesel, which had been setting for a short time, into the 94. Very shortly afterwards the W-I-F light came on, I drained the water filter, and never had any problems, then or since, with the motor.

In the filter you cut open I would guess that the shiny surface you described on the filter media would be water, but I have no experience with what water would look like on a filter surface. So, any information you come up with in the future about this situation will be a big learning experience for me.

Since there is a drain plug in that tank one thing I would do is drain about a gallon out of there and let it set for a while in a glass jug and see what it ends up looking like. Hopefully what you get out of the tank is from the bottom.

Don

[waynosworld]

I did forget to mention that the fuel filter had diesel fuel in it, I thought I dumped it out but when I made the first cut and turned it over to cut the other half, fuel dumped out of the cut I had just made, that filter element is soaked with diesel fuel and anything else that was in the filter.

As for the light, my filter has the sensor to light up the glow plug light when water gets into the fuel filter, but it has never been hooked up, I am not sure why, well I just went out and looked, the wire is not long enough, but I can make an extension tomorrow, I suppose that would tell me when I need to drain the water out.
It likely would be better to buy and install a pre-filter with a water trap that does that before the water even gets into the system, I have actually been looking at them on ebay since this issue started, but to install it I will have to mount it on the other side of the engine bay over by the radiator over flow reservoir behind the driver side headlights, as that is the only place I have room for anything larger than my fist, I had to find a place to mount the clip to hold the pre-filter I changed over to after this power loss issue started.
I have something like this one on the 720.
http://www.ebay.com/itm/DIESEL-FUEL-WAT ... xy3HJTI0Ur
What are you guys using?

[plenzen]

I use this for a water separator. I use it in conjunction with the OE one that is next to the fuel filter.
The picture with my hand in it shows the pre-filter from WIX for the diesel Mercedes.

The OE water separator has a fuel heater in the top of the housing and that's why I keep it there. The smaller one on the firewall is far easier to service should water accumulate in the tank. It has a small red ring in the bottom of it and if water is present it will float upwards letting you know how much water is there.

Its small and is from a Yanmar industrial diesel engine. I had a Racor separator on it when I got the truck from my dad and I had nothing but problems trying to get the O rings to seal on it and it ended up sucking air all the time.
The engine would run out of fuel climbing a hill. Driving around in traffic and on the level was fine but if it had to "work" at all it would lay down. I removed it and put this little guy on and it's been fine.

[plenzen]

I believe that Don may be correct in that the sheen is water.

Would be interested to see what the fuel that you drain from your tank looks like.

Just had a thought here

If you have a strong magnet you can run over the stretched out media and see if it collects anything from the element.
If it "rusted" it should be ferrous and stick to magnet. Wipe it onto a clean white paper towel and see what you get.

Maybe fold it up and put it in a sandwich bag and into the freezer and see if it freezes. Might be a way to see if it is water or not,,,,,,,,,,,,,,,,,,,,,,,,,, maybe.

Paul

[handcannon]

My 94 Chevy has just the stock W-I-F detection, but it apparently works well from my experience a few years ago. I don't know yet what will be used in the 73 Datsun when I get the SD-22 running in it. After this problem you are having I definitely will do something.

I like the suggestions that plenzen made, magnet and freezer. Maybe even try a section of the filter media, although it may have dried out in the meantime. Maybe even drain a bit of fuel out of the tank and put it into the freezer to see what happens.

Something that plenzen said makes me wonder if the problem could be air intrusion under high demand situations. Is it possible that something around the pre-filter is allowing air in under high usage? The small amount of air that enters during around town driving may not be excessive enough but what the stock system can take care of. However, the filter media you have there seems to indicate otherwise. Did you use single, or double, clamps on the fuel line going onto the pre-filter?

Although this situation involves a gas motor, an acquaintance had a mostly stock 70's era Toyota FJ40 and was having problems with it when under high gas usage, higher engine RPM's. The problem for him turned out to be his fuel filter. He had a clear glass filter with a replaceable element, and it turned out that the seal for the filter was leaking air under high usage situations. He replaced the complete filter system with a different one of the same type and his problems were stopped.

Don

[waynosworld]

Well I did both things today so far, I emptied the tank and I changed the banjo fitting on the road afterwards and I still have the same issue, when I put the pedal down it lost power even before I was on the hiway/freeway, I stopped and changed out the banjo fitting and I still have issues.
There was crap in the tank, when I removed the plug I purposely watched the fuel coming out, it was one color at first(clearish), then a couple minutes later it changed to amber color, it's a small drain hole so not a lot comes out but it kept coming out till I emptied almost 5 gallons, when I put it into clear containers it all appears to have mixed again so I will have to wait for it to separate/settle again.
I emptied the tank and I also emptied the fuel filter, I then filled the fuel filter with fresh fuel and re-installed it, poured the other 5 3/4 gallons into the tank and started it up, after it was warmed up I took it for a test drive.
It doesn't appear that fuel or the banjo fitting are the issue as it is still happening, nothing has changed.

[plenzen]

I'm wondering if the pickup in the tank is your problem.
That was a gasser truck before yes ? Wondering if the diesel has taken its toll on things involved with that piece of gear. It certainly sounds like a demand starvation problem. It's "sucking" but can't get what it needs. I think perhaps your next step is to try and get the pickup out of the tank and have a look. Sadly. That may be a bit of a "project"

[waynosworld]

I'm wondering if the pickup in the tank is your problem.
That was a gasser truck before yes ? Wondering if the diesel has taken its toll on things involved with that piece of gear. It certainly sounds like a demand starvation problem. It's "sucking" but can't get what it needs. I think perhaps your next step is to try and get the pickup out of the tank and have a look. Sadly. That may be a bit of a "project"

I thought of that also on the drive I just took, just before the drive I blew air from the front of the truck to the tank and I heard air and seen smog coming out the fill tube when I really gave it a lot of air, then I put the hose back on and pumped on the hand primer for a very long time without results, that got me thinking that maybe the actual fuel pump has an issue, so I added an electric fuel pump back by the tank and wired it into the key and finally got fuel, I buttoned everything up and took it for a drive, I got 10 miles and right after I hit the second up grade it started losing power again, I turned around and basically stopped on the freeway entrance till it started running properly again and entered the freeway, it was a slight down grade, I made it to the next upgrade and started loosing power really bad about half way up, I got to the top of the hill on the side of the freeway(break down lane), and stopped just before the next exit, popped the hood and the pre-filter was empty but it was still running, so I took the exit and filled it to the top with diesel at a Shell Station thinking maybe the pick up tube has a hole in it or it broke off part way up, the filter filled up and off I went, it appeared to be fine until the next up grade, I made it to the top and back down the other side but it was running real bad, I stopped at the bottom of the hill, popped the hood and the pre-filter was full, but I had been driving down hill for a half mile but it was still running like crap, I let it smooth out, took the next exit(a mile) and drove the back roads home without any issues.
OK, I added the electric fuel pump when I could not get the hand primer to pull the fuel from the tank, there was no resistance when I was pumping that hand primer, but I checked it after the pre-filter was full of fuel and there was resistance, I am wondering about the fuel pump now, but my thinking says the hoses after the fuel pump are not high pressure hoses, they are just rubber fuel hoses, so I am thinking that the high volume electric fuel pump should supply enough pressure to help the stock fuel pump as it is not a really high pressure pump otherwise it would blow them fuel lines up.
I am also wondering if the electric fuel pump can force the fuel by the stock fuel pump, I didn't bypass that pump.
I am running out of things to point at, it's likely not the filters, the hand pump didn't pull the fuel from the tank after I blew the line out so I started it and that didn't pull the fuel from the tank either, next I put one of the new cheap filters in the line and started it again and ran it for at least a minute without any fuel showing up in the cheap filter, that is when I added the electric fuel pump and I put back the better pre-filter.
I filled the tank to the top and lost power again at the next upgrade around 3/4 miles from the station.
If the tube had broke off it likely would not run for long, let alone driving it miles and miles on side streets without an issue.
I don't see any bubbles in the pre-filter after it is full, can't tell before it is full as it is not a totally clear filter.
I suppose I could put a 5 gallon gas can in the back of the truck and run a fuel line to it and put the end of the hose in the can and try driving it, but one of these times it's not going to make it back home.
This engine never dies, it just loses power and I keep it just above idle to make sure it doesn't die/stall when not running properly, after it smooths out/doesn't sound funny I start driving it again.
I opened all the injection lines to see if any of them didn't change the idle, they all effected the idle the same.
Can the injection pump be the cause of this?

[plenzen]

I would still suspect the in tank pick up or even the insides of the fuel lines starting to collapse etc. The idea with a separate fuel tank is a good idea. Run a separate return line to it as well.
I recall my dad had an issue with his gasser motor home he converted to diesel. After a few years there was a rubber hose inside the fuel tank that joined a couple things together and the diesel fuel had turned it all funky and soft over the years and it plugged itself closed in the tank. He ended up repairing it in the dark in the rain on the side of the highway half way up a hill.
Some of those old 1970's rubber lines did not get along very well with diesel fuel.
The fact that you have managed to collapse a few of those in line filters would seem to me that the lift pump is working OK.

[waynosworld]

I forgot to mention this is a diesel frame with a diesel tank and lines.
As I said, I blew air thru the fuel line back to the tank, it was clear, I didn't blow air thru the return line though, that was easy enough to do, so I just did it, and fuel blew out the fill tube as the tank is so full.
I am considering removing the vent line from boost to see if that changes anything, it will run a lot richer and hotter EGTs, but finding that pre-filter empty makes me think it is not that, that makes me think fuel pump issues now, that it was still running with an empty pre-filter is baffling to me.
Keep in mind that the fill tube for the tank goes all the way across the truck above the tank, that tank is completely full of fuel all the way to the top as that fill tube still has fuel in it also, so even if the pick up tube is broken off it is under the fuel level/submerged right now, it still had an issue completely submerged.
I am going at this one thing at a time, it appears to not be getting fuel at hiway/freeway rpms on up hill grades, and we are not talking about real hills, just slight upgrades.

[Carimbo]

I don't have a clue if it looks bad or not..

Look at your second photo of the fuel filter, the one that shows the center section of the fuel filter. That is supposed to be the clean (filtered) side. No matter how dirty the outside of the filter looks, or the cup (also the dirty side), the clean (filtered) side better look clean. I see all kinds of gritty crud on the clean side. Which means it is likely to have migrated into the IP.

Before we condemn the IP, have you checked for air intrusion? Splice in a section of clear fuel tubing at the IP fuel out fitting and check for tiny bubbles immediately after the problem reappears. Shouldn't be any.