Gunk in fuel filter, but tank is clean (1972 Valiant 225)

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troubbble

troubbble

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We pulled the fuel filter and blew it out to check it, and a reddish liquid came out that dried to white. It was fine grain, like clay or silt. We thought we had a rust or dirty tank issue, so dropped it to check it out, but it's sparkly clean in there. The port of the sending unit had some dark red gunk around it. The fuel pump is also new-looking (we've only had the car a month, so don't know for sure, but it is a shining light in an otherwise grody under-hood landscape). The car was run very little over the past year. We had probably a gallon of gas of an unknown age in there, then added 2-3 gallons of ethanol-free 93. The gas that we pulled out was clean. These are the facts thus far.

Does anyone have any suggestions?
I'm thinking I'll pull the sending unit and take a look, but I'm not sure it could cause the issue.

Related: Does anyone have any votes for or against using carb cleaner and pressurized air to blow out the line from the pump to the tank? Figuring we might as well get it clean while it's all apart...

Just thought I'd ask for more input as we try to figure this out. I'm wondering if it's just old gunk and the problem has since been removed, but want to make sure we look at everything we should.
 
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It's probably coming from the lines themselves.
You can run some CLR or muriatic acid through them to dissolve the rust on the inner walls of the line.
Carb cleaner won't eat the rust, but only blow out what's loose right now.
I like muriatic because it works as soon as it goes through, but you have to be careful with it since it's basically thinned hydrochloric acid.
With CLR you have to fill the line and let it soak for an hour or so, but it's safer because it even more watered down muriatic.

You can get either one at a hardware store.
 
You may blow off the filter sock on the pickup tube in the tank if you have the sender installed. But I bet you already knew that.
Yote
 
Compressed air through a line that's open at both ends,,, no problem. If you remove the sender assembly you will need a new seal there.
 
Compressed air only gets what is loose at the moment, and the CLR or muriatic dissolves it ALL out.
 
Just wanted to stop back and say thanks for the input - the sending unit sock had disintegrated and the unit itself was in rough shape so we replaced it. I think it may have been the source of some of the gunk. We also blew out the lines and cleaned them with CLR.

The new unit won't give us a reading so we've got to see if it's getting enough power (reads fine on the multimeter when not installed) but that's a whole other issue.
 
troubbble said:
Just wanted to stop back and say thanks for the input - the sending unit sock had disintegrated and the unit itself was in rough shape so we replaced it. I think it may have been the source of some of the gunk. We also blew out the lines and cleaned them with CLR.

The new unit won't give us a reading so we've got to see if it's getting enough power (reads fine on the multimeter when not installed) but that's a whole other issue.
Click to expand...


Two things:

1) Did you use the old lock ring? If not, expect it to leak, the newer ones are chincy.

2) Do you have the ground strap from sending unit to the hard line? It's a metal piece with a clip of sorts on each end and it goes from sender to hard line right at the tank (effectively creating a connection over the rubber line).
 
Bad Sport said:
1) Did you use the old lock ring? If not, expect it to leak, the newer ones are chincy.
Click to expand...

I did use a new one. That's too bad! I may have the old one around still.

Bad Sport said:
2) Do you have the ground strap from sending unit to the hard line? It's a metal piece with a clip of sorts on each end and it goes from sender to hard line right at the tank (effectively creating a connection over the rubber line).
Click to expand...

I did reattach that, but it's possible it's not making a connection. I didn't realize that's what that was. I'll clean up the strap and the hard line and see if that solves the problem. Thanks!
 
troubbble said:
I did use a new one. That's too bad! I may have the old one around still.
Click to expand...

Do yourself a favor and find the old one and use it. I learned the hard way, as well as many others on here about those new rings.

I replaced my sending unit, all was good until I filled my tank, yup, you guessed it, leak. I wasn't a happy camper.
 
We have all learned that lesson the hard way.
 
So, somewhat unrelated, when I pulled the new sending unit back out to test it with the multimeter I didn't drop the tank or anything, just pulled the lines off and pulled it out. I put the unit back in, and just as I got the lock ring tapped into place nice and snug, gasoline started shooting out of the outlet, geyser-style. Could vapor pressure in the tank have built up that fast and caused that? I was utterly shocked, and also, I now worry about the conditions in the tank and the fate of the pump. I'm going to check the vapor line for blockage, but might as well ask...
 
Bad Sport said:
2) Do you have the ground strap from sending unit to the hard line? It's a metal piece with a clip of sorts on each end and it goes from sender to hard line right at the tank (effectively creating a connection over the rubber line).
Click to expand...

I cleaned off the strap clips and the hard line to make sure it was making a connection but to no avail. Good thing to check, though!
 
The old 30r7 fuel line has likely had it's toll taken on age, and our ethanol-added gas.
A handful of years ago they actually revamped 30r7 to handle ethanol
You should replace all the rubber lines
If you want to go the extra mile replace all of your rubber fuel lines with 30r9 (often called fuel injection hose)
 
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