Dirty Fuel

[ssapach]

So on my 1986 454 I'm currently fighting a bit of a fuel problem.

I was driving to the city to get some exhaust work done when it all started.  Truck would start to sputter and lose power at highway speed, but would be fine if I slowed down a bit.  Then after a bit of driving it would do it all over again.  So I was constantly losing speed.

So I stopped and took the fuel filter out of the carb and I put an inline filter between the fuel pump and the carb.  The truck ran fine after that.

When I got a new carb filter I put it back in and left the inline filter before the carb.  I cut open the clogged filter and it looked like this:



So with a new carb filter and clean inline filter before the carb the truck was running fine again.  I drove it maybe 40 km before it started acting up again.  I knew it was the fuel filter so I changed it again.  Runs fine again.

One more go at it, didn't even make it 40 km this time and it was sputtering and losing power.  I was in town and didn't have a filter so I just removed the carb filter and left the inline filter.

The trouble is that the carb filter is catching what looks just like fine dirt and plugging from that, but all this stuff is passing through the first filter.  So if I'm running my truck without the carb filter little bits at a time here and there, am I going to run into serious carb/engine trouble because that fine stuff is now going into my carb/engine?

Today was the 3rd plugged filter I removed from the carb, I drove the truck home without that particular filter in.  I know this isn't going away any time soon so I figure I'd start with the fuel lines themselves.  The steel lines have sat empty for 20+ years while the truck was on propane.  Although they were plugged on the ends, they were bone dry and I figure I have to start somewhere.

But I took the lines off from the selector valve to the fuel pump and they seem clean as new inside.  I pushed a piece of white cloth through and it comes out clean, or as clean as can be to my eyes.

All I'm left with here is the fuel tanks, selector valve and the steel lines from each tank to the selector valve.  I can't imagine the selector valve has that much stuff built up in it.  Everyone tells me its the tanks.  Before I put them on the truck I had a look inside and they looked clean, they even had a bit of diesel left over from the previous vehicle they were in.  I guess I should have just washed them out real good then when it would have been easy.

So what does everyone think, did I cause myself some pricey damage down the road by driving without that little bitty filter? 

Also, should I just give in and remove the tanks?  Or is it possible to rinse them out good enough while they are attached to the truck?

[Captkaos]

You need to drop the tanks and clean them out if you are getting that much dirt in the filter.  Or get new tanks.  I imagine the sock filter on the sending unit is probably gone?

[ssapach]

Both sending units still had the filters on the suction tubes.  One sending unit was brand new.

What gets me is that I have 2 filters before the carb, both are supposed to be able to filter the same micron size (8-10 micron I believe), yet it all makes it through the first filter and plugs the second.

I found a larger 4 micron filter to put inline for the time being.  I at least want to run the fuel out of the tanks rather than have to drain them and either reuse the already dirty fuel or else toss that fuel out.

[bake74]

    Not only should the tanks be cleaned, you better clean all your lines too.  That is a dirty filter, way too much dirt in there.

[ssapach]

So I took off the drivers side tank, there was some crud floating around the bottom. 

Funny, it was nice and clean when I put it on the truck initially.

Also, the little filter on the end of the suction tube had come off and was just hanging out in the tank doing nothing.

So I drained the gas out.  I drained most with a little pump/filter setup I made but then my pump quit working.  Then I took the tank out and dumped the remaining dirty stuff into a pail and rinsed the tank out a couple times with the hose.  I'll rinse it once more then take it back in and dry it out and have another look make sure nothing obvious is in it before I put it back on the truck.

Any other suggestions before I put the tank back on? 

After I get it back on I'll do the passenger side the same.  Then I might just put some magnetic lights on the frame and drive the truck a bit before I put the box back on, just to make sure its all running smoothly again.

[78 Chevyrado]

If it got that nasty, and you had already had the tanks out before this you need to avoid wherever you've been buying gas like the plague.  might be the station owner needs his tanks cleaned and is too cheap to do it.  that's incredibly dirty.  depending on what time you fill up, you may be showing up right after the tanker fills the stations tanks which is the worst time to fill up.  if you see a gas truck at the station, find another station to fill up at.  theres an old chevron around here that, no lie, if i fill up there my filter is clear until i run his gas through it, then it turns dark, fast.  so i dont go there anymore.

also if the carb filter is catching all that dirt to the point of clogging and you took it out, everything it would have caught is likely making mud in the float bowls of the carb.  if you can, unhook the fuel hard lines at the tank and by the engine, put some carb cleaner in it and blow it out with compressed air; repeat till what comes out is clear.

[ssapach]

Although the tanks looked clean before, there could have been stuff hung up where I couldn't see.

Also, I'm not sure about south of the border, but in Canada apparently all gasoline now has at least 10% ethanol.  I've been told that the ethanol actually breaks up any buildup in fuel tanks and lines that the gasoline alone wouldn't have a problem with.  So essentially it could have been fine if it hadn't been for the ethanol.  I'm not sure how true this is though.

Got one tank cleaned, dried and back on the truck.  I put the shop vac in through the sending unit hole and let it suck air through the tank for about 15 minutes.  Dried it up really nice inside. 

I sure hope it isn't all coming from fuel stations.  There is only the one station in the nearest town and that's where I've filled up the most so far.

I'm going to drive the truck a bit before putting the box back on in case I have another issue requiring the removal of the tanks again.

[bake74]

     78 chevyrado is 100% correct on everything he said, my own experiences have taught me the exact same conclusion.

[78 Chevyrado]

I'm going to drive the truck a bit before putting the box back on in case I have another issue requiring the removal of the tanks again.

That's what I'd do.  Be careful tho, it'll be squirrely like that, especially in rain with no box on it.

[ssapach]

With less weight on the back I'll really be able to feel the raw power of the old big block and 4 speed.

[ssapach]

So I got this all sorted out.  Drove the truck for about 120km round trip and then I removed the fuel filter.  Looked like this:



The last trip it didn't even make it 40km before getting too filthy to drive highway speed.

It's running great now.  I'm just hoping that the next time I fuel up I don't get a bunch of crud in my tank again. 

Also, the truck is a little rougher without the box on.  Not too much power that I'd lose control, but it was dry out as well.  But not smooth enough to want to drive like that for any long distances.

[VileZambonie]

Never get gas when they're filling the tanks. That's typically when all the crap and sediment will go right into your tank.