Hey guys, I decided after reading the FAQ that I should not be annoying and make a thread with several different questions, so I'll start over with this one:

Yesterday, the truck I'm working on (76 Supercab 2wd 4spd 300 c.i.) began runnning terribly, after its first drive on the road in years (it MAY have been started about a year ago, but I know for a fact that the owner let the truck sit for years on end - the tags date to 2002). It only had a little gas in it, so I think it got sloshed around along with the water and dirt that must have formed inside the tank. When I pulled the fuel filter off today, it was BAD - the gas didn't smell very potent, and was a darker amber color rather than the clear-yellow of new gas. So, with the new filter on, and a good dose of carb cleaner down the jets, it runs better, but still misfires pretty bad.

My question is this - i'm pretty sure that the carb will need replaced - but is it smart to put a new carb on while the fuel is still dirty? Even with a filter, it still seems like it might be a waste of time and money.

Should I stockpile some fuel filters, change them often, and try to clean out the old dirty gas with the old carb on?

Hmmm....


Thanks all!

JF

 

jfarcas, drop the gas tank and drain the gas out into some type of container, hopefully the gas tank has not been refilled.

Replace the rubber fuel line while you have the gas tank off.

When you got the gas tank back in and refilled with good gas, then replace the fuel filter.

Run the engine, and see how the engine is running.
Probably going to need a carburator kit or a rebuilt cartburator.

- buck -

 

Is there any way to avoid dropping the tank?

I'm sure it's a nasty chore on such an old truck, right?

 

Take to car wash or try rinsing the work area with a high pressure sprayer. Then Spray down with a Aero oil or a good quality rust penetrating oil all the nuts and the threads on bolts on gas tank prior to removing them.

The best way to clean the tank is to drop it, you can then visually inspect when the tank is clean.

While the gas tank is off, remove the fuel hose on the engine or by the fuel pump and blow out the fuel lines of any debri or cantaminants.

 

I'm not lazy, but I've done enough fuel tanks to know how fun they are so I'd prefer searching for an alternative route. (Thanks for the info though, I appreciate it!)

What do you think about this:

Keep a small amount of gas in the tank, about 2 gals at a time to pick up residue left on the bottom of the tank - run the truck on short, safe trips, change the fuel filter every other trip or so (they're only 2 bucks a piece, so I don't feel too wasteful about that) until the carb starts to runs smoother and the fuel looks real clean, then rebuild the carb?

 

I tried that approach on one vehicle that sat for several years. I should have done something more with the tank: Even after dropping the tank, cleaning and flushing it the best I could in the driveway, replacing the pickup tube, running three in-line filters, I still had brown sediment show up in the carb's fuel bowl after rebuild.

FWIW, I'm surprised those old carb gaskets have not started leaking...yet. I can appreciate not wanting to drop the tank, can't help but think you'll wind up having to do it anyway.
Keep us posted, Mike

 

Use a bunch of Chrevron with "techron"Fuel treatment
. Treat every tank. It's pretty good stuff.

 

Yeah, try running alot of fuel system cleaners, they do help, but nothing will beat fresh gas and a carburator rebuild.

 

First buy a large inline fuel filter and add it to the fuel line. A clear one perferably so you can see how dirty it is. Then run a high percentage (50/50 mix) of E85 fuel in it if its available in your location. That will clean it out real good. Prepare to replace the filter a couple times. Also it wouldnt hurt to open up the carb and inspect the jets to make sure they arent plugged.

 

Before you spend money on a rebuild kit.

Get the truck trunning and do this.

spray carb cleaner around the outside of the carb where the butterfly shaft comes out (I forget the actual term).This will determine of the shaft and bushing are worn out.
Spraying Carb cleaner in this area will show if it leaks in air or not.

Many times people invest money in a kit only to find out this part of the carb is worn out and is NOT replaceable.They don't last forever.

They end up just replacing the carb anyway.

 

Ok, so here's the update - I got the truck running much better than before, I think the main problem was all the crap in the filter line. It still misses, mainly at idle... but I found something real weird this morning that certainly had something to do with it. As I turned the ignition switch to "on" to toubleshoot some electronics, I heard an intermittent sparking sound, which I thought I had heard before but overlooked. I tried to locate to sound and finally narrowed it down to the wires that run to the ignition coil. With a test light I checked them and there was a horrible flickering in them! I ran over as many of the wires in the engine compartment as possible (I'm not the best at this kind of thing, but I'm learning..) and couldn't find the source - but then it stopped! I'm sure the problem with my misfire has something to do with the flickering of the electricity to the ignition coil, eh? I went over all the ground and rubber connectors, cleaned them, and reinstalled them.

That made me so happy. I've never seen that before.

I put some B-12 Chemtool fuel cleaner in the tank and drove it around town today and it drove MUCH better. I'm gonna go with the dual fuel filter setup, with a large clear one inline. I know a place that sells jet fuel - I had no idea that would actually help the fuel system, that's real interesting.

Anyway, I think it's gonna be okay. I'm planning on getting a rebuilt carb eventually. I'll check that throttle shaft for leakage, thanks for the advice.

And thanks to all you guys, I'll keep ya updated!

 

Here's a trick to know.

When looking for ignition problems like you just mentioned .

Do it when it is dark out .

They show up " Real Good " then.

When I bought my Mustang back in 1987.
5 guys were in line ahead of me.
They all turned the car down because it ran "Lousy".

I had a suspicion that it was ignition related so I asked the woman of I could stick around until it got dark. She made coffee and we talked for an hour.

Once it got dark we went back out and started the car up, popped the hood & you should have seen the "light show" from ignition wires and coil arcing all over the place.

I immediately told the woman I'll buy the car if she will accept $500.00 less so I could afford the repairs.

she accepted and 3 days and $150.00 later (all new ignition parts and more), the engine just purred .... so that weekend I drove it to a reunion 300 miles away without a problem.

"Do it in the dark "

 

Hey guys,

I decided to update this older post rather than starting a new one.

(FYI, I'm working on a 76 Supercab 2wd with a rebuilt 300 six/4spd)

I've driven the truck for a few months now, changing fuel filters every 300-500 miles, and while changing it the other day, I broke off the tip of the filter in the carb. housing. I cursed for a bit, then took the carburetor off, knowing that I'd have to drill and tap the threads. Check out all the rusty sediment in the fuel bowl:




My question is this: how much does it cost to get the fuel tank cleaned, and what kind of place does these things? How much harm would it be doing to the engine if I continued to run it in this condition?

(I've posted this in the 300 inline six forum and haven't gotten a reply)

Thanks again!

JF

 

Iv cleaned them out before by using a hot pressure washer.I guess the car wash would subsitute.Just pressure wash and let dry a few days.Also I dont know how good it is but they sell a DIY fuel tank coating kit.anybody used one of these kits?Does it work.Im afraid it will start flaking off and clog up everything.Im kinda interested for my tank..


Tim

 

Run the gas tank as empty as possible.
Read post #2 and #4 of this thread.
There are quality kits specifically used for cleaning and treating tanks.

If the tanks is very rusty, best thing is to replace the gas tank.