OT, or maybe not - Trying to restart truck that had bad gas

[stembridge]

No, not THAT kind of bad gas, but the kind that comes from sitting out for 6+ months without stabilizer in the tank. This is an '81 F-150 (straight six carbuerated engine) I'm fixing for a lady at our church that her son-in-law had messed up trying to repair a gas tank fuel filler hose problem.

Got the filler hose fixed, but I'm not getting much (if any) fuel to the carb and it won't start (except on ether, and then only for a second or two). I suspect the old gas jellied and is blocking the fuel lines. This truck has the engine-driven fuel pump (same as my '69). I did siphon the old gas out of the tank before I reinstalled it. It has about 4 gallons of fresh gas in it right now.

Anyone had to solve this kind of problem before? I'm open to tips. I plan to disconnect the fuel supply hose at both ends and try to blow it out tonight.

Should I also plan on rebuilding/cleaning the carb & fuel pump?

Thanks for any experience you can share...

es

[FORDification]

I doubt the gas has jelled up in only 6 months. It normally takes a while longer than that. However, it's possible the fuel lines and/or sending unit sock ARE plugged up. I'd start by removing the rubber fuel line (from the tank at the fuel pump and try blowing some compressed air through the line to clean it out. If that appears to be OK, then I'd reconnect that and disconnect the output side of the pump and crank the engine over and check for proper pump output.

[stembridge]

Well, I verified that the lines are clear from the tank to the fuel pump, but when I tried to blow air directly into the tank pickup tube, it's completely stopped up, so I think that's where my problem lies.

I should have some more time tonight to try and poke a wire through the tube and clear it out. I'm REALLY hoping I can clear it without having to drop the tank again!

es

[stembridge]

Thanks for the info. I got it running last night - woohoo!

The gas must have been sitting longer than six months, because it stunk to high heaven! I siphoned as much out as I could get (virtually all of it) while I had the tank out.

After determining that I had a blockage in the pickup tube (part of the sender unit in the tank), I was able to clear it (without having to drop the tank again) by pushing a piece of 12-gauge copper wire through the tube.

After more non-productive cranking, I verified that I was getting fuel up as far as the carb, so I next removed the top half of the carb and jiggled the float around. Sure enough, I heard a pop and a little gas spurted out of the float valve area - the valve had glued itself stuck with the old gas.

I filled the float bowl with gas and put it all back together. It started right up and seems to be running fine now.

Thanks again to all who responded!

es

[stembridge]

Well, it's not fixed again. Got about 3 miles down the road, running good up to that point, and it started hesitating worse and worse until it finally died.

My suspicion is that the rubber (non-fuel-rated) hose that the last person to work on the truck installed is collapsing and starving the engine. When I would let the truck sit for a few minutes, it would crank right up, and then choke and die within 30 seconds.

I have 15' of new fuel hose in the car, which I'll install tonight. Hopefully that will fix the problem...

es

[FORDification]

If you do have varnish in the tank and carb, I'm sorry to have to tell you this, but you're going to have to remove and clean them out. You might have gotten enough of the varnish out to initially start it, but it's going to continue coming loose and plugging things up.

However, it might be the gas tank venting. Is that truck's tank vented, and if not, are you using a vented cap? The next time it runs and then dies, immediately try removing the cap and see if there's a whoosh or rush of air. If so, you need a vented cap.

[stembridge]

Good point on the vented cap - it appears to be one (it is a locking cap that "snaps" in and you use the key to remove it). I did try starting the truck with the cap off before I fixed the stuck float, but haven't tried that since. I'll give it a try later this week (gonna be tied up with revival services at church through Wednesday!) and see if that helps. It makes scence, based on the way the truck is acting.

With regards to varnish, an old hot rodder at work told me to find a product called "Sea Foam," which is supposed to clean out the varnish without having to pull everything off. Anyone ever heard of it?

es

[stembridge]

It's not the gas cap...



Guess it's time to pull and clean the carb!

es

[stembridge]

I think I have it fixed now.

I pulled and cleaned the carb (looked pretty clean, but I shot carb cleaner through all the ports anyway) and put it back on. Blew air back through the fuel line, and verified bubbles in the tank.

Then, on a whim, I poured another 4 gallons of gas in the tank (I had put 3-4 gallons in it after I originally reinstalled it). I think that's what did the trick. I guess the tank pickup must not hang all the way down to the bottom of the tank.

At any rate, I did circuits around the house and machine shed for 15-20 minutes, and then left it to idle for another 15-20 minutes. It tried to quit on me once or twice while making circuits, but I was able to fast-pump the pedal and after coughing up a big black cloud, she cleared out again and ran smooth.

I'll run her again tonight, and if she stay running smooth, will take it back to the owner (who is still without a vehicle) this weekend.

Thanks again for the suggestions!

es