Running out of gas, but plenty of gas in tank!

Started working on the Jeep before I saw your reply. I installed the new fuel pickup and sock into the tank and started the Jeep. I took it for a test drive, and maybe made it three miles before it started faltering on me. I turned around and headed home, using lower gears, and coasting a lot. It stalled three times on the road up to my house.

When I popped the hood, the engine seemed unusually warm for such a short trip. The upper radiator hose was turgid and hot, and the radiator was hot to the touch. Carefully bleeding off pressure, I found the upper radiator hose and top tank full of nothing but air. I had plenty of fluid over the top of the radiator tubes, so I don't know why there was so much air pressure in the system. Thinking I actually did have vapor lock, I replaced the steel line that came out of the fuel pump to the filter with a full length of rubber line.

I did note while idling the engine that the fan did not seem to keep speed with the belt. It may just be because everything was hot, but the fan clutch was essentially useless. At one point, I was able to completely stall the fan with a rag, and it took a while to come up to speed. Now that it has cooled down, it seems to react like it should, so I don't know what to make of that.

I disconnected the fuel line and draped it down into a gallon jug, then started the engine and let it run for about 10 seconds. I got maybe a cup of gas. I don't know if that's enough or not.

Then I took the fuel pump off as you suggested, and it was indeed on the correct side of the cam lobe. It would have had to be, otherwise I would not have even gotten as far as I did. I manually actuated the lever arm twenty times and got twice as much gas or more than it did when the engine was running it. I did not get a chance to look inside the boar to see the lobe of the cam, because I had to get ready for work.

Tomorrow we are having a neighborhood gathering at our place, so all day will be cleaning before the event and clean up after. I hope to get back to this on Sunday.

My apologies, I don't know why those images loaded sideways, I took them correctly.

One other point of note, a neighbor whose friend was into Jeeps said they had a similar issue with one of his, and it wound up being a blockage in the return line on the frame. They ran the return line from the filter into a five gallon can of gas between the front seats, and it would drive like that all day long.

I don't I think mine is the same issue, because he was flooding out and I am starving out. If mine was flooding, it should pick up as I opened the throttle, but mine immediately falls on its face. Either way, I'm going to try it anyway to see what happens.

Pics for Medic.

Joe,

I ran the calculations, and I figured the cam turned almost 60 times in the 10 seconds I let it run (700RPM/60s=11.67RPS(crank)/2=5.83RPS(cam)*10s=58.3 revolutions). Given that I got more gas out of a third of the movements leads me to believe the lobe on the cam is short-stroking the fuel pump, causing my running-out-of-gas issue. Also, if the pump is so detrimented, it may also be providing a significantly lower pressure, most of which is probably getting lost through the return port. I wonder if I can boost it by blocking off the return line?

Plans Sunday involve inspecting the cam lobe through the fuel pump port and digging through my shed to find the Carter vane pump I know I have in there but just have to find. I'm tempted to plumb it into the fuel line near the engine, even though I know they're better pushers than pullers, but just to test it without having to cut into the new line. If it runs more than it has been even with that handicap, I'll mount it to the frame back by the tank.

As I said, I know the cam is worn because of the valve noise (which would also explain the lack of power, if the valves are also not lifting high or long enough to get a good charge), so it stands to reason that the pump lobe would be similarly worn. I'll let you know what I find out Sunday evening.

Thanks,
Nick

Joe,

No dice. I found the fuel pump and tested it, works just fine. Installed it, and wired it to the oil pressure switch, so it will shut off when the engine does. The only thing I would add is a prime switch that would mount under the hood that would allow me to run the pump manually for filling the float bowl.

I started the engine and let it idle. It ran relatively well, so I took off for a test drive. I made it about a quarter mile before it quit- the negative lead came off the pump. Fortunately there was still enough fuel in the bowl to start again, so I headed off again.

I made it another couple miles before it died again, so I pulled to the side of the road and checked the leads on the pump- all well there. The fuel had drained out of the filter, or it stopped filling, so I gave the carb a kick hoping there was enough in the accelerator pump to start it and allow the pump to kick on, which there was, and it did.

I continued on from there, and on deceleration I noted a strong popping from the exhaust, which in my experience denotes a lean condition. It idled fine, and accelerated strong in first gear, but I never made it out of third before it fell on its face again. I'd had enough, so I turned around and headed home.

It faltered pretty consistently the whole way home, so I coasted a lot. It stalled twice on the way home, but I was able to restart it and run long enough to limp it home in fits and starts. It was still idling when I pulled in the drive, so I raised the hood. The glass inline filter was covered in fine rust, which can only have come from the tank, and thence from the return line.

I'm absolutely stumped. I don't know if the rust I picked up is enough to stop the flow of fuel, but rust in the fuel is bad regardless. I'm going to pick up new lines for the return, and since I have to drop the tank to access the end of the steel line anyway (again, again), I'm going to siphon the tank, take it out, and rinse it out.

If it's still starving out after everything is clean and brand new, I'm just going to burn the bloody thing to the ground, I'm just fed up and getting nowhere.

Joe,

The tank is plastic, it can't rust. That said, it did have rust in it, likely from the return line. I dropped the tank last night, removed the tank from the guard, and washed everything. I sprayed the tank out with water, then rinsed it and let it drain. I'm going to paint the guard before I put the tank back into it, to prevent that from rusting away as well.

I'm in the process of replacing the return line today, so with the exception of the tank itself and the carburetor, absolutely everything in the fuel system will be brand new. Also, I had the needle and seat out of the carburetor 2 weeks ago when I rebuilt the carb, but I'll do it again just in case.

Thanks for your continued help, I appreciate it. I have never had this much trouble out of a Jeep before, and I've owned Jeeps of varying types for the last 25 years.

Nick

Joe,

Long story short, it's back to 'normal'.

Short story long:

I started by priming and painting the tank guard, then installing the lines my wife bought while I was out moving some dirt for a neighbor earlier. This morning. I pulled both filters and replaced them, and while the lines were off, blew compressed air through them. Predictably, I got nothing from the new return line, but I got a glut of blackish gas from the feed line. Not sure what that was about, as the steel and rubber lines were brand new day before yesterday, probably rusty gas, but at least it's all out.

I reinstalled the tank when the guard was dry, making sure the lines were not crimped by bad placement, and put in 10 gallons of brand new gas, not the stuff I took out last night in case there was rust in it. I rewired the fuel pump to include a relay to ensure full power to the pump, and made it so I can manually prime the line by removing a connector from the relay and touching it to the positive terminal of the battery. I did so, and found that the pump can very easily pull fuel as well as push it.

I pumped the pedal twice (that's what I meant by 'kicked the carb'), and the engine started straight away, with the fuel pump humming right along. I bid adieu to the wife, and ensuring I had my phone in case the trip went awry, I headed out on yet another test run.

I managed to make it further than I had in the last three trips, and pushed on. I had a hard time fighting back the consideration of hesitation as trouble instead of its usual weakness (which it was- it is still, after all, a multi-hundred-thousand-mile engine of unknown lineage). On the highway, I got it up to an honest-to-goodness sixty-something miles an hour (cable drive speedometers are a vague guess at best), and held it there for about ten minutes, when I got to the next town. I turned around there and headed back, bringing it back up to that sixty-something miles an hour and holding it until the next stop, my town.

I decided to take a chance and pressed on to the next town on the other side, getting it up to speed, dropping back for curves then ramping back up. There were a few hills, which I hit in 4th and held to see how she would do under load (where she faltered most a couple weeks ago). She put her rusty old shoulder into it and just pushed, and while we lost almost 10 mph by the time we crested, she did NOT run out of gas!

I took what we call "the back way home, " a twisty country road, and I pressed her as hard and fast as I dared flog a 39-year-old clapped-out Jeep on curves to test her under more varying loads. We were back on the gravel before I knew it, and had an uneventful trip home.

So, if I make the last repair the genesis of the problem, it was the rust from the return line (or that combined from the original feed and return, over years of sediment) in the tank. But the gist here is, I replaced EVERYTHING except the tank and carb, making sure both of the latter were washed clean but good, and only then had success. What a bloody nightmare.

I don't know if the cam is entirely at fault, but I'm going to leave the electric fuel pump in place. I still have the mechanical pump in as well, just in case the electric one decides to go out. I have a 4.0 H.O. Waiting in the wings to install, and this 4.2 will eventually be kitbashed together with another 4.0 H.O. To make a stroker for my '82 Scrambler.

Joe, thanks again for your help, I greatly appreciate it.

Nick

Joe,

Yeah, my Scrambler came with the execrable T5 as well, and the God-awful 2.73 axle gears. Our '82 CJ-7 (the recent patient) has the same gears because it also came with a T5, but some previous owner was savvy enough to trade it out for the T-176 and shafts. I plan to change the gears out for 3.54s. We're not going to lift or wheel it; it's actually my wife's Jeep and she wants it 'just a little beefier than stock'.

The T5 in my Scrambler locked into third gear a few months after I bought it when a shift dog came out of place and stuck the synchro to the gear. I rebuilt the transmission, and after seeing a slew of red Permatex as I disassembled it, I realized I wasn't the first guy to get into the guts of this thing. I wound up having to replace the input and main shafts because the needle bearings between them had destroyed them both- a fatal flaw due to the design of the input shaft collar and shim setup. I spent $650.00 rebuilding it, only to have it fail about 3 years later when the input shaft bearings went out _again_ (it would make a steel-gargling noise in every gear but fourth, the only gear where the input and main shafts are turning at the same speed).

I scrapped it and built a T-18a from a 1978 F350 using a Novak conversion. It's an absolute bombproof trans, but my mileage went from 18 to 10 with only that change! Had I to do it over again, I would try to find an AX-15; I had one of those in a '95 XJ, and it was a great transmission, never a problem. If it hadn't been only 2wd, I would have it still today, but I sold it.

Nick