1961 CJ5 Starting Issue

[Simpsomt]

Ok here's a mystery - recently bought a 61 CJ5 and instantly ran into issues while driving. The Jeep would suddenly die and wouldn't start back up. Took a look and notice the gas tank was full of rust. I assumed the gas tank was the culprit behind my issues so I replaced the tank, in-line fuel filter, fuel sender, took the fuel pump apart and added fresh gas. After putting everything back together now it wont start. Any ideas?

[LarrBeard]

After putting everything back together now it wont start. Any ideas?

Since you had fuel issues, let's start down the fuel system.

Pull the gas line at the carburetor. Crank the engine and verify fuel to the carburetor. Pull the top off the carb. Make sure that the needle valve is open and fuel is in the bowl. I would not be surprised if you had crud in the carburetor.

If that's working, pull a spark plug wire and verify spark at the plug. Pull a plug. Wet, dirty, nasty, worn out?

That should at least give you an idea if you are missing fuel or spark - and you can move on from there.

[Simpsomt]

Looks like I am not getting any fuel to the carb. I pulled the gas line and cranked it a few times and got nothing. Does that mean I have a leak in my gas line somewhere or is my fuel pump bad?

[LarrBeard]

Looks like I am not getting any fuel to the carb. I pulled the gas line and cranked it a few times and got nothing. Does that mean I have a leak in my gas line somewhere or is my fuel pump bad?

Well, we've found at least one problem. I would undo the gas lines and blow them out with air. The fuel pickup in the tank could have crud in it. If the lines are clear, maybe the fuel pump, but I'd jury rig a gas line to the pump inlet and see if it will suck fuel from a gas can before I'd pull it off. With your history of a nasty gas tank, I'd suspect a plugged line.

[gmwillys]

Wasps and bugs tend to find their way into the pickup of the fuel line. It doesn't seem to matter if the fuel cap was on or off, the little buggers find their way in. Rust is another common culprit.

[Simpsomt]

Wasps and bugs tend to find their way into the pickup of the fuel line. It doesn't seem to matter if the fuel cap was on or off, the little buggers find their way in. Rust is another common culprit.

OK I cleaned out the gas line and made sure everything was tight. It fired right up and ran great. Took it out to lunch and ran a few errands. Came back to the house and parked it. Went to take it out for one more errand a few hours later and started OK but as I started driving it the engine started to sputter and then quit. I limped my way back to the house but it was pretty dicey. For whatever reason it didnt want to idle and kept sputtering and even back fired a few times.

Also noticed this afternoon my oil light kept coming on when I would hit the gas. I checked and I have plenty of oil.

Any ideas?

[LarrBeard]

If it makes you feel any better, you are having typical issues people see with old Jeeps that are starting to wake up and run in a second or third lifetime.

Because you had what looks a lot like a fuel line issue, I'd clean out the lines again to get that last little piece of crud out of things, Check the fuel filter again - it may have loaded up.

A backfire usually isn't a fuel issue - it says that a valve was open at the wrong time. I wonder if you could have a valve sticking open?

The oil light coming on is a new one to me. It may be totally unrelated to everything else. Any noises that would indicte low oil pressure at the time?

[Simpsomt]

Great question.. I just installed a new muffler so I am still getting used to all of the noises. That being said, I dont think I heard anything unusual when I lifted the hood. What type of noise should I be listening for if it's a low oil pressure issue?

[LarrBeard]

What type of noise should I be listening for if it's a low oil pressure issue?

The first sign of low oil or low oil pressure in most engines is an increase in lifter noise - a lot of clattering. I've heard it said that hydraulic lifters have saved more engines than oil pressure gauges or oil lights.

The other noise I have heard when oil pressure gets very low is a solid thunk-thunk from down deep in the engine - a lot deeper toned "thunk" than ignition knock.

You drive an old Jeep as much by your senses as any gauges. You listen for strange new noises. You feel different vibrations. You smell fuel leaks or the sharp oil smell of gear lube vs. the normal fumes from the little oil leak around the valve lifter cover.

[Simpsomt]

Crap - I just started it and am hearing a lot of noise. The dipstick says it's full of oil. Should I drain out the oil and start investigating? Any recommendations?

[LarrBeard]

Crap - I just started it and am hearing a lot of noise. The dipstick says it's full of oil. Should I drain out the oil and start investigating? Any recommendations?

I hate to try to troubleshoot by email and remote control = I almost always never have all the information I would like.

A. If you have not changed the oil, by all means do so. Look at the oil you drain out. Is it all oil? Is there water in it? Does it have gas in it? Water and anti-freeze whip up into a frothy mess that mixes in the oil. Do you see any metal shavings in it? I'd change the filter as well.

B. Can you get an oil pressure gauge that you can connect into the plug where the oil sensor mounts? That will tell you if you have oil pressure or not. At idle even 10 PSI should be enough to prevent engine damage, but you should see 30 PSI for a good engine. Low pressure could be oil pump, or badly worn bearings internally.

This is starting to look like more than we can do as an email troubleshoot - you might need to get a mechanic to look it over. In an hour or so he can probably give you a good idea of what is going on in that engine,

[Simpsomt]

I got the oil changed out and didnt notice anything out of the ordinary. I will try to oil pressure gauge tomorrow evening.

[gmwillys]

Noise isn't always the end of the world. If you didn't find metal, then some fresh oil would help. With a known good oil pressure gauge, check the pressure. Also pull the the valve cover to ensure oil is getting up to the top end. Most likely if there is noise, it comes from the top end first.

If you do not have any/low oil pressure, check the distributor where it connects to the oil pump drive. I have heard of, but not seen it personally, where the end of the distributor breaks off.

[LarrBeard]

I got the oil changed out and didnt notice anything out of the ordinary. I will try to oil pressure gauge tomorrow evening.

Clean oil always helps and not having any unwanted additives in the old oil gives you some confidence that you don't have an internal crack, head gasket leaking water into the crankcase or bearings scraping themselves into filings.

The oil pressure gauge will give you an idea as to just what is happening with lube for the top and bottom end.

gmwillys is right - noise isn't always bad. F 134 lifters make more noise than people are accustomed to in modern engines. In my '48 there is one lifter that takes about 30 minutes to get warm enough for the click-click to quieten down.

But - it seems to have started again....

[Simpsomt]

Checked everything out last night and had good oil pressure. Thank god!

[gmwillys]

That is a relief. So, how did it run after sitting?

[Simpsomt]

Didnt get a chance to take it out last night. Hoping to get it out tomorrow for a bit!