My weak F-134 engine

Hello all.

I have some major problem with my F-134 engine. I will describe it all and its going to be a long one:
(sorry for my english...)

General - My CJ-5 has F-134 and standard ignition and fuel systems: points dist. + ball. resistor + Carter YF + mechanical fuel pump ...
I own that jeep (and engine) since 1986. Its not my daily driver for many years. Since 1986 i didnt open the engine but adjusted the ex. valves and install a newrocker arm.

Symptoms - For years i know my jeep is weak. Hard to take up hill and sound tired (compare to other cj-5s). When the engine work on idle it sounds good and 'round'. In the last year it began to be so weak that even taking a turn on paved road makes him hesitate. Sometimes its just shut off while standing in the traffic lights. The main problems are not when i drive in line but on turns.
The engine doesnt smoke but my spark plugs are always black (dry) and it seems to let out a lot of vapors from the 'pipe' (i use drop tube from the ex. valves).

What i already did - I rebuilt my Carter YF and adjusted it. I changed my YF with another one. I rebuilt my fuel pump. I took off the ball. resistor and then install it again. I changed the ditr. and adjust the points. I even changed the fuel filter several times. Doesnt matter what i did - my F-134 will not like to make an effort as turn on a paved road.
I didnt suspect the coil or the spark plugs wires so i didnt touch them (yet).

Future - ?
I finished all my ideas. The next step is to take the engine to leakage test.
Any ideas?

Ziv

 

Maybe your exhaust system is plugged (muffler) or tail pipe bent restricting good exhaust flow. A compression test is a good idea. With the draft tube it is hard to see any engine blow-by while going down the road. By removing the coil wire from the cap and holding it close to engine while someone cranks engine should give you a nice blue spark about a 1/4" gap or more, will indicate a decent coil. Check each plug wire the same. If weak spark, you may have burned points and/or bad condenser.

 

Black plugs indicate too much fuel, I would think.

 

I had the same problem. Engine ran smooth on idle and had good compression but no power when driving. It had sat for years without use.
The distributor was not advancing so no acceleration.
Pulled the distributor and sent the whole thing to a guy in San Diego Calif. that specializes in rebuilding old distributors.
He also "recurved" it a little to provide even more acceleration than stock.
Came back looking like new if not show quality. really peped up the F 134 to better than original acceleration.

 

1. Check the compression both dry and with a little oil in the cylinders and report back the results. If compression is not even or close in all cylinders or if less than 100 I would rebuild the engine.


2. If compression is good (100-120), then I would check the timing, and check for vacuum leaks. (Black plugs could be too much fuel... or a vacuum system leak)

3. replace the coil, get a new distributor with electronic ignition and try it out.

 

Thanks all.

I will try new directions from all the inputs above: coil and all the ignition system. Also cheack the condenser. I already bought electronic distributor but it will get to the holy land in october.
After or prior to all that i will do leakage test. I dont trust the simple compression test, as i understand it (put compression gauge to each cylinder and give a quick start).

Thunderpig - please explain your first two ideas.

I will report my progress.

Ziv

 

In the compression test. You do a standard compression check with the gauge connected to each cylinder (one at a time). Crank it over a few seconds and check the reading. Normal should be 120 on all four cylinders (new) but a used engine like yours will likely be lower than that. Probably 100 or greater is acceptable. All cylinders should be similar in readings. For example 100, 105, 103 110... If you get 100, 85, 102, 108 or something then that means something is wrong with cylinder 2. It doesn't tell you what's wrong....yet.
If your compression readings are good the first time, you do not need to do the following!

Now repeat the whole procedure but squirt 10cc of motor oil into each spark plug hole first. Then check compression again.

If your piston rings are worn or even broken, the addition of oil in the cylinder will cause the compression to improve significantly.

If the addition of oil does not improve compression then you likely have a valve problem.


This maybe be the same as the "leakage test" you are refering to.



Then my other idea is to check your vacuum system. Easily checked by spraying carburetor cleaner along the entire length of the vacuum system tubing and connections. While engine is idling, listen for the engine to draw down when you spray. That indicates a leak at that spot.

 

Thunderpig,
The "Leakage-test" I have heared of is by pushing some air pressure (i dont know the recomended psi) to one open spark plug hole. If the pressure stay steady its o.k. If not, then you have to listen to the place the air will come out of. You do it to each plug.
Im not sure i understand all the logic behind that method.... and probably i miss some parts of it.

I just have to find the time to do it. That is the main problem right now. This cj-5 is my "summer jeep" because its soft top that you can roll-up in the crazy summer here.

Ziv

 

O.K

I replaced the coil and get the same symptoms. I also noticed a very (very) small fuel leakage from the fuel line, which i have to fix again.

So i did the compression test described in the mechanics manual. By that method i cranck 4 continuous times for each cylinder and wrote each reading:
cyl 1 - 90 100 120 120
cyl 2- 90 100 110 120
cyl 3 - 60 90 100 110
cyl 4 - 60 90 100 110
according to the method, i added a bit of oil engine to each plug hole and did the same again:
cyl 1 - 90 130 150 160
cyl 2- 80 110 130 130
cyl 3 - 90 120 125 130
cyl 4 - 90 120 130 130

Any ideas? my valves?

Ziv

 

those #'s look damn good to me. heck i would say brand new you wouldnt have much over 120 psi

 

If compression is good and ignition is good, might check timing and advance of the distributor.

 

Howdy, with black plugs and stalling on cornering I would first suspect the carb float was set too high, flooding the engine, but you have tried another. Not likely that both were set wrong unless the manual you are using has a misprint.
Just grasping at straws now. Could it be that the body is shifting on worn mounts and causing a ground wire to come loose, hince the problem going up hills and around corners? Or the other case might be a power wire (like to the coil) shorting out under similar conditions.
You also said it stalled in traffic. Does it restart easy? Is it worse when it is warm or cool? Will the engine clear out if you rev it up with the clutch in or in neutral?
Does it sputter, blubber or backfire going downhill without giving it fuel?
Stupid me, I thought it was always Summer there!

 

Fuel pressure too high? Maybe a fuel pressure regulator is in order.

 

You may have something in the tank that is moving around and blocking off the fuel line on hills and in the corners.

One of my old trucks had the cap left off one season by a previous owner and hornets got in and built a nest.

Pieces of that floated around in there and would get sucked onto the outlet by the pump and close off the line. Blowing back through the line with a hand pump would clear it till the next time. Usually occurred when I let the fuel level fall below a quarter of a tank.

 

Mr. Gangrene. look at my answers above.

 

In that case i will expect the fuel pump to be empty in the moment it shut-down. This is not the case. Its always full or close to full.
Ziv

 

Can you compare your fathers CJ5 to yours and see if there are any physical differences in the two?

Does your oil pressure drop off just before you loose power?:hurrican:

 

1960willyscj5-
My fathers cj-5 is normal and has much more power. I had a strange idea to switch parts and try to find the problem that way. Its just a double work.
About the oil pressure-i didnt notice that. Will try next drive.

Ziv