running poorly - F-head

Well, so far I have replaced the Carter YS carb with a good rebuilt one, replaced the fuel filter, blown out the fuel lines,installed new spark plugs, and just tonight, replaced the fuel pump and added $10 gas.
The Jeep starts and idles fairly smoothly when cold - 1/2 choke or so, but misses and kinda bogs on acceleration -will not maintain a steady rpm - So I took it around the block and it has no power - after a couple of trips around the block, it did not have enough power to back itself up the driveway without revving the snot out of it - I had to put it in low range (fairly flat driveway too). Heard some pretty good misses from the tailpipe as I got toward the garage.

I have to be missing something simple, right??

 

My first thought was points, too.

Or maybe a vacuum leak?

Pete

 

Tune it up. I originally bought my 46 from a guy for $200 because he couldn't get it to run. I had to tow it home. Tune up was all it needed (except for the rust)

 

sounds like timing. Grab the distributor shaft and see if you can wiggle it from side to side. Watch the points gap as you do this. You could have bad dist. bearings. been there. done that.

 

Same here, Points,condenser,plugs,wires,coil and carb. Thats about all there is to em

 

Well, no points anymore - Pertronix conversion was done this summer -
This is getting frustrating - These little Jeeps are dead simple, and I keep swapping parts with no effect.......
It all started (pardon the pun) when it stalled pulling out of my driveway (see F-head stalled post earlier).
Thanks for the insight -

 

I thought the Pertronix either works or doesn't, no inbetween.

 

I had one that drove me crazy too..Here to find out it was the gas line..It was new also BUT it started to break apart on the inside thus restricting the gas flow , ran like crap ..Its just a thought only costs 5 bucks for new line ..also take your air hose and blow air through the gas line to the tank .(take the gas cap off) I have seen idiots blow apart there tank for this stupid trick..some old gas tanks have a filter inside them looks like a chids sock..Try it ..If your iginition is okay,timing okay dwell okay whats left.......FUEL .....Let us know...

 

i know this may be really obvious but have you tried playing with the feul mixture? my jeep was running poorly because it was running way to rich i leaned it out and its running much better now. its always the simplest things that i over look.

 

If yur kid holds the end of the plug wire and jumps when you rotate the crank, then you got spark

if the pump sprays a liquid line 4 feet or so then you got gas.

check timing (could have jumped a tooth or more in timing gears)
check carb base settings.

take your hand pump and pump backwards from the pump to the tank. to blow out the lines.

My old '51 pickup was given a new (old) tank by a PO that had the cap left of for some reason... made a real good place for the local hornet community to build their nest in... found this out when I blew back into the tank and small pieces of nest were floating around in the gas I could see through the inlet under the cap. this stuff will block a line and starve the carb and pump.
Aggrevating.
Ping Pong balls do the same thing.... or did some one sugar your tank when you weren't looking?

 

Massive vacume leaks? Carb still firmly attached?

I hesitate to ask but if its running incredibly hot ( no H2O in the the radiator) it can act like that. Low oil quantity can also cause problems.
The low water or no flow cause excessive block and intake manifold temps. The fuel isn't just atomized it vaporizes and the engine runs lean, causing more heat and loss of power. A bad water pump, blocked crimped hose, siltation in the bottom of the radiator blocking the return, low water quantity.

Low oil quanty can cause higher operating temps, it can also cause lose of compression in the cylinders due to oil not lubricating the rings, higher blow by in the crankcase.

Either of these problems appear to go away when the engine cools then reappear as the operating temp is reached.

2 cents from southern Illinois

 

I vote for tuneup/timing also. Throw a vacuum gauge on it too. It should have 15-20 in.Hg. at idle and the needle should be steady, not jumping all over the place. Run a compression check too and let us know what you get.

 

Gonna try to get out to the garage in the next week or so - I'll keep you posted on the progress.....or lack of.

 

Well, I swapped the distributor cap and checked for vacuum leaks (found none) plug wires did not appear to be arcing at all - no change.
The Jeep will idle for a few seconds, then start to bog down and die out. If I pump the gas I can get it to stay running for a bit.

 

Crazy thought. When you put in new plugs, did you try to upgrade? I ask because I did that, but was not able to supply them with the power they needed to produce the "bigger spark". Switched back to what was called for, and everything smoothed out.