Idle on F head

I have a 57 CJ5 Stock F head.

today once it warmed up the idle went from normal to almost dying. it would sputter then jump back up...and so on and so on. after it ran for a while like that it would die and would not start. if i let it cool off it would run like a champ again. any thoughts???
I have an electric fuel pump that is pumping...it was on it when i bought it so i don't know the flow...what should it be?

Any help would be great...i have a big ride on sat and need some help.

Thanks

Tommy

 

Vapor lock is what???

how would i test the coil...

New fuel filter and fuel lines so that is clean. Thanks

Tommy

 

My guess it is somewhere in the fuel delivery. Any rust in the gas tank that could be restricting the gas flow to your gas pump? It is just a matter of elimination all the way to the carburetor. And if you have a solex carb there is a screen filter just below the gas inlet line. One of my jeeps had this as a problem and it took me forever to find out what was stopped up.

You can do a quick test of your gas tank by bypassing it. Get a small gas can and drop a rubber fuel line in it. Remove the gas line from your pump and attach this to the fuel pump. And put about a gallon of gas in the gas can and see if it still has problmes. Be careful with the placement gas can. Might want to do it outside and have a water hose nearby just in case.........

 

I will check the tank for internal rust...the rest of the fuel lines, filter and pump have all been replaced in the last 3 months. the only thing that was added was an electric pump...but i am not sure of the flow rate or even how to tell...it does pump gas throught the line consistantly but it doesn't seem like alot of gas. it only does this once the engine has reached warm...when it is cool it runs well...i found this out the hard way...after about 25 mins on the trail it started cutting out. it made it hard to get home.lol

Tommy

 

Thanks for the tip....i will give that a try and post back....

I really like that this site give good strong info and doesn't BS people around like some other sites...this place is great


Tommy

 

Once warm it will idle some but if i touch the pedal it will die... same with the hand throttle. it is like it starves out of gas. would a coil do that once warm? it seems to be getting gas fine in the carb but once it is hot it dies everytime i touch the gas and some times it just sputters out anyway after about 10-15sec.

Tommy

 

Sound like the exact same thing Glenn....i am picking one up today...i figure for 10 bucks it can't hurt to replace it anyway.
Plugs are new with the fuel system...same with wires

Tommy

 

I know you weren't being funny...when i replaced them they were nasty gone...some of the plug itself was melted...lol worst plugs i have ever seen

 

Not as likely as the other suggestions but what if your electric fuel pump is flowing too much fuel. The excess fuel slowly builds up in the bowl and closes the needle and seat. When the needle closes off, the fuel pump senses the pressure and decreases the flow. You let it set a few minutes and some excess fuel runs into the engine which in turns will cause it to run rough when you start it back up again. This will also foul out the plugs quicker. I had to install a fuel pressure regulator to keep mine down at 5 1/2 psi.
I also had a problem with the vapor lock on mine when it was hot out. My fuel pump is mounted low on the firewall on the drivers side. The fuel line runs from it up along the driver's side fenderwell then across the front of the engine. I had my fuel filter inline on the fenderwell and laying horizontally. This line was getting warm from the exhaust manifold. Also a friend told me to tip the fuel filter up slightly so the outlet was higher than the inlet. He said this prevents the fuel from getting air bound in the filter. With it tipped up the fuel pushes the air out of the line.
PS... my f-head had a miss on idle that went away as the rpm's went up. Points replaced with correct gap. Checked all the usual stuff with no luck. I set the dwell with a meter and it was off by 2 with the correct point gap. I adjusted the dwell and the the miss disappeared.
Good luck and sorry about the long post.

 

Thanks for the tips davet, i am going to try the coil this evening and see how it goes...if not i may try a regulator on my Fuel pump and a few other tips from here.


Thanks

Tommy

 

Coil swap worked like a charm...now all i have to do is find another windshield and i am set.

Tommy

 

Just managed to get my 134 running. I was working on points, timing, fuel, carb, fuel tank, wiring. Everything. It turned over. It would fire every now and then. Wouldn't run. Pulled the plug wires, determined TDC, and direction of rotation, reinstalled plug wires, rigged light to - coil, when I turned the distributor and the light came on I tightened it down, and tried the starter again. KABOOM she ran, not well, the timming was still off and what with the straight pipe it was a litttle loud. I turned it off loosened the distributor tried the start again and was met with starter growling and silence.
The moral of the verbage is the distributor relies on its block contact and clamp for the ground. I grabed a jumper cable attached it to the block and clamped it to the distributor body, checked to see if the points sparked when I bridged the gap with them open.
A weak ground might decrease the coil voltage and effect the straingth of the spark, causing your timing light to have a difficulty senseing the voltage spike, leading to no flash. Engine will run but timing light is intermitant. I sanded and brushed the dist, its clamp bolting area etc, cleaned everthing up and it starts right off.
Everything else said has also been true, the bad ground coming from the mechanical
connection is a little odd so I thought I would bore you with my experience.
Good luck