At high speeds the 47 hesitates. Im talking 55-60 mph. At low speeds no problem. When it does do it, if I ease up on the pedal alittle it stops. As soon as I increase speed it does it again.
Rebuilt Carb. New points, condenser, cap, rotor, vac. advance.
Timing is dead on the ball. New points set to 18. Valves adjusted. SLIGHT little miss on Idle, I cant seem to get rid of.
Other then that it drives great. Im STUMPED !!!
What you describe is typical of fuel starvation. Could be the result of a bad fuel pump. If there are any leaks (bad connections) in the line from the fuel pump to the tank. If you have a filter in the line somewhere it could be the culprit.
First thing I would check is the coordination of the throttle plate and metering rod. Also check to make sure that the metering rod and high speed jet are the correct ones for the carb, make, model and year.
If it is fuel starvation from fuel pump or fuel line it typically takes a short while at the high speed for the hesitation or pulsation to occur.
Thanks for the replys Ray, and chipper. The hesitation does take awhile to occur at the high speed. Will change the fuel filter, and check the lines, and clean out the pump bowl. If it still persists. I will change the pump. Will let you know what happens. Thank you both again!
That slight miss at an idle could be a vacuum leak, I chased one and found it was the vacuum line going to the vacuum advance.. I also agree that the high speed hesitation could be fuel starvation, the float could be set to not open soon enough or shut off too soon. along with several other things.
Is it at the same throttle detent, or at high speed while under acceleration? I had a similar if not identical problem with a 62 Imapala with a 235 and a powerglide, and it was fuel starvation, I had a slight crack in the rubber hose connection from the tank to the steel fuel line, and it was leaning things out under a real demand. Is the engine running hotter? A lean mixture is a hot mixture. I noticed it more climbing hills and SUSPENSION BRIDGES (I will never forget that!!!!)
I thought that I had a problem with the strainer in the tank, so I was blowing back the line with compressed air and heard air leaking from under the car, when I closed the cap on the tank. Even though the system was vented it could not keep up with the volume of air that was going into the tank, forcing it to find the crack in the hose
Good luck
John
oops I hit the button twice, sorry
John
Replaced the fuel filter, Cleaned out the pump bowl & screen.
Blew out the lines from pump to carb, and tank to pump tonight. Checked for leaks, and found none anywhere.
Took it out for a test drive, and the hesitation was still there.
When ever Im cruising at about 50-55 no problems. As soon as I try to accelerate, and it reaches about 60-65 she starts to buck.
I let off the gas to 50-55 again no problems.
Should I replace the pump?
Try replacing the pump as a test and see what happens.
:) :grin:
The pump is the most probable cause....Sounds like a text book example.
I had a "48" that stalled at high revs. I had the carby rebuilt (at great expense) plus a new fuel pump; all to no avail.
Ultimately we went for a run without the air filter and the problem went away. What it was is that there is a piece of felt in the top of the filter and it had shrunk with age and the edges were no longer located. At high revs it was sucked down and blocked the air flow. Tossed it away and no more problem.
Just a thought to consider.
Terry H
Ordered a pump from Chevs of the 40s. Hope to see it by Wed. Will post with the results. Thanks again to all who reponded.
Every owner of any "antique" car should have a new spare fuel pump in the trunk. If for no other reason just for peace of mind when you are on the road.
Make sure that the fuel pump has a modern diaphram. Most of the original pre-80s diaphrams will not last with the alcohol and other stuff in modern gas.
Just ordered another one for the Trunk!! Thanks Gene!
I also just orderd a spare pump fpr my truck just in case. Thanks Gene and the Filling Station loves you...Oscar :love: :love:
In all the thousands and thousands of miles of driving my old cars I only had to change the pump on the road once. The carburetor was dry and not getting gas.The fuel pump didn't help because there was no gas in the tank to pump. :)
I have changed more than one at home though, mostly due to oil leaks. Also I can tell when the pump is getting weak, it takes longer for the carb. to fill after the car has sat for a few weeks.
Hey Oscar,
You and the pick-up and those new plates will do just fine. AND, look great. Where's the show.... Redding??
What happened with the 53 Bel Air over the weekend???
Bill.
Hi Bill, the show I am going to is in Durham. It's right next to Chico. About the belair. I went and drove it on Friday and it drove pretty nice. She was as stock as can be. She needed chrome work due to the KO chrome in 53. I told her I wanted it. She said she had to go to Sacramento for her grand daughters graduation and would call me on Monday. I waited all day yesterday for the call and when I got home I left a message on her cell phone to call me. She called back and told me she sold the car to a gentleman about 3:00 P.M. She said she thought I was going to call her but she was suppose to call me. I was ready and excited but sometimes things don't work out the way you want them to. I'm not losing any sleep over this because I will find another one. Have a good Chevy day...Oscar
:cry:
Oscar,
You should definitely get some nice weather up there. Usually lots of sunshine in Chico.
Weird how the 53 deal went. Good to hear you're not all wacked out about not getting it. Even just re-chromed bumpers cost big bucks. Who knows what other 'needs' it might have had. Altho the purchase price was fairly low. As you say, another one will come along.
Have fun in Durham / Chico.....
Bill.
Thanks Bill and if I win a trophy for 1st in stock I will be a happy camper...Oscar
:cool2:
Oscar,
I'll bet you would be. And if you don't it'll still be a great outing. 300 miles in the pick 'em truck!! Change of scenery and so on. You might even spot another '53 Bel Air along the way!!!
Have fun!!!
Bill.
Installed New Fuel pump from chevs of the 40s. Hesitation is even WORSE now. Cannot even get above 40 MPH without violent
jerking like the car is running out of gas when I try to accelerate???
Check the dip tube in your gas tank. It might be slightly blocked which could also cause your hesitation problem.
:) :grin:
Could a hole in my Gas Tank cause this problem???
No but water in the gas could. Did you blow out the gas line from the fuel pump back? If you use the 10% Ethanol gas the water should not be a problem unlless there is a ton of it. You will also see the water in the fuel bowl with the gas floating on top.
If all else fails I would rempve the carb. bowl cover and see if there is a load of junk in the bottom of the bowl obstructing the flow into the main jet (where the metering rods fits into)....or trade it in a on good '39.
Gene,
Yes, I blew out the line from the pump to the tank. I heard it blow in the tank like there was no obstruction. I already had the carb. apart, and cleaned that out also. There appears to be no water in the gas. This has really got me confused!!!
Im hitting dead ends on everything I try?
It could be an ignition miss. You may have done this but the first thing I would try is a condenser, then points, then plugs, then a coil if I had a spare....and the low tension wire between the coil and dist.
Rebuilt Carb. New points, condenser, cap, rotor, vac. advance.
Timing is dead on the ball. New points set to 18. Valves adjusted. SLIGHT little miss on Idle, I cant seem to get rid of.
The above was mentioned in his first posting, but one of the new parts could still be defective.
Talked to one dude a long time ago that had the exact same problem. He blew out the fuel line between the pump and the tank and there was no restriction. The air was blowing back just fine, however the same "starvation" for fuel problem persisted......especially at higher speeds. Finally discovered that there was a large piece of debris in the tank and the sucking action from the fuel pump would suck the debris into the dip tube and when there was no sucking action from the pump the piece of debris would roll away from the dip tube. It all depended upon how fast the fuel pump was pumping as to how badly the dip tube was blocked which related directly to how much fuel starvation he had.
:) :grin:
I had the problem JYD mentioned, after fighting the problem for several weeks on our 1965 Pontiac family car. I did all the things you have done plus I almost burned the car, I disconnected the coil wire and the fuel line at the carb, this took a while on the side of the road. When I had my wife hit the starter while I watched to see if there was fuel flow the fuel pump pumped a good stream of gas onto the manifold, which was promply ignited by the coil wire laying on the manifold. My wife helped me throw dirt on the burning gas by throwing a handful of gravel down the throat of the 2 barrel carb. after I got the fire extingushed I then pulled the intake and cleaned the rocks out. When we got home, after several delays of 15 minutes each 20 or 30 miles, I pulled the gas tank. Small children, ours or neighbors had put several items into the tank. One of them was a cellophane wrapper off of a cigarette pack, it would suck down over the small brass screen tank outlet, plug off the flow, then when the pump quit pumping the cellophane floated up and the process started all over. Before you pull your hair out go the extra mile, check out that tank, and the line from the tank to the carb.
If you think this story is too strange to be true, just ask my wife, she has no reason to lie. And she has her memory back after brain surgery about 15 weeks ago. She remembers some things I wish she would forget.
Nothing coming from you would be too strange to be true. :)
Nothing coming from you would be too strange to be true.
Man, ain't that the truth?!!!
:/ :grin:
The truth shall set you free!
I just met your brother at a judges meeting this morning. Impressed me as a much better trouper than you. Fair evaluation?
Story from about 20 years ago. Happened at Pontiac dealer that I call on. Mechanic pushes no-start car into his stall. WAs a Pontiac 6000 4 cyl....in which the spark plugs are in the front of the engine. He sees that the engine is flooded so removes the spark plugs and proceeds to turn the engine over with the starter to blow the excess gas out of the cylinders. The spark plug wire connectors are hanging there in front of the engine. The "spark" ignites the gas and the gas hits the service dept. wall along with the flames. Result, badly blackened wall. Fortunatly nothing caught fire.
Story from about 50 years ago. I was trying to start a 1949 Cadillac. Used oil pump can filled with gas to squirt some fuel into the throat of the carb. Engine backfires in the process. Flame follows stream up to nozzel of squirt can. My heart stopped.
I am sure that we have all done some stupid things and lived thru them.
Raymundo,Actually My Bubba was trained as a peace officer, and that makes him somewhat of a trooper, everything else I taught him well.... Raymundo from what I know about you, I would be suspicious of any evaluation you came up with (FWIW)
But he is an ok guy, just don't make him angry.
Bookem Danno.
OK, Back again to the hesitation problem. Now I have installed a new Fuel tank, and Fuel pump. Blew out both lines, pump to tank, and pump to carb. New points,plugs,cap,rotor,wires,vac. advance. Swapped Coils. Took apart Carb, and cleaned out.
Timing right on the ball, Points to 18.
IT STILL DOES IT.
What have I missed???
Install another accelerator pump in your rebuilt carburetor and see if that helps.
:) :grin:
Try replacing the coil to distributor wire or just hook up a jumper wire and see if it changes. Gas cap vent plugged up? Incorrect float setting?
"Try replacing the coil to distributor wire"
You did not mention that new plug wires were intalled--everything but.
Is the coil wire to the cap a very solid connection? I have been tearing my hair out over a very similar promlem as yours and just this morning found that the coil wire is loose and has been arcing. I have a nice idle, but as the revs increase, the wire vibrates and creates a surging at steady cruise speed.
