The Stovebolt Site Forums The Shop Area Engine Shop Truck sputters and dies when trying to give it gas

my 1954 chevy truck with a 235 will idle all day long but when I try to give it a little gas it just dies or will eventually raise the rpm but sputters the whole time. I've tried adjusting the timing a little but it just sets the idle a little higher or lower. I'm excited I've finally got it to fire up, now I need to make it accelerate when I give it gas. It snaps, crackles and pops so much when I try to give it gas, I'm about ready to call her Rice Crispys. Thanks for any information, I am new to this and this is my first thread. I'm sure there are already answers in these forums someplace, just not sure where to look.

So did you set the timing correctly? How much is it raising your RPMs? Is your vacuum advance moving the distributor? Have you checked fuel filter and fuel pump pressure?

Just a few thoughts off the top of my head.

Chris

If sure about timing.....

Check all places vacuum could leak..... Manifold, hoses, fittings, carb gaskets, ports.

Rebuild carb. Needs it anyway. Eliminates a lot of possibles.

Probably not the answer but how's your choke sequence?

Probably not the answer but how's your choke?

[quote=ndkid275]So did you set the timing correctly? How much is it raising your RPMs? Is your vacuum advance moving the distributor? Have you checked fuel filter and fuel pump pressure?

Just a few thoughts off the top of my head.

The timing isn't set correctly, I have no timing light. I was hoping to get it running good enough to get it to the shop. I'd turn the distributer until it idled smoothly, which it does idle smooth. It raises the RPM approximately from about 800 to 1200 RPM. I put a new fuel pump on it and replaced the gas tank, cleaned all of the lines and rebuilt the carb, altho not to sure if it's rebuilt correctly or not. I'm beginning to think it has carb issues. Seems like the vacuum advance is free and moves OK, is there a way I can tell? Thanks so much for the reply. Stovebolt forums is the place to go when getting a little frustrated.

Thanks for the reply. I've been looking for a vacuum leak and will keep looking. I rebuilt the carb but being a rookie I'm never sure of what I might be missing. I'm 64 years old and this was my first carb rebuild! Thanks so much again for the reply.

I'm really not sure about the choke sequence. The choke plate moves. How would I check the sequence? Please forgive me, I'm old, 64, and can use all the help I can get. Looks like I came to the right place for help. Thanks so much for the reply.

To check for vacuum leaks, get a can of ether or carb cleaner. Spay the rubber hoses and connections where vacuum is connected. Spray the base of the carb where it mounts to the intake. If the engine races, you've found your leak.

Perhaps non-functioning accelerator pump? Check if gasoline sprayed into carb throat when accelerating (engine off).

Yes, agree. Push on throttle while looking down carb throat. See if it squirts gas.
Don't think vacuum advance would totally keep motor from revving at all.
"Get it to shop" says you are not a DIY person? The stovebolt is for beginners/DIY'ers and all else. Give it a shot.
Congrats on rebuilding carb. I screwed up several at first.

You could have:
1. Forgot a part.
2. Wrong ball in a hole
3. Not cleaned it good enough
4. Messed up the needle and seat assembly
5. Not done the float level or the float drop properly
6. Wrong gasket or blocked a hole with a gasket
7. Have a warped body

I have done all these things and more. Unless you are in a hurry. Do it over again after studying the instructions and the internet and asking Stovebolt. Your problem can easily be a carb problem. The squirt test will help identify. What carb do you have? Those 1bbl are easier than most and fun to learn on. Many good carb guys on here. Do it again. On a good day with plenty of light and a clean work area.

Many of us are older than you, so, to me you are young.

The advance is operated by manifold vacuum. You can check it but sucking on the hose to see it move the lever..........maybe. But like I said it would not keep motor from revving to higher than idle.

Understand you are looking for vacuum leak. Worthwhile.

I’m not much of a mechanic but something in the back of my mind, from 50 years ago, says your float is sticking in the carburetor. Another option could be a piece of dirt in the carb. It floats up and plugs jet when you press the gas pedal then floats away when you let off. I experienced that after rebuilding a 63 VW bug carburetor. A gnat got in before I closed it up.

More information is needed.
Has this truck sat for an extended period?
Has the gas tank ever been cleaned or replaced?
Have you adjusted the valves?

I'll give it a try. Thanks

I do see gas sprayed into carb. when engine is off. thanks for the reply.

Vacuum advance not working. Simple to test. Start the truck and let it idle. Open the hood and stand where you can see the distributor. Reach over and blip the throttle and watch the mechanism on the bottom of the distributor to see if it moves. If it doesn’t you probably have a bad diaphragm. Good luck.🛠

Thanks for the reply. I have a single bbl Rochester carb on it. I do see gas when I push on the accelerator. I have been thinking about taking the carb off and going over everything again. I'll clean everything again and like you said, make sure I don't have the wrong size ball in the wrong hole. I wasn't real sure if I had the float level right so I'll check that again. It does seem like there are a bunch of good guys on The Stovebolt. I really appreciate all of the reply's.

I think my float is free, but as far as dirt in the carb, I'm going to take it apart again and give it a good cleaning one more time. Thank you for the reply.

The truck has sat for some time. I replaced the gas tank, replaced the gas pump and cleaned the lines. I've never adjusted the valves. I have rebuilt the carb, but like I was saying to bartamos, I'm going to take it of and try to make sure everything is good. Thanks too much for the reply.

Thank you too much. I'll give that a try and see what happens. Thanks for the reply.

I've cleaned and rebuilt the Carter YF carb on my '61 Apache, and the Holley Performer on my '60 Impala. On both occasions, it took more than one try to get everything back together correctly, and running right.

Don't despair. Take your time and go through all the checks. Float level and float drop are very important.

-Kevin

It seems you are able to feather the RPM upward, while sputtering. You say you have a strong squirt down carb throat. So we are still stuck between fuel and spark.
We first think that something is keeping carb bowl from being, or staying, full enough to maintain high demand, but is good enough for idle dribble.
So we do a squirt test as an easy thing to observe. You saw a squirt. In this case, not conclusive. The feather up (increase in RPM) you describe can be low fuel delivery barley catching up to throttle demand, but not quite. That has a list of reasons from gas tank to bowl level to vac leak.

We also think it could be spark not timed or not strong. It starts and idles, so it's not totally screwed up.

So since you don't have a timing light and you do have spark and you have turned the dizzy and NO change..........
You can either do more fuel tests or some ignition spark/timing tests.

Next Fuel test:
1. Pump flow test at carb connection

Spark test:
1. Get a timing light and a vac pump/tester.
2. Points, condenser, rotor, cap, wiring, coil

If you can feather motor RPM enough to see if vac advance moves, that's good to do.

You said "finally got it to run". This indicates you have been doing work. What all have you done specifically?


What is the history?
1. We need to know everything you have done? besides carb.
2. When did it last run good?
3. What happened when it stopped running good?
4. How new are distributor parts?
5. Have you or anyone removed distributor?
6. Have you checked firing order on distributor and plug wire routing to correct plug?
7. Is gas old or new?
8. Do you have any actual "backfiring" at carb or at exhaust? or just mild coughing at carb.
9. Are you 100% sure that choke if OFF? and stays off.
10. How much RPM are you able to get to? 1000, 1500

Many times these question jog a memory and poster realizes something....but if not please answer.

Thank you for responding to my basic questions.
The symptoms you described in your original post do not indicate carburetor problems. They indicate valve train issues, specifically sticking/slow-to-rebound valves.
Since you took the leap to open up the carburetor, you may, or may not have created an additional malfunction. This makes troubleshooting very difficult.
This is why many of us preach to test every component which makes an engine run right EXCEPT the carburetor. Save the carburetor for last. It seems never to be the carburetor.
What I would do now is forget about the carburetor for now since the engine will idle "all day long".
Pull the valve cover.
Look for bent push rods.
If the there are no bent push rods, start the engine and run at idle and look for oil showing up in the weep holes in the top of the rocker arms.
Get back to me after you do this.
There is more to check, but I don't want to flood you with to much information all at once.

Thanks too much for the reply. I'm eventually going to go through the carb again and clean again, and I'm not to sure if I set the float level and drop perfectly. Like they say, try try again right? Thanks again.

I'm able to get what I think is a strong stream of gas down the carb while looking down it. I'm not sure if I got the float level and drop set correctly. I'll take the carb off again and do more cleaning and check the float again. I'll get it running again and check to see if the vacuum advance is working. As far as history with the truck, it was my brother-in-laws truck and I'm sure he had it running as he would show up occasionally at my house with it. I'm not sure what he was doing with it, but he got sick and it sat for some time in his barn. He passed, so I bought the truck from my sister and it sat in my garage for about 7 years. Last year I finally got started working on it. I replaced the gas tank, cleaned the gas lines and replaced the fuel pump. I replaced the distributer cap, points and rotor. I have never pulled the distributer, not sure about my brother-in law, but I have checked firing order. I changed to an alternator and did all that goes along with that. Before I rebuilt the carb, I would get it started, it would still run rough, but I'd get quite a bit of gas running down the side of the carb, and have some running out between where it sits on the intake. That's why I tried my hand at rebuilding the carb. I'm thinking I might not have set the float correctly so I'll do a little more cleaning and check the float. I'm going to check the vacuum advance and look a little harder for vacuum leaks. Thanks for the list to think about. My problem right now is it's getting close to the Thanksgiving holiday, my family will be here, and my wife doesn't drive so I'll be driving Miss Daisy to the store on more than one occasion and have less time to spend on the truck, Small price to pay for all of the good eats tho. I'll keep things posted as I get a chance to do them. Thanks so much again.

Happy Holidays. Return when you can.

Not looking to hijack the post, but I'm back with the same issue.....perhaps two people with the same issue could shed some better light on the subject......67 K 20 - 250 Rochester 'B' manual choke. This summer I posted, and the replies were basically the same...I did all the tests & checks, with exception of removing the valve cover, looking for a bent pushrod....I once again took apart the carb - confirmed the small & large balls were where they were suppose to be....as with the internal springs....I again sprayed carb cleaner in every port & hole I could find, & blew plenty of compressed air through the passages....The one thing I found that I had missed was the 'flat rod' that attaches to the accelerator pump was sticky with reside... I steel wooled the flat rod & cleaned the slit it went through. I reinstalled the carb on the truck and it starts & idles wonderfully...but as soon as I start to give it gas it stumbles & wants to stall, but I'm able to catch it.....If I feather the pedal, I can get the RPM's up, but it takes a bit of doing......& again, it seems to be better running on choke..... I don't have a fuel issue, The gas I use is non ethanol, & still use Startron....My question is the float setting....upon slight acceleration, would the reservoir empty so quickly that the fuel pump could not keep up with it?..I'm talking slight acceleration, not dumping my foot into it......

...how about the accelerator pump? I've had similar problems with both the 4 barrel and single barrel carbs. .
Just something to think about.

Complete carb rebuild - kit from Mikes's carburetor.....

I second the accelerator pump as a possible issue. I cleaned my Rochester type B carburetor three times before I found the tiny port that the accelerator pump discharges into the carb throat was partially blocked. Assuming it’s a Rochester type “B” this may help.

Rochester Carburetor Information, Installation and Service Bulletins - Pre 1960

Thanks to Keith Hardy’s Old Online Chevy Manuals, for providing us this wealth of information.

Thank you so much for the links, and they do prove interesting....Actually I'm growing weary for the amount of times I have taken this carburetor apart..... On my previous post of earlier this year, I stated buying a Chinese reproduction just to see if in fact it is the carburetor, and I honestly feel that it is...so once I proved there's a fault with the OEM Rochester "B" I still would have an issue with the Rochester "B".....as I would not use the Chinese reproduction as the fix or solution.....It was recommended that installing a Carter 4375S YF carb would be a better substitute, I obtained one, however the linkage would not line up, and there was no way to try it.....This Carter is the correct application, however the linkages are specific to the carburetors and will not interchange. I might add when I did have the carburetor apart I did check the accelerator pump buy filling the bowl & it did squirt, with that said I was confident that it was working correctly......Why is it that I don't recall any of theses issues back in the day ??.....I drove the wheels off a 68 C10 back in 1972 and never had a lick of trouble....Now it seems most every carburetor post is about this bogging issue????

Mine had a tiny bit of dirt in the carb that clogged when I tried to go. Needs thorough cleaning, me thinks.

perhaps it isn't the carburetor, and you keep fixing something that isn't broke. If you keep doing something over and over, and keep getting the same results, I would look elsewhere. Just a thought. Why not use the chinese caruburetor if it works? The one you have doesn't work, already the chinese one is better than what you have. And you have already given them your money.

Ok - lets look at this logically.....I'm not a master mechanic....but on the initial start..(cold) - I pull the choke & turn the key....the truck starts, after an initial warm up I gradually push in the choke....every thing is fine runs like it should.....nice idle....with a very slight tap to the accelerator the bogging starts, let up to an idle, and feather the pedal to obtain a higher RPM to take off in first gear..... but not smooth...its rough, just overall miserable....Vacuum was checked & ruled out, as with timing, & vac advance....Just brainstorming at this point....and will resume in the spring when I can work on it...The previous owner installed an HEI distributor, from previous posts it appears that the installation was correct with 12 volts going directly into the circuit....On another note Mike's Carburetor has a new replacement "B" for earlier models 6 cylinders - I believe for 216 & 235. Kinda wondering what that's all about.....Just having a tough time considering any other places on the engine where the problem could be.....

I know you say your timing is good. How advanced is it?

I hate to say this, but with 4 full pages of posts and running around in the same circles, it is time for you to take this truck to a someone who knows what they are doing.
There must be a reputable shop in or near Canton, Ohio who can help you.
Carl

Fuel filter?

Glenn...How I wish.....OK hypothetically, if we rule out the carburetor, and any internal engine damage....the focus shifts to electronics.....In my case the only modification is an OEM HEI distributor. - I really have to wonder why the PO replaced the distributor. Well actually, I found some of his posts on another forum where he was trigger happy with doing things with this truck & fortunately only got as far as changing the distributor....As best as can tell....does the wiring look correct?

No.

Man of few words