The Stovebolt Site Forums The Shop Area Engine Shop Warm starting problems.

What does it mean when my engine won't start when warm unless it's been at least ten minutes since I last shut it off? Something need adjusting?

Oh, it's a '59 235.

Hello, Usually that problem is a flooded
engine because of a leak down of fuel from the carb. That is if it is a carb engine and not a injection system. Try looking in the carb after you shut it off to see if it is dripping fuel.If it does you will need to rebuild the carb.
Hope this helps...Chb46

JimB: Define warm? Need more information as to condition of engine? Overheated? What? Hard re-starting after an engine has been running could be caused by many things. The carb can be flodded. The choke can be closed. Could have too much fuel pump pressure. Could be vaporlock, from heat control valve sticking or ignition troubles. Bad plugs or incorrect ignition or valve timing. Need to know how hot the 235 is running? General condition of how the engine has been running, valve and ignition timed properly? What I mean is has/is the 235 in good shape and has been running OK, and just recently developed a hot re-start problem? Give us more details and more to work with. Repost info! :confused:

I'm having the same problem with a '54 235. I found a missing heat riser spring, replacing that helped some. I also found a small leak at gas tank fitting. I ran mine 80 miles at 65 mph, drove through Dallas and it ran like a charm with a good steady idle, but when it's at operating temp it doesn't like to restart unless choked, a deft pump on the throttle or starting fluid. This is my last big glitch in a year long project of swapping out the old 3 speed for a 5 speed, a new rear end, open drive shaft, disk brakes, shoulder harness, etc.

realmccoy / JimB : This overused term "hardstarting" covers such a wide variety of troubles and problems its necessary to determine under exactly what conditions the hard starting occurs. Its important to know: 1. hard to start all the time? 2. only when cold? 3. only when hot? (describe how hot?) 4. only after the engine has been turned off for a while? 5. once started, is the hard starting condition accompanied by missing, pinging, knocking,or a failure to keep running? 6. does the engine crank slowly, while trying to start? 7. has engine been tuned/plugs changed recently? Checked timing? 8. Have you rebuilt the carb recently? From the sound of things I feel you have been checking things out, but you'll have to dig a little deeper. You should not have to move the throttle, or use fluid to start. If float bowl is full and vacuum passages are clear, should start. Did you check fuel pump delivery? Should be between 2 to 5 lbs of pressure (with 2/2.5 being ideal) and 3/4 to 1 pint per/min to the carb. Sounds like you have a lean mixture as you have to add fuel/fluid to start. Check manifold bolts, and all carb screws you may have a vacuum leak. Also check gaskets at air horn to float body, and float body to throttle body for leaks and tighten. Check carb to manifold gasket & tighten. If you have recently rebuilt the carb you may have put one of the gaskets in backwards/upsidedown. They only go in one direction. If you have a vacuum leak the float will not vent/fill to the correct level and idle mix will be too lean. Float needle/seat can be dirty or worn. Check float level? Check float bouyancy, does it leak? Float hinge maybe binding or broken? Also check fuel lines to carb, fuel filter for leaks or blockage. Something is restricting the fuel to the float bowl and/or evaporating it, (vaporlock) or a vacuum vent is plugged. If you use a vacuum gauge and you attach below the carb at carb base it will not tell you if you have a vac leak in the carb body itself, as it can be internal. The power valve/power piston high side of the carb does not seem to be the problem. Your troble is in the low speed/idle system and/or fuel delivery. You need to check this stuff out. Repost your findings and be safe!!! :confused:

Chevyman: Thanks for the reponse. Let me answer a few of your questions to see if we can narrow it down some more. Hard start only after reaching operating temperature, but not overheating. Problem shows up in a drive across town. Once started, runs fine. Engine cranks a bit slow. Have changed plugs, checked compression (cold), set points and then timing. Carburator rebuilt because it had been siting for 7 years. Set float with measuring guage, does seem like a lot of fuel weeping around the carburator, have tightened several bolts. Have not checked manifold bolts, valves or done a warm compression check. That will come this weekend when interior is finished. JimB, forgive me for jumping your claim with my question, but since we have similar problems, maybe this discussion can help at least one of us. I've learned a bunch reading all the different posts.

realmccoy: Tighten the manifold bolts. Looks like you have plenty of fuel to the float bowl. Problem seems to be vacuum leak to float bowl, and possible worn throttle body. The fuel should be weeping around the float bowl and/or throttle shaft. A small vacuum leak from air horn to float bowl (gasket)has put the float/mixture off balance. The float bowl chamber of the carb should be "neutral" (at atmospheric pressure) to work correctly. If you look at the throttle body there will be 2 holes, one above, and one below, the closed throttle valve. The one below is the idle port. The idle port is where the idle mixture screw seats, and what your engine starts on. The port above the throttle valve is the low speed port for low speed running and restart after running. Both these ports are in tandem circuit to the float bowl. Fuel flows (is pulled through them) by the venturi effect (vacuum) of the carb throat when starting, and manifold vacuum when running. (The more air that flows through the carb venturi, the more inches of vacuum created and the more fuel is pulled from the bowl.) They are very small calibrated passages (gasoline to air ratio) and are possibly plugged or dirty/gummy. Do not use a wire or pick or anything sharp to clean them, as they can be damaged. Use carb cleaner. Suggest complete rebuild. Dismantle carb and soak in cleaner for couple hrs. Blow dry/out all passages, and check with air to see if clear. Pick up a zip kit from one of the better supply houses in the Dallas area, they should have one in stock. You need a kit with all the pieces/gaskets. Would also advise you pick up a manual for your truck/carb, if you have not already. Be sure to replace the spring/ball below power valve if orginal ball is rusty/damaged. Also install new pump plunger and spring if old is worn or broken. If after cleaning and inspection check throttle body for fit/wear. If shaft bores are worn badly you will have a vacuum leak here, and will not fit to the idle discharge holes correctly, and/or the throttle valve will not close correctly. You can find another B carb at a wrecking yard for parts, if you need to replace throttle body, and/or float etc. Do you have a vacuum gage? As is the best way to set idle mixture. Seat mixture screw very lightly, then back out 1 1/2 to 2 turns. Then set idle speed screw to run 475 rpm. Then adjust mixture screw for highest vacuum. Thats it. Good Luck!!! :rolleyes:

realmccoy: Tighten the manifold bolts. Looks like you have plenty of fuel to the float bowl. Problem seems to be vacuum leak to float bowl, and possible worn throttle body. The fuel should be weeping around the float bowl and/or throttle shaft. A small vacuum leak from air horn to float bowl (gasket)has put the float/mixture off balance. The float bowl chamber of the carb should be "neutral" (at atmospheric pressure) to work correctly. If you look at the throttle body there will be 2 holes, one above, and one below, the closed throttle valve. The one below is the idle port. The idle port is where the idle mixture screw seats, and what your engine starts on. The port above the throttle valve is the low speed port for low speed running and restart after running. Both these ports are in tandem circuit to the float bowl. Fuel flows (is pulled through them) by the venturi effect (vacuum) of the carb throat when starting, and manifold vacuum when running. (The more air that flows through the carb venturi, the more inches of vacuum created and the more fuel is pulled from the bowl.) They are very small calibrated passages (gasoline to air ratio) and are possibly plugged or dirty/gummy. Do not use a wire or pick or anything sharp to clean them, as they can be damaged. Use carb cleaner. Suggest complete rebuild. Dismantle carb and soak in cleaner for couple hrs. Blow dry/out all passages, and check with air to see if clear. Pick up a zip kit from one of the better supply houses in the Dallas area, they should have one in stock. You need a kit with all the pieces/gaskets. Would also advise you pick up a manual for your truck/carb, if you have not already. Be sure to replace the spring/ball below power valve if orginal ball is rusty/damaged. Also install new pump plunger and spring if old is worn or broken. If after cleaning and inspection check throttle body for fit/wear. If shaft bores are worn badly you will have a vacuum leak here, and will not fit to the idle discharge holes correctly, and/or the throttle valve will not close correctly. You can find another B carb at a wrecking yard for parts, if you need to replace throttle body, and/or float etc. Do you have a vacuum gage? As is the best way to set idle mixture. Seat mixture screw very lightly, then back out 1 1/2 to 2 turns. Then set idle speed screw to run 475 rpm. Then adjust mixture screw for highest vacuum. Thats it. Good Luck!!! :rolleyes:

Umm,

My "hot-start" problems seemed to be more starter-related: this pertains to 235's on 6-volts.

When they got "good & warmed up", they crank really slow, and just don't seem to have enough "spin" to get the engine going.
(When cold, same battery, same starter, etc, they started just fine, even at 5 degrees F !)

I'm not discounting all the carb stuff mentioned above, but how's your engine cranking when hot ?

Frank

[ 12-19-2001: Message edited by: Frank54 ]