[grovermyson]

So my Bronco runs good while driving around town. I do have an issue that I’m not sure if it’s normal or not. When the Bronco sits for 6 to 7 days and not started at all, it will take 5 to 6 turns of the ignition and will finally fire up. As long as I start it every few days it will start right up. But when it sits for a week it will take a bunch of turns of the ignition to get it going. What exactly causes this or is it normal? Thanks! Oh yeah the carb is a 2150….


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[Doosenberry]

Good question. I can only speculate, honestly. My Bronco would do that exact same thing. That was with a 351m and an Edelbrock 750cfm carb. If it sat more than two days then I would have to crank it several times to get it to fire up. I'm assuming the gas was either evaporating from the carb, it was draining back down the fuel line, or both.

My F100 doesn't have this issue. It has a 302 and a 2100 2bbl carb, similar to the 2150 you have. I had it sitting all of Friday, Saturday, and Sunday this weekend and I went and fired it up first try today.

Maybe it has something to do with the mechanical fuel pump? Someone on here has to have more knowledge on this issue as it's not that uncommon to come across with these 70's trucks and Broncos.

 

[grovermyson]

Thanks for your input doose!


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[canuckistan97]

Same on mjne, just press the gas pedal ~ 10 times before you crank it


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[packagerjr]

I have a 351m and Eddy 1406. Within a day or two of its last run it’ll fire up almost instantly. A week or two since last run and I’ll have to crank it for 5+ seconds but never had an issue getting it to pop off on the first turn of the key.

I have attributed it to gas evaporation and the pump needs by some time to get more gas up there.

EDIT: I floor the pedal once to set choke on all cold starts.

 

[4EyedTurd]

Mine does the same after sitting for a few days, I speculated either the fuel pump letting fuel drain back to the tank or the fuel bowl in the carb is leaking maybe.

 

[grovermyson]

Same on mjne, just press the gas pedal ~ 10 times before you crank it


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Would pressing the gas pedal do anything before cranking? It’s all about the mechanical fuel pump bringing gas to the carb…no?


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[canuckistan97]

Would pressing the gas pedal do anything before cranking? It’s all about the mechanical fuel pump bringing gas to the carb…no?


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you got a mechanical pump or electric? mine got switched to electric pump


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[grovermyson]

351m all stock mechanical fuel pump


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[Doosenberry]

Would pressing the gas pedal do anything before cranking? It’s all about the mechanical fuel pump bringing gas to the carb…no?


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Yes, it would actually. So, in theory, this is how it should work. I've even seen this in the owners manual on these trucks.

You put the key the ignition and turn it to "run" or the first position if you prefer calling it that.

Then you press the gas pedal to the floor and then bring it back up. This sets the choke and has the accelerator pump put a shot of gas down the intake.

Next, you turn the key to the second position, "start" and it should fire up. The choke should be set and it should run until warm.

After that, it should start with nothing more than a turn of the key once the engine is warmed up.

On my truck, the choke is jacked up, so I press the pedal once to get that shot of gas down the intake and then I crack the throttle just a little with my foot on the pedal. Once I start it with the key, my foot on the throttle keeps it from dying since there is no choke. Is what it is for now anyway. Also, if my truck is warmed up and I try starting it again and press the gas pedal by mistake, it'll hard start like it's flooded. Such a picky engine. If that happens, I hold the throttle open a little and crank it and it takes a few seconds to clear the gas and then it fires.

 

[grovermyson]

Great info! Didn’t have a clue about that…thanks.


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[Doosenberry]

Great info! Didn’t have a clue about that…thanks.


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Yeah, no problem. If it doesn't start when you do it that way, then there's something else going on like I was mentioning in my first post. That's why I'm not 100% sure why my Bronco used to hard start like that. Granted, mine had aftermarket stuff on it when I got it, so who knows what all had been tinkered with.

 

[packagerjr]

Yes, it would actually. So, in theory, this is how it should work. I've even seen this in the owners manual on these trucks.

You put the key the ignition and turn it to "run" or the first position if you prefer calling it that.

Then you press the gas pedal to the floor and then bring it back up. This sets the choke and has the accelerator pump put a shot of gas down the intake.

Next, you turn the key to the second position, "start" and it should fire up. The choke should be set and it should run until warm.

After that, it should start with nothing more than a turn of the key once the engine is warmed up.

On my truck, the choke is jacked up, so I press the pedal once to get that shot of gas down the intake and then I crack the throttle just a little with my foot on the pedal. Once I start it with the key, my foot on the throttle keeps it from dying since there is no choke. Is what it is for now anyway. Also, if my truck is warmed up and I try starting it again and press the gas pedal by mistake, it'll hard start like it's flooded. Such a picky engine. If that happens, I hold the throttle open a little and crank it and it takes a few seconds to clear the gas and then it fires.

Mine works just as you describe although I had to fiddle with getting the choke right a bunch. Will fire off around 1000 rpm and make its way near 2K over a minute or two until I goose the throttle again.
I have had warm start (120-160 F) hard starts especially if I do give it a little gas pedal beforehand. Now I know to stay out of it till it cranks. I have had to floor the pedal and crank to clear out a flood. It may crank for 10+ seconds but will eventually clear enough to fire. And clear out my sinuses from the gas smell.

 

[Doosenberry]

Mine works just as you describe although I had to fiddle with getting the choke right a bunch. Will fire off around 1000 rpm and make its way near 2K over a minute or two until I goose the throttle again.
I have had warm start (120-160 F) hard starts especially if I do give it a little gas pedal beforehand. Now I know to stay out of it till it cranks. I have had to floor the pedal and crank to clear out a flood. It may crank for 10+ seconds but will eventually clear enough to fire. And clear out my sinuses from the gas smell.

Yeah, when it works it's great. Like I mentioned before, when you initially press the pedal down, it sets the choke and, I failed to mention what you pointed out, it sets the high idle cam which is why it's idling higher for you on a cold start.

As it warms up, the choke opens and when you blip the throttle after it warms up, you're taking it off the high idle cam and putting it back in the regular position. Don't quote me on it, but I think if you blip the throttle before the engine warms up, it'll go back to the regular position and the engine will die and you gotta reset the high idle cam.

All of this is why I have to hold the throttle open a little after initially pressing it to the floor during a cold start on my truck, because it's not all functioning as it should. Once mine is warm though, you just gotta bump the key and it starts. Like, as soon as you feel the starter kick, you just let go of the key and it's running, you don't even have to hold the key there and let it crank. That part of it is nice.

 

[Rob_64-365]

I would say your excessive cranking would be from your float bowl draining the fuel down into your engine.

The needle & seat attached to the float, that control the amount of fuel to enter the carb are not sealing properly, and when all the fuel leaks into the engine two things happen.

The 1st is you have to crank and crank to fill the float bowls with fuel again before it can feed the engine.

The second, and more concerning thing is that all of that raw fuel drains down into your engine each time, essentially washing your cyllinders & diluting the oil with gas, which kills the lubrication qualities of oil. This will take out rings & all of your bearings, so its pretty important to address this asap.

Check your oil, is it overfilled, and smelling like gas?

It's a very common issue with a carb that sits to have fuel evaporate & cause sludge & one little speck of that debris can cause the float bowl needle to not seat properly. The other possibility on an old vehicle is that it could also be caused from old rusty fuel tank & even the fuel lines.

The band aid fix, is to clean the carb, carb rebuild kit, & get an in-line filter on the fuel line so if your tank & lines are full of rust/sludge tank debris, that are not re-clogging things up, but be sure to check the tank & lines & if they are rusty inside, they probably need to be replaced.

 

[miesk5]

Yo Grover,
As Doosenberry advised.
And;

Cold Starting Problem

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CONDITION	POSSIBLE CAUSE	CORRECTION
Engine cranks but will not start.	1) Choke not closing.	1) Inspect choke adjustment and for something binding. Adjust if necessary.
2) Choke linkage binding.	2) Lube with WD-40 and check for something bent. Adjust if necessary.
●3) No gas in carb.	3) Check fuel delivery. Look for plugged filter or clogged lines, bad pump, stuck needle & seat, and fuel pressure.
4) Accelerator pump defective or blown out.	4) Replace the pump. Problem is usually caused by bad gas, dirt in gas, or vacuum leak or ignition problems causing engine spitback.
5) No spark or engine problems such as bad compression.	5) Diagnose & correct the problem.

 

[grovermyson]

Such great, expert analysis from all of you. Thanks!


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[grovermyson]

Yes, it would actually. So, in theory, this is how it should work. I've even seen this in the owners manual on these trucks.

You put the key the ignition and turn it to "run" or the first position if you prefer calling it that.

Then you press the gas pedal to the floor and then bring it back up. This sets the choke and has the accelerator pump put a shot of gas down the intake.

Next, you turn the key to the second position, "start" and it should fire up. The choke should be set and it should run until warm.

After that, it should start with nothing more than a turn of the key once the engine is warmed up.

On my truck, the choke is jacked up, so I press the pedal once to get that shot of gas down the intake and then I crack the throttle just a little with my foot on the pedal. Once I start it with the key, my foot on the throttle keeps it from dying since there is no choke. Is what it is for now anyway. Also, if my truck is warmed up and I try starting it again and press the gas pedal by mistake, it'll hard start like it's flooded. Such a picky engine. If that happens, I hold the throttle open a little and crank it and it takes a few seconds to clear the gas and then it fires.

Hey I tried this method that Doose suggested that was in the owners manual. Wouldn’t you know it fired right up! Son of a gun….I then changed the oil and saw, and no smell of gasoline. Thanks again….


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[Doosenberry]

Good stuff! I know you've been keeping your Bronco in factory condition, so it makes sense that it would still startup properly if done that way. The question now is, does it start right up that way after several days of sitting? Or was that how you did it this last time?

I even made a couple short videos of starting my truck, because of this thread, just to show people that carbed engines are actually pretty quick to start, warm or cold. My Bronco has a Sniper on it and it doesn't start any faster than my truck does.



Dont mind the annoying seatbelt buzzer. These were made a day apart for the cold and warm starts.

 

[packagerjr]

My cold is just like that unless it has sat for a week or longer - then it takes more cranking but will still pop off when it gets some gas.

My warm start is definitely weaker than yours and usually requires some pretty quick throttle taps to get it off low revs. It won’t stall if I don’t tap the throttle, but it sounds like it may if you look at it the wrong way.

Thanks for posting.