77 Bronco ignition or carb problem?

[grasshopper]

Doing some long needed work on my 77 Bronco that I have had since high school-- my latest problem is it stalls and quits after it warms up to operating temp. Been a recurring problem over the years but never this bad. Initially thought was ignition problem so replaced practically entire ignition system (Breakerless Duraspark II)including plugs, cables, module, distributor pickup coil, ignition coil. Also replaced voltage reg and start solonoid. Runs good and smooth but as it warms up, begins to miss, starves for fuel (acts like it) and eventually dies. Can restart almost immediately and does the same thing after a couple of minutes or quicker if you give it some gas. Thought maybe bad fuel pump so replaced it, did the same thing. Changed out the ignition module again, did the same thing. Started messing with the EGR valve (Integral backpressure) and noticed that if I depress the diaphram a little as it starts to stall, it seems to delay the stall a little as I press the EGR diaphram up and down a few times...but eventually stalls completely. I don't think it is vapor locking...carb is not getting that hot...My thinking now is carb related problem...anyone have any ideas on if I can solve this with some carb adjustments or is it rebuilt carb or carb kit time...carb has been rebuilt once already about 10 years ago???....THOUGHTS ANYONE....don't want to pay a mechanic.... my little "do it myself" project....

 

[rovernut]

Doing some long needed work on my 77 Bronco that I have had since high school-- my latest problem is it stalls and quits after it warms up to operating temp. Been a recurring problem over the years but never this bad. Initially thought was ignition problem so replaced practically entire ignition system (Breakerless Duraspark II)including plugs, cables, module, distributor pickup coil, ignition coil. Also replaced voltage reg and start solonoid. Runs good and smooth but as it warms up, begins to miss, starves for fuel (acts like it) and eventually dies. Can restart almost immediately and does the same thing after a couple of minutes or quicker if you give it some gas. Thought maybe bad fuel pump so replaced it, did the same thing. Changed out the ignition module again, did the same thing. Started messing with the EGR valve (Integral backpressure) and noticed that if I depress the diaphram a little as it starts to stall, it seems to delay the stall a little as I press the EGR diaphram up and down a few times...but eventually stalls completely. I don't think it is vapor locking...carb is not getting that hot...My thinking now is carb related problem...anyone have any ideas on if I can solve this with some carb adjustments or is it rebuilt carb or carb kit time...carb has been rebuilt once already about 10 years ago???....THOUGHTS ANYONE....don't want to pay a mechanic.... my little "do it myself" project....

I had that problem with a 72, and it drove me freakin' nuts. After changing ignition and fuel parts forever, it turned out to be the chrome fuel caps (I just had to have....it was the eighties) that did not vent properly. It would flood when the tank was full, and starve as it ran down toward empty.

 

[76Explorer]

With the engine cold, remove the breather and check the position of the choke plate(it should be nearly closed), start it up and let it warm. If the choke plate doesn't open before it starts sputtering, manually open it with your finger, and if that stops the sputtering, then your choke needs adjusting. If it doesn't solve the problem, then keep restarting it long enough for the engine to get really warm, turn it off and pull up a chair, and watch the carb, your looking for little white smoke signals coming out. and if they do, it's time for a rebuild kit

 

[Seabronc]

It does sound like a carb problem, but if the EGR has an effect, I'd check to make sure it isn't stuck open. It is not supposed to be open when the engine is just idling or cold, it could have some carbon buildup that is sticking it. I'm not a fan of rebuild kits because they don't address all the problems with old worn carbs, nothing like a new carb /emoticons/[email protected] 2x" width="20" height="20" /> .

Good luck,

>-

 

[89Bronco58]

10 years is along time for a carb to not be rebuild, i strongly suggest you take it apart, clean it very well and rebuild what you can, and then reset it once back on the truck