I have a 87 bronco with the 351W,4barrel and the auto tranny I believe it is the 3 speed. I have had this thing for about 9 months now and barely drive the thing because of all the problems. First it has a problem with stalling. When I start going if the gas is pushed down too much it just stalls but if I ease into the gas with hardly nothing at all it works fine. It seems that it stalls easier in the colder weather. When it stalls the rpm go from about 900 to 500 and there is nothing I can do after it reaches 500. Another problem is when the truck is warm it does not want to start at all it just tries to crank over but goes very slowly. I have already replaced the starter but I bought a cheap one from advanced auto parts. When I turn the truck off I lift the hood and on the driver side valve cover there is smoke coming out of the little hole underneth the oilcap. Is there a pcv system on this bronco because I have never seen it before. Is it normal for the oil pressure gauge to start dropping as soon as the truck starts idleing like at a stop sign. Could someone give me a step my step on the vacuum hose setup because alot of my temperature switches don't have anything hooked up to them(they are more on the passanger side of the bronco.) If this helps I am only getting maybe 5-8 miles a gallon out of this thing. If someone could help me with this thing I would be so thankful I don't want to drive my mustang in the winter.

here is a list of things I already replaced

Starter, Acc. pump on carb, fuel pump, fuel filter on the carb, plugs were in good shape, timing advance unit on the distributer, air filter.

Thanks Steve

 

I would get a mechanical oil pressure guage and see what its realy doing. at idle hot you should be around 15-20 psi , at road speed you should run around 40 psi, I cant tell you how to set the timing cuz i dont know what distributor you have, but you need to set the timing first, Then go to the fuel system, are you running a HOLEY? if so check the float level if stalls every time you hit the gas, and the timing is right, it sounds like you have a fuel starvation problem, and all engines should have a (PCV) system intact, go to your local parts store and invest $12 in a haynes manual for your bronco it will help you with the hose, vacum line, and alot of other stuff.
hope this info helps some. DW

 

"I have had this thing for about 9 months now and barely drive the thing because of all the problems."

Yup, sounds like a Bronco all right!

 

The carb on it is the factory one which does look to be a holley. The timing is set to 10 degrees so I think that is fine. I do have the book but cannot find a chart or any description on how to hook up the vacuum lines. As for the pcv system I have no idea how to hook it up because I don't have any lines at all for the thing. Thanks Steve

 

Did you disconect the (spout) connector in the wireing harness when you checked the timming? if not you didnt get a accurate reading, Your pcv valve should be in one of your valve covers and connected by a rubber hose to intake manifold, as far as your other vacum lines, untill you get it running right, plug every thing that you can find thats sucking air, (vacum leaks), do this first, stop all vacum leaks on the motor, Then find the spout connector for the distributor, unplug it, crank the engine make shure its not idled to high
650-800 rpm, then set your timing, turn off the motor, plug your spout connector back in, Then go from there, if your plugs and plug wires are in good condition, Then you may have a problem in the fuel system, once you have it running okay then you can start trying to plumb and replace vacum lines, Hope this helps some! DW

 

This bronco does not have the spout connector because it has the vacuum advance on it. I found the pcv valve and it has 2 vacuum lines comming out of it the first one is connected to something but the other one has a screw in it to plug the line. Do you know where it should go. What plugs into the filler neck on the driver side valve cover. There is a plug right under the oil cap that needs something plugged into it. Thanks Steve

 

We'll see that presents another problem because a 87 wouldn't have a vacum advance dist. in it, so know we have to wonder what else has been changed and why? it's make it dificult to figure out onver the net. is it points or electronic ? The bigest vacum lin on the pvc valve should go to a vacum tree or nipple thats threaded into the intake. but you need to see if the vacum adv is working or not, remove the dist. cap connect a peice of vacum hose to the dist. look inside it and suck on the hose and see if the plate or advance arm moves, then check the vacum hose that was connected to the dist, at idel it should have no vacum, the vacum should come in when you hit the throtle. and go from there dont forget to listen for and stop any vacum leaks. DW

 

The vacuum advance does work. I am pretty sure it is points. How can you tell. I have one line going into the pcv that is going to the intake but the other plug on the pcv is plugged with a screw is this normal. Thanks Steve

 

Its one someone has pluged for some reason or another. as long as you dont have a vacum leak it'll be okay for now, if you have a haynes book, look up distribtors and there shoul be a diagram of what a point type, and a electronic dist looks like, i dont know how to tell you the difference, but if it's points then you need to check the point gap and replace the points if need be, then when you get the ignition system ruled out go back to the carburator issues, you mention earlier that smoke cam from oil cap ?? Have you done a cold compresion test on this engine?? DW

 

No I have not done a cold compresion test on the engine. I will look in the haynes book to figure out if it is points or not. Thanks Steve

 

It sounds like it's not getting enough fuel, as you've deduced by all the parts you've replaced. Have you pulled the spark plugs? What do the tips look like?

 

The spark plugs were in nice shape nothing bad on them. Thanks Steve

 

Try choking the engine when it is warm and will not start (force the choke butterfly closed). If it starts, you probably have a vacuum leak. Also try it when the engine is idling - if the rpm's increase, then you probably have a vacuum leak.