Frustrating new problem... Help please!

[broncotom]

so... I was driving the old bronco after it sat for longer than I'd like to admit(about 6 months) when I started losing power under heavy throttle. it seemed to do ok as I was accelerating from a stop but once I got up to speed if I gave it some more throttle to blow out the cob webs, it would cut out and lose all power for about a half a second. let off the throttle and it would kick back in and run again. after a few of those episodes I decided it was time to take it home before it died on the road and I had to hike home to get the truck to pull it back.

I brought it home and parked it in the drive way while I drove to the parts store to get a new fuel pump hoping that was the problem. got home, started it up, and as I backed out of the driveway it died again and I could not for the life of me get it going again.

new fuel pump - still no go. fuel filter - no go. So I decided it was time for a carburetor rebuild thinking plugged jets since it would run if I poured fuel directly in the carb and I had neglected it for so long maybe the shitty ethanol fuel messed it up. Rebuilt the carb and put it on yesterday.

Finally got it fired back up!!! my excitement wore off really fast when I realized it was idling really really fast. messed with the needles and could not get it to slow the idle down. not sure what the deal is there but I'm definitely lot a carb pro so I might be missing something...

That is problem #1...

problem #2 is that I hopped in thinking I'd shift into gear knowing the idle is really high and just see how she did driving around. put it into gear and the idle slowed down and sounded "normal." then it slowed down some more... and some more... and some more until I smelled oil and the engine died! Very frustrated and feeling pretty defeated at this point.

I need help guys. any thoughts?

Thinking back to the first time the engine was cutting out on me when I brought it home I remember smelling oil then too but it was right after an oil change so I didn't think anything of it. now that it's doing it again I'm thinking something more seriously is wrong.

HELP ME!

 

[DirtDonk]

For problem one, check the choke linkage. If you turn the main idle speed screw down (not the two idle/air mix screws) and the speed does not change and the screw just drops free of the throttle lever, then the linkage is being held up by something.
And that something is usually the choke linkage.

Unless you had the butterflies out of the throttle shaft during the rebuild? If not, then it should not be jamming up there. But if you did it's possible they did not get re-centered exactly correct.

Good luck.

Paul

 

[broncotom]

I did. a buddy of mine told me I should remove them during the rebuild... wish I had not listened to him. I remember it kind of was sticking after I finished the rebuild. I just figured it would loosen up over time. guess I'll be taking that back apart. thats easy enough. just time consuming. the bigger problem is going to be figuring out why it dies when in gear now. and whats with the smell of burning oil? I just don't know enough about it to even be able to guess at that yet.

Thanks for the info Dirt. that should help me fix problem #1...

anybody want to take a stab at problem #2?

 

[DirtDonk]

To fix the blades, I think you would do this:
1. Loosen the main idle screw so there's no way for it to hold the linkage.
2. Loosen the screws (four of them, or maybe all eight?) and make sure the blades are free floating in their slots. Then wiggle the shaft(s) around so that they are perfectly centered in their bores.
3. Inspect the blades closely to make sure that all four are oriented properly with the bevel set so that when closed they sit flush against the bore.
4. Then, with the blades fully seated in their bores, tighten the screws again.
This should guarantee that they can close fully and you will get the minimum idle, to the point that you can kill the engine by turning the idle screw out.
Make sure that the secondary linkage (if this is a 4bbl) is not binding up and holding the primary blades open.

When setting the idle, make sure that the choke linkage is in no way touching the primary throttle linkage or you'll get a false idle that might "kick down" one more time as the engine warms. It's possible that this was problem 2, but it's a bit premature to know at this point.

Remember the idle speed is a dance between ignition timing, idle speed screw setting, and the idle air mixture screws. But those last two don't have to be at the same exact setting as most people think.
The initial setting (whatever that might be, but let's say 2.5 turns out from gently seated) is just to get the ball rolling. Once you're getting close you turn each screw independently until things are just right. Back and forth several times even. That's the dance.
If one screw turns out to like 2.25 turns and the other likes 3.5 turns, so be it. They're usually within a half-turn of each other, but there are too many variables and they rarely need to be exactly the same number of turns.

What kind of carburetor is this? Stock 2bbl or aftermarket 2 or 4 barrel?
Are you running a PCV valve to the back (or front) of the carburetor or intake plenum? Don't run it to a single runner. Just make sure it's pulling from a common point.
Power brakes? Make sure that the hose is not leaking. Vacuum leaks are a very real possibility with your symptom.
What about vacuum advance? Is it connected to ported vacuum?
What about initial timing? Should be 10-13 BTDC for most of our rigs, but at least 6 BTDC and good vacuum.
What about the ignition itself? Points? Electronic? Aftermarket or factory?

Anything else we should know about your truck's engine? Other mods like headers and such?

Paul

 

[BR549]

Did you put fresh gas in it when you replaced the fuel pump.?

 

[Rustytruck]

Oil check the valve covers, check for leaking out the ends of the intake manifold and especially since you were replacing the fuel pump check the oil pressure sensor and its extension tube. Mess those up and they leak oil. My original oil pressure sensor blew the fitting off the top and squirted oil right on to the exhaust manifold. These Parts are under pressure so when they leak you really know it.

 

[broncnaz]

Check for a vacuum leak. It can cause high idle speed and may cause the mixture screws seem not to have any effect.

 

[broncotom]

To fix the blades, I think you would do this:
1. Loosen the main idle screw so there's no way for it to hold the linkage.
2. Loosen the screws (four of them, or maybe all eight?) and make sure the blades are free floating in their slots. Then wiggle the shaft(s) around so that they are perfectly centered in their bores.
3. Inspect the blades closely to make sure that all four are oriented properly with the bevel set so that when closed they sit flush against the bore.
4. Then, with the blades fully seated in their bores, tighten the screws again.
This should guarantee that they can close fully and you will get the minimum idle, to the point that you can kill the engine by turning the idle screw out.
Make sure that the secondary linkage (if this is a 4bbl) is not binding up and holding the primary blades open.

When setting the idle, make sure that the choke linkage is in no way touching the primary throttle linkage or you'll get a false idle that might "kick down" one more time as the engine warms. It's possible that this was problem 2, but it's a bit premature to know at this point.

Remember the idle speed is a dance between ignition timing, idle speed screw setting, and the idle air mixture screws. But those last two don't have to be at the same exact setting as most people think.
The initial setting (whatever that might be, but let's say 2.5 turns out from gently seated) is just to get the ball rolling. Once you're getting close you turn each screw independently until things are just right. Back and forth several times even. That's the dance.
If one screw turns out to like 2.25 turns and the other likes 3.5 turns, so be it. They're usually within a half-turn of each other, but there are too many variables and they rarely need to be exactly the same number of turns.

What kind of carburetor is this? Stock 2bbl or aftermarket 2 or 4 barrel?
Are you running a PCV valve to the back (or front) of the carburetor or intake plenum? Don't run it to a single runner. Just make sure it's pulling from a common point.
Power brakes? Make sure that the hose is not leaking. Vacuum leaks are a very real possibility with your symptom.
What about vacuum advance? Is it connected to ported vacuum?
What about initial timing? Should be 10-13 BTDC for most of our rigs, but at least 6 BTDC and good vacuum.
What about the ignition itself? Points? Electronic? Aftermarket or factory?

Anything else we should know about your truck's engine? Other mods like headers and such?

Paul

Stock 2 bbl motorcraft 2150. PCV valve goes to the front of the intake plenum. I do have power brakes.

I can check timing but wouldn't that effect the idle? it idles pretty smoothly. just really fast. then when it's in gear it smells like oil and starts to sputter after 20 or 30 seconds. shift back to park and idle speeds up and runs fine. just fast.

everything else is stock

 

[broncotom]

Oil check the valve covers, check for leaking out the ends of the intake manifold and especially since you were replacing the fuel pump check the oil pressure sensor and its extension tube. Mess those up and they leak oil. My original oil pressure sensor blew the fitting off the top and squirted oil right on to the exhaust manifold. These Parts are under pressure so when they leak you really know it.

This wouldn't have an effect while idling? it doesn't have a problem until I shift into gear as I stated in the last response above this one.

 

[broncotom]

Did you put fresh gas in it when you replaced the fuel pump.?

Yes I did.

 

[broncotom]

I'm going to try to mess with it again this weekend. look for vacuum leaks, oil leaks, and who knows what else. guess I'll just see if I notice anything unusual and report back.

 

[boonz28]

I'm going to try to mess with it again this weekend. look for vacuum leaks, oil leaks, and who knows what else. guess I'll just see if I notice anything unusual and report back.

Good luck Tom! I hope you find your problem and its something simple

 

[oldiron]

I just went through this last weekend. EXACT set of circumstances and symptoms. I went through all the steps you have only to find that the power valve was leaking. Sitting for long periods with ethanol blended fuel can have that effect. Something to look into.
Greg

 

[blubuckaroo]

It sure could be a bad power valve.
But the oil smell has me concerned. It might be a vacuum leak on the underside of the intake manifold, that sucking in oil. That's not very common with the original iron Intake manifold,, but I guess it could happen.
I would try to identify any weak cylinders by pulling the plug wires off the distributor one at a time with the engine running. You'll notice the engine running rougher with the good cylinders disconnected, but little or no difference when you disconnect a weak cylinder.
This will definitely show you which has the vacuum leak.

 

[Jaxgtc]

I had a Chevrolet years ago that did the same thing. The double walled exhaust pipe collapsed on the inside and restricted the exhaust, bogging it down every time I put a load on it. It was really something different. Not sure how the EB exhaust and pipes are constructed, but might be worth checking the exhaust system to make sure you have good flow.

 

[jckkys]

I don't see any reason to think you ever diagnosed the original fuel starvation problem. No trouble shooting process I know of involves replacing parts until you get lucky. It's easy to check fuel pump output at the carb and doesn't require buying any parts. The pickup filter in the fuel tank could be plugged up and the new pump and filter can't fix that. The instructions in the carb rebuilding kit would never tell you to remove the throttle plates but would describe the choke linkage set up and idle adjustment. This 2150 rebuilding instruction by the ranger station is excellent;http://www.therangerstation.com/tech_library/pdf_documents/motorcraft_2150_carb.pdf. I would read and print the whole thing.
The original valve cover makes adding oil a messy job and any spilled oil will get on the exhaust manifold where it burns and smells.

 

[broncotom]

I just went through this last weekend. EXACT set of circumstances and symptoms. I went through all the steps you have only to find that the power valve was leaking. Sitting for long periods with ethanol blended fuel can have that effect. Something to look into.
Greg

when you say exact set of circumstances what do you mean? did it die after you put it in gear? or as you were driving down the road? or do you mean it idled really fast like mine? sorry, I have too many problems to know which one you are talking about.

probably doesn't matter in the end since I put a new power valve in as part of the rebuild but I'm curious. thanks Greg.

 

[broncotom]

It sure could be a bad power valve.
But the oil smell has me concerned. It might be a vacuum leak on the underside of the intake manifold, that sucking in oil. That's not very common with the original iron Intake manifold,, but I guess it could happen.
I would try to identify any weak cylinders by pulling the plug wires off the distributor one at a time with the engine running. You'll notice the engine running rougher with the good cylinders disconnected, but little or no difference when you disconnect a weak cylinder.
This will definitely show you which has the vacuum leak.

I'll try the spark plug idea. I still don't understand how, if it was a vacuum leak, it wouldn't effect the idle but it does once I shift it into gear. thats what has me stumped.

 

[broncotom]

I had a Chevrolet years ago that did the same thing. The double walled exhaust pipe collapsed on the inside and restricted the exhaust, bogging it down every time I put a load on it. It was really something different. Not sure how the EB exhaust and pipes are constructed, but might be worth checking the exhaust system to make sure you have good flow.

Thanks for the idea. I could see this potentially being an issue but how would shifting into gear make the blockage worse? In my mind it wouldn't change whether you were in gear or not. should be consistent whether in gear or in park.... right?

 

[WheelHorse]

Pull the vac advance hose off of the vac advance on the dizzy and see if that makes a difference.

Make sure the PCV valve is operating correctly.

Double check for any vac hoses that you may have left off or cracked unknowingly while removing and reinstalling the carb.

You did use new gaskets when you installed the carb back to the intake, correct?