Bronco Not Starting (Firing)

[lynchsg]

If you live in a state that requires emissions testing or you just want to keep originality then every thing will have to be OEM specific.
Unfortunately the EGR tube plate needs to be removed to drill out the broken tube if you can't get a hose on the broken tube end (you may have to make a new gasket...exacto blade, scissors and bulk gasket material).
The carb can be cleaned (if as mentioned the float is brass) and put back together with a rebuild kit. Old carbs tend to have warped surfaces that create vacuum leaks. So do purchased rebuilt carbs. Wether you try rebuilding your old carb or purchase a rebuilt carb, check flat surfaces with a straight edge (something you know is truly flat, within .002") and a feeler gage (.002-.003") front to back, side to side and diagonally in several places. If the .003" feeler gage passes under the straight edge you might get away with filing the flat carb surface. Usually around the bolting areas are where surfaces warp.
You can try cleaning out the EGR valve, but the internal diaphragm usually go bad with time. Replacing the EGR valve is best. They are costly. You can try cutting the EGR base gasket to match your old gasket...
I removed everything, replaced the intake and carb (with a manual choke) from Edelbrock. Also put a 14×4" K&N air filter and housing on top of the carb. But I live where there are no emissions testing.
Anyway you go, bare minimum is a lot of cleaning and checking of old parts. New EGR and rebuilt carb will cost you as will aftermarket parts.
Hope this helps some.

 

[wyo58]

I pulled the carb. Oh boy.

First thing: there was about 1/4" of gas sitting on top of the engine. (You'll also note that the choke heater tube snapped off where I'm pointing from the mounting plate during de-mount, lots of rust.):

View attachment 30933

The passenger side port on the EGR valve / plate was completely clogged with fossilized oil:
View attachment 30934

The venturi needle? brass housing on the drivers side was cracked and split. The passenger side has a hairline and imagine will open up in time:
View attachment 30935

And last but not least, the power valve gasket appears to have a crack. The spring/valve weren't operating completely perpendicular to the plate:
View attachment 30936

Some questions here:

1) My rebuild kit came with the thick (1/4") gasket that sits between the carb and the EGR plate, but not the gasket between the intake manifold and EGR plate. As you'll see from the first photo (and below), the gasket that was mounted on my engine had a special cut-out connecting barrel to barrel:
View attachment 30937

Obviously, I'll need to replace this gasket. All of the aftermarket EGR to manifold gaskets look similar to this, without the special cut-out:
View attachment 30938
Will this "closed off" gasket still function properly? Assume so since EGR plate connectivity will go "over the top" of the gasket.

2) Does the cracked venturi matter? Should I replace this part of the carb? Carbs Unlimited has this aftermarket assembly.

3) Any thoughts on what if any carb components caused the gas to sit on the top of the engine / inside the intake manifold? Is there still a possibility that there's a timing / valve issue here?

4) Any suggestions on how to get the extra gas out of the intake? Not crazy about using a wet vac (fumes). Siphon?

5) Any suggestions on how to repair the broken choke heater tube? Having a hard time finding the entire plate assembly online.

Thanks all.

L7

Looking at the gasket it looks like it has been burned out buy exhaust gasses and all the fuel thats been in there from the ruptured power valve.

2. That looks like the carb has had water in it and made the seam open up. Yeah I would try to replace it somehow.

3. as stated the ruptured power valve dumps some fuel.

4. dab up what you can and the rest should evaporate.

5. If you can't get a hose on it I'd check the salvage yards.


This all explains why you have fouled plugs and standing fuel in the intake and a no start, power valve feeds the booster ventures.

 

[lucky7_1080]

Thanks @Motech.

There's not much meat left on the ****** fitting:


I suppose I could attempt to JB a new tube on. (Dorman sells fix it kits for this w/ appropriate fittings to attach to the back of the choke. I'm curious however if I could simply eliminate this component altogether. Does the choke really need a heat riser to function given the electric spade connection? I saw a wide range of "blank off plates" for this OEM ******.

The other riser attaches to what appears to be attached to a vacuum actuated device that sits behind the choke. Is this needed?:


Are any of these components required for emissions compliance?

Also curious whether the EGR valve and plate can be eliminated altogether? And same question as above, but assume the EGR is there specifically for emissions compliance.

Thanks!

L7

 

[wyo58]

My personal opinion is to not remove the EGR plate, just clean it out. Alot of times when you start to remove things it just leads to the next thing that have to be removed. Now don't think I'm an emission freak because I'm not, lol. Yes the heat riser for the choke does work in unison with the electric part of it ( comes off a little faster if I remember correctly. I think it is a steel line through the plate. If you can't find one maybe you could drill out the pipe as it passes through the metal and then either glue it or solder it to both the coiled pipe and the plate. If you get it super clean and flux the heck out of it the solder should stick. JB weld could work and be much easier to deal with as well.

 

[lynchsg]

The part you arrow too is called a "dash ***" and keeps the rpms from dropping fast when decelerating. Lowers hydrocarbons, supposedly.
It is part of the emissions system. As is the the tube to the choke which is looking at intake manifold vacuum.
Blanking it off and the EGR ports are definitely better for ease of maintenance.
But it won't pass an emissions test.

 

[lynchsg]

Correction, as wyo58 stated. The broken tube is a heat riser looking at temperature, not vacuum.

 

[Motech]

Thanks @Motech.

You're very welcome.

There's not much meat left on the ****** fitting:

I suppose I could attempt to JB a new tube on. (Dorman sells fix it kits for this w/ appropriate fittings to attach to the back of the choke. I'm curious however if I could simply eliminate this component altogether. Does the choke really need a heat riser to function given the electric spade connection? I saw a wide range of "blank off plates" for this OEM ******.

Absolutely. Eliminate it and you'll be fine with your electric choke. If it stays on too long, you can back it off a little.

The other riser attaches to what appears to be attached to a vacuum actuated device that sits behind the choke. Is this needed?:

Are any of these components required for emissions compliance?

That's your "Choke Pull-Off" diaphragm, and it is real important. When the choke is closed, it needs to open up a little bit to stay running that's what that does, it pulls the upper choke plate open just enough to keep it running at high idle. Then, when you tap the throttle, that's the device that causes it to drop down to the next lower high idle speed.

There will be a instructions for adjustment with the kit, but first you want to check if it works. (Hmm... How to get around the censors on this one) You'll want to put a hose on it and with your mouth, provide negative pressure (vacuum) to see if: A. The lever pulls all the way back into the diaphragm housing, and B. If it stays there.

Some have a bleed off feature, a little hole (or small, round purge opening for the censures) that will bleed off vacuum as it's applied. In those cases, you should still be able to draw the lever all the way in with the vacuum you apply, but it won't stay there. It will extend back out as soon as you let up. As long as you can draw it pretty close to fully drawn in, you'll be okay. But if you can't pull it in with each breath, you'll need to replace it.

(Those types, bleed off types, are usually only found on 4 barrel carburetors. I do not see a bleed off port on yours, so I believe it should simply work or not)

It's important enough to make a difference between an excellent cold start and really poor running, choking, embarrassing cold start.

Now if you're lucky, and it works as designed, and it's never been tinkered with much, it won't really need any adjustment when reassembled. Still need to check though.

Also curious whether the EGR valve and plate can be eliminated altogether? And same question as above, but assume the EGR is there specifically for emissions compliance.

Although all are necessary for emissions, the choke heater pipe is redundant with that electrical coil, and a block off plate will never be questioned.

The choke pull-off we just discussed would be considered a tamper if removed, but even more so, it would cause really poor cold drivability.

The EGR valve is definitely for emissions only. And this is one of the few emissions reduction devices that actually robs you of power.

If you were to try to remove it, you would end up with mounting studs too tall for your carburetor that will probably not be easy to remove, and misaligned throttle linkage geometry that might be a PITA to correct.

Plus, there is also a slight performance gain in having that spacer between the carburetor and manifold.

So just leave it all there, and hooked up as it should be. If you want to eliminate the EGR flow for increased power, simply stick a BB in the hose.

 

[johnnyreb]

Hi folks - hoping someone here can help me troubleshoot a non-starting California '79. Here's the situation:

I fired up the truck one afternoon just to move it and clear the driveway. It started fine no issues, choked properly, warmed it up, kicked the choke off at the pedal after ~5m. Pulled it out of the driveway and onto our street, parked it uphill on a slight slope (20% grade). Ran great. It had been raining for ~2 weeks straight (truck is not garaged), and we had a clear no-rain day when I moved it.

About 4 hours later, I went to fire it back up and pull it back. I couldn't get it started, and couldn't get it to fire properly. So, I just dropped it in neutral and rolled it back to our driveway. Once there, and after letting it sit for 30m due to the possibilty of flooding, tried to get it to fire again. Checked to make sure carb was getting gas (it is). I was able to get it to fire, but had to keep the pedal buried and even then it was just barely running. When I let off the pedal, would immediately die. Timing issue? There is quite a bit of gas sitting on the sides of the carb, and on top of the intake manifold due to what I believe is failed gasket between carb and manifold. However, this has been in a failed state for last ~year and has been running fine with no issue. I ran through a series of troubleshooting:

- Tank is full of gas.
- Fuel pump is functional (it's brand new). Pulled fuel hose from carb inlet, turned it over, gas moving well.
- Fuel filter not clogged (per above).
- Checked all spark plug wiring.
- Pulled distributor cap, checked rotor and checked for moisture (both new).
- Coil sparking properly (pulled plug from cyl. 1, turned it over, strong spark.
- Replaced coil as test.
- Replaced ignition module as test.
- Solenoid and regulator brand new, putting out proper voltage.

Am curious if anyone has any thoughts here, specifically whether pulling it up on an incline could have had any impact.

Can provide more details as needed! Thanks all.

Glad it never caught on fire like mine did .

 

[johnnyreb]

Not firing on starting fluid is always interesting. I suppose spark plugs could be wet and fouled, or you are getting no spark.

There is a cheap inline spark tester I like to use. Pictured below, available at places like harbor freight. You can verify spark to each cylinder, or at least coming out of the coil.
Then you know for sure.

If you know you are getting spark and it will not fire on starting fluid my next step would be compression test.
Compression test won't tell you if ignition timing is off, but it will tell you if cam timing is off. Could be timing chain jumped.

obviously you know more about the engine that any of us, but if I pulled it into my shop that is where I would start.

If you have compression and spark, then you know for sure it is a fuel issue.

In edit, Have you pulled the dipstick to make sure your oil pan isn't full of gas? That creates tons of other issues like flooding the engine with too many gasoline fumes and making it act flooded.

If he has spark going through the plug. My guess is he killed the plugs, Check to make sure the PLUGS ARE FIRING---IF YOU ARE GETTING FIRE TO THE PLUGS AND THE PLUGS ARE NOT FIRING--YOUR PLUGS ARE DEAD--Get a new set. Flooding one can **** plugs.

 

[L\Bronco]

There will be a instructions for adjustment with the kit, but first you want to check if it works. (Hmm... How to get around the censors on this one) You'll want to put a hose on it and with your mouth, provide negative pressure (vacuum) to see if: A. The lever pulls all the way back into the diaphragm housing, and B. If it stays there.

Ha Ha Ha!
That is funny Motech! (The censor thing, the method is great!)
I had an alternate method.
If there's no bleed (which appears to be the case here) You can also just push the plunger all the way in and plug the feed port with your finger. Release the plunger and see if it holds. (It will come out a bit, but not all the way.) If it returns fully, replace.
Cheers

 

[lucky7_1080]

Thanks all. I'm just waiting for some parts to come in to complete the rebuild and re-mount. Couple items to note:

- The manifold and bottom of the EGR plate were pitted due the clogging of one of the EGR plate ports. (I suspect that this may also be where I had some gas leaking out, gasket was shredded.) To remedy this and avoid replacing the entire manifold, I'm going to start with Remflex and have a custom gasket cut and ready to mount. Let me know any thoughts here.

- @Motech I'm on the fence re: the choke stove. I'm leaning towards just remounting the original stove and JB'ing in place at the plate. This stupid little plate is ~$30 shipped, so I'd likely just cut / cap my existing and re-mount.

- Tested the choke pull-off and its working well, so will re-use.

- I'm fully rebuilding the carb. All in, ~6-8 hrs. Venturi assembly is being replaced, EGR valve is being replaced.

- I'm going to hold on plug replacement since I pulled one, tested and it's sparking well.

Will keep you all posted once it's remounted mid-week.

Thanks again.

L7

 

[johnnyreb]

Thanks all. I'm just waiting for some parts to come in to complete the rebuild and re-mount. Couple items to note:

- The manifold and bottom of the EGR plate were pitted due the clogging of one of the EGR plate ports. (I suspect that this may also be where I had some gas leaking out, gasket was shredded.) To remedy this and avoid replacing the entire manifold, I'm going to start with Remflex and have a custom gasket cut and ready to mount. Let me know any thoughts here.

- @Motech I'm on the fence re: the choke stove. I'm leaning towards just remounting the original stove and JB'ing in place at the plate. This stupid little plate is ~$30 shipped, so I'd likely just cut / cap my existing and re-mount.

- Tested the choke pull-off and its working well, so will re-use.

- I'm fully rebuilding the carb. All in, ~6-8 hrs. Venturi assembly is being replaced, EGR valve is being replaced.

- I'm going to hold on plug replacement since I pulled one, tested and it's sparking well.

Will keep you all posted once it's remounted mid-week.

Thanks again.

L7

ONE MIGHT BE THE ONLY ONE---all it takes is to flood it one time and you can **** the plugs and it will NOT HIT AT ALL

 

[L\Bronco]

- @Motech I'm on the fence re: the choke stove. I'm leaning towards just remounting the original stove and JB'ing in place at the plate. This stupid little plate is ~$30 shipped, so I'd likely just cut / cap my existing and re-mount.

An option there is to drill out the rusted off pipe, (that came from the choke housing) clean up the end of the original pipe, and with some careful reshaping, you can reinstall it into the hole. (It doesn't have to be a perfect seal there, the carb pulls a bit of air through it via a small vac port within the choke housing.) The heat at that point might be too much for JB weld is all.
Cheers

 

[lucky7_1080]

Thanks all. Got everything mounted back up earlier today. I filed the choke stove as suggested, and added a bit of JB as a precaution.

Cranked the engine, got a half-second fire and then no fire. Pulled the butterfly back, opened up the barrels and confirmed that it flooded out again, gas sitting back on top of the engine as before. After this, I went ahead and replaced all the plugs as a precaution, and attempted to fire again and no dice. (To note: I didn't clear the gas from the top of the engine after replacing the plugs and attempting to fire.) I've left the carb completely open to air out the standing gas...

At the point, I'm at a loss. Should I:

1) Pull everything back off again, clean the gas out and try again?
2) Is it possible that there is in fact a timing issue and valves aren't opening properly?

Any guidance would be much appreciated.

A

 

[lynchsg]

Pull the carb and let the gas evaporate.
Did you change the bowl float needle and seat? I would assume so seeing as they probably came in the carb rebuild kit?
Did you adjust the float level? The instructions in the kit should tell how to bend the float tang.
Did you check the brass bowl float to see if it was sealed by holding it under gas or water in a glass jar or see through plastic receptical to see if any bubbles came out of it?
If it is a plastic float showing bubbles with this testing method, toss it. If it is brass and leaks air (checking for bubbles or shake it for liquid inside) it can be repaired, although, a new one is preferable.
Starting the engine with starter fluid and it starts will let you know it is a carb issue.
At that point, if you did everything mentioned above, a rebuilt carb may be best.

 

[wyo58]

Okay bac to the basics.
1. does the rotor on the distributor spin when you turn the engine over? If it does the cam is turning.
2. do you have compression in the cylinders? pull the plugs and test them.
3. is the rotor lining up with number 1 on the distributor when number one is on the compression stroke?
if not the timing chain could have slipped a tooth.

 

[Motech]

One of the reasons I said those carburetors are so cooperative is because there are no sealing surfaces below the float bowl fuel level.

If your carburetor is truly flooding over that much without even running, it can only be:
• Very high float bowl level
• Fractured float bowl (never seen it)
or... OR
• Fuel line incorrectly installed on, say, a bowl vent pipe for example
(we've all done it once at least)

 

[lucky7_1080]

Pull the carb and let the gas evaporate.
Did you change the bowl float needle and seat? I would assume so seeing as they probably came in the carb rebuild kit?
Did you adjust the float level? The instructions in the kit should tell how to bend the float tang.
Did you check the brass bowl float to see if it was sealed by holding it under gas or water in a glass jar or see through plastic receptical to see if any bubbles came out of it?
If it is a plastic float showing bubbles with this testing method, toss it. If it is brass and leaks air (checking for bubbles or shake it for liquid inside) it can be repaired, although, a new one is preferable.
Starting the engine with starter fluid and it starts will let you know it is a carb issue.
At that point, if you did everything mentioned above, a rebuilt carb may be best.

Thanks. I'm going to let it evaporate overnight and try again tomorrow.

Yes, I changed the float, needle, needle seat.

I adjusted the float level to match the original level, ~1mm from the top of the bowl.

I replaced a black, plastic/rubber float with a brand new brass float. I did not test the float to see if it was air-tight.

To start the engine only with starter fluid, would you suggest crimping the fuel line pre-pump, or pulling the carb off altogether?

 

[lucky7_1080]

Okay bac to the basics.
1. does the rotor on the distributor spin when you turn the engine over? If it does the cam is turning.
2. do you have compression in the cylinders? pull the plugs and test them.
3. is the rotor lining up with number 1 on the distributor when number one is on the compression stroke?
if not the timing chain could have slipped a tooth.

1. Yes, I believe so as all wires were tested at the plug - each is receiving spark. I pulled driver front plug, grounded to block to visibly observe spark as well and it's sparking.

2. I haven't tested compression in the driveway as I don't have a gauge. I can do this as a next step if compression is likely the culprit. Assume I'll need an assistant to crank the engine while I observe the gauge?

3. Not sure on this one - would need some guidance on how to confirm this.

 

[lucky7_1080]

One of the reasons I said those carburetors are so cooperative is because there are no sealing surfaces below the float bowl fuel level.

If your carburetor is truly flooding over that much without even running, it can only be:
• Very high float bowl level
• Fractured float bowl (never seen it)
or... OR
• Fuel line incorrectly installed on, say, a bowl vent pipe for example
(we've all done it once at least)

Thanks.

1. Float bowl level is interesting. As I noted in earlier reply, I did need to bend the tang to match the original level (~1mm below top of the bowl). This was higher than the condition when I installed the new brass float. Before adjusting, float was more like 1.5mm - 2mm below the top of the bowl, so much lower. Should I adjust the float back down slightly to force a lower level?

2. As noted above, this float is a brand new brass float. Suggest pulling and submerging to test?

3. Fuel line is installed correctly. Bowl was empty when I reinstalled the carb, filled up nicely when reinstalled. I also installed a brand new filter at the fuel inlet on the front of the carb, and removed the (supply hose) in-line filter that was installed prior.