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Bewildered - confounded - just plain lost...

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Nunyas

Nunyas

Yoda
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To sum it up, I just have no idea what the deal is. The B just has 0 power if I can get it to run long enough to try and move it, as of late this morning. I ended up 2.5 hours late to work because I couldn't figure out why the car is behaving like it is. So, I'm here looking for suggestions, tips, and hints into things I should check.

First the symptoms:
-the B Starts
-the B idles after starting (smoothly most of the time)
-the B starts to rev up when I give it gas, but then stalls
-If it doesn't stall after reving it'll idle extremely rough
-If I apply choke it idles higher and it'll rev higher, but lacks power

What I think I know:
-I think the HS6 is still good. It's freshly rebuilt. It worked all last week without issue.
-I think the SU Fuel Pump is still good. Every time I think I have a supply issue, I check the fuel line for pressure at the carb and it has always been good.
-I checked today to make sure fuel is getting into the bowl. With the pump on, I opened the lid a little and lifted it enough to let the fuel flow and eventually over fill the bowl.
-It's on a fresh full tank of gas. I drive the car daily, and fill it with 'hi octane' fuel. So, I'm 99% sure the gas isn't "bad".
-The ignition should be good. It has a Crane XR700 that's ~never~ needed adjustments since I got the car. The dist cap is new, and looks good. The plugs are new and look good (aside from having a lean running color on them). The plug leads are new and good.
-No matter how many flats "Rich" I go on the HS6, the car behaves the same.
-The car is getting both FUEL AND Spark: otherwise it would not even idle.

Things I've checked so far:
-I've traced the wires and checked and cleaned ignition wires in the wiring system, from the fuse block to the ballast resistor, to the coil, and to the XR700 leads.
-I've check the dist, to make sure it's all clean inside, and to make sure no moisture is getting inside.
-I've checked to make sure the heater valve isn't leaking on the dist.
-I've checked fuel pressure at the bowl.
-I've checked to make sure fuel is going INTO the bowl.

I initially thought ignition problem, because this morning it initially would not go past 1k RPM without dieing. Later, I found it will go up to at least 3K without dieing, but only if it's on 'choke idle'; using the gas pedal results in stalling, or no power.

Now, I'm thinking it may be fuel supply issue. I've checked everything from the fuel tank to the float bowl. I removed the fuel filter this past weekend, and it's eating away at me, making me think that doing so was a major faux paux on my part. The only thing in the fuel supply system I have NOT checked is for blockage between the bowl and the bridge (i.e. the jet and its plumbing).

Things that lead me to believe it's blockage in the jets:
-On FULL choke it used to idle a hair under 1K RPM with extremely rich characteristics (i.e. cyclic rough idle).
-On FULL choke NOW it idles up to 2.5K - 3K RPM smoothly.
-When I step on the gas it starts to rev up, but stalls if I give it too much pedal.

It could be something else though... It may only be coincidence, but bumps seemed to help the symptoms come and go.

I guess the carb piston could be getting stuck or something. I haven't looked into it since the problems started. So, I don't know if that's an issue, yet.

erm...

I think I've started down one of those paths where I'm typing what I'm thinking and I'm just rambling on...


ANYWAYS, thoughts or opinions anyone? Any and all feed back will be appreciated.

Thanks for reading
 
Last time you replaced your dizzy cap, wires and rotor, did you save them? If so put them back on. New ignition parts are known to be troublesome at times.

Have you checked the timing? Did the dizzy slip out of position?

Just guessing here.
 
Rob - "-I think the SU Fuel Pump is still good. Every time I think I have a supply issue, I check the fuel line for pressure at the carb and it has always been good."

The pressure is always going to be good if the fuel pump runs, even badly - that's just the nature of a SU fuel pump. You need to check the volume of fuel being pumped. Disconnect the fuel line from the carburetors and stick it into a 1 quart container, then turn on the ignition. The quart should fill in slightly less than 1 minute. If the time it takes to fill the container is significantly more that a minute, you will have found your problem, then it is just a matter of isolating where the problem is. It could be the fuel pump wasn't adjust correctly or the diaphragm is old and stiff, or you could have a clog in the line, etc. Your symptom (engine will run at idle, but not under load) is typical of a fuel delivery problem (it could still be a timing issue as Steve suggests). See my, Fuel Delivery Troubleshooting Guide under the Carburetor & Fuel section of the library for tips on isolating where the problem is.
Cheers,
 
Thoughts:

1) if you're not running premium plugs, it would help to install them to diagnose the problem. I prefer the NGK iridiums, but they're spendy. The point is to get a plug that will fire through extremem mixtures and not foul as easily - that would eliminate the igntion system and help it run so that you can make adjustments to the carb. (assuming that is the problem)

2) the last thing you changed before this happened was the fuel pump. What happens if you go back to the facet? Easier said than done, I'm sure.

3) when you flood the float bowl, does gas run out the jet inside the carb? It should.

4) did you remove the air filter?

5) Last time this happened to me it was that I needed to add damping oil to the piston. I had pulled the piston out and forgot to re-fill it when I re-installed it.

hope this helps.
 
Damper oil was my first thought after reading the symptom, too. A long shot with Rob tho: Usually very thorough. Sounds 'fuelish" to me as well, especially considering the "bump" part. Whacking on a failing SU pump can get it to supply fuel for an additional 50 miles or so... across "Alligator Alley", for instance. /bcforum/images/%%GRAEMLIN_URL%%/wink.gif

If possible, I too say try going back to the "other" pump before you tear into the carb too much. If, as Eric says, the fuel ploops out the jet head when the bowl's overfilled, you've got a problem somewhere else.

Good 'sequence of ramblings', BTW. /bcforum/images/%%GRAEMLIN_URL%%/laugh.gif
 
Ahh, Houston, we have a fuel delivery problem here.
 
<div class="ubbcode-block"><div class="ubbcode-header">Quote:]The ignition should be good. It has a Crane XR700 that's ~never~ needed adjustments since I got the car.[/QUOTE]

I recently had problems with my crane - never had any problems before & it started doing exactly what you're describing...I went through all the same steps & ended up installing a Pertronix distributor that solved the problem....but, my Crane was about 15 years old How old is yours? Can you check to see that its 'doing' its thing across the entire spectrum?
 
I've run into a bunch of distributor problems lately. One was my tr6 that would run ok for 2 minutes, and then start to misfire. If I reved the engine, the miss got worse, and then it would backfire, intake or exhaust(Thought I junked the muffler, blew a 10ft blue flame) A distributor fixed it. I also worked on a B that wouldn't rev over 3k rpm. A dist. got it up to 4500, but the throttle shafts were shot, a weber has it screaming now. The last was my B, mallory module, hif conversion. Totally redid the carbs, but could only tune it to idle with no power, or have power but not idle. Borrowed a dist. and it runs fine now.

I know the petronix and other modules that replace the points say that worn bushings are never a problem, but I don't think that is true. They are electonic devices, much more sensitive than points (as far as trigger position goes) and I think they are more prone to bad ignition problems with a worn distributor. All of the above cars had either the magnetic or light triggers and bad distributor bushings.
 
A swag suggestion. Unbolt the air filter(s), take the base of the air filter off of the carbretor and then give it a try.

See if this changes anything.
 
Another off the wall suggestion, check the frost plugs in the inlet manifold (they sometimes do fallout, after a carb backfire etc) also check to make sure the mixture needle has not come loose in the piston.
Good luck
Ric
 
good suggestions all! I got home around 7:30 tonight, and given the short amount of light I had left, I decided to check the fuel system; starting at the carb and working my way back. First, I checked to see if the 'over flowing' bowl was flooding the throat. It wasn't. Next, I checked to make sure I was getting an "over flowing" bowl, like I thought I had initially. I wasn't. After that, I decided to make sure I was getting fuel pressure. There was a little, but not a lot. So, I decided that I need to make sure I was getting fuel flow, and I was astonished to find I was getting NONE!!! *sigh* So much for "I think the pump is good". With the fuel line disconnected from the carb, and the ignition switched on, I heard 0 ticks, and had 0 flow.

So, thankful that I have a later car with the points accessible in the trunk, I pulled the pump cover off, and removed the points cover. I then reconnected the power lead, and switched on power. From there, I could see that the lever system wasn't working quite right; most likely because I hadn't set it properly. I found that if I stuck my finger next to the lever to prevent a small amount of movement it would proceed to operate normally and build pressure. So, I removed the points assy, and threaded the lever system another full turn. That seems to have corrected the issue with fuel delivery, for the time being.

I think I may need to look at it more closely, and to decide whether or not the current setting is correct, or if I need to adjust it further.

This morning, while waiting for my ride I decided to look through my Haynes manual, and in there I found that it had "gap" settings for the points displacement when the diaphragm is screwed into the lever system correctly. At the time of viewing the information, I had no idea what it was talking about. Now, however, I understand how the 'correct' gap settings are achieved, and that the system is NOT 'non-adjustable' like I originally thought.

Since I've run out of light to make any further adjustments tonight, I will definitely make it a priority to get back there and make sure the gap is set correctly first thing after I get home tomorrow night.

Once again, thanks for all the feedback everyone. Ya'll really helped me reconsider what I had thought was a 'known good' and find the real source of the issue.
 
first off, sorry for all the long posts.

problem solved. However, I found it impossible to adjust the 'gap settings' as specified by the "Haynes" manual. When I got it even close to the settings the pump did not work at all. So, I put it back to the way I had it last night, and it seems to perform as expected.

It got me to the Disney Studio and back home today. So, if the pump isn't set 100% correct, it must be set close enough that it functions and keeps the carb in supply of fuel.

Thanks again for all the tips, hints, and suggestions everyone!
 
It should ~just~ be at the "throw over" point. If it works, you're likely close enough! /bcforum/images/%%GRAEMLIN_URL%%/wink.gif
 
I encountered some more minor problems with the pump yesterday. It wasn't tripping the points as effectively/reliably as it should have been. The result was that it would pump but not at the correct flow or at a high enough pressure. Ending in the carb running out of fuel until the pump would activate again; which seemed to take my intervention by goosing the gas or down shifting or running over a 'cats eye'.

So, I looked at it again today. I loosened up the lever system one more turn, and it would not trip anymore. I noticed that if I lifted the lever base slightly off the pump housing it would actuate at a rate I remember hearing when I originally got the car. At first I started to look for something to shim the lever system with, but then I remembered the lever system on my pump has a 'leg' (for lack of a better description). So, I grabbed my needle-nose-pliers and bent the leg down slightly.

I do believe I've nailed it this time. With the iggy switched on, if I loosen the fuel line going into the carb, I immediately get fuel spritzing out through the loosened connection and the pump immediately starts ticking ticking away.

Like I just said, I think I nailed it down today. However, I tomorrow's Memorial Day Malibu drive will be the "true test" as to whether or not the pump is operating at 100 capacity.
 
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