Idle stumble questions.

[Anonymous]

Hello, I have a '65 Mustang, 200ci with the autolite 1100 carb, and automatic tanny. The car had been sitting for about a year before I bought it. I only lived a few blocks from the fellow I bought it from, so I drove it home.

The first thing I did, because it stunk badly like it had bad gas... was pop the plug from the tank and drain all the gas. It looked a little dark. The next thing I did was disconnect the fuel line from the tank and fuel pump and flushed it out. When I flushed the line, a little bit of brown sludge came out. I put a very heavy fuel system cleaner in the tank and a gallon of gas shook the car back and forth a bit to mix it up. I let it sit overnight and then drained it again the next day. The gallon or so that came out looked ok. I then took the top off the fuel pump to change the fuel filter and the filter was dark brown and looked like it was full of mud. I then took the fuel pump apart and it looked the same. I cleaned the fuel pump inside, top to bottom with carb cleaner and installed a new fuel filter.

Then I cleaned the fuel line from the fuel pump to the carb. And yet again, a little but of brown goo. I have never rebuilt a carb myself, but by looking at the inside, it was coated with the brown goo also. I cleaned it top to bottom with cleaner and put it back together. Now before the car sat for a year, the guy told me the motor and carb had been rebuilt.

I then put more fuel cleaner in the tank, some octane booster, and some high test 93 gas (about 6 gallons) and let it sit a day again. Then I put all the lines back together and primed the carb. I started the car and everything was running rough for about a minute and then it ran as smooth as can be. It revved good and didn't stink anymore.

I ordered the Petronix Ignitor Pointless ignition and coil. I put new plugs in it, new rotor button, new cap, new wires and the pointless upgrade. It started back up, but the timing was way off, so I set it to 12 initial timing with the vacuum advance disconnected and plugged.

I hooked up a tach and set the idle at 750 RPMs. The vacuum is ok and I set the mixture to get maximum vacuum.

Now to get to the point... The car idles perfect. It has great take off. No knocking or anything... but, there are 2 distint problems.... When the car is fully warmed up, it runs rough when idling in gear. It sometimes quits, but starts back up quick... you can rev it a few times and it runs fine again. The problem will only happen every other time or 2 that you stop at a light, but only happens when the car is fully warmed up.

The second problem is when the car is fully warmed up, if you gun it in park or gear it tries to stall then doesn't. It tries to quit, but then goes into the full rev like it never happened.

Anybody have any ideas? What do I look at next? I thought about attempting to rebuild the carb, but may just buy a new one if the price is right and the float and everything is already peachy.

 

[Anonymous]

Hey, I am also having an electrical problem. I don't think it is related, but I'll shoot anyway.

With the headlights on, when I rev the car... the headlights and instrument lights get brighter. Is there something wrong with my charging circuit? Could I have a bad alternator?

Thanks.

 

[JackFish]

You shouldn't have any trouble rebuilding the carb by the sounds of it.
It may be something as simple as a float adjustment and an accelerator pump rubber thingy.
Or a gasket issue, or maybe there's a loose screw or something. :wrench: Or a choke malfunction, or.... somebody else jump in here.... :

 

[JackFish]

Hey, I am also having an electrical problem. I don't think it is related, but I'll shoot anyway.

With the headlights on, when I rev the car... the headlights and instrument lights get brighter. Is there something wrong with my charging circuit? Could I have a bad alternator?

Thanks.

Probably OK, maybe check the belt tension, and/or the voltage regulator to start with.

 

[johnnyzoom]

I wonder if your choke is opening up all the way. When the car is warmed up I'd take a look at that.

Also, check this link for a great tutorial on tuning the Autolite 1100 by Cobra Six:

http://fordsix.com/forum/viewtopic.php? ... olite+1100

 

[Anonymous]

I rebuilt the carb today and it was actually pretty simple. But I am still having the same problems.

Might I ask, since I have a 42000 volt coil and the Petronix electronic ignition.... should the spark plug gap be different? What should the plugs be set to? Also the diagram says if I have a ballaster resistor (1.5 ohms) that the ignition wire and red lead have to meet before the resistor goes to the ignition coil. I have traced the wires from the battery to the ignition switch to the coil and cannot find a resistor of any kind. It says not all cars have them, but I have seen where some Mustang sites insist that I do have one beyond a doubt. If I do where is it and what does it look like?

I supposed that could be the only other solution to my problem. The carb was way out of whack before I rebuilt it, and now it is perfect. The car has never ran better.... until it warms up, it is exactly the same as before.

 

[CZLN6]

Howdy back Atgrazi:

What a great description of your situation. Thanks! Online trouble shooting/diagnosing is risky at best.

1st, don't waste your money on high octane fuel if indeed this engine has been rebuilt. You really need to find out what was included in the rebuild. If the stock steel shim head gasket was replaced with an aftermarket composite you will likely be down on CR. Buy a tank of Chevron gas with Techron fuel system cleaner in it. You've done a thorough job or cleaning up the system. The Techron gas will cap it off.

Since you've rebuilt the 1100 carb you should have replaced the SCV with the new one in the kit. That a good cleaning and a new accelerator pump will eliminate several question marks. Double check the choke system to verify that it is fully open once warmed up and that the vacuum pull-off mechanism is functioning properly. To do that, once it is warmed up pull off the air cleaner and visually verify that the choke butterfly is fully vertical and snuggly so. If it is floppy you may need to tighten the coiled spring inside the choke housing. If it is vertical, blip the throttle to see what effect the vacuum pulloff has on the choke butterfly. It should have no effect once the engine is warm. If it does flutter the choke, again, the choke coil spring inside the housing need attention.

The coiled springs can break and do loose tension over time.

Once you've solved or eliminated the choke as the source of your stumble, the next item to consider is the Load-a-Matic distributors advance mechinism. When you installed the Petronix, did you inspect the springs and advance plates? They should move freely. Again, the stock springs can loose tension over time. You should see a heavy spring and a lighter spring. The attachment posts should not be too worn.

Finally check to make sure the vacuum cannister is holding steady vacuum pressure. A slow leak in the diaphram will cause the appearance of good vacuum functions, but at a steady idle or cruise speed it will work as expected for awhile, depending on the size of the leak, and then not! You bleep the throttle a couple times and it returns to normal. Again, with time and wear, the diaphrams can lose snap and/or leak. It this appears to be the case, the only real solution is to replace the cannister.

On the Petronix upgrade you can open the gap on your spark plugs to .040" to .050" depending on the condition of your engines and your plugs. If you get a high speed miss, close down the gap until it disappears.

Depending on your trans and your elevation you may want to try more initial advance too.

Hope that gets you down the road a little farther. Have you purchased a Shop Manual yet? They are about $50.00 and worth it.

Adios, David

 

[Anonymous]

The springs on the plate in the distributor are good. The vaccum diaphram on the distributor is good also. The coil in the choke is good. The butterfly does open up all the way and does not flutter. Petronix recomended my gap to be set to .45, The stock plugs I took out were all set to .35 I think. I put brand new autolite plugs set to .45. I will try them at .40, then .35 and see what that does too. The needle valve was sticky before I replaced it and I was so hoping that was the problem, lol. But with the new needle valve and seat it runs better, but still stumbles when fully warm. I will buy a shop manual in a few weeks after I get caught up. But if I start cursing too much I'll charge one. I will check into the vacuum a little more. Do I need to locate this so called resistor though, for the ignition? It runs the same way it did before, may be a bit better now. I do not think that little resistor would cause this anyways... but I have had dumber problems.

Thanks for the quick response.

 

[Anonymous]

I have fixed the stumbling! It was my fuel pump! It showed 6.5PSI, but after the motor warmed up (about 20-30 minutes) it went to 3 PSI, then 0! The fuel pump completely quits after 45 minutes, and now won't work at all! I replaced it with a $20 pump from Advance Auto Parts and the stumbling is gone.

Now I have a new problem though. It may be float related, the float is good and is not taking on gas and I have it set to the rebuild guide's suggested setting of 1 1/32 I believe it was. The car randomly quits when going down hill or if you gun it real quick. It doesn't stuble anymore, it just goes completely dead. It will start back up really quick though. It doesn't smell rich or seem too lean. I have played with the mixture screw until I was blue in the face... so I do not believe that is my problem (it idles as smooth as can be where I have it).

Does the float now sound like a place to start again? Or may this be a setting for the anti-stall dashpot??? Or vacuum related? There just seems to be a lot to cover for the same problem, lol.

Thanks!

 

[mkgcars]

I have had similar issues.

I was going to say there were all solved, but I hit some Sunday afternoon traffic at 495/Mass Pike and my 170" died on my in the toll booth line which was 15+ cars long.

Some things to check (well, things I know I'm going to check):
- Is the accel pump set so that as you move the gas pedal linkage it the accel pump moves? You don't want any lag. (this solved a lot of my original take-off problems)

- When it's fully warmed up (and not just 15-20m of idle, but after a real 30m of driving) check the idle. Maybe it's running lower than you expect. I think the spec is 550-600 in drive w/lights and AC on.

- The float spec is +/- 1/32. Could always try raising it 1/32 given the behavior on the hill. (The other thing on the hill is, you may be taking your foot off the gas - which brings us back to the idle setting).

It may also be we're just running into some of the classic 1100 issues.
Lets hear what others have to reply with as well.

PS: What size jet are you running? I know my old 200" had a 64, but I think it's common to run them a bit higher (66-70 depending on engine) so the 1 and 6 cyl don't run as lean - to decide this you may want to read your plugs and see if the outer cyls look a bit lean.

matt

 

[Anonymous]

It has the stock jet size.

 

[Anonymous]

I set the float level to 1 and 5/32 as recommended in another post and it is running even better. It no longer quits going down hill or around sharp turns. I currently have to have the idle set at 650 in gear to keep it from quitting when I put it in gear. I have solved another problem and have seemed to find another.

The car smells like it is running super rich, but if I lean it out any at all it will start to stumble. If I richen it anymore it will stumble. I have it right between the stumble points and it runs perfect as long as the idle is set high. It doesn't stall out under any load even if I gun it now. It just wants to quit if I set it to idle at 550 RPMs!

I guess I will start replacing all the vacuum hoses. Where is the vacuum canister the other guy was talking about? All my vacuum lines run to the manifold as far as I can see. I sprayed all the lines with soapy water and do not see it bubbling or acting up anywhere. And the vacuum pressure is around 16 or 17lbs from my initial reading (if I remember right). I have a cheapy actron vacuum gauge.

 

[ludwig]

You might be studying the wrong end of the car. If it runs fine for a long period of time and then just up and poops out, then starts right back up after a wait, or if it dies when you gun it hard, you may be picking up some crud in the gas tank that blocks the fuel inlet. This wouldn't show up with a bad fuel pump. A good one with good suction will do this.
The answer is to clean out the tank. Either by flushing out the fuel where the sender is and pouring some tank cleaner in the filler, or by taking the tank out and having it flushed by a pro (or you). Or you could just get a new tank. They are only about $200 dollars.
In an old car that has stood for a while with a paritially filled tank, water vapor condenses and sinks below the gasoline to the bottom. This water will make rust scale on the floor of the tank or even eat through the tank.

 

[CZLN6]

Howdy back:

Your stock Load-a-Matic distributor needs a specific, modified vacuum signal from the Autolite 1100 carb with the Spark Control Valve (SCV). That vacuum hose goes from the carb, not the manifold, to a nipple on the end of the vacuum cannister, which is on the side of the distributor. Some early models have a metal tube which screws on on both ends. Some have a hose and nipples.

IF you have a Load-a-Matic distributor and it is not hooked up to the SCV port in the 1100 carb you may have found a big piece of your problems.

The shop manual calls for a setting of 12 degrees of initial advance. You might want to try 15 degrees.

Adios, David

 

[Anonymous]

There is a metal hose that goes from about middle ways up the carb to the vacuum diaphram mounted on the distributor. I thought you may have been referring to something else I was missing.

Everything seems fine as long as it is idling high. I will try more advance. It is 12 initial right now, I will advance it a hair and see where it leads me.

When I changed the fuel pump I looked at the filter I put in a few weeks ago and it was clean as can be. I may go the route of a new fuel tank and lines soon anyhow. I have heard the old gas tanks were very dangerous if you are rear-ended. I though I might go with a better made tank, like a high capacity fuel cell. I will do something about that anyhow, because it seems the float in the tank may be bad, my wiring has good continuity and the gauge works right with proper voltages applied from a regulated power supply. It seems the float in the tank is stuck at 1/8 of a tank though.

 

[mkgcars]

You may have already checked on some of this or know it, but I'll throw it out there.

Is it smelling rich when you first start it up (maybe just choke setting), or rich after running a while?

The mixture setting is really for lower revs (is my undestanding), and above that it's really the jet that decides the mixture. So, if you're running original jet I'd doubt it was set too rich. My '65 200 came with a 64 and that shouldn't be too rich - even a 67-68 probably fine. Which is what brings us back to checking the fuel pump pressure and timing. More timing should allow a more complete burn.

Couple other things that may be worth doing (for peace of mind):

- May want to make sure the timing mark on the harmonic balancer is in right spot - if you haven't. May be easiest to just take out all the plugs, and then rotate engine until the mark on the balancer is at 0 mark. Now look down the #1 spark plug hole, slightly rotate the engine back and forth and confirm where it's peak is at - and check where the timing mark is. If it's off then note this as your 0 point when doing your timing.

- Check the plugs and see what they look like. Tan or light gray is good and would indicate its not too rich. They'll look blacker if its running rich.

- May want to check how much pressure the new fuel pump is putting out.