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Hard start after sitting 66 289

11K views 30 replies 8 participants last post by  bolensboneyard 
#1 ·
It's been a long time since I have started something without EFI. Got my 289 four barrel 4100 carb starting and running great but if it sits for two days I have to pump it several times to get it to prime. Can't remember if that is normal or not. I do not think I ever had to pump more than a few times on these old classics. thanks Bobby
 
#3 ·
I agree, sounds normal. EFI works so well it makes a carb look bad. :)

Depending upon how hot the day, up to half of the gas will have evaporated from the carb by the time the engine cools off. Later carbs were more sealed but most have fuel bowls open to the air so after a week they may have nothing left in the bowl. In that case pumping the pedal doesn't help until the engine has turned over enough times to put some gas back in the carb. Be patient, it only takes a few seconds to refill the bowl. Then pump the pedal once and it should start like 'normal'.
 
#4 · (Edited)
My truck starts on the first try even with 300,000 plus on the odo thanks to fuel injection.
My 70 on the other hand does take a couple of cranks on the ignition and a couple of gas pedal pumps to get it started after a couple of weeks sitting idle.
After that she will fire right every time on the first try.
It's normal with carbed engines.
I have a clear fuel filter between the tank and the fuel pump just to make sure the pump is operational.
 
#5 ·
get a phenolic spacer between the intake manifold and the 4100 and it will always start right away. i do have the same setup.
 
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#6 ·
Thanks gang for the heads up. I do have an aluminum spacer between the carb. and the manifold. I tried it a little while ago after it sat for a day. Two pumps and she hit once. After that I turned her over for ten of fifteen seconds twice and pumped got nothing. This is the first try after going one notch rich on the choke. I pulled the air cleaner cover off and it looked like it could be a hair open so I removed the whole cleaner. It caught the choke on the way up and the choke plate slapped down. After that it looked tighter. When I got back in and hit the key it started right up just like I had already started it and it ran fine even at low idle. The plate has a tendency to hang up on occasion when it is full open but I am wondering if it is hanging up a hair on the lip. I have looked it over close and cannot find a reason why it would. I thought the rod might have been rubbing on the air cleaner but there is plenty of clearance. I have a hipo air cleaner on it and the carb. is the 1.8 venture not the 1.12 hipo carb. It would have had the big air cleaner with the door set up. I wonder if that in some way effects the vacuum because of the pcv system?
 
#7 ·
...I do have an aluminum spacer between the carb. and the manifold...
I do have to confess - I didnt read your whole thread before I reply. I thought it was just hard to start after sitting for 30min or so, thats why I suggested the phenolic spacer. But anyway if I were you and I love working on cars, I would ditch the aluminum spacer and get an phenolic one right away. As you have the "old" 4100 be sure to get a spacer with a PCV (phenolic spacer + PCV = rare!)
it WILL help you to start the car after a long ride when you start it again after 15, 30, 60 min... and it MAY help after starting after a few days, but its normal to hit the gas a couple of times.
I usually do it like this: I start the car after a day = one gas pedal hit, I start the car after 2 days = 2 gas pedal hits...and so on...max hits for me are 4-5 and she will always start without cranking the starter more then a sec. (EDIT: my pertronix ignition helps also for easier starting)
 
#8 ·
Thanks any idea who supplies these spacers? I have a Mallory dual point distributor so though it's not high energy it does well once the car has been started. I talked to a carb. shop guy and he gave me some insight but thought I should focus on the choke which is where I have been for a day or so. Need to get back to it tomorrow.
 
#9 ·
#10 ·
I have two '66s with 289s one of which has a fiber carb spacer on top of the factory aluminum one; the other has only the factory aluminum spacer. Those two act identically as far as this long term starting issue is concerned.

I am still running experiments but I am not sure I can tell a difference between the two at any time. Besides a wideband AFR meter I also have a temperature probe inside the air cleaner measuring the temperature of the air going INTO the carb; a carb spacer can't do anything about the air entering your carb. On a hot day, with A/C running, that inlet air can be nearly 160F because it comes through a hot radiator and past a hot engine. No matter what kind of spacer you use when you shut off the engine the carb is still sitting in a bath of 150F air which is going to evaporate the fuel inside. Gas starts to boil at around 100F; your carb bowl can't help but start to empty itself in that kind of heat.
 
#11 ·
It's the gas evaporating out of the front fuel bowl. To verify this, take the top plate of the carb off after it has been sitting for a few days. If the front float isn't floating, you'll have to crank the starter (pumping gas) before it fills. You can add gas to the empty/low front bowl and it will fire right up. That's life with a mechanical fuel pump and a vented carburetor.

One way to eliminate this issue is to install a low pressure (4-6 psi) electric fuel pump and bypass your mechanical pump. Set it to go on at "run". Then, no matter how long the car has been sitting, turn the key to run and listen to the pump running. You should also hear the float bowl filling up until the float rises and shuts the flow off. Then turn the key to start and it will fire right up. On the downside, these pumps are noisy, unless you opt for an intank pump. If you go that route, you'll end up buying a whole new tank, and if you do that, consider upgrading to a fuel cell.
 
#13 ·
One way to eliminate this issue is to install a low pressure (4-6 psi) electric fuel pump and bypass your mechanical pump. Set it to go on at "run". Then, no matter how long the car has been sitting, turn the key to run and listen to the pump running. You should also hear the float bowl filling up until the float rises and shuts the flow off.
Just to clarify, yes the flow will stop, but, at least the way mine is hooked up, the pump will continue to run. Not sure how you will know when the bowl is full, unless the pump changes tone, but not a big deal. This isn't like every car with EFI I've owned, where the pump cuts off once the fuel line is pressurized.

But I had not thought of starting the car this way. Thanks for posting.

BTW, electric pumps should *always* be wired so that they will shut off if the engine is not running; e.g, in an accident. I wired mine through an oil pressure switch.
 
#12 ·
it's looking more and more like evaporation. I tried starting without pumping yesterday and she fired once. Hit the key again with two pumps and she fired and ran low idle but quit. last time three pumps and she fired up and kept running smooth. The idle steadily increased from 700 to 1200 rpm. I had shut it down adjusted at 700. I backed it off two turns to 800 and let the choke open full. I am going to try and start this morning and see what the rpm does and readjust if necessary in order to get a balance between the high idle and idle. Choke was all the way closed and the temp. was 10 degrees below what it has been the night before. I had been also pumping the hell out of it as I cranked and that did not seem to help in the past. The carb. tech also told me that running a paper filter open side would cause it to evaporate faster. I am running a hipo air cleaner (open side) and only have a 1.08 venture. He also said besides the choke being a hair open that the rubber floats could be shot so I will probably change them. Any thoughts on brass verses rubber? I do appreciate the insight gang and add these things to the mix for better understanding over all on the forum. Bobby
 
#14 ·
Electric fuel pumps come both ways. Some shut off when the bowl is filled and some don't. EFI has no fuel bowl so it would be difficult to know when to turn off any pump. It is very common for EFI pumps to run continuously since starting and stopping would change the fuel pressure which often controls the mixture especially with Bosch systems.

I added an electric pump to a non-Mustang back about 1980 to solve a similar fuel problem. Even though the pump never shuts off the sound of the (yes, noisy) pump changes when the carb bowl fills and shuts off nearly all of the fuel flowing through the pump. I know by listening when the bowl is full; only then do I attempt to start the engine.

If you wire the pump through an oil pressure switch, etc., you can't listen for shutoff since the pump won't run until the engine starts. Its a minute bit safer and makes Ralph Nader happy but it defeats the purpose for which I added the pump. Cars ran on electric pumps without such a safety switch for 50 years; its your car make your own decision. Similar logic would say all Mustangs need air bags since new cars use them for safety reasons.

The carb. tech also told me that running a paper filter open side would cause it to evaporate faster.
What filter you use, if any, has nothing to do with evaporation. The evaporation takes place from the float bowl vents in the top lid of the carb and also sticking up inside the air cleaner.

The idle speed when first started is not the same adjustment as when the engine is warm. There is a high-idle screw on the passenger side of an Autolite that sets high idle to something like 1600 RPM (when checked with a warm engine) using a cam in the choke linkage . When the choke is disengaged the high-idle screw does nothing and another screw on the driver side adjusts for the warm idle near 600 RPM. The two adjustments are independent of each other.
 
#17 ·
This thread reminds me of how GMs always had to be pumped forever when I was a kid. I don't remember Fords being like that.

So, in 66 did you just push the pedal all the way down with the key off to set the choke? I can't tell you how many times I was with people who didn't know how to turn the key on and set the choke on '70s and '80s cars. They pump and pump like it was part of driving. Really annoyed me. Then they'd flood it, and of course still not know how to deal with that either. I guess holding the pedal down when you smell gas may not be intuitive.

On topic, I'd get a carburetor rebuilt if I was having to pump a lot. It may not make it perfect, but not knowing if it could hold the fuel longer would drive me nuts.
 
#18 ·
I know all this but the one missing piece of the puzzle which you have now given me and I thank you is that the high idle speed of 1600 and the fact that it should continue until the choke is open is the detail I was missing. I have had the low idle at start of 650 to 750 rpm and as the choke got to open approx. 1/2 inch it soared to 1600 rpm and I thought this should be no higher than 1000 to 1200 rpm. I have been playing with both for the last two days trying to achieve what was already there. Now I know I should have waited until the choke opened and kicked down. I have a 66 6 cyl that I usually kick down to achieve this but this four barrel v eight GT is the first one I have ever played with. If I am not understanding you correctly please feel free to readjust me. My cup is empty. Bobby
 
#20 ·
If I am not understanding you correctly please feel free to readjust me.
Your description seems to be correct. I think you are now on the right track.

There are a wide variety of electric fuel pumps. The first ones I know about were the English SUs which came into use c1935 but were still being used 50 years later. Those are somewhat strange in that they only pump when the pressure in the line drops below 'normal' which for them was only about 2 psi. They had the same problem of carb bowls drying up even back in the 30s so the procedure for starting an old English car was to switch on the ignition which started the SU pumps clicking. As the fuel pressure went up the click rate slowed down and when the clicking, i.e. pumping, stopped entirely then, and only then, was it time to start the engine. That also worked as a check on your fuel system since if your engine wasn't running but the clicking never stopped then you had a problem with either your pump or the carb. The pump clicking rate while driving depends upon how much fuel you are using. The pumps were also thought to be so unreliable that many cars had two of them running in parallel so that if one quit working you still had a chance to make it home. :) Some of us still drive those strange old boats.

I also own a low pressure carb car which came from the factory with a return fuel line from the carb to the tank much like EFI cars normally have. That still didn't solve vapor lock so I had to convert it to use an electric pump pushing fuel forward from the tank.

There are so many possibilities out there that its likely that almost anything has been done on some car, somewhere in the world.
 
#21 ·
I spent the whole day yesterday addressing problems with performance. Thought I would update progress and possible help others in the process. The GT is starting fine cold as of the opening volley. I took her out for a run and find I have some hesitation and surging but for the most part no stalling or backfiring. The following is the short list of what I encountered in my quest to bring out the best possible performance for a stock 66 just being born. The right rear brake was dragging as it was overtight. I did not adjust this one. Had a helper. No more surging after that adjustment. The hesitation was still there but mostly at lower speeds. I ended up with backing off on the mixture half a turn and retarding the spark a little. My exhaust indicated rich so I had been going by that but the lower hesitation speeds turned me to richen it more. Took it out for a last run as I had nothing left for energy. I ran as is should. I will see how it cold starts tomorrow and run it again to be sure. I may have to back off another quarter turn if any. Let you know. I know this is another issue but I have a hertz competition plus four speed with up to the left reverse. This shift comes out of rev. and wants to stay keeping me from using the other gears unless I go back and forth playing with it some. I checked it out and greased it before it was installed. Shifts smooth in all gears. Only a problem when I use reverse. Bobby
 
#23 ·
Thanks to all who have replied to these posts in case I missed someone. Here is where I now sit. I have fixed the starting problem and it was multi faceted. I final straw was when my choke stuck open bad enough to pull it apart and investigate what that problem was (never mentioned that one). It turned out to be some sand stuck in the little piston inside the choke. That was also causing my choke plate to look closed but not seat. Starts now almost like EFI One pump and five seconds of crank. I found that if I engage the reverse slowly she will not lock first in and jam. Works fine. I still have a problem with hesitation and a small loss of power mostly in the lower gears. I am now at a point where I am retarding my spark once again and will try that today. It has been steadily improving with adjustments to carb. and dist. but not yet right. I have a Mallory dual point dist. installed and it is vintage. Not sure if the balance between points (dwell) is right or possibly intermediate jets clogged but I should be an expert on this carburetor by the time it's fixed. If it is the carb. Bobby
 
#24 ·
Play with your distributor timing and I'm betting that you'll be able to fix those driveability issues. Modern fuels burn slower than "back in the day" so you should try and advance the timing. I've actually nix'd the carb setup completely for EFI and my distributor timing is much different than the factory settings. I can't say for sure but your carburetor setup may require timing more similar to mine than factory.

Mine is 16 degrees initial advance, mechanical advance starts at 1500 rpm and adds 18 degrees at 3500 rpm for a total of 34. I don't use vacuum advance at all.

Always check for pre-detonation ("ping") when making these drastic changes.
 
#28 ·
As of my last post I started messing with the dual point as I have felt right along the problem was more in the distributor. I purchased it rebuilt be a shop and the carburetor was built by me. Not that I don't make mistakes (lots) but I know what I did. It does ping once in a while but mostly hesitation. I have followed advice on the dist. up till now to retard the spark even though four plugs are carbon up and four clean. This was based on low speeds having more hesitation. Made more sense to me to advance but I am always willing to learn (been learning for 50 years). What I found was the dist. was way off dwell. One set of points showed resistance when closed and we could not get the parameters necessary in accordance with tech. support at Mallory. Don't have the figures in front of me but I believe they are in the ballpark you supplied in your post. In addition to this the points were set at .016 per the original tech .rep but the correct info is .022 on the gap. I also changed the condenser as the one installed was no longer a good number according to the rep. I will put her on the dwell meter tomorrow. I bet you are right! Meanwhile I have spoken to my cousin who ran a carb. shop for years and he advises me to rebuild the 1.12 venture 4100 I have on the shelf and shelve the 1.08 as the hipo carb is a better one. Also advised me to go up two sizes on the main jets. I burn real gas without alcohol but I agree it's not what we used to get. Even blue Sonoco was better. Bobby
 
#29 ·
You never mentioned you have two 4100s. 1.08 vs 1.12 will have nothing to do with your reported starting problems. Starting uses only the primary barrels so its the same as starting with a 2100 which were usually 1.14s. Any of them should start the same. Also, just being a 1.12 does not make a 4100 a HiPo carb. The '64 Comets used a 1.12 4100 on a low compression 289 similar to the Mustang D-code engine which used a 1.08 4100.

Similarly point dwell has little to do with anything until you get to much higher RPM. As long as the points open and close it makes little difference at all what the gap might be for either single or dual point systems at, or near idle speeds. For a dual point system using an 8-lobed rotor one point set 'makes' contact allowing current to the coil while the other set 'breaks' the contact and creates the spark. Unequal dwell on the two points affects total dwell to the coil slightly but each cylinder still gets the same dwell and relative timing. What condenser you need has nothing to do with dual points or the points at all; its the coil that determines what condenser you should use.

Hard starting after sitting is not a distributor problem; its a carb problem. A distributor problem would give you the same hard starting all the time. The Ford factory jets were already on the rich side for fuel either then or today. Using larger ones will only tend to foul the plugs and make starting even more difficult. The difference between E0 and today's E10 in an Autolite is 0.4 AFR which is similar to changing less than one jet size. You can't tell such a small difference exists without an AFR meter in your exhaust (which is where and how I get my data). Even if you could tell that difference its only at cruising speeds. Main jet size has nothing at all to do with your starting and idle mixture.
 
#30 ·
Perhaps you should read all the posts and everything in them. As I have stated the starting problem was solved by finding a vacuum leak in the secondary circuit. It has since started fine. In fact. One pump and two seconds of turning the key fires it every time without an electric fuel pump. The problem I have been addressing in later posts is hesitation at running speeds in all gears. The 112 carb is in case I could not solve the problem with ignition. I was advised to build it with larger jets by my cousin who has been in the carburetor business for fifty years and races on the NASCAR circuit. The carburetor I have came off of a police 428 and I know what a HIPO carb is. The only difference is the manual choke as far as my GT can tell unless the larger jet size were to take care of my hesitation problem, again, in case you miss it, if it isn't taken care of with addressing ignition. And lastly the points have been set as has the dwell on my car and the hesitation is gone. It runs like a watch in all gears. If you want a car that has a computer to run it that's fine your choice. Personally my 2012 has that and that little v6 has 310 HP. And by the way, I have been a certified Aircraft Mechanic for 43 years so I know all about numbers. I am not interested in debating electronic issues on a fifty year old automobile just enjoying what it is. I am also not a green kid, so if you feel you have to piss higher on the wall than anyone else have at it. My cup is always empty. That's the way to learn. I am open to that even after sixty years of turning a wrench. I do not dispute your technical data, but your taking things out of context in order to impress me with it is a waste of my time and is self serving to say the least. My brother in law is a doctor and he is always trying to impress me with that crap but what works is usually written between the lines of BS, so skip it if you can. If you have a headache you can take an aspirin, or a marvelous combination of aspirin and other chemicals because years of pharmaceutical research says so. Or, you can find out what is causing your headache, go calm down, and be better off than spending years medicating yourself. Thanks to all who have given me something to think about and consider in my quest; and thanks to you Ivy 66; I'm sure you basically have good intentions, but I don't care to be talked down to.
 
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