My Willys 3A and 3B Community
3A, 3B, DJ Technical Knowledge Base => "Original"-- Technical Questions, Answers, Observations => Topic started by: Doug on November 28, 2010, 06:22:52 PM
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When I park my jeep when hot and try to restart ten minutes later, it is hard to start. When I say hard to start, I mean I will have to keep massaging the gas pedal for 2 minutes until it settles down to keep if from stalling. �I assumed this was due to the fuel boiling in the lines. �Today, I also notice when I had the hood up that I could hear the carburetor pressurized by the boiling of fuel and slightly overflowing when parked hot and engine off.
Is there a setting or adjustment that may be off in my carb that causes this?
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What is the temperature of the thermostat your using and what pressure radiator cap? You should be using a 160-170 deg F thermostat and a 7 psi radiator cap.
You may have to much fuel pressure also.
If the fuel boiled in the lines that is called vapor lock and it likely would not start at all. I suspect what is happening is the fuel pressure is to high causing the fuel to leak past the needle and seat at the float flooding the engine. Running a high temp thermostat and high pressure rad. cap adds to the problem.
EDIT: you could also have a bad needle and seat.
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Some questions:
Carter or Solex carb?
Stock or electric fuel pump?
If stock fuel pump, with or without vacuum?
Is your heat riser stuck or free?
How close to the exhaust are your fuel lines?
Larry
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Carter WO, mechanical fuel pump, 2-3/4 PSI fuel pressure, without vacuum. � �Heat riser functions. � Fuel lines not particularly close to heat riser. �However, I do you an oversize fuel line from pump to carb ( 3/8" in lieu of 1/4" so that it fits a ford fuel filter at the carb). � I am running a 180 degree thermostat. �Jeep operating temperature is 185 degrees with the higher thermostat. �However, it did this before when I ran a 160 degree tstat.
Issue only occurs when the jeep has been run and then parked and then try to start up ten minutes later while still hot. �Then it wants to stall unless I pump the gas pedal for a minute or two. �
I am guessing that the slightly larger fuel line plus the fuel filter (metal) hold more fuel than stock. Then it probably expands when heated up and overwhelms the float valve. That would then flood the carb. What I can't understand is why does it take one minute of running to straighten out.
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If you just hold the throttle open instead of pumping it does it die? I mean, hold it wide open when you try to start it and as the engine picks up rpm's then let off the throttle easy until it smooths out. Or, does it refuse to start if it is held wide open?
It very well could be a defective needle and seat.
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I think Carl and I are confused by the same thing. If it's boiling over then the issue would be flooding which would make for hard starting. The answer would be to simply hold the pedal all the way to the floor until it starts AND until the flooding is cleared. Don't pump, but don't let it over rev once it starts either.
I'm wondering too about your fuel pressure. Stock, it should be about 4.5lbs at 1800rpm.
As for the flooding, the size of the fuel line and the filter should have no effect. Here are some things to look at:
As mentioned, needle and seat. If the needle is an older one with a neoprene type tip it's possible ethanol has damaged it.
Float set too high. Self-explanatory
Fuel lines too close to exhaust. The line from the pump OUT should go straight towards the fender, then make a turn upwards towards the carb inlet.
Leak in the float. Sometimes the floats develop pinholes (if metal) or get saturated (if composite).
Missing or incorrect insulator gasket between carb and manifold. (Fuel diffuser and gasket).
(http://www.walcks4wd.com/images/Products/thumbnail/DCP_7255.jpg)
Larry
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After my last post I got to wondering about that thick gasket and if it got replaced some time along the way with a thin gasket.
How long has it been doing this and what changes have you made before it started doing it.
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I have the thick gasket. �Not sure if it has the v or not but it is definitinely the extra thick gasket. �This is my fuel line setup (http://i116.photobucket.com/albums/o26/peeb1964/002.jpg)
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Lines look good. Just out of curiosity, do you have the spacer between the fuel pump and the block?
Did this just start? Did you change gasoline brands (sounds stupid, I know) by any chance?
Aside from that, it sounds like the prob is in the carb. Take the top off and inspect the needle and seat. Check the float, see if it has fuel inside. Check the float setting making sure the gasket is moved aside when setting it.
Larry
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I do not have a spacer under fuel pump. I may have recited the fuel pressure incorrectly. I remember when I checked it a year ago it was within spec. The issue is not new, it has always done it, I just wondered if there was a cure so I would not have to keep tolerating it. i did not change gas brands. I will check the carb settings. You say when measuring float level, do not include the gasket thickness in the measurement.
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Those Mexican replacement pumps are usually OK so I think we're back to the carb. Yes, set the float without the gasket.
(http://i863.photobucket.com/albums/ab191/rocketeer_2010/Jeep/woadjustment1.jpg)
(http://i863.photobucket.com/albums/ab191/rocketeer_2010/Jeep/floatlevelsetting.jpg)
Larry
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Thanks
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I got to wondering about the needle and seat problem with the 10% and 15% Ethanol gas so I called Walck's. I told him I had one of the expensive original Carter kits I bought from them and asked if the Ethanol was an issue with the old rubber needle. He said of all the kits they have sold over the years none have given trouble. I had to agree because my carb may have never been rebuilt and it is doing ok so far too.
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Not all needles have rubber/neoprene tips. Most are just metal. My current carb has an all metal needle as do each of the spares I have.
Larry
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I would prefer the all metal but I have what I have.
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When I park my jeep when hot and try to restart ten minutes later, it is hard to start. �
I've been watching this thread with great interest. Was there not a thread on the old forum discussing this exact same problem? I ask that question because I'm not really sure. Some of you will remember that on the old forum I discussed the problems I was having with my carb overhaul. It wasn't till after my overhaul that I started experiencing the problem exactly as Doug has it described above. That's when it came to mind that someone else had sought help with a similar problem earlier. Seems like a possible solution was that the metering rod was not dropping completely into the main jet far enough to stop the fuel from draining from the bowl into the hot intake manifold and boiling away. But then, it takes a really good seal to stop fuel from flowing so I don't know how the metering rod could ever do that???? Nevertheless, after I went back into my carb, reinstalled the old metering rod and a few other parts, that problem as well as others went away. Did I just get it right this time, did it really take the old metering rod, etc., to fix my poor running carb, or was I just luckier to get the settings right this time? I really don't know.
I've been watching to see if some of the same answers emerged that I thought I saw on the other forum. If someone knows of the location of that thread on the other forum please reveal it. Thanks.
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I guess it's possible for the metering rod to do that. One thing I noticed when reading the text about adjusting the metering rod I noticed some contradiction in the adjustment of it. They tell you to back out the idle screw on the throttle plate stop and adjust the metering rod linkage with the tool. Then they tell you to set the idle. Then they say that when the throttle is closed with the idle screw holding the plate open so it will idle the metering rod should be seated in the jet in the bottom of the carb.
Well, I'm here to tell you that is a contradictory statement. If you set the metering rod seated in the jet with the throttle plate completely closed and then open the throttle plate so the engine will idle the metering rod will NOT be seated.
One text goes into detail about how to test the metering rod seating after using the tool and describes how to set it without the tool. I don't have the tool and I have plenty of time to do the bench testing and I understand how it should work.
With that in mind I am going to devise my own way to set the metering rod and when I get everything worked out I will describe what I found and did.
I am also in the process of making my oversize throttle plate shaft. I have the body reamed out now and have the shaft fitted and a few cuts made. I am taking photo's and will do a thread on the subject.
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This one:
http://cj3apage.proboards.com/index.cgi?action=display&board=Tech&thread=1583&page=1
or this one:
http://cj3apage.proboards.com/index.cgi?action=display&board=Tech&thread=1592&page=1
and this one:
http://cj3apage.proboards.com/index.cgi?action=display&board=Tech&thread=1500&page=1
Larry
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Thanks for the links, I read them.
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Thanks Larry, for digging the links out.
Like Carl, I read each one of them again. It was fun to relive much of my troubled past with my carb. I thought there was a thread some time before I had any carb grief. And because I was having no grief it didn't mean much to me so I paid it little attention. It was probably something else.
So now it comes down to this:
Doug, have you received anything here that has helped you with the original question you asked about? I think there is an answer out there for your problem. I believe it is more common than realized. Since most carbs don't have that problem and others do, what is the difference? Wish we knew.
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I have not torn into the carb to figure it out. Been busy with holiday stuff. However, it runs good except for this minor issue so I am hesitant to go finding a problem. I believe it is one of three things, either the fat fuel line and large metal fuel filter hold more fuel which expands more than stock when heated and that overwhelms the float, bad float adjustment, or bad metering rod adjustment. I started to read all that metering rod stuff when I was in a hurry and my eyes just glazed over. I am going to have to read it sometime when I have the time to really study it. Really have no idea what you are trying to measure when you set the metering rod length.
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There is one more, somewhat obscure thing to consider and that is that some brands of ethanol boil easier than other brands. I have had good luck with Shell and Exxon/Mobil but have had problems, some serious, �with Sunoco. Ethanol is a PITA and can, and does, cause goofy problems. You might want to consider a change in gas before tearing into the carb. It's an easy test. Just a thought.
Larry
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To support what Larry wrote about different qualities of gasoline:
The very best quality gasoline for internal combustion piston engines is 100 octane aviation fuel. It is manufactured to strict FAA standards regarding vapor pressure, additives, burn rate, etc. I wold suggest that anyone experiencing any such problems as discussed above run a few gallons of aviation fuel (av gas) through the engine (empty out the last of the car gas first). You'll be amazed at how well the engine will perform and it may prove that your carburetor problem is really a problem with poor quality gasoline. Many race car drivers use av gas for better performance. Av gas is a bit more expensive at about $4.50 per gallon at most airports.
Just today I put my seasonal Jeep away for the winter. Before doing that, since it is going to sit for up to five months, I always drain the last of the automobile gas from the tank and then put in two or three gallons of 100 octane aviation fuel. It remains fresh for well over a year. It never gums up or leaves varnish residue in the fuel system. It is readily available at any airport that serves general aviation (small planes). You can either drive your Jeep to the pumps / fuel truck or you could pick it up in a regular gas can.
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Calvin, Would running av fuel full time burn valves, or do any other damage? Jim
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Jim,
You've asked an interesting question. �When I was 25 years old (1969) I used to run a small aviation business. �I could buy 80 octane aviation fuel for about the same price as I could buy premium gasoline at the station. �I owned a large block Chevy at the time. The av gas actually performed better in that car than premium (in those days it was called Ethyl). �I ran it for years. �It was pure octane (hydrocarbon C8-H18) and had no lead in it. �Aviation fuel was also available with a 100 octane rating. �It had lead added to increase the octane rating, much like former auto fuel (lead was added to hexane [C6-H14] or heptane [C7-H16] in order to get it to perform like octane). Of course, now other additives have replaced the lead in auto fuel since it has become unleaded. They also stopped making 80 octane aviation fuel and at the same time reduced the lead in the 100 octane fuel and called it 100LL. �The LL meant low lead so it could be used without harm in the earlier lower horsepower engines that had been built for the fuel without lead but also provided the higher octane rating required by the newer, larger engines. �The only aviation gasoline available now is the 100LL. � That's what I put in my Jeep yesterday to "winterize" it because it now has to sit for so long. �I drove it around some with that fuel in it yesterday before parking it and it actually seemed to perform better (but told myself that it was probably just my mind playing tricks on me). �All that said, I do not believe that the 100LL av gas would harm our little four cylinder engines at all. �The foregoing is the extent of my reasoning. �I welcome comments from others because I certainly am not familiar with all the aspects of the L head 134 engines.
NOTE: If you were to run av gas in a modern car it would quickly burn out the catalytic converter because of the lead in it.
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To followup on on that, when I was taking flight training in college, one of the A&P instructors had a replica Shelby Cobra with a 427 cid in it. Talking with him one day, he admitted he would run 100LL (av gas) through it occasionally to help burn deposits off of the valves left by today's "clean" gasolines. He did let me know rather quickly not to run this in newer engines because it would toast converters rather quickly. At the time, I had an '84 Chevy truck with a slightly modified 350 cid and a roommate that worked at the airport. Being young and adventurous, we put a few gallons of the 100LL in my truck and ran it through. While it didn't turn it into a drag car, it did provide a slight increase in performance.