Joined: Feb 16, 2007 Posts: 206 Location: Gold Coast Australia
Posted: Thu Jul 21, 2011 3:10 pm Post subject:
Just changing parts is not a good way to solve such problems as it is shooting in the dark. It can become very expensive though. Your problem will be something quite simple & you'll kick yourself when it is found.
http://www.secondchancegarage.com/public/186.cfm Let's think logically about what can cause a problem like this only happens after you have been running for a while....that eliminates many things including vacuum lines unless they are thermostatically operated.
One recent suggestion like tank vent could be possible. when the problem occurs remove the fuel filler cap. What happens?
bad muffler can cause such an issue as can restricted exhaust but that is why we would plug in a vacuum gauge....it will help identify these type things without putting a wrench on the vehicle except to maybe remove a plug on the manifold if needed. _________________ John GIBBINS
ASE Master Medium/Heavy Truck & Auto Technician 2002 USA
Licensed Motor Mechanic NSW # MVIC 49593 Current
YOU CAN'T TROUBLESHOOT WHAT YOU DON'T UNDERSTAND
Joined: May 14, 2009 Posts: 972 Location: South Dakota
Posted: Thu Jul 21, 2011 5:43 pm Post subject:
By you saying that it comes out of it's cutting out by simply stepping on the gas a little makes me suggest another test. Remove the hose between the crossover and airfilter. With the engine idling poorly, lightly spray carb cleaner into the inlet of the crossover. If the engine smooths out, you have a idle circuit fuel starvation problem. I had this on mine which caused the engine to actually almost die, come back and then do it over and over. Surging on and off would be a good description. You could still have a vaccum leak in the system that causes this, or my final problem was in the carburator itself. If you take the top of the carb off with the curved air horn, you will see the float chamber and float assembly. There is a 2 or so inch tube that probes down into a deep hole. It's brass and pushes into the top of the part you just removed. ( up from the bottom) It has two very small holes in the side of it. My BRAND NEW kit supplied this tube. One of the two holes was blocked with a brass shaving. I gently pushed it out with a small orifice cleaning broach, ( smaller than a pin). This small barely visable blockage caused the fuel starvation in the idle circuit which caused the bad idle. Hope this helps more. John
Posted: Thu Jul 21, 2011 5:47 pm Post subject: Engine Citting Out
Hi, all, Thanks Artificier, I certainly agree that that just changing parts is the wrong and expensive way to go. Since I rebuilt this jeep, I have not spent a dime on parts as I either bought everything new and NOS when I could or had some items rebuilt by professionals. I hesitate saying how much I have in the project but everything, except the differentials, has been gone through in some manner.
I did check to see if the problem was caused by the gas tank or lines and it is not as I removed the cap and nothing changed.
One thing that I mentioned which did not get much attention is that we have seen some sort of thick oil or grease around the base of the carb; for the life of me, I don't know why I didn't check that out more thoroughly. We did today and found we could tighten the two nuts more than I realized but we did not give it a test.
We did torque the head again at 65 and found that it is at least that much all around.
My son and I had a discussion as to why I do not have a vent line between the two screws of the fuel pump as shown on Page 162 of TM9-8012; after giving it much thought and removing the fitting discovering that it has a ball check valve that will allow air or vacuum out but nothing in, I remember that several years ago we had a long post and as I recall that a change was made on later engines that substitued the fitting for the line. Does anyone remember this situation.
We are excited and looking forward to making the vacuum test. Thanks Artificer for the reference as it appears to be excellent. I could not find a port/removable plug on the intake manifold. There is a picture of the vacuum gauge being used on Page 80 with a good descsription of the test but it is not clear to me exactly how this is connected. I notice that on Page 79 there is a picture of testing fuel and vacuum pump pressure and we want to do that also. Then for a test drive. Thanks again everyone, we have learned from each of you. Semper Fi Ben and Ben _________________ Semper Fi Ben M38 & M100
My OldSalt comes from about 20 yrs as a deap sea sailor in the merchant marine. I was an engineer and ran the engineroom on numerous steam ships.
The fact that you can pull the choke and smooth the engine out means that for whatever reason it is going lean. This could be caused by not getting enough fuel or perhaps by heat boiling the fuel, causing vapor lock, or a vacuum leak. You've had the carb checked and overhauled so it isn't likely to be that.
Do you have the proper thick gasket under the carburetor? It is about 1/4" thick and has a v shaped metal piece that sticks down into the manifold to stir up the fuel mixture. The thickness helps insulate the carb from the heat of the manifold.
Check the fuel lines location both before and after the fuel pump. Is any part of it close to the exhaust? You might want to rig a pressure gauge to check the fuel pressure at the carb inlet. Is it too low? Is it high enough when cool but then drops down low when it heats up? A Carter carb needs about 4psi. A Solex needs 2 or less.
The spray vacuum test will point out any possible vacuum leaks on the intake manifold gasket.
When I asked about a regular miss, I was wondering if it involved just one cylinder or more than one. If it was missing on just one cylinder the miss would be a very regular beat. The fact that it gets worse and finally dies probably means that more than one cylinder is involved. If it was just one cylinder it would be able to continue running.
The fact that you can step on the gas and it clears up makes me think it's not low fuel pressure. If the carb were running out of gas it would get worse when you open the throttle. Good luck with the rest of the tests.
Posted: Fri Jul 22, 2011 8:33 am Post subject: Engine Cutting Out
Hi Oldsalt, thanks for the come back; sounds as if you had an interesting career.
As you can guess, I was answering others when your post came in. In response to you, I am not sure about the choke but will test again as soon as we take a spin.
Yes, I have the proper gasket under the carb---interesting that you mention this part as it was I who, to my knowledge, first posted about this odd looking critter several years ago and it was followed by a lot of chatter; as I recall, several seem to think that the v metal component underneath didn't matter but I have it on mine. We did tighten the two nuts some yesterday and who knows, that may have been our problem---as I said no test yet.
Also interesting is your comment about the fuel lines possibly being too close to the exhaust system; frankly, I do not know but good question. If you look at pictures on Pages 116, 124, l27 (best), 132, 141, 152, and 162, I see the fuel line as it leaves the fuel pump going straight up or vertical and then bending to connect with the carb. To me, this places the line much closer to the exhaust manifold than mine. Because of my problems of the engine cutting out,to the best of my memory, I allowed a mnor change to my goal of a factory restoration to route the line on a 45 degree slant toward the fender before going to the carb.
We are planning on going with the carb cleaner, fuel and pressure, and engine vacuum tests. If we can figuing out the connecton Page 80.
In the meantime, thanks for your thought provoking post. Semper Fi Ben & Ben _________________ Semper Fi Ben M38 & M100
I would think the carb bolts being loose would be a prime candidate, but you said in earlier posts that you've had the carb professionally overhauled twice. I assume that it was removed for that work. It's hard to imagine that it was re-installed twice and left loose in exactly the same way both times. Even a tiny difference in the position of those nuts, if they are the cause, would at the very least alter the pattern of the problem.
Some of the things I suggested, like the fuel lines near the exhaust, are just minor possibilites but as you go farther without figuring this out, you need to look at the more unlikely possibilities.
As for hooking up the vacuum gauge, you need to find a connection on the manifold where you can screw a gauge in. You could also tee into a vacuum line for something like the wipers, but you want to hook on as close to the manifold as possible to get the best reading. Personally I think the spray test will be easier and has the added benefit of telling you where the leak is.
Hopefully tightening the carb base has the problem fixed. Good luck.
You want a manifold connection for the vacuum gauge test. You have two choices. 1-Remove one of your hand primer jets and install an adapter for the end of your vacuum hose. 2-Remove the "t' for the vacuum pump hookup and use that port. You want to read engine vacuum only not the boosted vacuum created by the dual fuel/vac pump. _________________ Wes K
45 MB, 51 M38, 54 M37, 66 M101A1, 60 CJ5, 76 DJ5D, 47Bantam T3-C & 5? M100
Posted: Sun Jul 24, 2011 5:54 pm Post subject: Engine Cutting Out
Hi All, just an update. We have no answer yet but we have learned a lot today and are making progress. For any novice who might be monitoring this thread, to find a port to attach a vacuum gauge as close to the intake manifold as possible, as Wes suggests, there are two vacuum lines coming from the fuel and vacuum pump (See Page 162 TM9-8012); the outside one goes to a T survicing the windshield wipers and the other branches from the T goes across the motor. The inside line near the motor is the one to follow to a front side of a T inserted into the top of the intake manifold; the port on top of the T is plugged. This is a bit confusing. See picture on Page 116. The T that is obvious is the one going to the wiper, etc and not the one you want; if you look closely, you will see Line C goes behind that T into the T on the intake manifold and you can even barely discern the plug. The picture on Page 124 more clearly difines the intake T and plug. By removing the line from the fuel and vacuum pump and then removing an inserting the plug into the port vacated by the vacuum line, we found it much easier to attach our gauge---finding a connection to attach the gauge was much more difficult but we did.
Upon stating the motor, the gauge hand quickly went to just out side of the normal setting. Substituing another gauge, the hand was barely outside the normal range into a red area indicating that our timing was slightly off ---we had just set this exactly a couple of days ago, we thought but upon attaching our timeing light again, it showed we are slightly off (couple of degrees). As the engine was hot, we stopped for the day.
The pointer was not steady but waivered slightly. Will keep you further updated. We can not express our gratitude sufficiently to let you know how much we have learned from all of you who have posted. Thanks and Semper Fi. Ben and Ben _________________ Semper Fi Ben M38 & M100
Sounds like you have a plumbing error on your jeep.
Quote:
the outside one goes to a T survicing the windshield wipers and the other branches from the T goes across the motor. The inside line near the motor is the one to follow to a front side of a T inserted into the top of the intake manifold;
Rge line from the wiper "T" goes to the distributor not the cossover pipe. The line from the other side of the distributor goes to the crossover pipe.
The vacuum test gauge should be connected to the intake manifold at item F. It would be best to remove line G from the fitting F. and attach gauge there on F.and leave the top port plugged if item F is a "T" fitting. Some jeeps you may find item F is a 90 degree elbow. _________________ Wes K
45 MB, 51 M38, 54 M37, 66 M101A1, 60 CJ5, 76 DJ5D, 47Bantam T3-C & 5? M100
Posted: Sun Jul 24, 2011 8:27 pm Post subject: Engine Cutting Out
Hi Wes, thanks for your post. Actually, my plumbing is the same as the drawing; it was my wording, "it goes across the motor' that gumed up my post. As the line from the T shared with the wipers does go to the distributor---I really didn't mean that it went to the cross over pipe. I have the T on the intake and since the port on the top is the same thread and size as front of the T where the line goes from the Fuel and Vacuum pump, it seemed a bit easier to remove G and then use the plug from the top to plug the hole, then attach the gauge on top (more hand room); however, if it makes a difference in reading, we can change it. But, thanks for you post as some one trying to learn from this thread probably would read it wrong without you input. Semper Fi Ben BTW, I seem to remember using the sketch by Bob several years ago to check out my system---I note you edited it yesterday _________________ Semper Fi Ben M38 & M100
The web site clock is about 10 hours fast. I edited the drawing about 2200 today Sunday.. _________________ Wes K
45 MB, 51 M38, 54 M37, 66 M101A1, 60 CJ5, 76 DJ5D, 47Bantam T3-C & 5? M100
Posted: Wed Jul 27, 2011 2:07 pm Post subject: ;Engine Cutting Out
Hi All, after going through several tests and adjustments, we are back to square one. After a short discussion of some questions, I am asking some even more pointed questions and hope all of you will respond:
1) After rechecking timing, at the moment it is about 3/32" off we think but we have had a big discussion as to exactly what is 'on." We can find no picture of our exact check point in any manual we have. Our eninge is not the original but one overhauled at a depot Serial No. 30287 (M38 Serial No. 22797); ours has a timing indicator over the pulley with 2 points and a valley inbetween; since the motor turns clockwise, we have assumed that the line in on the pulley should line up with the first point to be at 5 degrees before TDC; I have thought the second line should line up with the top point but my son thinks 5 degrees before TDC might be the valley inbetween. Does anyone have picture of this setup? And, how critical is 3/32" +- a tad?
2) More and more we are looking at the gas line location. We can not find a good picture of the complete route from where it enters the engine compartment all the way into the fuel vacuum pump. I had to redo this entire line and I remember now of my search for the proper route 5 years ago and never found one. We think that it is possible that the line as it comes in runs too close to the exhault pipe. Also, the picture in the manual leaves some doubt of the flexible hose route attaching to the pump. Does anyone have a reference or a picture they could post?
3) The question is asked in this thread if using the choke makes the engine stop it process of slower idling and dying. The answer is NO it does not. At times, after it dies, the only way to get it started when it is real hot is to hold down the accelerator and it seems to finally clear as if it is flooded; yet, other times, it will only start if one pumps the footfeed; other times it needs to cool. In this connection, when it is first started cold and then running some, it idles smoothly but as it gets real hot and still running without signs fo dying, the it seems to have a slight miss at idle a little more pronounced the hotter it gets. Any further comments or questions?
4) Test of fuel pressure taken at the end of the line used to connect to the carb shows 4 psi, maybe a tad over; manual says 4 1/2 to 5 but one writer said it needed to be at least 4 minimum which it has. Test of the engine vacuum taken at the T on the intake manifold indicated a timing problem and we had a about a 10 degree late timing situation; now as I said above it is within 3/32" we think of 5 degree BTDC but not sure of correct setting and haven't changed it since we area not sure and my son is adament in his believe that where it is would not be that critical in a combat vehicle. Oddly enough, when we changed the timing to what we believe is more correct, the vacuum test became worse indicating that we were slightly further off; the two gauges we have are old and might not be reliable.
5) The carb cleaner spraying did not change anything that we could discern nearly using a can of cleaner. These test included spraying around carb gasket and manifolds as well as around vent and vacuum connections. Any further comments?
Again, thanks so much for all your time taken to help us---we still are at total loss but we can say we have learned a great deal following your suggestions. We hope we receive more input soon. Semper Fi Ben and Ben _________________ Semper Fi Ben M38 & M100
Joined: Feb 16, 2007 Posts: 206 Location: Gold Coast Australia
Posted: Wed Jul 27, 2011 3:01 pm Post subject:
I use a vacuum gauge for most things including timing & provided you have it hooked in right you should do the same....by moving your distributor to get best idle rpm & best vacuum on the gauge then move the distributor housing back about 3/32" & locking up.
Vacuum gauges don't usually get bad & if the needle is not @ 0 make allowance on your reading.
3/32" @ the timing marks is 4 or 5* out & there is never any guarantee that timing marks are correct on a pulley.
Quote:
and my son is adamant in his believe that where it is would not be that critical in a combat vehicle.
I would take that advice with a grain of salt & a combat vehicle is no different from any other, as far as settings being correct!
Your fuel pump pressure is fine & there is evidence of flooding @ idle if the vehicle cuts out then you need to hold WOT [wide open throttle] to get the vehicle going again _________________ John GIBBINS
ASE Master Medium/Heavy Truck & Auto Technician 2002 USA
Licensed Motor Mechanic NSW # MVIC 49593 Current
YOU CAN'T TROUBLESHOOT WHAT YOU DON'T UNDERSTAND
One small grain of personal experience I'd like to pass on. You want to be sure you engine is idled all the way down when you are checking the timing. The distributor has a centrifugal advance in it and you want to be setting the timing with the centrifugal weights fully retracted. If you try to set the timing with the timing partially advanced it will not be correct. I found this out the hard way on my brothers jeep recently. I was setting the timing on it before we got the carb overhauled and it wouldn't idle too good, so the idle was set a little higher than normal. The timing kept moving around while I was setting it. I finally realized what was happening and slowed it down to set the timing. It made a big difference when I finally got it right.
I doubt this is causing your problem, but you've been working hard on the timing so I thought I'd bring it up.
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