Slat won't stay running
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Slat won't stay running
hello all
been awhile
tried to start my 42 slat
little gas in carb and it runs great for a few seconds then dies
loosened lines at carb and found no gas
what is the best way to diagnose problem?
try new fuel pump
or look for possible fuel line blockage
[fuel filter is one of ron's inserts]
thanks
dave
been awhile
tried to start my 42 slat
little gas in carb and it runs great for a few seconds then dies
loosened lines at carb and found no gas
what is the best way to diagnose problem?
try new fuel pump
or look for possible fuel line blockage
[fuel filter is one of ron's inserts]
thanks
dave
GPW 31262 DOD 6 23 42
Slat 122876 DOD 2 26 42
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Re: Slat won't stay running
Possible valve in pump stuck from the E-10 fuel. Try blowing back with an air gun into the line between pump and carburetor.
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Re: Slat won't stay running
Could be also this little guy in red on the picture (intake needle pin) that is stuck closed.
I've got the needle problem last week with a garden tractor carb.
You can try to open the valve by blowing air at the carb inlet.
Yves
As Joël said, E10 is likley the cause.I've got the needle problem last week with a garden tractor carb.
You can try to open the valve by blowing air at the carb inlet.
Yves
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Re: Slat won't stay running
No fuel coming out of the fuel line at this point, so the needle valve in the carb is not in play at this time. Maybe after you get fuel up.
Blowing back through the fuel line is the wrong direction to break a stuck check valve loose in the fuel pump. They are normally closed in that direction. You might try blowing from the tank side of the pump toward the carb. That would be the direction the check valves would normally open.
You might need to prime the engine more than once to get the fuel from the tank all the way through the fuel system to the carb.
My CJ does the same thing if it sits for a while and I do what you are trying. Takes more than once.
Why the original fuel pumps had hand primer levers.
Blowing back through the fuel line is the wrong direction to break a stuck check valve loose in the fuel pump. They are normally closed in that direction. You might try blowing from the tank side of the pump toward the carb. That would be the direction the check valves would normally open.
You might need to prime the engine more than once to get the fuel from the tank all the way through the fuel system to the carb.
My CJ does the same thing if it sits for a while and I do what you are trying. Takes more than once.
Why the original fuel pumps had hand primer levers.
Last edited by Wolfman on Fri May 25, 2018 5:55 am, edited 1 time in total.
Mike Wolford
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Re: Slat won't stay running
And I forgot, give the carburetor a rap (anyways) at the brass inlet with the handle of a plastic screwdriver. It will help unstick a stuck needle.
And give some fresh gas.
And give some fresh gas.
2011 MVPA PIONEER AWARD - MVPA #1064
HONOR GRAD-WHEELED VEHICLE MECHANIC SCHOOL 1960 - US ARMY ORDNANCE SCHOOL(MACHINIST) ABERDEEN PG 1962 - O-1 BIRD DOG CREWCHIEF - 300,000+TROUBLE FREE M-38A1 MILES
LIFE MEMBER AM LEGION-40/8-DAV
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COL. BRUNO BROOKS (ARMY MOTORS) IS MY HERO
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Re: Slat won't stay running
That E-10 gasoline will also eat through a diaphragm if it sets long enough.
I would do as said by the guys above, especially priming it a bit longer in case it just didn't have time to pump gas through the line. Take the simple things first approach.
For anything that sits for a while, like lawnmowers, tractors, boats, and Jeeps that are not driven a lot, I am careful to only use 100% gasoline, which is still sold, especially at gas stations near a lake. Alcohol in gasoline will totally wreck a 2 stroke engine because it allows water to mix with the fuel, and boat motors are not cheap. I also add a stabilizer to the fuel, my favorite being "Seafoam".
The E-10 gas has a lot of problems, one being separation issues which creates sludge that will clog things up, and cause things like float valves and check valves to stick. One of the worst ideas in the last 30 years, it doesn't have any benefit, other than perhaps cutting costs to produce, and I don't know it does that.
I would do as said by the guys above, especially priming it a bit longer in case it just didn't have time to pump gas through the line. Take the simple things first approach.
For anything that sits for a while, like lawnmowers, tractors, boats, and Jeeps that are not driven a lot, I am careful to only use 100% gasoline, which is still sold, especially at gas stations near a lake. Alcohol in gasoline will totally wreck a 2 stroke engine because it allows water to mix with the fuel, and boat motors are not cheap. I also add a stabilizer to the fuel, my favorite being "Seafoam".
The E-10 gas has a lot of problems, one being separation issues which creates sludge that will clog things up, and cause things like float valves and check valves to stick. One of the worst ideas in the last 30 years, it doesn't have any benefit, other than perhaps cutting costs to produce, and I don't know it does that.
A.C.Fults
East Tennessee
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Re: Slat won't stay running
The float needle & seat is the starting point & other suggestions are fine. But diagnosis is in order.
A doctor uses a stethoscope to listen to & eliminate heart or breathing issues. A mechanic uses a fuel pressure vacuum gauge [$15 from HF].
This will quickly check & pin point or eliminate the fuel pump as being instrumental to your problem.
Many fuel pumps are blamed & replaced unnecessarily @ great expense, for no appreciable result.
A doctor uses a stethoscope to listen to & eliminate heart or breathing issues. A mechanic uses a fuel pressure vacuum gauge [$15 from HF].
This will quickly check & pin point or eliminate the fuel pump as being instrumental to your problem.
Many fuel pumps are blamed & replaced unnecessarily @ great expense, for no appreciable result.
John GIBBINS Member Institute of Automotive Mechanical Engineers [Ret], ASE Master Medium/Heavy Truck & Auto Technician USA -2002 Licensed Motor Mech NSW MVIC 49593 Current 2015
TO DIAGNOSE, TROUBLESHOOT OR FAULT FIND ANY AUTO SYSTEM....
Understand how system parts interact with one another. GOOD parts can then be established & the NOT GOOD problem/s part/s isolated for repair or replacement.
TO DIAGNOSE, TROUBLESHOOT OR FAULT FIND ANY AUTO SYSTEM....
Understand how system parts interact with one another. GOOD parts can then be established & the NOT GOOD problem/s part/s isolated for repair or replacement.
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Re: Slat won't stay running
With an eye to the Mechanic's Mantra:
Try the non-invasive suggestions FIRST.
Diagnosing them is FIRST.
Then you may discover something that requires tools or new parts
then, hopefully you will have "fixed" the problem.
OK....the fuel system is based on the idea that you have fuel available to the carb at ALL times. It may evaporate in the bowl if left long enough so "priming" like you have done is the FIRST thing to do as it is not only a DIAGNOSTIC tool, but a SOLUTION to the symptom of sitting too long.
Unfortunately, it is possible for something as simple as AIR to enter the fuel system between tank and fuel bowl. In that situation, it takes longer to move fuel from the tank to the carb bowl.
This can often be solved by using the priming handle on the fuel pump if the issue is just evaporation in the carb bowl. However, there are multiple places in the "system" that can allow air into the lines and consequently allow the fuel to leak/evaporate.
1) bad sealing gasket in firewall fuel strainer
2) leaky flexible section of fuel line
3) non-sealing gasket on fuel pump bowl
These can allow fuel to drain back to the tank (air entering fuel strainer gasket) for instance. A leaky flexible section of fuel line may allow fuel to leak out and evaporate at a rate slow enough if the fuel strainer gasket is leaky that it evaporates rather than drips on the garage floor. A leaky fuel strainer gasket may also allow fuel to be siphoned back to the tank if the fuel strainer gasket is "good" if the fuel level in the tank is below it in the cowbelly below the frame. A minute leak in the fuel pump gasket may allow fuel to leak just enough to be evaporated and not drip on the floor.
So....before grabbing wrenches or ordering parts, try to start your jeep while someone carefully adds a small amount of fuel down into the carb to see if she runs...it may take 2-3 ounces and it may take 2 or three tries to get fuel UP to the carburetor.
Things you CAN do is to make sure all lines are tight, that the fuel bowl bale is screwed down TIGHT, and the fuel strainer lid is screwed down TIGHT as well. If you haven't ever replaced the fuel strainer gasket, you might consider it time to clean it out anyway and replace the gasket, making sure there is only ONE gasket on there! You might also consider temporarily replacing your metal fuel bowl on the pump with a glass one so you can SEE if there is any level of fuel in it at all (bubbles are not really a good sign that air isn't being introduced into the system at some point!). Lastly, have you inspected the flexible gas line? What is the history? Who installed it and when....they can also leak air as it is less dense than gasoline and, perhaps allow a tiny leak to let fuel evaporate without a trace.
You are definitely chasing down something maddening that probably only occures when the jeep sits for a long time and that is not uncommon!
Try the non-invasive suggestions FIRST.
Diagnosing them is FIRST.
Then you may discover something that requires tools or new parts
then, hopefully you will have "fixed" the problem.
OK....the fuel system is based on the idea that you have fuel available to the carb at ALL times. It may evaporate in the bowl if left long enough so "priming" like you have done is the FIRST thing to do as it is not only a DIAGNOSTIC tool, but a SOLUTION to the symptom of sitting too long.
Unfortunately, it is possible for something as simple as AIR to enter the fuel system between tank and fuel bowl. In that situation, it takes longer to move fuel from the tank to the carb bowl.
This can often be solved by using the priming handle on the fuel pump if the issue is just evaporation in the carb bowl. However, there are multiple places in the "system" that can allow air into the lines and consequently allow the fuel to leak/evaporate.
1) bad sealing gasket in firewall fuel strainer
2) leaky flexible section of fuel line
3) non-sealing gasket on fuel pump bowl
These can allow fuel to drain back to the tank (air entering fuel strainer gasket) for instance. A leaky flexible section of fuel line may allow fuel to leak out and evaporate at a rate slow enough if the fuel strainer gasket is leaky that it evaporates rather than drips on the garage floor. A leaky fuel strainer gasket may also allow fuel to be siphoned back to the tank if the fuel strainer gasket is "good" if the fuel level in the tank is below it in the cowbelly below the frame. A minute leak in the fuel pump gasket may allow fuel to leak just enough to be evaporated and not drip on the floor.
So....before grabbing wrenches or ordering parts, try to start your jeep while someone carefully adds a small amount of fuel down into the carb to see if she runs...it may take 2-3 ounces and it may take 2 or three tries to get fuel UP to the carburetor.
Things you CAN do is to make sure all lines are tight, that the fuel bowl bale is screwed down TIGHT, and the fuel strainer lid is screwed down TIGHT as well. If you haven't ever replaced the fuel strainer gasket, you might consider it time to clean it out anyway and replace the gasket, making sure there is only ONE gasket on there! You might also consider temporarily replacing your metal fuel bowl on the pump with a glass one so you can SEE if there is any level of fuel in it at all (bubbles are not really a good sign that air isn't being introduced into the system at some point!). Lastly, have you inspected the flexible gas line? What is the history? Who installed it and when....they can also leak air as it is less dense than gasoline and, perhaps allow a tiny leak to let fuel evaporate without a trace.
You are definitely chasing down something maddening that probably only occures when the jeep sits for a long time and that is not uncommon!
Chuck Lutz
GPW 17963 4/24/42 Chester, PA. USA 20113473 (USA est./Tom W.)
Bantam T3-C 1947
GPW 17963 4/24/42 Chester, PA. USA 20113473 (USA est./Tom W.)
Bantam T3-C 1947
- iowa
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Re: Slat won't stay running
thanks for all the advice!
I tried blowing air from carb line down to the fuel pump.
at first, nothing happened
then I heard a 'pop' or loud 'click'
and then air bubbling up in the fuel tank
so tried starting again
using little fuel in the carb
did this about 5x (as this has worked before)
but no luck
it runs for about 2-3 secs then dies
after all this
I did check the line out of the filter
and there was no fuel here
does it sound like the fuel pump diaphragm rupt'd?
dave
I tried blowing air from carb line down to the fuel pump.
at first, nothing happened
then I heard a 'pop' or loud 'click'
and then air bubbling up in the fuel tank
so tried starting again
using little fuel in the carb
did this about 5x (as this has worked before)
but no luck
it runs for about 2-3 secs then dies
after all this
I did check the line out of the filter
and there was no fuel here
does it sound like the fuel pump diaphragm rupt'd?
dave
GPW 31262 DOD 6 23 42
Slat 122876 DOD 2 26 42
L-4B 43-572 DOD 8-31-42 82nd of 100 Silver Fort Sill planes!
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Re: Slat won't stay running
If there was no fuel in the line past the firewall mounted fuel strainer then perhaps that is where air is entering the system. If you have a spare gasket, why not remove the top and check to see if it filled with gas tank gunk in the brass filter screen. If you have one of Ron's paper filters then replace it.
While you are at it, check the dipstick level and filler tube with a sniff test for gasoline in the crankcase. What is the history of the fuel pump?
Is there any chance that pop-click was one of the two valves in the fuel pump popping OPEN? Do you have a glass bowl on it and is there fuel visible?
I suppose you could tear into the carburetor but a way to test it would simply be to install a fitting for neoprene gas line HOSE and putting it into a 1 gallon plastic tank sitting up on the cowl. You have to "prime" that line in advance, but if the jeep runs OK like that, cross the carb off the list.
That leaves the pump, the flexible hose and the fuel strainer as potential leaking places.
If you do not find gas smell in the oil filler tube or the level of oil HIGHER after trying to start the jeep and cranking it for a while, then you MIGHT be able to eliminate the pump diaphragm as the culprit...that is, as long as you KNOW that the pump has a modern one installed and not an original that has been eaten through by E10.
While you are at it, check the dipstick level and filler tube with a sniff test for gasoline in the crankcase. What is the history of the fuel pump?
Is there any chance that pop-click was one of the two valves in the fuel pump popping OPEN? Do you have a glass bowl on it and is there fuel visible?
I suppose you could tear into the carburetor but a way to test it would simply be to install a fitting for neoprene gas line HOSE and putting it into a 1 gallon plastic tank sitting up on the cowl. You have to "prime" that line in advance, but if the jeep runs OK like that, cross the carb off the list.
That leaves the pump, the flexible hose and the fuel strainer as potential leaking places.
If you do not find gas smell in the oil filler tube or the level of oil HIGHER after trying to start the jeep and cranking it for a while, then you MIGHT be able to eliminate the pump diaphragm as the culprit...that is, as long as you KNOW that the pump has a modern one installed and not an original that has been eaten through by E10.
Chuck Lutz
GPW 17963 4/24/42 Chester, PA. USA 20113473 (USA est./Tom W.)
Bantam T3-C 1947
GPW 17963 4/24/42 Chester, PA. USA 20113473 (USA est./Tom W.)
Bantam T3-C 1947
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Re: Slat won't stay running
Chuck asked: "Is there any chance that pop-click was one of the two valves in the fuel pump popping OPEN?"
Or OUT of its bore? BW
Or OUT of its bore? BW
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Re: Slat won't stay running
Suggest one checks the fuel pump is working properly, as advised [pressure/vacuum test] earlier.
If it is working fine it is eliminated from the equation.
If the heart is working properly there is no need for surgery [valves or diaphragm] or a transplant [replacing the fuel pump].
If it is working fine it is eliminated from the equation.
If the heart is working properly there is no need for surgery [valves or diaphragm] or a transplant [replacing the fuel pump].
John GIBBINS Member Institute of Automotive Mechanical Engineers [Ret], ASE Master Medium/Heavy Truck & Auto Technician USA -2002 Licensed Motor Mech NSW MVIC 49593 Current 2015
TO DIAGNOSE, TROUBLESHOOT OR FAULT FIND ANY AUTO SYSTEM....
Understand how system parts interact with one another. GOOD parts can then be established & the NOT GOOD problem/s part/s isolated for repair or replacement.
TO DIAGNOSE, TROUBLESHOOT OR FAULT FIND ANY AUTO SYSTEM....
Understand how system parts interact with one another. GOOD parts can then be established & the NOT GOOD problem/s part/s isolated for repair or replacement.
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Re: Slat won't stay running
Does the pump have a priming lever? Maybe that noise was the compressed air snapping it back into the down position.
2011 MVPA PIONEER AWARD - MVPA #1064
HONOR GRAD-WHEELED VEHICLE MECHANIC SCHOOL 1960 - US ARMY ORDNANCE SCHOOL(MACHINIST) ABERDEEN PG 1962 - O-1 BIRD DOG CREWCHIEF - 300,000+TROUBLE FREE M-38A1 MILES
LIFE MEMBER AM LEGION-40/8-DAV
7 MIL SPEC MAINTAINED MV'S
COL. BRUNO BROOKS (ARMY MOTORS) IS MY HERO
HONOR GRAD-WHEELED VEHICLE MECHANIC SCHOOL 1960 - US ARMY ORDNANCE SCHOOL(MACHINIST) ABERDEEN PG 1962 - O-1 BIRD DOG CREWCHIEF - 300,000+TROUBLE FREE M-38A1 MILES
LIFE MEMBER AM LEGION-40/8-DAV
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Re: Slat won't stay running
You should not be able to blow air in the line at the carb. and hear bubbles in the fuel tank.
The check valves, in the fuel pump should prevent this from happening.
The click in the pump, when you applied air ( 120 PSI ?? ) at the carb., was most likely the check valves coming out of their sockets, inside the fuel pump.
I am thinking it is time to pull the fuel pump and disassemble for a look.
The check valves, in the fuel pump should prevent this from happening.
The click in the pump, when you applied air ( 120 PSI ?? ) at the carb., was most likely the check valves coming out of their sockets, inside the fuel pump.
I am thinking it is time to pull the fuel pump and disassemble for a look.
Mike Wolford
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AOPA ( 50 yrs)
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Re: Slat won't stay running
Yep, should never blow compressed air from the carburetor fitting toward the fuel pump.
I agree that hearing that pop, and then bubbles in the tank, is a good indication the check valves have been pushed "pop" out of the bores. If that is the case, it is not a big deal to correct.
I agree that hearing that pop, and then bubbles in the tank, is a good indication the check valves have been pushed "pop" out of the bores. If that is the case, it is not a big deal to correct.
A.C.Fults
East Tennessee
Shade Tree Mechanic more than 50 years.
None of us are as smart as we pretend to be.
East Tennessee
Shade Tree Mechanic more than 50 years.
None of us are as smart as we pretend to be.
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