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Chris913653
Samba Member
Joined: February 26, 2012
Posts: 212
Location: South Africa
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 Posted: Mon Jan 16, 2017 2:04 am Post subject: Carburetor woes... |
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Hey everyone!
So, I am not 100% sure if this is a fuel pump issue or a carb issue but I will explain..
I recently put my old fuel pump back into my bug with new seals on it as to prevent it from leaking, it's an original VW alternator style one.
Anyways this fuel pump has never given me issues and after replacing it I took the car for a 10 - 15 minute drive and everything was fine.
Last night I took the car for a drive out and as I started ascending a slight hill she cuts out. It wasn't instant but the engine was dead within about 5 - 10 seconds.
So I go out back and make sure there is still strong spark at the dizzy, seems fine... I take the air filter off and see that there is still a decent squirt of fuel when I pump the throttle...
Get back in and she starts... Within about 30 seconds she dies again...
So basically, if I flood it, she will start and idle for a few seconds, and want to die, but if I feather the throttle in a specific way she'll stay running, but if I try to accelerate she dies...
I am going to test the pump, but to me this sounds carb related? I tried adjusting the mixture screw as well as the idle screw which didn't help...
Any suggestions? |
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garyt
Samba Member
Joined: June 14, 2015
Posts: 763
Location: Burgundy
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| Posted: Mon Jan 16, 2017 3:53 am Post subject: Re: Carburetor woes... |
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Obviously you should change to fuel injection.... (joke)
Sorry, - I reckon you must retrace your steps and take it off and put it on again. |
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mikewilkinson007
Samba Member
Joined: October 26, 2016
Posts: 554
Location: Nebraska
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| Posted: Mon Jan 16, 2017 9:10 am Post subject: Re: Carburetor woes... |
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Start with the pump as that is the last thing you worked on. Then go to the carb (float)???
_________________
72 Super - Marina Blue
1641 AH Dual Port
Dual Weber ICT 34's
Bosch 034
Long Gone: 70 Vert, 66, 68, 73SB, 70, 72, 61 Rag and a 64 with a cinder block in the spare tire well. |
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ashman40
Samba Member
Joined: February 16, 2007
Posts: 15985
Location: North Florida, USA
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| Posted: Mon Jan 16, 2017 9:41 am Post subject: Re: Carburetor woes... |
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You didn't identify the model year, the carb model or the distributor you have installed. Does this problem only occur up hill? Or, is there still a problem after you got home?
A common thing to check with fuel pumps are if they are leaking into the crankcase. Pull the oil dip stick and see if it smells of gasoline. The oil level may also be unusually high. If it does/is, your fuel pump is leaking into the hole on the top of the case. You will need to replace your pump and drain/replace you engine oil.
Assuming you have a stock engine with a Solex carb...
Check the fuel level in the carb bowl. Start by running the engine for a bit to fill the fuel bowl. The float and carb inlet valve should fill the carb bowl until the fuel level is 19mm (3/4") from the top of the fuel bowl. You will need to remove the top of the carb (5 screws) to measure this. The float is sensitive to the car being nose-up or down. This can cause the carb to flood as fuel will overflow the bowl and raw fuel will drain down the the carb throat.
_________________
AshMan40
---------------------------
'67 Beetle #1 {project car that never made it to the road  }
'75 Beetle 1200LS (RHD Japan model) {junked due to frame rot}
'67 Beetle #2 {2019 project car - Wish me luck!} |
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Chris913653
Samba Member
Joined: February 26, 2012
Posts: 212
Location: South Africa
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| Posted: Tue Jan 17, 2017 12:22 am Post subject: Re: Carburetor woes... |
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| ashman40 wrote: |
You didn't identify the model year, the carb model or the distributor you have installed. Does this problem only occur up hill? Or, is there still a problem after you got home?
A common thing to check with fuel pumps are if they are leaking into the crankcase. Pull the oil dip stick and see if it smells of gasoline. The oil level may also be unusually high. If it does/is, your fuel pump is leaking into the hole on the top of the case. You will need to replace your pump and drain/replace you engine oil.
Assuming you have a stock engine with a Solex carb...
Check the fuel level in the carb bowl. Start by running the engine for a bit to fill the fuel bowl. The float and carb inlet valve should fill the carb bowl until the fuel level is 19mm (3/4") from the top of the fuel bowl. You will need to remove the top of the carb (5 screws) to measure this. The float is sensitive to the car being nose-up or down. This can cause the carb to flood as fuel will overflow the bowl and raw fuel will drain down the the carb throat. |
Apologies, 34 PICT - standard carb, '72 with a SVDA dizzy.
Yes, that was my reasoning for replacing the pump in the first place as an aftermarket pump I bought was pumping fuel into the case after only driving about 400km with it...
When I look down the throat of the carb and pump the throttle, I do see a good squirt of fuel, the engine starts, and then dies if I try to accelerate... |
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modok
Samba Member
Joined: October 30, 2009
Posts: 26787
Location: Colorado Springs
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| Posted: Tue Jan 17, 2017 3:14 am Post subject: Re: Carburetor woes... |
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Sounds like you sucked a chunk of something into a carb passage, BUT, it is true a weak fuel pump could act in a similar way. How to tell?
Fuel pressure gauge. |
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helowrench
Samba Member
Joined: August 27, 2003
Posts: 567
Location: dallas texas
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| Posted: Tue Jan 17, 2017 5:08 am Post subject: Re: Carburetor woes... |
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| Chris913653 wrote: |
| ashman40 wrote: |
You didn't identify the model year, the carb model or the distributor you have installed. Does this problem only occur up hill? Or, is there still a problem after you got home?
A common thing to check with fuel pumps are if they are leaking into the crankcase. Pull the oil dip stick and see if it smells of gasoline. The oil level may also be unusually high. If it does/is, your fuel pump is leaking into the hole on the top of the case. You will need to replace your pump and drain/replace you engine oil.
Assuming you have a stock engine with a Solex carb...
Check the fuel level in the carb bowl. Start by running the engine for a bit to fill the fuel bowl. The float and carb inlet valve should fill the carb bowl until the fuel level is 19mm (3/4") from the top of the fuel bowl. You will need to remove the top of the carb (5 screws) to measure this. The float is sensitive to the car being nose-up or down. This can cause the carb to flood as fuel will overflow the bowl and raw fuel will drain down the the carb throat. |
Apologies, 34 PICT - standard carb, '72 with a SVDA dizzy.
Yes, that was my reasoning for replacing the pump in the first place as an aftermarket pump I bought was pumping fuel into the case after only driving about 400km with it...
When I look down the throat of the carb and pump the throttle, I do see a good squirt of fuel, the engine starts, and then dies if I try to accelerate... |
When (during attempted acceleration) it is trying to die, what happens if you repeatedly floor the throttle?
Does it sluggishly continue to accellerate?
The rason I ask is the Accel pump fuel inlet is much lower than most of the normal passages, and under a low fuel bowl level, you can still coax fuel into the engine this way.
My recommendation is to remove the carb, and spend an hour or two cleaning the passaged, and reassemble with a new carb kit.
NOTE: dont use air pressure to blow through the passages unless you regulate the pressure down to 25-30 psi. A can of carb cleaner will do what you need with the little tube. High air pressure made me lose the accel pump check ball once, and I had to figure out how to overcome.
_________________
Current VWs:
70 bug vert for wifey
73Thing bucket o rust
73 914 1.7
12 Passat 2.5 Highway cruiser |
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Randy in Maine
Samba Member
Joined: August 03, 2003
Posts: 34890
Location: The Beach
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| Posted: Tue Jan 17, 2017 8:30 am Post subject: Re: Carburetor woes... |
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After you do the carb cleaning, please replace that distributor cap. It will leave you walking sooner than later.
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Chris913653
Samba Member
Joined: February 26, 2012
Posts: 212
Location: South Africa
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| Posted: Tue Jan 17, 2017 11:40 pm Post subject: Re: Carburetor woes... |
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| helowrench wrote: |
| Chris913653 wrote: |
| ashman40 wrote: |
You didn't identify the model year, the carb model or the distributor you have installed. Does this problem only occur up hill? Or, is there still a problem after you got home?
A common thing to check with fuel pumps are if they are leaking into the crankcase. Pull the oil dip stick and see if it smells of gasoline. The oil level may also be unusually high. If it does/is, your fuel pump is leaking into the hole on the top of the case. You will need to replace your pump and drain/replace you engine oil.
Assuming you have a stock engine with a Solex carb...
Check the fuel level in the carb bowl. Start by running the engine for a bit to fill the fuel bowl. The float and carb inlet valve should fill the carb bowl until the fuel level is 19mm (3/4") from the top of the fuel bowl. You will need to remove the top of the carb (5 screws) to measure this. The float is sensitive to the car being nose-up or down. This can cause the carb to flood as fuel will overflow the bowl and raw fuel will drain down the the carb throat. |
Apologies, 34 PICT - standard carb, '72 with a SVDA dizzy.
Yes, that was my reasoning for replacing the pump in the first place as an aftermarket pump I bought was pumping fuel into the case after only driving about 400km with it...
When I look down the throat of the carb and pump the throttle, I do see a good squirt of fuel, the engine starts, and then dies if I try to accelerate... |
When (during attempted acceleration) it is trying to die, what happens if you repeatedly floor the throttle?
Does it sluggishly continue to accellerate?
The rason I ask is the Accel pump fuel inlet is much lower than most of the normal passages, and under a low fuel bowl level, you can still coax fuel into the engine this way.
My recommendation is to remove the carb, and spend an hour or two cleaning the passaged, and reassemble with a new carb kit.
NOTE: dont use air pressure to blow through the passages unless you regulate the pressure down to 25-30 psi. A can of carb cleaner will do what you need with the little tube. High air pressure made me lose the accel pump check ball once, and I had to figure out how to overcome. |
Thanks! The best I can get is for the car to idle, any more and she'll die, so I am thinking either low pressure from the pump or there is a jetting problem... Will do some more investigation soon. |
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Chris913653
Samba Member
Joined: February 26, 2012
Posts: 212
Location: South Africa
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| Posted: Tue Jan 17, 2017 11:40 pm Post subject: Re: Carburetor woes... |
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| Randy in Maine wrote: |
After you do the carb cleaning, please replace that distributor cap. It will leave you walking sooner than later.
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Will do, struggle to find decent parts in South Africa... mostly EMPI... |
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ashman40
Samba Member
Joined: February 16, 2007
Posts: 15985
Location: North Florida, USA
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| Posted: Wed Jan 18, 2017 1:05 am Post subject: Re: Carburetor woes... |
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| Chris913653 wrote: |
| Thanks! The best I can get is for the car to idle, any more and she'll die, so I am thinking either low pressure from the pump or there is a jetting problem... Will do some more investigation soon. |
The carb runs off of the fuel in the fuel bowl. The fuel pump's job is to refill the fuel bowl before it runs out. At idle, the fuel pump should have no problem refilling the carb fuel bowl. As suggested above, remove the top of the carb to check the level of fuel in the carb bowl.
Your problem is not related to the fuel pump if it is happening at idle and your have fuel in the bowl.
You mentioned your engine having trouble when you try to accelerate. What happens if you very very slowly open the throttle? Does it accelerate slowly without hesitation?
Check your distributor. The left side vacuum port on the 34Pict is for the distributor vacuum advance. Is your SVDA connected to this port?
Have you confirmed your vacuum advance is working? Two ways to check this:
1) Disconnect the vacuum advance hose from the carb and suck on the end with your mouth. While sucking, place your tongue over the end. The vacuum in the hose and vacuum can should pull on your tongue. If the vacuum leaks out and the hose does not remain attached to your tongue your distributor's vacuum advance is leaking. You should also see the advance mechanism in your distributor move as you suck on the hose.
2) Disconnect the vacuum advance hose from the left port of the carb. Cap the carb port. Find another port on the carb or the intake that has vacuum at idle. With your timing light, check the idle timing (7.5BTDC?). Connect the distributor vacuum advance hose to the port generating vacuum. You should see the ignition timing JUMP by 8-12deg and remain steady. This proves the vacuum advance is working.
_________________
AshMan40
---------------------------
'67 Beetle #1 {project car that never made it to the road }
'75 Beetle 1200LS (RHD Japan model) {junked due to frame rot}
'67 Beetle #2 {2019 project car - Wish me luck!} |
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Chris913653
Samba Member
Joined: February 26, 2012
Posts: 212
Location: South Africa
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| Posted: Wed Jan 18, 2017 2:54 am Post subject: Re: Carburetor woes... |
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| ashman40 wrote: |
| Chris913653 wrote: |
| Thanks! The best I can get is for the car to idle, any more and she'll die, so I am thinking either low pressure from the pump or there is a jetting problem... Will do some more investigation soon. |
The carb runs off of the fuel in the fuel bowl. The fuel pump's job is to refill the fuel bowl before it runs out. At idle, the fuel pump should have no problem refilling the carb fuel bowl. As suggested above, remove the top of the carb to check the level of fuel in the carb bowl.
Your problem is not related to the fuel pump if it is happening at idle and your have fuel in the bowl.
You mentioned your engine having trouble when you try to accelerate. What happens if you very very slowly open the throttle? Does it accelerate slowly without hesitation?
Check your distributor. The left side vacuum port on the 34Pict is for the distributor vacuum advance. Is your SVDA connected to this port?
Have you confirmed your vacuum advance is working? Two ways to check this:
1) Disconnect the vacuum advance hose from the carb and suck on the end with your mouth. While sucking, place your tongue over the end. The vacuum in the hose and vacuum can should pull on your tongue. If the vacuum leaks out and the hose does not remain attached to your tongue your distributor's vacuum advance is leaking. You should also see the advance mechanism in your distributor move as you suck on the hose.
2) Disconnect the vacuum advance hose from the left port of the carb. Cap the carb port. Find another port on the carb or the intake that has vacuum at idle. With your timing light, check the idle timing (7.5BTDC?). Connect the distributor vacuum advance hose to the port generating vacuum. You should see the ignition timing JUMP by 8-12deg and remain steady. This proves the vacuum advance is working. |
I hear you, I will check this tonight and see what's what. Remember in my previous post that I do have to fiddle with the throttle to keep her idling, she won't idle on her own... |
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DeathTrap
Samba Member
Joined: February 26, 2004
Posts: 1757
Location: Sacramento/Vermont
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| Posted: Wed Jan 18, 2017 4:13 am Post subject: Re: Carburetor woes... |
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not impossible that it's flooding AND starving
leaky needle seat
plugged jets passageways
poor electrical connection
failing cutout solenoid
plugging filter
kinked fuel line
sucking air before pump
bad check valves in pump
AND a clogging fuel pickup tube sock
fix all those and check back
you could take it down to the service station and have them put it on the scope to check the ignition
(oh I must have been having a flasback)
Eliminate ignition possibilities as best you can |
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Chris913653
Samba Member
Joined: February 26, 2012
Posts: 212
Location: South Africa
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| Posted: Mon Jan 23, 2017 12:43 am Post subject: Re: Carburetor woes... |
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Hi All,
To provide you with an update on this, I have found the problem.
Not sure how well you'll be able to see on the terrible video I took, but the problem is the inlet valve (not sure if that is the right name) on the carb...
So I am assuming that the float will determine how much fuel is let into the carb bowl, and this is no longer functioning, so I am going to take the carb to my VW specialist and have them sort it out as well as clean out and rebuild my carb while they are at it, as I also need to replace my choke in any case.
So if I manually fill the carb bowl, she will run perfectly until that fuel runs out...
Link
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anilv
Samba Member
Joined: July 26, 2009
Posts: 39
Location: Malaysia
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| Posted: Mon Jan 23, 2017 2:01 am Post subject: Re: Carburetor woes... |
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If you pull the line from the tank (before it goes to the pump) does a lot of fuel gush out?
A blocked in-tank filter (sock) would cause the problems you've been having so if only a trickle comes thru from the tank try running the car with an external fuel source. A gravity feed direct to the carb (bypassing the pump) will help identify if its the tank, pump or carb.
Anil |
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Chris913653
Samba Member
Joined: February 26, 2012
Posts: 212
Location: South Africa
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| Posted: Mon Jan 23, 2017 2:07 am Post subject: Re: Carburetor woes... |
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| anilv wrote: |
If you pull the line from the tank (before it goes to the pump) does a lot of fuel gush out?
A blocked in-tank filter (sock) would cause the problems you've been having so if only a trickle comes thru from the tank try running the car with an external fuel source. A gravity feed direct to the carb (bypassing the pump) will help identify if its the tank, pump or carb.
Anil |
I tested the pump into a plastic bottle and there is definitely no issue with the pump, it's definitely the carb not letting fuel in. |
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