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Jetfxr69 Samba Member
Joined: December 28, 2018 Posts: 1293 Location: White mtns nh
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Posted: Mon Jun 21, 2021 8:29 am Post subject: Re: Add me to the list of bucking, hesitation, now no start |
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Just fixed the same problem on mine a few weeks ago. Double relay. One of the coils got weak and would momentarily let the contacts open. At first it was so short a duration, that I felt a slight miss occasionally. It then progressed and got so bad, I could barely keep it running.
Consider that the DR sends voltage to the pump and the system is regulated to maintain about 28-35 psi fuel pressure at all times. Unused fuel is simply pumped back to the tank. If those contacts open, even for a split second, the voltage to the pump is lost momentarily, and therefore the fuel pressure drops. Not enough to stall, but enough to feel a skip. Then as my DR coil got weaker, it caused a longer break in pump voltage, and then the bigger stumble and eventually barely running.
At first I suspected AFM wiper board ( after verifying all ignition components good). But the board was clean and I swapped in another just to see. Found an old DR in a box of shit, threw it in, and voila! Been happily buzzing about since. _________________ You can't be a real country unless you have a beer and an airline. It helps if you have some kind of a football team, or some nuclear weapons, but at the very least you need a beer. Zappa
‘77 westy Seamus
‘76 tintop Crusher
‘77 westy The Judge
‘72 tintop bastard westy Hudson |
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Daverham Samba Member
Joined: August 27, 2009 Posts: 1397 Location: USA
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Posted: Mon Jun 21, 2021 11:22 am Post subject: Re: Add me to the list of bucking, hesitation, now no start |
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Sounds kinda like what I just went through. Turns out it was 3 of the wires on the AFM plug. The plug was on the AFM nice and tight, but look at the wire terminals inside the plug. Some of them had been pushed back deep inside the plug and they weren't contacting the pins. My bus was parked for like 10 weeks because of this mystery problem!
I've also had similar symptoms in the past.
• Once it was Temp Sensor 2 needed to be replaced (near cyl #3)
• Once it was a clogged fuel line at the tank (rusty bits & pieces in there)
• Once it was a loose wire on the double relay connector
• Once it was a loose ground wire (also near the double relay).
All very similar symptoms. Good luck. You'll find it. |
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Jetfxr69 Samba Member
Joined: December 28, 2018 Posts: 1293 Location: White mtns nh
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Posted: Mon Jun 21, 2021 1:26 pm Post subject: Re: Add me to the list of bucking, hesitation, now no start |
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Daverham wrote: |
Sounds kinda like what I just went through. Turns out it was 3 of the wires on the AFM plug. The plug was on the AFM nice and tight, but look at the wire terminals inside the plug. Some of them had been pushed back deep inside the plug and they weren't contacting the pins. My bus was parked for like 10 weeks because of this mystery problem!
I've also had similar symptoms in the past.
• Once it was Temp Sensor 2 needed to be replaced (near cyl #3)
• Once it was a clogged fuel line at the tank (rusty bits & pieces in there)
• Once it was a loose wire on the double relay connector
• Once it was a loose ground wire (also near the double relay).
All very similar symptoms. Good luck. You'll find it. |
Once it was a leprechaun and he stole me lucky charms! 🤪🍀 _________________ You can't be a real country unless you have a beer and an airline. It helps if you have some kind of a football team, or some nuclear weapons, but at the very least you need a beer. Zappa
‘77 westy Seamus
‘76 tintop Crusher
‘77 westy The Judge
‘72 tintop bastard westy Hudson |
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vw76westy Samba Member
Joined: May 06, 2007 Posts: 1584 Location: so cal
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Posted: Mon Jun 21, 2021 5:23 pm Post subject: Re: Add me to the list of bucking, hesitation, now no start |
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just curious
have you tried starting bus
with afm disconnected ??
have you not been able to start it at all
or you can start it sometimes....
can you notice any consistency to bucking
such as bucking after 5 min of driving (or 30min of driving)
or every time your going up a hill
hesitates on streets but not freeway (or vise versa) _________________ order your BAY WINDOW T-SHIRT here http://www.thesamba.com/vw/classifieds/detail.php?id=1526918
quote from bay window bus buyers guide........
The Type 4 engine is considered by many to be VW's finest air-cooled motor, |
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ivwshane Samba Member
Joined: May 19, 2011 Posts: 1920 Location: Sacramento ca
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Posted: Mon Jun 21, 2021 6:06 pm Post subject: Re: Add me to the list of bucking, hesitation, now no start |
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It won't start any more. It turns over but it won't actually get past that point. When it was running, the bucking/hesitation happened randomly but it would usually be a few misses here and there and then it would progressively get worse and start stalling. All travel was on flat ground. _________________ 77 westy 2.0 FI
69 ghia coup 1600dp
70 single cab |
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Jetfxr69 Samba Member
Joined: December 28, 2018 Posts: 1293 Location: White mtns nh
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Posted: Mon Jun 21, 2021 6:21 pm Post subject: Re: Add me to the list of bucking, hesitation, now no start |
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Did you run a jumper bat voltage lead to the pump? Then the pump will run constantly, bypassing the DR. _________________ You can't be a real country unless you have a beer and an airline. It helps if you have some kind of a football team, or some nuclear weapons, but at the very least you need a beer. Zappa
‘77 westy Seamus
‘76 tintop Crusher
‘77 westy The Judge
‘72 tintop bastard westy Hudson |
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ImAddicted Samba Member
Joined: April 24, 2012 Posts: 1195 Location: Unorganized Territory, Maine
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Posted: Mon Jun 21, 2021 8:09 pm Post subject: Re: Add me to the list of bucking, hesitation, now no start |
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Jetfxr69 wrote: |
Did you run a jumper bat voltage lead to the pump? Then the pump will run constantly, bypassing the DR. |
You can easily run one from the coil to the pump _________________ 1979 Transporter (sold)
KC1MUR
strfish7 wrote: |
Original condition, which means something different on this forum than anywhere else! |
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vw76westy Samba Member
Joined: May 06, 2007 Posts: 1584 Location: so cal
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Posted: Tue Jun 22, 2021 2:29 pm Post subject: Re: Add me to the list of bucking, hesitation, now no start |
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your no longer looking for a part thats going to fail
and that should make finding problem a whole lot easier
start by making sure
that everything is getting power
fuel pump, coil , etc .
and also try starting bus with afm disconnected
from here you should be to isolate problem to
1 or 2 parts _________________ order your BAY WINDOW T-SHIRT here http://www.thesamba.com/vw/classifieds/detail.php?id=1526918
quote from bay window bus buyers guide........
The Type 4 engine is considered by many to be VW's finest air-cooled motor, |
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ivwshane Samba Member
Joined: May 19, 2011 Posts: 1920 Location: Sacramento ca
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Posted: Tue Jun 22, 2021 3:42 pm Post subject: Re: Add me to the list of bucking, hesitation, now no start |
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You say to disconnect the afm, by that I assume you mean unplugging the large electrical plug on the wheel well?
Here is my game plan for today:
Remove a wire from a spark plug and see if it arcs against the body metal.
If good then check the coil by taking the wire that connects to the distributor coil and seeing if it gets a spark by placing it near the body metal.
If that is good then I need to check the resistance of the coil (center probe to positive post?).
If that checks out then I’ll test the fuel pump by running power from the battery to the pump to see if it is pumping (do I need to plug both sides of the pump while I connect a temp hose to the exit side of the pump or should no fuel come out on the exit side if the pump is off).
If that runs fine then I’ll need to check the double relay, which I’m not sure how to do.
If that checks out I guess the last thing to check would be fuel pressure.
Does my game plan look good or am I missing something or do I need to change the order up or do a particular procedure differently? _________________ 77 westy 2.0 FI
69 ghia coup 1600dp
70 single cab |
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vw76westy Samba Member
Joined: May 06, 2007 Posts: 1584 Location: so cal
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Posted: Wed Jun 23, 2021 1:22 pm Post subject: Re: Add me to the list of bucking, hesitation, now no start |
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no
that is not what im saying
afm = air flow meter
when you open the hatch from inside the bus
the afm is the first thing you see on right side
you are referring to ecu computer
if the afm is disconnected
the ecu has a default setting for everything that will allow bus to start
you cant drive with afm disconnectted
you can barly throttle gas
but it will give you clues to know if matbe afm is bad
or something that connectsto it is bad _________________ order your BAY WINDOW T-SHIRT here http://www.thesamba.com/vw/classifieds/detail.php?id=1526918
quote from bay window bus buyers guide........
The Type 4 engine is considered by many to be VW's finest air-cooled motor, |
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vw76westy Samba Member
Joined: May 06, 2007 Posts: 1584 Location: so cal
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Posted: Wed Jun 23, 2021 1:35 pm Post subject: Re: Add me to the list of bucking, hesitation, now no start |
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your game plan skips around
and gos back and forth to much
what good is checking fuel pump
if your not checking power to the fuel pump
if no power, usually a bad double relay
but if the double relay aint getting power
then thats afm
if bus start just fine with afm meter disconnected
but not with afm connected
test afm ....
if afm checks out
then the temp2 sensor should be removed and tested
side note when testing temp2 test cold test warm test hot
then test for measurment of curve
ive had temp 2 that test good cold and test good after its hot
but fail when warm (think of a cold bus on a hot day or a hot engine on a very cold day) _________________ order your BAY WINDOW T-SHIRT here http://www.thesamba.com/vw/classifieds/detail.php?id=1526918
quote from bay window bus buyers guide........
The Type 4 engine is considered by many to be VW's finest air-cooled motor, |
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ivwshane Samba Member
Joined: May 19, 2011 Posts: 1920 Location: Sacramento ca
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Posted: Wed Jun 23, 2021 2:52 pm Post subject: Re: Add me to the list of bucking, hesitation, now no start |
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Alright, so how do I disconnect the afm? Just remove the S tube? _________________ 77 westy 2.0 FI
69 ghia coup 1600dp
70 single cab |
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ImAddicted Samba Member
Joined: April 24, 2012 Posts: 1195 Location: Unorganized Territory, Maine
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Posted: Wed Jun 23, 2021 3:16 pm Post subject: Re: Add me to the list of bucking, hesitation, now no start |
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Plug on the top back side. There’s only one wire bundle going to it, can’t miss it _________________ 1979 Transporter (sold)
KC1MUR
strfish7 wrote: |
Original condition, which means something different on this forum than anywhere else! |
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ivwshane Samba Member
Joined: May 19, 2011 Posts: 1920 Location: Sacramento ca
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Posted: Wed Jun 23, 2021 4:19 pm Post subject: Re: Add me to the list of bucking, hesitation, now no start |
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ImAddicted wrote: |
Plug on the top back side. There’s only one wire bundle going to it, can’t miss it |
Thanks, I completely forgot about that plug. _________________ 77 westy 2.0 FI
69 ghia coup 1600dp
70 single cab |
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Jetfxr69 Samba Member
Joined: December 28, 2018 Posts: 1293 Location: White mtns nh
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Posted: Wed Jun 23, 2021 6:26 pm Post subject: Re: Add me to the list of bucking, hesitation, now no start |
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Two minute check is to twist a piece of wire around the + coil connector, turn the key to on, and then touch the other end of your jumper wire to the pump power blade( or stud), and listen for the pump to run. You dont need to disconnect anything. If the pump is good, the fuel will just circulate through the injector manifolds and retun back to the tank.
Another check that incorporates the afm cut-off switch and the DR, is to turn the key on, and after removing the air filter, reach in gently with a screwdriver or dowel and push the afm flapper door open off its stop. If you hear pump come on, then you just verified ignition switch, afm cut-off switch, and DR are allowing power to the pump. _________________ You can't be a real country unless you have a beer and an airline. It helps if you have some kind of a football team, or some nuclear weapons, but at the very least you need a beer. Zappa
‘77 westy Seamus
‘76 tintop Crusher
‘77 westy The Judge
‘72 tintop bastard westy Hudson |
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Jetfxr69 Samba Member
Joined: December 28, 2018 Posts: 1293 Location: White mtns nh
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Posted: Wed Jun 23, 2021 6:30 pm Post subject: Re: Add me to the list of bucking, hesitation, now no start |
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Also, verify your points cam follower is not broke. I had one that ran like shit right up till it broke off, and then it was lights out. Sometimes they crack and fold over, allowing you to run shitty due to a change in gap. Eventually the phenolic piece just breaks off, and then you will never get a spark as the points will not open( no follower remaining to ride on dist cam lobe).
Check that before you waste time checking spark at plug wire. _________________ You can't be a real country unless you have a beer and an airline. It helps if you have some kind of a football team, or some nuclear weapons, but at the very least you need a beer. Zappa
‘77 westy Seamus
‘76 tintop Crusher
‘77 westy The Judge
‘72 tintop bastard westy Hudson |
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ivwshane Samba Member
Joined: May 19, 2011 Posts: 1920 Location: Sacramento ca
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Posted: Wed Jun 30, 2021 3:56 pm Post subject: Re: Add me to the list of bucking, hesitation, now no start |
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Ok I finally got some bus time and a helper.
With the time I had I was able to eliminate a couple things…I think.
I tested a plug wire lead and I did not see any spark. I plugged in a NGK BP6ET (which has four electrodes) and I didn’t see anything but I don’t have faith in my methodology).
I tested the main lead from the coil to the distributor cap and it got spark.
I measured the ohms on the coil and it was 3.0.
I removed the fuel pump and left the filter attached and got good flow after the filter so the filter is good.
I hooked up the fuel pump to a 12v source and got a good stream and normal sound.
So the only thing I haven’t tested was the double relay and looking at ratwell’s site I’ll need to reread it again as far as testing goes.
http://www.type2.com/bartnik/dblrly.htm
I did get to turn the engine over a couple of times but it required full throttle. However as soon as you let off the pedal it would die.
Thoughts? _________________ 77 westy 2.0 FI
69 ghia coup 1600dp
70 single cab |
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raygreenwood Samba Member
Joined: November 24, 2008 Posts: 21510 Location: Oklahoma City
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Posted: Wed Jun 30, 2021 4:46 pm Post subject: Re: Add me to the list of bucking, hesitation, now no start |
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ivwshane wrote: |
Ok I finally got some bus time and a helper.
With the time I had I was able to eliminate a couple things…I think.
I tested a plug wire lead and I did not see any spark. I plugged in a NGK BP6ET (which has four electrodes) and I didn’t see anything but I don’t have faith in my methodology).
I tested the main lead from the coil to the distributor cap and it got spark.
I measured the ohms on the coil and it was 3.0.
I removed the fuel pump and left the filter attached and got good flow after the filter so the filter is good.
I hooked up the fuel pump to a 12v source and got a good stream and normal sound.
So the only thing I haven’t tested was the double relay and looking at ratwell’s site I’ll need to reread it again as far as testing goes.
http://www.type2.com/bartnik/dblrly.htm
I did get to turn the engine over a couple of times but it required full throttle. However as soon as you let off the pedal it would die.
Thoughts? |
So.....think about this for a minute.
You tested main high tension wire.....FROM THE COIL.....and got spark......but.....you got not spark at the BP6ET spark plug you had connected to one of the spark plug wires....right? Thats what you wrote.
So.....two choices here....maybe three:
1. Did you hold the spark plug down so it was touching the cylinder head or engine case? If not...then you will not get a spark because there is no "ground"
2. If you did ground the spark plug....and you got no spark......and you did state thst the coil IS supplying spark.......it likely means that the ROTOR is not distributing that spark.....or the distributor is not turning (make sure its installed all the way in the engine) ....or your distributor cap has some serious issue....like a broken carbon contact in the center that is supposed to contact the rotor.
3. Or.....you may not have a good ground to the engine case. Check ground straps.
Ray |
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SGKent Samba Member
Joined: October 30, 2007 Posts: 41031 Location: Citrus Heights CA (Near Sacramento)
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Posted: Wed Jun 30, 2021 5:13 pm Post subject: Re: Add me to the list of bucking, hesitation, now no start |
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Shane - just put your timing light on #1 ignition wire and crank the motor. If the light flashes you have spark. If the light does not flash then you do not have proper spark. See what the timing is when it sparks.
There have been a plethora of condenser failures the last few years and they will do all that you have had happen to you. If you have a condenser around I would replace it to see what happens. If you have points the rubbing block breaks sometimes and changes the dwell. If you have an electronic ignition it may have gone bad. The timing light will answer it either way if the timing is way off or all over the place.
If you have spark, the next thing you would do is sniff the tail pipe for raw gas or look at a plug to see if it is wet. If it is wet or you smell fuel then you have fuel and spark so next you would do a smoke test to look for vacuum leaks. You can buy one off e-bay cheaply and have it in a day or two, or if you have a ride to Citrus Heights come borrow mine. Why HF doesn't sell them I don't know. All it takes is an empty metal paint can and a couple fittings plus some way to regulate air pressure. One can even use an aquarium pump as the air source and a small piece of old tee shirt or towel tossed in the can burning to make smoke. Lowe's has empty one gallon metal paint cans, Home Depot does not - only plastic. Same for some of the paint stores. _________________ “Most people don’t know what they’re doing, and a lot of them are really good at it.” - George Carlin |
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ivwshane Samba Member
Joined: May 19, 2011 Posts: 1920 Location: Sacramento ca
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Posted: Wed Jun 30, 2021 6:48 pm Post subject: Re: Add me to the list of bucking, hesitation, now no start |
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I should have tried the timing light, I didn’t even think of that.
When I tested the spark plug I did not try to touch it to metal (doh!).
I also realize I didn’t do the afm tests mentioned earlier.
I built my own smoke machine so I’ll check for that. _________________ 77 westy 2.0 FI
69 ghia coup 1600dp
70 single cab |
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