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borninabus
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Joined: May 18, 2006
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Location: Prescott, AZ
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SGKent
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Joined: October 30, 2007
Posts: 17520
Location: State Capitol CA (Sacramento)
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 Posted: Mon Jun 18, 2012 3:03 pm Post subject: |
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| dabble wrote: | Hi guys - I am having a problem with my 78 2.0 FI:
I replaced the plugs, wires, cap, and rotor. I set my idle at 1k rpm, and my timing is in spec at 7.5*btdc and 28* btdc 3500rpm.
My problem is this:
I have a sputter/pop/backfire when I let off of the accelerator. It does not make this sound when I am on the throttle. It does not sputter/pop/backfire as much when I am stationary and press the throttle. The sound goes away immediately when I depress the clutch.
I've checked for vacuum leaks and I can't find any. Thoughts? Decel valve need to be replaced?
Thanks! |
air getting into exhaust or bad decel or loose vacuum hose / broken tee. |
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dabble
Samba Member
Joined: April 21, 2004
Posts: 148
Location: Seattle, Wa
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| Posted: Mon Jun 18, 2012 3:18 pm Post subject: |
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| SGKent wrote: | | dabble wrote: | Hi guys - I am having a problem with my 78 2.0 FI:
I replaced the plugs, wires, cap, and rotor. I set my idle at 1k rpm, and my timing is in spec at 7.5*btdc and 28* btdc 3500rpm.
My problem is this:
I have a sputter/pop/backfire when I let off of the accelerator. It does not make this sound when I am on the throttle. It does not sputter/pop/backfire as much when I am stationary and press the throttle. The sound goes away immediately when I depress the clutch.
I've checked for vacuum leaks and I can't find any. Thoughts? Decel valve need to be replaced?
Thanks! |
air getting into exhaust or bad decel or loose vacuum hose / broken tee. |
I just replaced the exhaust with a new one - no leaks there. I'll check again for vacuum leaks. I bought some carb cleaner so I can try that tonight.
Is it weird that it only does it when the bus is actually moving? Any way to test the decel valve?
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babysnakes
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Joined: August 19, 2008
Posts: 3778
Location: West Boca Raton, Fla.
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| Posted: Mon Jun 18, 2012 5:00 pm Post subject: |
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In the Bentley, FI section, p24.Disconnect decel valve wire from atf pressure switch, ground disonnected wire to clean metal and listen for a click at valve. No click-bad valve.
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'69 SC under resto
'72 deluxe daily
'78 Westy motor transplant in progress
'71 super vert
1st bus, '67 Westy in '83. Thank you '74 Pontiac Ventura.
Luftwagens
420GOAT wrote:
..dont ever ever ever ever EVER, compare any bus forum to a bug forum... |
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SGKent
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Joined: October 30, 2007
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Location: State Capitol CA (Sacramento)
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dabble
Samba Member
Joined: April 21, 2004
Posts: 148
Location: Seattle, Wa
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| Posted: Wed Jun 20, 2012 10:59 am Post subject: |
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My bus is a 73 with a 78 2.0. GE is the engine code (I think...).
My vacuum hoses don't look the same as the one in the ratwell picture, but I'll check to make sure they're all connected and not leaking.
Does anyone sell a replacement kit for vacuum hoses? Or should I just try to piece together new hoses?
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Randy in Maine
Samba Member
Joined: August 03, 2003
Posts: 29742
Location: The Beach
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| Posted: Wed Jun 20, 2012 11:13 am Post subject: |
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| Post a picutre of your engine set up. Also what is the number on that distriburtor you are running? |
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Westfabulous
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Joined: January 07, 2007
Posts: 4083
Location: The tropic of Canada, dodging the giant flying moose of Surrey!
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| Posted: Wed Jun 20, 2012 11:36 am Post subject: |
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| dabble wrote: | My bus is a 73 with a 78 2.0. GE is the engine code (I think...).
My vacuum hoses don't look the same as the one in the ratwell picture |
Do you have an automatic? That would be one reason why the hoses are different.
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Stuartzickefoose
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Joined: February 07, 2008
Posts: 5373
Location: Edmonds, WA.
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| Posted: Thu Jun 21, 2012 4:36 pm Post subject: |
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What is the proper technique for setting the AFM at a rough placement as far as the adjustment for enriching and leaning out the mixture? and how should it be set in relation to the throttle body idle adjustment screw?
1978 FI 2.0
see sig line
_________________
MINE - 1978 Westfalia ~ Maisy ~ FI, Hydraulic Valves, Electronic Points, 2.0 (NEED A SET OF HEADS, PM ME IF YOU HAVE A SET)
DAD's - 1972 Westfalia ~ Sticky ~ 1.7(?) 914 motor, allison electronic ignition, electric fuel pump, dual webers w/o choke.
“Don't cry because it's over, smile because it happened.”
“Those who mind don't matter, and those who matter don't mind.” |
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SGKent
Samba Member
Joined: October 30, 2007
Posts: 17520
Location: State Capitol CA (Sacramento)
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| Posted: Thu Jun 21, 2012 4:48 pm Post subject: |
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| Stuartzickefoose wrote: | What is the proper technique for setting the AFM at a rough placement as far as the adjustment for enriching and leaning out the mixture? and how should it be set in relation to the throttle body idle adjustment screw?
1978 FI 2.0
see sig line |
don't go there without an air to fuel meter to test with. It is like shooting bullets without being able to see where the target is or where the bullets are going. Colin has one, let him drop by. |
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Stuartzickefoose
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Joined: February 07, 2008
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Location: Edmonds, WA.
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| Posted: Thu Jun 21, 2012 5:01 pm Post subject: |
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| SGKent wrote: | | Stuartzickefoose wrote: | What is the proper technique for setting the AFM at a rough placement as far as the adjustment for enriching and leaning out the mixture? and how should it be set in relation to the throttle body idle adjustment screw?
1978 FI 2.0
see sig line |
don't go there without an air to fuel meter to test with. It is like shooting bullets without being able to see where the target is or where the bullets are going. Colin has one, let him drop by. |
i have access to one, and was going to tune it properly there, but how should i set it to get it close? 3 turns out, or something?
_________________
MINE - 1978 Westfalia ~ Maisy ~ FI, Hydraulic Valves, Electronic Points, 2.0 (NEED A SET OF HEADS, PM ME IF YOU HAVE A SET)
DAD's - 1972 Westfalia ~ Sticky ~ 1.7(?) 914 motor, allison electronic ignition, electric fuel pump, dual webers w/o choke.
“Don't cry because it's over, smile because it happened.”
“Those who mind don't matter, and those who matter don't mind.” |
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tootype2crazy
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Joined: October 08, 2007
Posts: 443
Location: St. Louis Missouri
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| Posted: Mon Jun 25, 2012 6:30 am Post subject: |
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I have been running FI for about 7 months now and it has been great. The problem I have been having is between 2000 - 3000 rpm it runs rough and pops in the exhaust will revving it. It has a tiny flat spot upon acceleration as well. It has great power overall, though. Especially above 3000 rpm its great.
I suspected the AAR, I took it out adjusted and tested it and it is ok. I also suspected a vacuum leak so I checked every single connection yesterday, taking it all apart and putting it back together, no change. I also thought it might be the coil and distributor cap and rotor. A while back while turning the distributor to adjust the timing the cap came loose while the engine was running, destroying the cap, rotor, and coil. I put a used set on that I had in the basement from and old engine. Is it possible that those parts are causing this? The problem has gotten progressively worse from over the last few months, seemingly from the time I put the ignition components on, although I can't be sure of that.
I also checked and greased all the electrical connections yesterday. It did seem to give it a little more pep, but did not change the rough running between 2000-3000 rpm.
Is there something I'm overlooking or that I should test? I have been through the troubleshooting in the L-Jet manual but I just can't pinpoint anything.
_________________
1979 Sunroof Deluxe Bus with the sunroof and its parts sitting in my closet and a westy pop-top to cover the hole. Lower 1/5 of the body is gone from rust. Freshly rebuilt 2.0 with Federal FI and newly restored heat exchangers. |
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dabble
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Joined: April 21, 2004
Posts: 148
Location: Seattle, Wa
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| Posted: Mon Jun 25, 2012 9:15 am Post subject: |
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Went camping this weekend...
Made it 30 miles to work on Friday with no problems - just some intermittent popping/backfiring.
Put in a full day of work on Friday and started the next 60 mile leg of the trip to Anacortes. More consistent popping/backfiring, loss of power, and felt like the engine was missing. Still made it to Anacortes running and mostly happy.
I re-did the timing and checked all of my ignition and vacuum connections on Saturday before embarking home on Sunday.
Trip home on Sunday had much more backfiring and loss of power. Stopped and re-did timing and checked hoses - couldn't see any problems. One thing I noticed was that my vacuum advance was not working when revving the engine up to 3500 rpm.
Driving home and the bus dies on I-5. It starts and runs, but dies when I let off of the accelerator. I checked for vacuum leaks and couldn't find any, timing is set at static because I can't rev it up to 3500 rpm without it dying.
Towed it home and I'm at a loss. Help? Suggestions on a shop to take it to in Seattle? 
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Stuartzickefoose
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Joined: February 07, 2008
Posts: 5373
Location: Edmonds, WA.
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| Posted: Mon Jun 25, 2012 10:59 am Post subject: |
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start with the vacuum advance problem...not good
_________________
MINE - 1978 Westfalia ~ Maisy ~ FI, Hydraulic Valves, Electronic Points, 2.0 (NEED A SET OF HEADS, PM ME IF YOU HAVE A SET)
DAD's - 1972 Westfalia ~ Sticky ~ 1.7(?) 914 motor, allison electronic ignition, electric fuel pump, dual webers w/o choke.
“Don't cry because it's over, smile because it happened.”
“Those who mind don't matter, and those who matter don't mind.” |
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SGKent
Samba Member
Joined: October 30, 2007
Posts: 17520
Location: State Capitol CA (Sacramento)
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| Posted: Mon Jun 25, 2012 11:07 am Post subject: |
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| tootype2crazy wrote: | I have been running FI for about 7 months now and it has been great. The problem I have been having is between 2000 - 3000 rpm it runs rough and pops in the exhaust will revving it. It has a tiny flat spot upon acceleration as well. It has great power overall, though. Especially above 3000 rpm its great.
I suspected the AAR, I took it out adjusted and tested it and it is ok. I also suspected a vacuum leak so I checked every single connection yesterday, taking it all apart and putting it back together, no change. I also thought it might be the coil and distributor cap and rotor. A while back while turning the distributor to adjust the timing the cap came loose while the engine was running, destroying the cap, rotor, and coil. I put a used set on that I had in the basement from and old engine. Is it possible that those parts are causing this? The problem has gotten progressively worse from over the last few months, seemingly from the time I put the ignition components on, although I can't be sure of that.
I also checked and greased all the electrical connections yesterday. It did seem to give it a little more pep, but did not change the rough running between 2000-3000 rpm.
Is there something I'm overlooking or that I should test? I have been through the troubleshooting in the L-Jet manual but I just can't pinpoint anything. |
Have you put your timing light on it to see if the timing is bouncing all over the place at in that range or cutting out - it needs to be rock steady.
If that is Ok you may have a worn spot on the AFM. Do you know how to look for that? |
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tootype2crazy
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Joined: October 08, 2007
Posts: 443
Location: St. Louis Missouri
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| Posted: Mon Jun 25, 2012 11:20 am Post subject: |
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| SGKent wrote: | Have you put your timing light on it to see if the timing is bouncing all over the place at in that range or cutting out - it needs to be rock steady.
If that is Ok you may have a worn spot on the AFM. Do you know how to look for that? |
I'll do the timing light thing and see how that goes. I do not know what a worn AFM looks like, although I was thinking that could be it since it only runs bad in a certain rpm range, i. e. the most used one. Can you point me to the right direction for checking that out?
_________________
1979 Sunroof Deluxe Bus with the sunroof and its parts sitting in my closet and a westy pop-top to cover the hole. Lower 1/5 of the body is gone from rust. Freshly rebuilt 2.0 with Federal FI and newly restored heat exchangers. |
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Stuartzickefoose
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Joined: February 07, 2008
Posts: 5373
Location: Edmonds, WA.
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| Posted: Mon Jun 25, 2012 11:52 am Post subject: |
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| tootype2crazy wrote: | | SGKent wrote: | Have you put your timing light on it to see if the timing is bouncing all over the place at in that range or cutting out - it needs to be rock steady.
If that is Ok you may have a worn spot on the AFM. Do you know how to look for that? |
I'll do the timing light thing and see how that goes. I do not know what a worn AFM looks like, although I was thinking that could be it since it only runs bad in a certain rpm range, i. e. the most used one. Can you point me to the right direction for checking that out? |
take a knife and cut the seal on the top of the AFM (black plastic flat piece) off, and see if the area the arm moves across is worn in any place. (Someone back this up...im not the best at this)
_________________
MINE - 1978 Westfalia ~ Maisy ~ FI, Hydraulic Valves, Electronic Points, 2.0 (NEED A SET OF HEADS, PM ME IF YOU HAVE A SET)
DAD's - 1972 Westfalia ~ Sticky ~ 1.7(?) 914 motor, allison electronic ignition, electric fuel pump, dual webers w/o choke.
“Don't cry because it's over, smile because it happened.”
“Those who mind don't matter, and those who matter don't mind.” |
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tootype2crazy
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Joined: October 08, 2007
Posts: 443
Location: St. Louis Missouri
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| Posted: Mon Jun 25, 2012 12:21 pm Post subject: |
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Here is the AFM:
It looks ok to me.
Also the ignition is nice and steady.
_________________
1979 Sunroof Deluxe Bus with the sunroof and its parts sitting in my closet and a westy pop-top to cover the hole. Lower 1/5 of the body is gone from rust. Freshly rebuilt 2.0 with Federal FI and newly restored heat exchangers. |
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SGKent
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Posts: 17520
Location: State Capitol CA (Sacramento)
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| Posted: Mon Jun 25, 2012 12:28 pm Post subject: |
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the red RTV shows that someone has been in there before. Regular RTV has acids in it that cause corrosion in electronic parts. I see some lines in the circuit board although it does not look bad. If the timing is steady and the stumble goes away above 3000 RPM then it could be anything from a wire wiggling to a bad AFM. You can get some electronic contact cleaner from Fry's or Radio shack and spray a tiny bit on the board to see if it gets better.
Were it me I would start with a full tune up including plugs, valve adjust, compression test etc. It could also be a valve or valve seat floating. |
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tootype2crazy
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Joined: October 08, 2007
Posts: 443
Location: St. Louis Missouri
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| Posted: Mon Jun 25, 2012 1:00 pm Post subject: |
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Just a quick question: what should the normal vacuum be? I have a mighty vac with a gauge on it and would like to see if I'm pulling the correct vacuum. Also I would read this on the plenum, right?
The system I bought was used so I'm betting the previous owner of it was having similar problems. I might just spring for a rebuilt AFM to be sure.
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1979 Sunroof Deluxe Bus with the sunroof and its parts sitting in my closet and a westy pop-top to cover the hole. Lower 1/5 of the body is gone from rust. Freshly rebuilt 2.0 with Federal FI and newly restored heat exchangers.
Last edited by tootype2crazy on Mon Jun 25, 2012 1:07 pm; edited 1 time in total |
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