'78 FI Bus AFM Flap Hole
- dtrumbo
- IAC Addict!
- Location: Mill Creek, WA
- Status: Offline
'78 FI Bus AFM Flap Hole
Heretofore I've been too ashamed to share this with all of you. I have now swallowed my pride and I'm ready to tell my story as I found a very peculiar thing that I need to share with all of you in case it happens to you. One day last fall I drove my bus to work. After my shift, when I got in it to go home, it started fine and I drove out of the garage. When I got to the third stop light it died and would not re-start. It cranked and cranked, but no go. Some very helpful bystanders pushed me out of the intersection and off of the trolley tracks (I'd hate for my bus to meet its end by being hit by the stupid Tooner-ville trolley). Once safely parked I peered into the engine compartment looking for clues to my problem. Nothing obvious jumped out at me and when I'd crank and crank and crank I would eventually smell fuel. This implied my problem was one of the other two magic ingredients for bus-go. Spark or air. Since I was downtown on a Sunday afternoon with no substantial tools or other troubleshooting aids, I conceded defeat and called AAA. The very chatty flatbed tow driver took me and the bus home to my shop where he very skillfully lowered the bus into its exact parking spot right next to my Beetle that had the engine out occupying my time as my current project. Much to my wife's dismay, I'm NOT a multitasker. I need to finish one thing before I start another so the bus has sat until now while I finished my bug project.
Fast-forward to 2010, I'm finished with my bug and now onto the bus. I hooked up my remote starter and cranked it over. It starts and sorta runs up until you give it any throttle. I mean if you even look at the accelerator, it will die. O.k. Now I'm eliminating the second variable as obviously it's getting spark or it wouldn't start and idle. Now I'm leaning (pardon the reverse-pun) at lack of airflow. I pull the air filter element out and yeah, it's a little dirty, but the bus still won't run even with it out. I try sticking a long screw driver in the AFM to see if the flap is stuck. No, it moves freely and I discover that I can get the bus to run by increasing the amount that I manually open the flap while increasing throttle. In other words, if I open the flap with the screwdriver in my right hand while I simultaneously open the throttle with my left hand, I can get the bus to run through all throttle positions. If I remove the screwdriver from the AFM, the flap snaps shut and the bus dies. This indicates a massIVe air leak somewhere. I check all the hoses and find that a hose on the AAR is loose. O.k. this is not good, but couldn't really account for the fact that apparently NO air is passing through my AFM to keep the flap open. I then remove the S-boot hoping to find a breach which would explain the huge air leak. Nope, it's all good. I then decide to remove the AFM and have a look. Here's what I found.
A closer look.
It seems I have a hole in my flap! I found a nickel-size washer-without-a-hole laying down on the tin where it had fallen out of the air filter housing when I removed the air filter element. It looks like this.
It's supposed to be attached to here.
Well now, this might explain why the flap won't stay open! The "screen door on a submarine" analogy comes to mind. On further inspection, this round doo-dad used to be attached to the spring-loaded plunger you see here.
I'm completely guessing, but perhaps it's there so if the flap snaps shut, the plunger will allow this hole to briefly open and let some air pass through similar in function to the decel valve which would reduce emissions? Nice guess, huh, but probably way wrong.
I considered trying to reattach the washer-without-a-hole to the plunger with JB Weld or something, but I would never feel comfortable with the fix. I would always be afraid that I'd be a million-miles from home and that thing would break off again. I can tell you first-hand, if that happens, your bus isn't going anywhere but onto the back of a tow truck. I'm off to Ken's (www.thebusco.com) to see if I can score an new-to-me AFM.
More to come...
Fast-forward to 2010, I'm finished with my bug and now onto the bus. I hooked up my remote starter and cranked it over. It starts and sorta runs up until you give it any throttle. I mean if you even look at the accelerator, it will die. O.k. Now I'm eliminating the second variable as obviously it's getting spark or it wouldn't start and idle. Now I'm leaning (pardon the reverse-pun) at lack of airflow. I pull the air filter element out and yeah, it's a little dirty, but the bus still won't run even with it out. I try sticking a long screw driver in the AFM to see if the flap is stuck. No, it moves freely and I discover that I can get the bus to run by increasing the amount that I manually open the flap while increasing throttle. In other words, if I open the flap with the screwdriver in my right hand while I simultaneously open the throttle with my left hand, I can get the bus to run through all throttle positions. If I remove the screwdriver from the AFM, the flap snaps shut and the bus dies. This indicates a massIVe air leak somewhere. I check all the hoses and find that a hose on the AAR is loose. O.k. this is not good, but couldn't really account for the fact that apparently NO air is passing through my AFM to keep the flap open. I then remove the S-boot hoping to find a breach which would explain the huge air leak. Nope, it's all good. I then decide to remove the AFM and have a look. Here's what I found.
A closer look.
It seems I have a hole in my flap! I found a nickel-size washer-without-a-hole laying down on the tin where it had fallen out of the air filter housing when I removed the air filter element. It looks like this.
It's supposed to be attached to here.
Well now, this might explain why the flap won't stay open! The "screen door on a submarine" analogy comes to mind. On further inspection, this round doo-dad used to be attached to the spring-loaded plunger you see here.
I'm completely guessing, but perhaps it's there so if the flap snaps shut, the plunger will allow this hole to briefly open and let some air pass through similar in function to the decel valve which would reduce emissions? Nice guess, huh, but probably way wrong.
I considered trying to reattach the washer-without-a-hole to the plunger with JB Weld or something, but I would never feel comfortable with the fix. I would always be afraid that I'd be a million-miles from home and that thing would break off again. I can tell you first-hand, if that happens, your bus isn't going anywhere but onto the back of a tow truck. I'm off to Ken's (www.thebusco.com) to see if I can score an new-to-me AFM.
More to come...
- Dick
1970 Transporter. 2015cc, dual Weber IDF 40's
1978 Riviera Camper. Bone stock GE 2.0L F.I.
1979 Super Beetle convertible.
... as it turns out, it was the coil!
1970 Transporter. 2015cc, dual Weber IDF 40's
1978 Riviera Camper. Bone stock GE 2.0L F.I.
1979 Super Beetle convertible.
... as it turns out, it was the coil!
- vwlover77
- IAC Addict!
- Location: North Canton, Ohio
- Status: Offline
- vwlover77
- IAC Addict!
- Location: North Canton, Ohio
- Status: Offline
What is the part number on your AFM? I just looked at my spare and it has neither the circular plug nor the spring/shaft in it. The flap is one smooth aluminum casting. It looks like the spring/shaft would come into play not at idle, but when the flap is pushed wide-open.
Mine is 0 280 200 020 (on the plastic lid)
Mine is 0 280 200 020 (on the plastic lid)
Don
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78 Westy
71 Super Beetle Convertible Autostick
"When we let our compassion go, we let go of whatever claim we have to the divine." - Bruce Springsteen
---------------------------
78 Westy
71 Super Beetle Convertible Autostick
"When we let our compassion go, we let go of whatever claim we have to the divine." - Bruce Springsteen
- dtrumbo
- IAC Addict!
- Location: Mill Creek, WA
- Status: Offline
My plastic lid shows heat damage, possibly by someone using a heat gun to help loosen it up to pry off (Colin was stumped by it as well). This makes reading the numbers challenging, but here's what I think it says.vwlover77 wrote:What is the part number on your AFM?
The Bosch number is as yours, 0 280 200 020
The VW number is 022 906(?) 301 D
There is no guarantee that the cap that was on my AFM is the one that came with it.
I would love to figure out what the plunger/valve is for and to find a good used AFM that DOESN'T have one (like yours, Don) so I can rest easy knowing that it can't break off again.
- Dick
1970 Transporter. 2015cc, dual Weber IDF 40's
1978 Riviera Camper. Bone stock GE 2.0L F.I.
1979 Super Beetle convertible.
... as it turns out, it was the coil!
1970 Transporter. 2015cc, dual Weber IDF 40's
1978 Riviera Camper. Bone stock GE 2.0L F.I.
1979 Super Beetle convertible.
... as it turns out, it was the coil!
- Amskeptic
- IAC "Help Desk"
- Status: Offline
That thar is the famous "pop-off" valve that Porsche demanded of Bosch when people kept getting on their 911s-while-cold and the backfires would destroy what was then an $800.00 part.dtrumbo wrote: I would love to figure out what the plunger/valve is for and to find a good used AFM that DOESN'T have one (like yours, Don) so I can rest easy knowing that it can't break off again.
Colin
- dtrumbo
- IAC Addict!
- Location: Mill Creek, WA
- Status: Offline
This is exactly what I came up with this morning in the shower (I do all my best brainin' in there). An "exhaust valve" as such to relieve back-pressure from a backfire.Amskeptic wrote:That thar is the famous "pop-off" valve that Porsche demanded of Bosch when people kept getting on their 911s-while-cold and the backfires would destroy what was then an $800.00 part.
Colin
Hopefully I can find a good used one at Ken's (for substantially less than $800.00 ).
- Dick
1970 Transporter. 2015cc, dual Weber IDF 40's
1978 Riviera Camper. Bone stock GE 2.0L F.I.
1979 Super Beetle convertible.
... as it turns out, it was the coil!
1970 Transporter. 2015cc, dual Weber IDF 40's
1978 Riviera Camper. Bone stock GE 2.0L F.I.
1979 Super Beetle convertible.
... as it turns out, it was the coil!
- hercdriver
- Getting Hooked!
- Location: Beaver, PA
- Status: Offline
I bought this a few months ago with the intent of going back to a F/I setup.dtrumbo wrote: My plastic lid shows heat damage, possibly by someone using a heat gun to help loosen it up to pry off (Colin was stumped by it as well). This makes reading the numbers challenging, but here's what I think it says.
The Bosch number is as yours, 0 280 200 020
The VW number is 022 906(?) 301 D
I believe it came out of a 78.
It's a Bosch part.
0 280 200 020
vw 022 906 301 D
66 Beetle
75 Westy
Remember that there is nothing stable in human affairs; therefore avoid undue elation in prosperity, or undue depression in adversity. -Socrates
75 Westy
Remember that there is nothing stable in human affairs; therefore avoid undue elation in prosperity, or undue depression in adversity. -Socrates
- vwlover77
- IAC Addict!
- Location: North Canton, Ohio
- Status: Offline
I wonder which is an "early" style versus a "late" style?
I was under the impression that the black plastic/rubber stop on my AFM was designed to break away during a backfire.
I was under the impression that the black plastic/rubber stop on my AFM was designed to break away during a backfire.
Don
---------------------------
78 Westy
71 Super Beetle Convertible Autostick
"When we let our compassion go, we let go of whatever claim we have to the divine." - Bruce Springsteen
---------------------------
78 Westy
71 Super Beetle Convertible Autostick
"When we let our compassion go, we let go of whatever claim we have to the divine." - Bruce Springsteen
- Amskeptic
- IAC "Help Desk"
- Status: Offline
That's just a nice door stop. Nothing is ever supposed to "break away" in an airstream that leads directly into the innards . . .vwlover77 wrote:I wonder which is an "early" style versus a "late" style?
I was under the impression that the black plastic/rubber stop on my AFM was designed to break away during a backfire.
Colin
- vwlover77
- IAC Addict!
- Location: North Canton, Ohio
- Status: Offline
OHHH!!! I get it! The round piece is supposed to stay attached to the shaft and drumbo's has broken off. Duh!Amskeptic wrote:Nothing is ever supposed to "break away" in an airstream that leads directly into the innards . . .
Colin
Dick, Why not eliminate the shaft and spring and permanently attach the round piece to the flap with JB Weld on both sides? I would think you'd have no worries then.
Don
---------------------------
78 Westy
71 Super Beetle Convertible Autostick
"When we let our compassion go, we let go of whatever claim we have to the divine." - Bruce Springsteen
---------------------------
78 Westy
71 Super Beetle Convertible Autostick
"When we let our compassion go, we let go of whatever claim we have to the divine." - Bruce Springsteen
- dtrumbo
- IAC Addict!
- Location: Mill Creek, WA
- Status: Offline
I might just do that. That would offer the advantage of not having to tune a new-to-me AFM since mine works fine electrically and in all other ways other than the gaping hole in the flap.vwlover77 wrote:Dick, Why not eliminate the shaft and spring and permanently attach the round piece to the flap with JB Weld on both sides? I would think you'd have no worries then.
- Dick
1970 Transporter. 2015cc, dual Weber IDF 40's
1978 Riviera Camper. Bone stock GE 2.0L F.I.
1979 Super Beetle convertible.
... as it turns out, it was the coil!
1970 Transporter. 2015cc, dual Weber IDF 40's
1978 Riviera Camper. Bone stock GE 2.0L F.I.
1979 Super Beetle convertible.
... as it turns out, it was the coil!
- dtrumbo
- IAC Addict!
- Location: Mill Creek, WA
- Status: Offline
O.k. so I talked to Ken and we decided that the re-manufactured AFM from Fuel Injection Corporation is the better bet than a used, who-knows-what-condition AFM from a bus that doesn't run anymore which is why it's being parted out at Ken's junk yard. You gotta love a guy who will talk you out of buying something from him. If you haven't had the pleasure of dealing with Ken Madson at The Bus Company (www.thebusco.com), I highly recommend him.
Soooo... on Don's suggestion, I just finished removing the broken plunger and JB-Welding the cap back onto the flap. We'll see how good of a job I did in 24 hours and if it's at all questionable, I'll get the rebuilt one from FIC.
Soooo... on Don's suggestion, I just finished removing the broken plunger and JB-Welding the cap back onto the flap. We'll see how good of a job I did in 24 hours and if it's at all questionable, I'll get the rebuilt one from FIC.
- Dick
1970 Transporter. 2015cc, dual Weber IDF 40's
1978 Riviera Camper. Bone stock GE 2.0L F.I.
1979 Super Beetle convertible.
... as it turns out, it was the coil!
1970 Transporter. 2015cc, dual Weber IDF 40's
1978 Riviera Camper. Bone stock GE 2.0L F.I.
1979 Super Beetle convertible.
... as it turns out, it was the coil!
- dtrumbo
- IAC Addict!
- Location: Mill Creek, WA
- Status: Offline
The (JB) weld appears to have held. I'll be reassembling tomorrow morning with my new vacuum hose I'm expecting to arrive from AutohausAZ today.
Hopefully I'll be able to report that I have a running bus again.
Hopefully I'll be able to report that I have a running bus again.
- Dick
1970 Transporter. 2015cc, dual Weber IDF 40's
1978 Riviera Camper. Bone stock GE 2.0L F.I.
1979 Super Beetle convertible.
... as it turns out, it was the coil!
1970 Transporter. 2015cc, dual Weber IDF 40's
1978 Riviera Camper. Bone stock GE 2.0L F.I.
1979 Super Beetle convertible.
... as it turns out, it was the coil!