Mech.Fuel Pump - Pressure test at Colin's request on O72 Bus

Carbs & F.I.

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Oregon72
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Post by Oregon72 » Mon Aug 16, 2010 3:46 pm

Bump -- Anyone have any thoughts on the safety of my setup?
-'72 Westy-

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dtrumbo
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Post by dtrumbo » Mon Aug 16, 2010 4:00 pm

I'd love to tell you it's all good, but I just don't know and I'd hate to give mis-information. I looked for a schematic of that type of relay, but didn't find anything other than "hook this wire to that and it just works". I was hoping to find an actual schematic so I could figure out what 31b does. Further, I can't imagine feeding a pulsing voltage from the coil to another coil (internal to the relay) as being a good idea. So... I don't know. Maybe an actual schematic of the relay will surface and we can take a look-see. Until evidence to the contrary is presented, Hal's word is pretty durn good.
- 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!

72Hardtop
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Post by 72Hardtop » Tue Aug 17, 2010 2:49 pm

Another option for mounting the relay would be JB Weld a strong magnet to the back of the relay and stick it up on the firewall near the regulator. This way it could be pulled down easily if need be.
1972 Westy tintop
2056cc T-4 - 7.8:1 CR
Weber 40mm Duals - 47.5idles, 125mains, F11 tubes, 190 Air corr., 28mm Vents
96mm AA Biral P/C's w/Hastings rings
42x36mm Heads (AMC- Headflow Masters) w/Porsche swivel adjusters
71mm Stroke
Web Cam 73 w/matched Web lifters
S&S 4-1 exhaust w/Walker 17862 quiet-pack
Pertronix SVDA w/Pertronix module & Flamethrower 40K coil (7* initial 28* total @3200+)
NGK BP6ET plugs
002 3 rib trans
Hankook 185R14's

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Oregon72
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Post by Oregon72 » Tue Aug 17, 2010 4:29 pm

72Hardtop wrote:
Another option for mounting the relay would be JB Weld a strong magnet to the back of the relay and stick it up on the firewall near the regulator. This way it could be pulled down easily if need be.
I should have thought of that. It would have been way better with no drilling. Oh well they are tiny holes.
-'72 Westy-

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Amskeptic
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Post by Amskeptic » Tue Aug 17, 2010 6:55 pm

Oregon72 wrote:
72Hardtop wrote:
Another option for mounting the relay would be JB Weld a strong magnet to the back of the relay and stick it up on the firewall near the regulator. This way it could be pulled down easily if need be.
I should have thought of that. It would have been way better with no drilling. Oh well they are tiny holes.
With a running engine, ground the green wire from the coil #1 that goes to the distributor. Fuel pump stop along with engine?
Kudos to Hal.
ColinLearningEveryDayWhenHeShutsUpForALousyMinute
BobD - 1978 Bus . . . . . . . . . . . 112,660 miles
Chloe - 1970 bus . . . . . . . . . . . 206,845 miles
Naranja - 1977 Westfalia . . . . . 112,885 miles
Pluck - 1973 Squareback . . . . . . 55,570 miles
Alexus - 1991 Lexus LS400 . . . 78,899 miles

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Oregon72
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Re: Mech.Fuel Pump - Pressure test at Colin's request on O72

Post by Oregon72 » Tue Sep 27, 2011 10:14 pm

Warning - Old thread revival ---

Got a question for ya'll --- If my bus has not been driven for several days, I find the fuel appears to have evaporated out of the carbs and upon cranking, the fuel pump doesn't seem to be filling the bowls so it doesn't fire up. A little gas poured down the carbs gets going enough to get it started and once it is up and running I can drive it all day long. As long as the bus doesn't sit un-driven for a number of days, it will start and run fine. Do you think there is something wrong with my fuel pump relay or the way I have everything hooked up (see diagram above)? It seems to be something that has just started recently.

Now that I think about it, I'm gonna go check the in-line fuse from the battery to the relay and see if that is OK - I'll feel like an idiot if that is what it is. :rr:
-'72 Westy-

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Amskeptic
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Re: Mech.Fuel Pump - Pressure test at Colin's request on O72

Post by Amskeptic » Wed Sep 28, 2011 9:15 am

Oregon72 wrote:Warning - Old thread revival ---

Got a question for ya'll --- If my bus has not been driven for several days, I find the fuel appears to have evaporated out of the carbs and upon cranking, the fuel pump doesn't seem to be filling the bowls so it doesn't fire up. A little gas poured down the carbs gets going enough to get it started and once it is up and running I can drive it all day long. As long as the bus doesn't sit un-driven for a number of days, it will start and run fine. Do you think there is something wrong with my fuel pump relay or the way I have everything hooked up (see diagram above)? It seems to be something that has just started recently.

Now that I think about it, I'm gonna go check the in-line fuse from the battery to the relay and see if that is OK - I'll feel like an idiot if that is what it is. :rr:
I was set up with the relay running off the alternator warning light circuit on the Road Warrior.
Car started even after a winter sit. However, after doing carb work where the bowls were drained, yes, I would have to prime the system. I already had the relay located where I could just run a simple jumper wire from the coil or battery to the #87 terminal of the relay, run the pump for five seconds and yer gud. Safer by far than running gas into the carbs :colors:
Colin
BobD - 1978 Bus . . . . . . . . . . . 112,660 miles
Chloe - 1970 bus . . . . . . . . . . . 206,845 miles
Naranja - 1977 Westfalia . . . . . 112,885 miles
Pluck - 1973 Squareback . . . . . . 55,570 miles
Alexus - 1991 Lexus LS400 . . . 78,899 miles

72Hardtop
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Re: Mech.Fuel Pump - Pressure test at Colin's request on O72

Post by 72Hardtop » Sun Jun 15, 2014 12:21 am

Old I know...looking at this thread again. I don't see an issue with the pressure of his mechanical pump. Solex carbs are built to tolerate no more than ~ 4psi at the inlet. His pressure in the video was fine and shouldn't have been an issue. The mechanical pumps on the 72 buses would generally yield what his findings were...perfectly normal.

It's also not difficult at all to remove a mechanical fuel pump on a 1972 bus. In fact, its a 5 minute job (engine in place).
1972 Westy tintop
2056cc T-4 - 7.8:1 CR
Weber 40mm Duals - 47.5idles, 125mains, F11 tubes, 190 Air corr., 28mm Vents
96mm AA Biral P/C's w/Hastings rings
42x36mm Heads (AMC- Headflow Masters) w/Porsche swivel adjusters
71mm Stroke
Web Cam 73 w/matched Web lifters
S&S 4-1 exhaust w/Walker 17862 quiet-pack
Pertronix SVDA w/Pertronix module & Flamethrower 40K coil (7* initial 28* total @3200+)
NGK BP6ET plugs
002 3 rib trans
Hankook 185R14's

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Amskeptic
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Re: Mech.Fuel Pump - Pressure test at Colin's request on O72

Post by Amskeptic » Sun Apr 12, 2015 8:34 am

72Hardtop wrote:Old I know...looking at this thread again. I don't see an issue with the pressure of his mechanical pump. Solex carbs are built to tolerate no more than ~ 4psi at the inlet. His pressure in the video was fine and shouldn't have been an issue. The mechanical pumps on the 72 buses would generally yield what his findings were...perfectly normal.

It's also not difficult at all to remove a mechanical fuel pump on a 1972 bus. In fact, its a 5 minute job (engine in place).
The Bentley manual says 5 psi for the dual carb buses. Doesn't say "3-5" like the earlier buses, says "5" psi, and I ain't gonna second guess that. The only time I flooded my crankcase with gasoline was when I had inadequate pressure to make sure the fuel level *pressed* the float *up* to *seal* the needle valve closed.
Colin
BobD - 1978 Bus . . . . . . . . . . . 112,660 miles
Chloe - 1970 bus . . . . . . . . . . . 206,845 miles
Naranja - 1977 Westfalia . . . . . 112,885 miles
Pluck - 1973 Squareback . . . . . . 55,570 miles
Alexus - 1991 Lexus LS400 . . . 78,899 miles

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