IDF 40 issues (I think)

[malcolm2]

Ok here is the whole story, for those that need it.

72 Bay window with a low mileage 914 2.0 engine, so a Carter electric Fuel pump was added along with a regulator to get 2.5 psi

Brand new Dual IDF 40s from Aircooled.net set up fees paid.

Carb barrels and idle balanced with the snail.

Currently has it's 3rd tank of fuel in it. Drove nicely for those 1st 2 tanks full. When I filled it up with the 3rd tank, I found that the float needles had ridges and leaked. so i purchase a set with viton tips.

Installed the float needles, checked the float setting and started driving. Leaks are gone, but I now get a light sounding back-fire from the carbs. Not sure if it is 1 carb or both. It started as only when shifting from 1st to 2nd.

But the back-fire now has gotten louder and more frequent at idle. The louder ones do seem to come from the tail pipe. Still a pop, just loader.

I removed the fuel pressure regulator, now get like 3 psi, but no change in the back-fire. Maybe a bit worse.

What is the next step here??

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My Toys: '75 Porsche 914, '92 Ski Nautique and now a 1972 VW Transporter Deluxe (punch list fixing)

[67rustavenger]

Start the engine and warm it.

If you have a tach. Press the accelerator slowly up to 1200-1500 rpm.
Is the backfire occurring in that range? If so, suspect a clogged idle jet on one or more of the carbs.
_________________
I have learned over the years.
Cheap parts are gonna disappoint you.
Buy Once, Cry Once!

There's never enough time to do it right the first time. But there's always enough time to do it thrice.
GFY's Xevin and VW_Jimbo!

[malcolm2]

it is not. Just at idle after warming. and 1 to 2 shifting when cold.

I do have a tach. I did notice, when warm, at a stop light, idling drops to 500.... sometimes. And I do hear the light pops. But I can use the pedal to increase the rev to 1000 and those go away.
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My Toys: '75 Porsche 914, '92 Ski Nautique and now a 1972 VW Transporter Deluxe (punch list fixing)

[Alstrup]

Linkage out od sync or clogged idle jet.
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https://www.thesamba.com/vw/forum/viewtopic.php?t=435993

[malcolm2]

[Alstrup]

Sorry. Fat fingers. Out of sync
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https://www.thesamba.com/vw/forum/viewtopic.php?t=435993

[Willin]

Perhaps go through the "best lean idle" procedure again?
When doing this the idle mixture screw is turned in till you hear that popping. Then turned back out to a certain point.
Maybe one of the screws is a little too lean?
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73 bus. Org. 1700 with dual Weber 40 idfs, bus header with Empi qp muffler, CB magnaspark 2 " ready to run kit".

[malcolm2]

Good plan. Traveling for work this week. I will report back.
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My Toys: '75 Porsche 914, '92 Ski Nautique and now a 1972 VW Transporter Deluxe (punch list fixing)

[mikedjames]

Viton needles seal well, but with the floats at a slightly different height to the brass needles because the rubber seals with a different amount of force on the needle - on my progressive I had to drop the "float level" about 2mm to stop fuel slopping down the carburettor throat causing juddering pulling away hard in second gear, but not first, or when going over bumps in the road, the engine would buck a fraction of a second later.
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Ancient vehicles and vessels

1974 VW T2 : Devon Eurovette camper with 1641 DP T1 engine, Progressive carb, full flow oil cooler, EDIS crank timed ignition.
Engine 1: 40k miles (rocker shaft clip fell off), Engine 2: 30k miles (rebuild, dropped valve). Engine 3: a JK Preservation Parts "new" engine, aluminium case: 26k miles: new top end.
Gearbox rebuild 2021 by Bears.

1979 Westerly GK24 24 foot racer/cruiser yacht Forethought of Gosport.
1973 wooden Pacer sailing dinghy

[malcolm2]

[malcolm2]

Did some checking today....

main jets are all clear. And my carb wire sync is good. I have the pulley system vs. the std hex bar.

I removed the fuel regulator and kept the gauge on the line. Bus started right up.... I read 2.5 PSI.

Drove a block and checked the gauge. it was down to 1.5 psi. I can kinda hear the electric fuel pump lightly whining.... I mounted it on the driver's side.

1 thing I never said, figured it was not an issue, and maybe it is NOT. But I don't have the HEAT PIPES connected. So there is HOT air coming out of the HE, pointing right at the fuel pump.

Last week, the issues started after a long drive.... maybe the hot air is causing something. Anyway, I added 1 heat pipe and the control valve. Now the heat is way above the pump and the valve closes off any direct flow.

Back to the fuel pressure. Drove more after my heat pipe addition. No POPS.... But the PSI is still super low. 1 psi even down below 1.

I think I have another pump, I might just replace this one and see what happens.
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My Toys: '75 Porsche 914, '92 Ski Nautique and now a 1972 VW Transporter Deluxe (punch list fixing)

[malcolm2]

Well Damn....

I returned to the garage and I could actually hear the fuel leaking into the barrels again.

Engine had been off for about 10 minute. I pulled the air filters and sure enough fuel was leaking into the barrels at a pretty good rate.

I disconnected the hoses and quit for the day.

The fuel tank is now 1/2 full. How is fuel siphoning past the electric pump and up to the float bowls and overfilling. Remember, I added the viton float needle valves.

Guess I will pull the top plate again tonight.

What the hell is going on? I thought going with an electric pump would be an upgrade.
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My Toys: '75 Porsche 914, '92 Ski Nautique and now a 1972 VW Transporter Deluxe (punch list fixing)

[67rustavenger]

The electric fuel pump works well for dual carbed engines.

I have one in my 2276 67 bug and it feeds a set of 48 IDA's.
This car doesn't get driven often. So I installed a fuel pump cutoff switch.
Drive the car, when I get home I turn the pump power off and let it idle until it stumbles as it's running out of fuel.

I imagine your bus engine compartment is rather hot when you park the bus after a drive. This may cause the fuel to boil out of the float bowls and down the carb throats.

You could do as I described above. Or install a set of phenolic carb base gaskets/spacers to help with the heat transfer to the barb bodies.
_________________
I have learned over the years.
Cheap parts are gonna disappoint you.
Buy Once, Cry Once!

There's never enough time to do it right the first time. But there's always enough time to do it thrice.
GFY's Xevin and VW_Jimbo!

[malcolm2]

that is the thing. It is not boiling the fuel from the floats. It is siphoning the fuel from the tank and overfilling the bowls. Even with Viton tipped float needles.

Even with the hoses removed the fuel keeps coming from the tank. I raised the loose end of the hose above the the height of the tank and the fuel stopped flowing.

I might try your CUT-OFF valve idea tho. Simple to try, but tuff to remember to cut it off every time I get out to do anything.

Keep the ideas coming, something is gonna stick.
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My Toys: '75 Porsche 914, '92 Ski Nautique and now a 1972 VW Transporter Deluxe (punch list fixing)

[malcolm2]

Found the Weber Facebook page and have been chatting with a veteran. He suggested that I set the floats at 14mm. So i did that. Can't say that I say much change in the DRIP situation. This video is after 1 test drive with that setting.


Link


I pull in, shut down and wait.... While I wait, I do some laser temp tests on the Btm of the carbs and the btm of the manifolds. Just to see if I am getting some kind of Heat Soak and a boil over.... max temps: carbs.... 92* and Manifold bases 150*F after checking every 5 mins for over 30 mins.

So I see this video after 5 mins. upto about 35 mins. Just a slight drip, maybe a 1/2 a teaspoon in one Right barrel and the same on 1 left barrel.

THINGS I HAVE DONE:
1. new fuel pump.... now consistently 2.5 psi
2. I do have the new Viton Tipped float valves
3. raised the hose from the pump. It now runs along the top of the firewall, into a TEE, and out... (down) to the carbs.
4. raised the floats from 12 to 14mm.
5. as the drip was slowing down, I loosened the E-tube... saw some bubbles, but the dripping continued for a bit longer.
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My Toys: '75 Porsche 914, '92 Ski Nautique and now a 1972 VW Transporter Deluxe (punch list fixing)