73 Bus Factory Carbs, stalling

Carbs & F.I.

Moderators: Sluggo, Amskeptic

Post Reply
User avatar
iwantmybustorun
Addicted!
Location: Coventry, CT
Status: Offline

73 Bus Factory Carbs, stalling

Post by iwantmybustorun » Sat Sep 02, 2006 10:58 am

This was never a post on the old site but Colin was helping out via pm's. Still no luck, so i though i would post it here so others could use the info that gets posted.

I have a 73 with the original 1700 t4 engine and solex carbs.
Just installed an svda, petronix, coil, cylinder head temp gauge, engine seal, and removed part of the original smog pump (the bottom half of the pulley).

The problem (or part of the problem) is that it has sat for about 2 years (new paint and bodywork) without fuel stabilizer #-o go ahead... i can take it. :blackeye:

So i've drained the fuel tank, tested the fuel pump, changed the filters, new plugs and oil, used carb cleaner (but have not taken them apart yet), cleaned and checked the idle cutoff valves for a "click" (which they have but are much weaker then the large one on the back left carb which i also replaced with a new one), and checked for vacuum leaks.

It will start and run for a while, usually if my foot is on the gas, then it will stall. Usually starts right back up, but then stalls again.

I am also getting smoke (oil burning?) that is coming up into the engine compartment from the cooling fan. This after only a few seconds of running the engine. I have also blown bits of mice's nests out of the muffler on a few occasions. Seems to have stopped now. Looks like they got into the noise dampening insulation while the windows were out.

Please send any info this way.
Thanks.
73 Westy
1700
Weber single progressive
[Crane ignition system out]
SVDA and points

User avatar
Amskeptic
IAC "Help Desk"
IAC "Help Desk"
Status: Offline

Re: 20 seconds running... then stall

Post by Amskeptic » Sat Sep 02, 2006 11:25 am

iwantmybustorun wrote: cleaned and checked the idle cutoff valves for a "click" (which they have but are much weaker then the large one on the back left carb which i also replaced with a new one), and checked for vacuum leaks.

It will start and run for a while, usually if my foot is on the gas, then it will stall. Usually starts right back up, but then stalls again.

I am also getting smoke (oil burning?) that is coming up into the engine compartment from the cooling fan. This after only a few seconds of running the engine. I have also blown bits of mice's nests out of the muffler on a few occasions.
Usually a stall after a couple of minutes of running, points to a fuel delivery issue. The cut-off jets do have little clicks, the central idling cut-off is a big old plunger that makes a more dramatic click.

Fuel pump tests have a pressure component and a delivery component. You can have good pressure and lousy delivery. Think of a garden hose with a spray nozzle where the faucet is barely cracked open. When you let go of the spray handle, you can see the hose stiffen up as it builds pressure. Eventually it will have full house pressure. But when you squeeze the handle, you only get a good blast for a second and then it just dribbles.

In some cases the tank screen can clog whenever there is a demand for fuel, then the rust particles disperse when you stop. The Bentley manual has a volume specification for mexchanical fuel pumps.

Is this stalling behavior during initial starting or when the engine is fully warmed up?
Colin
BobD - 78 Bus . . . 112,730 miles
Chloe - 70 bus . . . 217,593 miles
Naranja - 77 Westy . . . 142,970 miles
Pluck - 1973 Squareback . . . . . . 55,600 miles
Alexus - 91 Lexus LS400 . . . 96,675 miles

User avatar
iwantmybustorun
Addicted!
Location: Coventry, CT
Status: Offline

Post by iwantmybustorun » Sat Sep 02, 2006 11:58 am

Ok. Your garden hose explanation sounds like that could be what is happening.
Usually a stall after a couple of minutes of running, points to a fuel delivery issue.
It will not run for a few minutes however.
Is this stalling behavior during initial starting or when the engine is fully warmed up?
It happens at initial start up. It does not stay running long enough to get fully warmed up but if i keep trying to keep it running (i.e. start it, let it run, stall, and then try it all again) the problem gets worse. Meaning it will not run for as long before it stalls again.

I'm currently looking at my Bentley and i will try the section that outlines the way to Check for fuel pump pressure and delivery capacity.
73 Westy
1700
Weber single progressive
[Crane ignition system out]
SVDA and points

User avatar
satchmo
Old School!
Location: Crosby, MN
Status: Offline

Post by satchmo » Tue Sep 05, 2006 3:11 pm

Bits of mouse nest coming out the tail pipe? That's not good. I've never seen just 'a little bit of mouse nest' before. Usually, there is a lot of mouse nest. Especially when the nesting mice have access to unlimited quantities of dog food in the garage, and lots of time to stow it all in the muffler. Ask me how I know.

Anyway, when you start it up next time, check to see that you are getting good air flow out the tail pipe. Your symptoms could be caused by a choked exhaust. That should be easy to fix.

Tim
By three methods we may learn wisdom:
First, by reflection, which is noblest;
second, by immitation, which is easiest;
and third, by experience, which is bitterest. -Confucius

User avatar
covelo
Old School!
Location: Fairfax, CA
Status: Offline

Post by covelo » Tue Sep 05, 2006 3:32 pm

I would recommend rebuilding the carbs. It's a pleasant kitchen table job that doesn't take long and you may have gummed up passages in there that are hard to get at with the carbs in the bus. Given how much trouble I have had getting my carbs to work right (they're good now :knock on wood:), I would focus on them first.
‘80 Vanagon Westfalia - 54,400 miles
'91 Toyota Pickup (4WD long bed) - 199,960 miles
1987 Alfa Spider Veloce - 166,400 miles
2017 VW E-Golf - 5,600 miles

User avatar
iwantmybustorun
Addicted!
Location: Coventry, CT
Status: Offline

Post by iwantmybustorun » Tue Sep 05, 2006 5:38 pm

I've never seen just 'a little bit of mouse nest' before
I meant that bits at a time have come out. I don't think i have seen the end of it either.

But... earlier this summer, when i first started the motor work, after the 2 year storage period, it did run better (or at least for a longer period of time) before i changed the distributor and petronix. The bits came out at this point as well but the bus ran at idle without much problem. The problem seemed to have gotten worse.
I would recommend rebuilding the carbs. It's a pleasant kitchen table job that doesn't take long and you may have gummed up passages in there that are hard to get at with the carbs in the bus. Given how much trouble I have had getting my carbs to work right (they're good now :knock on wood:), I would focus on them first.
This is my winter project ( and yes i will fill the tail pipe with steel wool and add fuel stabilizer to the tank). :yawinkle:

I will try to fish the nest out and prep myself for the rebuild.

Thanks
73 Westy
1700
Weber single progressive
[Crane ignition system out]
SVDA and points

User avatar
iwantmybustorun
Addicted!
Location: Coventry, CT
Status: Offline

Post by iwantmybustorun » Mon Jun 04, 2007 2:55 pm

The issue appears to be this...
[albumimg]849[/albumimg]
in my gas tank. :-s
I plan to rebuild the original carbs but have not decided if they will be used again.
73 Westy
1700
Weber single progressive
[Crane ignition system out]
SVDA and points

User avatar
Bleyseng
IAC Addict!
Location: Seattle again
Contact:
Status: Offline

Post by Bleyseng » Mon Jun 04, 2007 3:16 pm

Rust and Dirt? Wow, you are the winner of the worst gas tank award :cheers:
Geoff
77 Sage Green Westy- CS 2.0L-160,000 miles
70 Ghia vert, black, stock 1600SP,- 139,000 miles,
76 914 2.1L-Nepal Orange- 160,000+ miles
http://bleysengaway.blogspot.com/

User avatar
iwantmybustorun
Addicted!
Location: Coventry, CT
Status: Offline

Post by iwantmybustorun » Mon Jun 04, 2007 4:45 pm

Actually ... NO rust. see my profile pics. if you look closely into the tank you will see it looks brand new!
Wow hu?! The dirt must have been vandals.
73 Westy
1700
Weber single progressive
[Crane ignition system out]
SVDA and points

User avatar
Danny79
I'm New!
Status: Offline

71 Transport Doing the Same thing

Post by Danny79 » Thu Aug 13, 2009 5:13 am

I have 71 that is doing the same thing, runs for a few seconds. Doesn't idel at all, runs better at higher RPM. It was last on the road in 2000.

New fuel lines - it had black tar like gels in the fuel line & filter. I drained the tank, and now, after rebuilding the carb, see little dirt particles in the fuel filter and they are making their way to the carb. The reservoir with the float in it had a sea of dark particles in it.

It seems to start better after it sits a few minutes. It will start, die out, and then want to wait to restart.

How much fuel should be in the carb when you open up the lid ? We might have rust and also a fuel pump problem.

Any advice and help to get it back on the road would be appreciated.

Thanks....Dan in Pittsburgh

User avatar
Bookwus
IAC Addict!
Location: City of Roses
Status: Offline

Post by Bookwus » Thu Aug 13, 2009 10:06 am

Hiya Danny,

Ah Pittsburgh, my ancestral home! Dagmar Street I can hear you calling.

Welcome to the IAC!

Since this Bus has been laid up for years and you are getting all kinds of crud outta the fuel system, I'm guessing that you are looking at dropping the tank, cleaning it out completely, probably sealing it up, replacing the in-tank filter sock, replacing all rubber fuel lines, installing a new in-line fuel filter, inspecting the fuel pump for action with an eye for possibly replacing it, and cleaning and re-kitting the carburetor.

In other words, overhauling the complete fuel delivery system.
I have cancer.

It does not have me.

User avatar
Gypsie
rusty aircooled mekanich
Location: Treadin' Lightly under the Clear Blue!
Status: Offline

Post by Gypsie » Thu Aug 13, 2009 12:24 pm

Welcome to the madness.
Bookwus wrote: In other words, overhauling the complete fuel delivery system.

I second this motion. All in favor?....

Depending on how it was stored (likely parked and forgotten with no attention paid to the long term effects of fuel left in the tank and lines) you would do well to fully refresh this system. Don't forget to blow out any 'hard' sections of fuel line (not certain if a 71 has this? )unless they were replaced as well.

I'm not surprised that the idle circuit is gummered up if your getting crap in the bowl.

Re-kitting the carb would include a full and thorough cleaning (jets and all).

I would also replace the perishables of the elect. (rotor, cap, wires, points, condensor, plugs...) Minor expense to eliminate them from the overall equation.

You should start a thread of your 71's rejuvination.
So it all started when I wanted to get better gas mileage....

User avatar
iwantmybustorun
Addicted!
Location: Coventry, CT
Status: Offline

Re: 71 Transport Doing the Same thing

Post by iwantmybustorun » Thu Aug 13, 2009 5:53 pm

Danny79 wrote:I have 71 that is doing the same thing, runs for a few seconds. Doesn't idel at all, runs better at higher RPM. It was last on the road in 2000.

New fuel lines - it had black tar like gels in the fuel line & filter. I drained the tank, and now, after rebuilding the carb, see little dirt particles in the fuel filter and they are making their way to the carb. The reservoir with the float in it had a sea of dark particles in it.

It seems to start better after it sits a few minutes. It will start, die out, and then want to wait to restart.

How much fuel should be in the carb when you open up the lid ? We might have rust and also a fuel pump problem.

Any advice and help to get it back on the road would be appreciated.

Thanks....Dan in Pittsburgh
Kudos to you Dan... for using the search tool before posting your own question. If my problem is any indication of the source of your problem, it looks like these guys are right. Your gas must have turned to varnish and you must have rust in your tank that is adding to the fuel delivery problem. I have a type 4 engine and that meant I had to drop the engine to get the tank out. Not sure if you have to do that with your type 1 engine to get the tank out but regardless, I think a tank cleaning is inevitable. Good luck.
73 Westy
1700
Weber single progressive
[Crane ignition system out]
SVDA and points

Post Reply