Petrol running back down the lines?

[swedishandgerman]

My Amazon Estate has never been a good stater from cold. That's a '68 B18A with a Stromberg 175 CD-S. Timing etc is spot on and it starts right up otherwise. It's just the first time a good time of cranking is required, then it bursts into life.

I've noticed there's no petrol in the clear in-line petrol filter between the pump and carb when the old car's been left standing. After a good few seconds of cranking, the filter fills up. After a few more seconds, the old thing bursts into life.

I'm sure there's no petrol in the carb:is it possible it's all draining back down the lines and a little one-way valve would sort it out?

[Faust]

I had a similar issue with my Amazon… so I fitted a non-return valve into the fuel line.

If I'm 100% honest, it didn't really make that much difference, and I removed it a few months ago as I needed to replace my (braided) fuel lines and never bothered to re-fit it. The longest I tend to leave the old heap standing between drives is a week, and after that period of time it takes about 3 seconds of cranking maximum to get him started. I regard this a bonus: that extra cranking helps to build oil pressure in your engine.

I guess we are all spoiled with all the fuel injection, ECUs and assorted gubbins fitted to modern cars. If you're used to getting into a newer car, you'll naturally expect all cars to fire up instantly at all time… and this ain't gonna happen with a car the age of an Amazon.

I look at it this way: your car is trying to tell you something. It's telling you to drive him more often! That way the fuel will never get a chance to drain back to the tank… and you get the pleasure of going for a good burn in your car.

[swedishandgerman]

Originally Posted by Faust

I had a similar issue with my Amazon… so I fitted a non-return valve into the fuel line.

If I'm 100% honest, it didn't really make that much difference, and I removed it a few months ago as I needed to replace my (braided) fuel lines and never bothered to re-fit it. The longest I tend to leave the old heap standing between drives is a week, and after that period of time it takes about 3 seconds of cranking maximum to get him started. I regard this a bonus: that extra cranking helps to build oil pressure in your engine.

I guess we are all spoiled with all the fuel injection, ECUs and assorted gubbins fitted to modern cars. If you're used to getting into a newer car, you'll naturally expect all cars to fire up instantly at all time… and this ain't gonna happen with a car the age of an Amazon.

I look at it this way: your car is trying to tell you something. It's telling you to drive him more often! That way the fuel will never get a chance to drain back to the tank… and you get the pleasure of going for a good burn in your car.

Yes, I should drive the old car more. Sadly, it's the same next morning or having left it for 4 weeks! And it's more than 3 secs cranking too. None of my other Amazons have done it, but I just looked back through the notes and see it had a new pump from Brookhouse about a year before I bought it - that's 4 years or so - based on what I read elsewhere on this forum recently, I wonder if those pumps aren't so great.

[Derek UK]

Not that long ago someone posted here that his Amazon, after sitting for a while, always took 21(?) seconds to fire up. I've never timed my estate but it must be getting on that way. FULL choke helps a bit but you do have to catch it and adjust in a bit as soon as it starts. 1 day parked it starts straight away and maybe after 2 days in the summer too. Another couple of days and it's back to churning. Encouraged by "come on you b*gg*r" it gets there in the end.
Fix? Electric pump, perhaps just running in initial ignition on and maybe on when the starter is running too. Off after that and back to the mechanical.
If anyone always parks their car nose down on a sloped driveway please post if you have the problem too.

[Underdrive]

In theory there should be enough fuel in the float chamber of the carb(s) to start the engine, even if it then stops again. If the pump has to fill up the float chamber before it will start then the fuel has either syphoned back 'tankwards' evaporated or leaked. A further thought, is the tank further back on the estate with a longer pipe?

[Ron Kwas]

Forum;

I think we are combining two separate conditions here which should be considered: Starting after short-term parking (up to a several days), and Starting after a long-term parking (over a week or so)...with two additional separate issues: Less than full Fuelbowls and empty Fuel Supply Line, and so possibly clouding a good understanding of what is happening.

I don't wish to overengineer this, but the way these two factors interact in the mid-term is where variations occur...here is a bit of a chart I came up with on the quick:


The way I believe I understand what's happening:
Since fuel falls past the open Bowl Valve, past an air-space and into the (atmospherically) vented Bowl, there is no way it can possibly be siphoned empty (a siphon requires an uninterrupted column!), and this is why Starting after short-term parking is typically almost instantaneous or within a couple of seconds...Fuelbowls are still quite full (little has evaporated), so there's plenty of fuel available, even if output valve in Fuelpump is leaking (slowly, within a few days or quickly within a few hours) and allowing weight of the column of fuel in Supply Line up to the Carbs to drain back down, emptying that line. Starting is from Fuel in Bowls, even though Fuel Supply line is empty...but we never notice any issue, because engine starts and is idling on fuel in Bowls as Fuel Supply line is slowly refilled...the drainback which occurred is essentially transparent to us...

If on the other hand, after a prolonged parking time (when in addition to drainback which occurred withing a few hours to a few days), bowls have had a chance to at least partially evaporate, and column of Fuel has most certainly drained back from Supply Line, we will have to crank for a while, until Supply Line and Bowls are both filled enough to allow Starting...

I fully expect this, and as other poster has mentioned, use this time to pre-oil the engine(!)...I even intentionally leave my Ignition disabled with my under-hood Service Switch, as I crank from the drivers seat (for about 20 sec) until I see Oil Pressure Indicator extinguish (or Gauge indicated pressure on P1800 ). Then I check pre-Carb Fuel Filter under hood, verify it is full...then I know I Fuelbowls are also full and I am ready to Start...I enable Ignition at Service Switch, and (having left Ignition Key ON), Choke, and engage Starter with Service Switch...Starting is typically immediate...and I know I have oil pressure(!)...and since I'm observing under the Hood, it allows me to monitor for, and immediately react to, a FuelBowl overflowing condition (these are more likely to occur as Bowlvalves get hung up on deposits and dried fuel gum in Bowl-valve, from evaporated fuel).

That's the way I do it! Cheers!

[Tail]

Get it with mine too, but i leave mine weeks and weeks sometimes, getting quite used now to hanging one of the Sealey remote fuel tanks from the bonnet, once it has started just changed the pipes over back to the main tank line and it will continue to run, it appears to me the fuel pump isn't being cranked fast enough by the battery to drag the fuel from the tank but once started the engine pumps far faster so the fuel is sucked through in seconds. As derek says parking even slightly nose down is enough to stop it.

link for the remote fuel reservoir i use http://www.ebay.co.uk/p/sealey-ms029...p2047675.l2644

[Derek UK]

The remote tank might come in handy sometimes but I'm happy to live with a 20 second churn. Those with weak batteries might not be so confidant in the winter. Of course if you use your car every day or even every 2-3 days, it's not much of a problem.
1 vote for parking nose down. Not many garages are like that though, thank goodness!
I have considered increasing the length of the hose between the fixed pipe and the pump and making it into smallish loop. This would retain some fuel to prime the pump even if the rest drained back to the tank. Could syphon back to the tank though especially if parked nose up. The high point of the loop would also likely be above the level of the fuel in the tank. Might work, but a clumsy fix. Anyone use a Filter-King unit between the pump and the carbs?

[davidw6092]

Maybe experiment with some insulation material under float chamber or wrapped around it to see if evaporation is an issue.Also look at a 740 starter motor conversion that spins the engine over a lot quicker.

[arcturus]

Of course you could always hand prime the carbs at the pump if you had the old style pump as on my B16