Fuel Leaks Cause Thermal Events! Yikes!!!!

[type26owner]

Had a small thermal event (fire) sometime in the recent past. Mostly likely happened while I was charging around the racetrack at Fernley. Charred the spark plug wires insulation a bit and the first two inches of the plastic fuel line from the tank. Scorched my paint off the block but stayed confined pretty much below the induction tubes thankfully. It was running okay Saturday when I first noticed the damage. Upon investigation I discovered I had folded the Weber's 40DCOE18 top cover rubber gasket back around one of the piston assemblies for the cold start unit on the forward carbie. Because the cold start units weep fuel there normally it went unnoticed unfortunately. When cornering at about 1G the fuel obviously sloshes up into that area and it must have happened under that condition.

While I had the carbie off I did some testing of the cold start units by inclining the carbie and looking for fuel leaks. It's obvious that it does leak fuel out the cold start units when cornering hard around right-handers. I'm removing the damn things and installing blanking plates pronto. One thermal event is enough and I don't want to press my luck anymore.

Needless to say my goal of building a 5vdc supply for my Weber throttle position sensor and getting it functioning didn't get done this weekend. Need the TPS to really dial in what's happening to the mixture for a closeup 3D mapping analysis with the AFM.

One bit of good news. Weber is back in business according to Webcon and producing new carbies again. I'll confirm that when I call Mike Pierce today.

[twincamman]

DUDE ----time for an on board fire system ------ed

[type26owner]

Hey Ed,
You're thinking in too small of terms. Should be able to leverage this incident into a fuel cell, driver's flame-resistant suit AND an onbroad fire system if I play this correctly. I'll have to do some major grovelling and wimper a bit though. Best tactic is to just drop very vague hints so it seems like they thought of it for you.

[type26owner]

Dropped my first hints and the reply was she wished the car had burnt up. Ouch! Hey, that was a low blow and the wrong reply. Better do some more of those chores piling up on that list.

It has been confirmed. Weber is back in business. Those blanking plates are $5 each.

[twincamman]

try reducing your life insurance ---explain how little your worth crispy---but if --suit--cell --etc---then you can increase the amount substantially ed

[rgh0]

Keith

I found I had to blank off the cold start system air intake many years ago on my 40DCOE's due to the fuel leaks in competition ( fortunately not the thermal event you observed). Since going to 45's have not had the same problem. Never pulled them apart to understand why but probably due to the bigger body putting the air intake higher above the fuel level or less leakage around the cold start pistons due to less wear.

Rohan

[type26owner]

Rohan,
By having the carbies inclined upwards on the engine any fuel that gets splashed up there stays puddled right over the cold start pistons. Even when brand new they must leak under that condition. When I inclined the carbie filling that area with fuel and then positioned it back to the tilted orientation it normally sits at there was about a ten second delay but fuel would weep out everytime. Bet it would be an okay design if the carbie were installed to tilt down instead of up and you never cornered hard enough to slosh any fuel to that side.

Realized I failed to communicate with my spouse effectively. When I made it perfectly clear I would be IN the car at speed when it caught fire then I got her to be concerned for my well being. Guess I've been spending too much time working on the type 26 Elan and she's just a wee bit miffed. The DB2/4_mk1 is next.

[type26owner]

Received the Weber supplied blanking plates to remove the cold start units. It is an iridited steel plate which about 1.5mm thick. Came with a brown paper gasket and shorted screws. My intention was to stop the fuel leaks not just slow it down a little. Only way I can see to do this is to glue on the plates and leave off the gasket. These Weber supplied paper gaskets wick the gasoline right through no matter how tightly you squeeze down on them.

Realized that if the fuel actually does not leak to the outside it will still be leaking just internally. It will fill up the cavity below the pistons and dribble into the throats by the large passageway downstream of the throttle plates. After all this effort to get the mixture correct this would be like shooting myself in the foot. Contemplating plugging up the passageway with a rubber stopper, putting on the blanking plate, removing the pistons and pouring epoxy into the piston wells filling them up completely. That ought to fix the problem once and for all. Can't see how to do any other way!

Been starting my engine without the cold start units since last weekend. It runs very poorly for a few minutes until it builds up heat to help vaporize the fuel. It spitsback and won't idle for at least 30 seconds now. Have to just get used to this cause it's better than having it burn up from a damn fuel leak.

[twincamman]

Kieth I have just purchased a fire bottle for the 7 and used the one from the vee for the ?lan----they are only 300 bucks --a little added insurance --the ?lan runs like a truck for the first mile --spits and expels flatus -etc but then clears and runs like a freight train after 2500 rpm ed

[type26owner]

Ed,
It's my understanding that an on-board fire supression system is useless in an open cockpit. I carry a dry extinguisher that's within reach when I'm strapped in the driver's seat.

Been using the cold start units for so long I didn't realize it would spitback. Kinda caught me out there. Guess that's an indicator the idle mixture is dialed in correctly.

[type26owner]

Rather than filling the piston cavities up with epoxy I think an aluminum plug that gets glued into place with Seal-All would be a better choice. Would put a female thread in the top so it could be pryed free later on if needed. That way I can disable the units and seal the fuel leaks but leave the cold start units in place so it looks to be still functional. Can even reattach the cable and have it appear to function via the knob on the dashboard. Looks are important too.
http://eclecticproducts.com/sealall/home.asp

[twincamman]

Kieth----I use a- FFF with both nozzles in the engine compartment --thats where the fire usually starts ---in any open or closed car --however the one nozzle in the drivers compartment with foam will stop a blaze ---it just feels like you wet yourself----which may happen in a fire ---when the ?lan comes home im putting one nozzle directly into the air box and the other pointed at the fuel line----a-fff washes off with water cleanly as opposed to powder which is bugger to remove --in the event of a fire its easier to pull the handle on the way out than to risk burns fighting the fire-with a hand held -I like to get as far away as possible --in the event of a blaze-like the next county --burns take so long to heal and are ugly after ed

[type26owner]

Glued blanking slugs into the piston bores of the cold start units and they worked great, no more fuel leaks.

The pistons just have to be lifted by only about one millimeter until the passageway feeding from emulsion jetting of the cold start unit is exposed and dumping all it's capacity. The pistons have to be lifted all the way to the other end of travel for the air passageway to be opened to get the mixture correct. The cold start unit does not properly work if it's not opened all the way for a cold start. Weber shows that there is a hot start position too. That is only positioned halfway. As far as I can tell it will flood the engine if you attempt to use the choke only halfway pulled out for either a cold start or a hot one. Anyways I don't have to remember this stuff since mine are now permanently sealed off.

Ready for trackday this Wednesday. It was 106F there last Sunday at 2:00 pm in the shade. Good thing my cooling system is working well even at maximum power. As long as I don't fill up with racing fuel I'm okay even running in that kind of heat.

[chrishewett]

I've been having a fuel leak problem at the carbs. It is weeping out where the carbs join the manifold. It doesn't happen all the time but may be when driving hard round bends.
Is this caused by the coldstart problem you are talking about here? If so why doesn't everyone have the same problem.
I'm just going out to buy a fire extinguisher!
Chris

[type26owner]

Hi Chris,
Everyone that has DCOEs fitted does have the same leaks! From the cold start units and from around the air trumpets.