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Discussion Starter #1
Hi all... I thought it may be helpful to share an update on my "fuel starvation during high-G, long-duration, left-hand turns" problem. Like more than a few people on this board, my car was suffering fuel starvation on the track -- but only during the kind of load described above. Having fuel cut out at 95-100mph on Turn 8 at Thunderhill is NOT a happy time. And it's also not good for the injectors I would imagine.

Anyhow, this problem seems increasingly endemic; mostly to 05 cars according to my dealer sources. It is well-documented here: Engine Hesitation During High Speed Cornering at the Track.

At any rate, this is a known issue with Lotus. Apparently, a sealant inside the gas tank deteriorates, and this allows fuel to "slosh away" from the fuel pickup, and the bit and chunks of the deteriorated sealant screw up the fuel intake as well. It's all explained in the thread above.

And I can't help but wonder how many more cars will experience this problem as their tanks age, and the sealant failure catches up to them.

The dealer closest to me, British Motor Car, which I have a lot of respect for, said the problem is covered under the three-year warranty -- but regretfully informed me that my warranty expired a week before I took the car in!!! And that Lotus wouldn't honor the claim, even though I was just a week late. Me = pissed off and frustrated. But "that's life" I thought.

Well, I made plans for Rob Dietsch of Dietsch Werks to put in a new tank. He ordered the tank from Silicon Valley Auto Group (the dealer closest to his shop), and in the process started a dialog with them on the problem. And I'm glad he did, because SVAG told him: The tank is covered under the 7-year emissions warranty! I have no idea why BMC didn't bring this up, but I decided to count my blessings, and not upset any apple carts, and just let SVAG do the work. (Even though BMC is much more convenient for me.)I just got my car back from SVAG. I haven't yet done a track day, but I have the new tank, and so I would think that the problem is solved. No more filling up the tank after every freaking run session again. Woohoo! So cheers to Rob of Dietsch Werks and Jordan at SVAG for saving me a lot of money. Some final notes:
  • Both BMC and SVAG told me that Lotus thinks the problem comes from either California gas additives, and/or any gas that is higher than 91 octane. Essentially, they think, these types of gas will break down the sealant that connects the tank's interior baffles to the inner tank walls. BMC said that Hethel didn't do any tests with California gas, and also noted that Lotus pointed out that super-high octane gas is prohibitively expensive in the UK (like 4x expensive!), and so they never anticipated owners putting in higher than 91. Lesson here? Avoid higher octane gas!
  • SVAG told me that the 05 cars have a unique tank design; that 06 and later tanks can't go into 05 cars. I find this curious, but I didn't press for details. But, FWIW, when Rob was about to install the tank, he noticed it was marked 05, and he didn't want to install a tank with the same crap-ass sealant, and thus begun his dialog with SVAG.
  • SVAG tells me that the "new" 05 tanks are essentially the same as the ones that shipped with our 05 cars, but that the sealant composition has changed, and this should preclude the problem from occurring again.
  • If anyone is curious, this is the language on my invoice: "Customer states vehicle cuts out during left turns on the track. Cause: Fuel tank. Verified customers concern. Removed fuel tank as needed. Removed fuel sending unit and inspected as needed. Found pieces of sealant at bottom of tank causing condition. Replaced tank as needed."
I should also thank Lotus for making good on this! I love that they acknowledge and support our track use -- because other manufacturers sell cars clearly designed for track fun, yet balk at any warranty claim linked to track use.
 

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I'm glad you got taken care of! Lotus actually does a really good job with warranty work when it comes to track days. They tout that the car is at home on the track, and back that kind of driving as long as it isn't abusive. Great company! :bow:
 

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That doesn't explain Cup Car problem

My 07 cup car, brand new, 4 miles on odometer, had same starvation problem on its very first tank of gas. Regardless, Lotus has been great, sending a crew to the track to check it out. I understand a fix is forthcoming.
 

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[*]Both BMC and SVAG told me that Lotus thinks the problem comes from either California gas additives, and/or any gas that is higher than 91 octane. Essentially, they think, these types of gas will break down the sealant that connects the tank's interior baffles to the inner tank walls. BMC said that Hethel didn't do any tests with California gas, and also noted that Lotus pointed out that super-high octane gas is prohibitively expensive in the UK (like 4x expensive!), and so they never anticipated owners putting in higher than 91. Lesson here? Avoid higher octane gas!
I'm sorry but this makes no sense at all -- my 2005 owners manual stated that the cars are tuned to run "optimally" on 93 octane but can accept a minimum of 91. The Lotus cars in Europe all run on the equivalent of 94 US octane. IMHO, higher octane gas is not the cause of the sealant breakdown.

Glad you got a new tank and hope the problem doesn't recur.
 

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Discussion Starter #8
I'll address Jack first: I'm only reporting what the BMC service rep told me. Maybe he misunderstood what the guy from Lotus NA told him (and whoever this guy is, he is the same guy that wouldn't fix the problem under my less-than-one-week-expired 3-year warranty!). Or, maybe the Lotus NA guy himself was feeding the service rep a line of crap. I don't know, but I'll dig a bit more for info. Regardless, at least the service reps at both dealers said that Lotus blames gas. :)

Matt: Well, if you go around Turn 2 at Thunderhill as quickly as possible, you'll soon find out if you have the problem. ;) ... Barring that, I think the tank needs to be removed and visually inspected. The sealant deterioration is illustrated in pics in the thread I linked to above. Also, FWIW, the problem only manifests in high-G situations. Nonetheless, it is VERY consistent. For the last 5-6 track days, if I had anything less than 1.5 gallons short of a full tank, I would get fuel starvation right at the apex of Turn 2 (which is pretty much at the end of that long, long-duration corner). It would also happen just before the apex of turn 8, but not with the same level of consistency.

Shawn and jlj3394: They had the car for quite a long time, but that was because they broke a part (fuel sender unit?) when removing the tank, and they needed to wait a while for the replacement. If memory serves, the Lotus "book" quotes this as a five-hour job. I know you do not need to remove the clam or any body panels.

Jack Miller: Right you are on the Cup cars. I have heard they suffer fuel starvation too, and Lotus is on top of that one as well. I can't remember the exact nature of the problem. (Don't cup cars have fuel cells?)
 

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Thanks for the info. I have about 6 months left of warranty on my 2005 car (late 05 build).

I first starting noticing this in Oct. 07 in T1 at Hallett which is a very fast uphill left hander in the ccw config. Me and my instructor encountered the cutout in all of the sessions last week at MSR-Cresson 3.1 ccw last week.
 

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Thanks for the info... glad to hear this is covered under the 7 year warranty as many of us are out of the 3 year
 

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Discussion Starter #11
Thanks for the info. I have about 6 months left of warranty on my 2005 car (late 05 build).

I first starting noticing this in Oct. 07 in T1 at Hallett which is a very fast uphill left hander in the ccw config. Me and my instructor encountered the cutout in all of the sessions last week at MSR-Cresson 3.1 ccw last week.
Wow... There sure are a lot of people suffering this problem. Makes me wonder just what's wrong with the sealant. I sure hope the "new" sealant is built to last. Otherwise, the only solution is to remove the tank, and solder the baffles the way they should have been done the first time. That's what Kverges did as shown here in post #98.
 

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The fuel cell is an option on the Cup car. I ordered it, since I had the fuel starvation problem with my 07 Exige S. Haven't yet had a problem with the fuel cell, other than the fact that the fuel gauge reads correctly exactly once and is wildly optimistic thereafter :)

Oh yeah, and the fuel cell is a pain in the ass to fill, requiring the use of a fuel jug.
 

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I also had a problem with 100 octane gas from King's Union 76 in Redwood City, CA. After filling up with this, for the next ~3 tanks the car started very poorly when cold. Of course, this doesn't sound like the above a sealant problem, since it went away after awhile and I have an 06. However, 100 octane seems like more trouble than it's worth, IMHO.
 

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This problem occurs for me at T3 at Streets of Willow CW when I take the fast line. It's pathetic and, like Jon, it happens with anything less than 3/4 tank (which I really cannot get my mind wrapped around - how does the sump go dry with 8 gallons of gas in the tank - mystifying).

I spoke with Allen at BHLotus and he says that Lotus will cover the cost if the tank is proven defective, but if the condition cannot be duplicated on the street then the owner must guarantee the cost to R&R the tank for inspection. I CAN easily duplicate the problem on Benedict Canyon, but not in the middle of the day near the dealership!

He also said that the problem is a combination of the tank being problematic by design and the fuel pump growing weaker with every bout of starvation. He's apparently working on a less costly fix than installing a well designed new tank or cell but that's months away. IMO, removing the tank for the inspection is worthwhile. With the problem growing worse with time, I have to imagine that it's a progressive problem which failing sealant would tend to be IMO.
 

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Discussion Starter #16
I spoke with Allen at BHLotus and he says that Lotus will cover the cost if the tank is proven defective, but if the condition cannot be duplicated on the street then the owner must guarantee the cost to R&R the tank for inspection. I CAN easily duplicate the problem on Benedict Canyon, but not in the middle of the day near the dealership!
Strange that Silicon Valley Auto Group would do the work with no strings attached yet another dealer throws this at you. Maybe it didn't even come up in my situation because SVAG had already removed, inspected and replaced two tanks, and they decided to not even mention Lotus's policy on the matter. Then again, British Motor Car didn't even know the problem was a 7-year emissions claim, so perhaps it speaks to the fact that Lotus is a small mom-and-pop car company that sets policy ad hoc.
 

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Bring this back -- so there is or isn't a fix?

I've had this problem also (Exige S 07 not many miles) and pretty much have to fill the tank after every session (not that I've had many sessions). It does boggle my mind that this problem exists in what is a "Track" car for the most part.

The "octane/additive" story is just more crap from Lotus.
 

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I experienced these same symptoms last month with my '06 Elise (built in Feb 2006). The fuel just cut out or hesitated on certain left hand turns, always in the same spot on the track. Same thing occurred in a relatively low speed (but high left hand cornering Gs) portion of an autocross course. I explained this to the dealer and they replaced the fuel tank upon the advice of Lotus NA. You could see the loose residue from the sealant in the old tank. I've had no further problems since the tank was replaced (under warranty).
 

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Discussion Starter #20
Bring this back -- so there is or isn't a fix?

I've had this problem also (Exige S 07 not many miles) and pretty much have to fill the tank after every session (not that I've had many sessions). It does boggle my mind that this problem exists in what is a "Track" car for the most part.

The "octane/additive" story is just more crap from Lotus.
I know some Exiges (or maybe Cup Cars?) have their own fuel problem; a different problem from what my car suffeered. You should ask the dealer to explain. Regardless, it doesn't matter. Your car is under warranty, isn't it? Just demand a fix; hopefully a new tank. Also: "more crap from Lotus"? You sound like an unhappy customer. :(
 
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