Land Rover Repair: Loss of power and engine sputter after heavy rain: is water finding its way in my gas tank?, gas caps, empty tank

Question
Hi John,
    I have a 97' Discovery that will lose power, and the engine will sputter after a heavy rain.  This happened the past two times that I drove after a heavy rain(8 days apart).  At both times I had near an empty tank of gas(approximately 4 gallons or less).  It would start up fine, but upon engaging drive and giving it some gas there was a lot of power loss and engine sputter.  The first time this happened I thought there might be water in my tank, and I drove to the nearest gas station and purchised a bottle of gas treatment.  I mixed it with about ten gallons of gas and drove off with no problems.  I used that entire tank off gas until the gas light went on with no problems at all.
    A little over a week later, we received another heavy rain.  This time,too, I had about 4 gallons of gas in the tank.  I started it the morning after and found the exact same symptoms as before:  sputter and power loss. I immediately drove to the nearest gas station and filled it up with gas, while using a bottle of gas treatment.  The car ran fine after this.  I inspected under the hood and saw no evidence of water getting on the plugs, and I believe my plug wires to be sound.  Is water somehow finding its way into my fuel tank?  I feel that this could be the culprit, but I am uncertain to how it is getting in there.  The only entry of water in my tank that I could think of is via those horizontally oriented gas caps(it does click when I turn it).  Could I have a bad seal under my gas cap?  I have not found any helpful information on this matter, and was wondering if you could provide some info.  I find your postings very informative and would appreciate any advice.

Thanks again,
Noah


Answer
Hi Noah,

I doubt you have water in your tank, unless you buy your fuel from the same station and THEY have the water problem.  Its been known to happen and most stations do have water in their tanks.  Its how they manage this water that is important AND it can find its way into YOUR tank.

I have a suspicion and you'll have to test this out:

Get yourself a spray bottle which has a "fine spray" or mist capability.  One evening, start your engine and open the hood (bonnet).  Spray a fine mist of water around your coilpack and sparkplug wires.  If you start to see sparks OR the engine starts to flutter (as you described) then the problem is either your wire set OR the coilpack.

Another possible problem could by your fuel pump OR fuel filter.  Fuel filter is easy to replace but fuel pump is expensive.  Talk to your local LR dealer to see if your Disco qualified for the gas tank recall.  Most Disco I's had the tank and fuel pump replace at LR's expense.  Seems the plastic fuel tank can develop cracks on top.

Lastly, there is a sticking exhaust valve problem with some 4.0 and 4.2 litre engines.  Carbon can buildup and cause the valve to stick.  This robs your engine of power and is most evident on hot, humid days and when your Disco has reached its normal operating temperature.  Misfires and stalls, hesitation and lack of power on hills is the usual signs.  The only solution is a complete valve job...ouch.  About $2000+ at most dealers.

I hope this helps and best of luck,

JohnMc