I've gone through the threads, searched the internet, read the manuals, and replaced parts and still having issues.

Here's my vehicle:

Land Rover Discovery I
Year: 1996
Engine: 3.9 V8 Petrol
Transmission: Automatic
Miles: 74,000
* British Spec, right hand drive.

History:

I bought it off a local that was going to part it out but decided not to since it was in such great condition...and it is. I looked in the records and found that the last dealer service was back in 2004 when it had about 62,000 miles on it. So that means for the last 6 years its only been driven 12,000 miles. I drove it for about a week and then started having issues.

What it is doing:

I start it up and drive away...almost immediately when I hit the accelerator it kind of lags in power and almost stalls. To keep it running I've found that I can keep my foot on the gas and brake or drop it to neutral as required as I decrease in speed, usually keeping RPMs around 2-3000. This will prevent the stalling while I'm driving.

However, when I stop and let my foot off the gas then it will stall and won't start up again. Cranks, but no starting...at least until I let it set for awhile.
After about 15-20 minutes, I have to keep pumping the gas pedal until I can coax it to start...sometimes it will, sometimes it won't. All the issues are very intermittent and I have not noticed a difference when its hot or cold outside. Although time that the vehicle is running is sometimes a factor. However sometimes it is difficult to start cold, but will still start none the less. It is after its been running and I turn it off that the not starting is often the problem.

I just tried this today: Started engine, no problem. Let idle for a couple minutes then hit accelerator a couple times to see if the idle would fluctuate, it didn't. Then I put it in drive, rpms fall as they should, but as soon as I hit the gas, it hesitated and rpms drop. It chugged a bit and I got moving. I let it idle down the street a bit and as soon as I would hit the gas though, it would hesitate and almost want to stall. I continued on doing the accelerator/brake method to keep rpms up while driving to get it up to normal operating temp. Got back, turned it off and it cranked right back up. However there is hesitation on hitting the gas pedal. Hmmm....

My initial guess, fuel or ignition problem. I heard of the crankshaft position sensor going bad...however, this vehicle does not have one (according to the dealer and I've looked all over for it).
So this is what I've replaced so far:

- Distributor
- Rotor
- Plugs and Leads
- Oil
- Fuel Pump
- Fuel Filter
- Mass Air Flow Sensor (MAF)

> I spoke with a local dealer that uses Auto Logic for diagnostics and they said that AL is very limited to the codes it will read and is unlikely to pick up the engine codes. Anyone ever hear of that?

> Check engine light illuminates for a millisecond during the lamp test and then shuts off...it seems it would stay on longer, most of the time I miss it coming on its so fast. However, it has never lit up at anytime.

> Fuel Pressure check is approx. 2.3 bar at the fuel rail which is normal according to the manual.

> The fuel pump always turns on whenever I go to start the vehicle, even when it just sits there and cranks but does not turn over.

Here's what I'm going to try next:

> Compression check
> Fuel Temperature Gauge
> Throttle positioning sensor

Any comments/recommendations? This is getting kind of expensive. Thanks.

On a side note, I do get some blue exhaust while idling and occassionally while driving. I've heard valve stem seals are often an issue and I didn't think it would be related, but I'm adding it in here just in case. Also, the midsection of the exhaust has a hole in it.

 

Check all of your vacuum lines for chracks, especially the advance. Re-check the air gap on the distributor.

The TPS may have something to do with it, but you will have to have it read with a scanner to learn the new TPS (most times). Fiddling with it can cause you problems even if you stick the same one back in. Be ready to take a ride to the scanner if you replace it.

 

Thanks for the response. This might be a dumb question...I'm only somewhat mechanically inclined. What do you mean by "the advance" for the vacuum lines? I checked all the lines I could find and the only one that had any issues was the fuel pressure regulator and I replaced that one already.
Also, what is "air gap on the distributor" and how is that checked?
Thanks again.

 

Here's something interesting that I verified yesterday. I currently have the carpet in the back turned up right now leaving full access to the fuel pump. I did this when I replaced the pump a week ago. So I can here the pump priming very clearly when I start the vehicle.

When I first start it up in the morning or after its been sitting awhile, the fuel pump is very "consistent" sounding as it primes up and the vehicle starts no problem.

But....after I've been driving a bit and I go to start it up again I turn the key to position II and can hear the fuel pump prime as normal for a second and then I hear a sloshing/sucking noise like it has air in the lines. Its very noticeable. Turn the ignition to start and sure enough the thing cranks but won't turn over. Hmmm.

The noise goes hand in hand with my starting problem.

It was also there with the old pump and I had suspected maybe the pump was having problems that's why I replaced it.

So now I'm under the assumption that my problem is fuel related. Fuel pressure regulator or relay maybe? Any ideas/comments are appreciated.

 

Contact the dealer with the VIN# and see if the fuel tank was replaced under the recall about 10 years ago.
There were faulty fuel tanks that would not vent properly and then the fuel pump could not pump fuel and the engines would stall.
Eventually the fuel tanks would crack (they are plastic) and then leak causing a fire hazard.
This affected DI's and Range Rover Classic's of many model years.

Also the fuel temp sensor going bad will cause hard starting when hot and rough running when hot, even engine stalling when hot.

Make sure you replace the fuel filter, behind the right hand rear wheel bolted to the frame.

 

I was wondering if you ever solved your issue? I am having similar problems with my 1995 Discovery and haven't been able to fix it. I have tried many of the things you did and haven't had any success. I am going to go out and try to listen to the fuel pump and see if I hear anything unusual like you did.

 

Ditto Spike. These are the EXACT symptoms which caused the fuel tank recall. I'd bet good money that the fuel tank has never been replaced to correct this problem.

 

Try replace the air flow meter.

 

did you ever figure it out? I am having the same issues...

 

I did figure mine out, but it was pretty "unique". Someone , prior to me having the Disco, did some tinkering and must have forgotten how everything went. My issue was with the vacuum hose that is supposed to go to the Idle Air Control Valve from the fuel pressure regulator. Someone had it connected to the nipple on top of the rocker cover instead of the IAC.
That,s probably not your issue, but be sure to check for vacuum leaks.