Disco 2 / Cranks but won't start

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explorer0863

Member
My Disco 2 is a 99 with the 4.0 Bosch engine; 175,000 miles.

I went to the post office the other day and after getting my mail the Disco didn't start. It would turn over but didn't start. Ended up calling AAA and towed it home. I checked spark, fuel, engine codes, inertia switch. All good. About 3-4 hours later I tried again and it was perfectly normal and ran fine for a few days.

A couple of days later my wife took the Disco and on her way to work she stopped for breakfast. The same thing happened: it would turn over but didn't start. I picked her up. We left the Disco at the breakfast place and I gave her a ride to work. About 8-9 hrs later, on the way back from work, I decided to go and check the Disco and give it another try. Again, it ran perfectly for a few miles, but it died for good at home.

One of my buddies told me to replace the crank position sensor; which I did. It was replaced with a Bosch sensor. It didn't work. Crank but no start. On my third attempt the muffler exploded. After the explosion, it was late and dark, so I didn't try to start it again until today.

Today I tried again and this time it fired up the 1st time. It was loud without the muffler, but finally the engine was running. After 10 minutes, I turned it off and now is dead again. Cranks but no start.

I've been thinking about an intermittent issue with the fuel pump or perhaps the coil packs? Any ideas or suggestions? What should I check next?

Thanks!

Tony
 

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jymmiejamz

jymmiejamz

Founding Member
Callsign: KN4JHI
The only thing I have seen cause a crank and no start on a DII, other than a bad crank sensor, is a bad fuse box in the passenger compartment. Crank sensors are often intermittent failures. I don't think I've ever seen a bad fuse box be intermittent.
 
nas90tdi

nas90tdi

Well-known member
I have had this exact issue on a Disco. I just can't remember what it was.
I bet that muffler exploding woke you up. I blew up a filter box one time with a backfire. Almost shit myself.
 
chris snell

chris snell

Administrator
Callsign: NW5W
Staff member
Changing the CPS is probably easier than troubleshooting a fuse box so I'd try that first. If it wasn't the CPS, well, now you have a known-good field spare CPS.

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jymmiejamz

jymmiejamz

Founding Member
Callsign: KN4JHI
chris snell said:
Changing the CPS is probably easier than troubleshooting a fuse box so I'd try that first. If it wasn't the CPS, well, now you have a known-good field spare CPS.

<div style="position:relative;height:0;padding-bottom:56.25%"><iframe src="https://www.youtube.com/embed/p3HYZsC9UGI?ecver=2" width="640" height="360" frameborder="0" style="position:absolute;width:100%;height:100%;left:0" allowfullscreen></iframe></div>
Click to expand...

I disagree. It is much easier to open the hood a check for power going to the coil than it is to replace a crank sensor. This is easier than you may think

There is a connector, C0449, on the right hand side of the engine bay which is between the fuse box and the coils. The power wires for each coil go through this connector. Pins 4 and 5 the the ones we're looking for, and the wires are green/brown and green/yellow. It is important to have the coils connected when checking for power, as this will put a load on the circuit. Without the coils hooked up, you will find battery voltage even if there is a problem.

Backprobe C0449 at pin 4 or 5 (same fuse feeds both) with the red lead of the volt meter. Hook the black lead to the battery or another good ground. Have someone crank the motor. If you get anything less than battery voltage, then you have a bad fuse box.



From what I remember the connector is right next to the fuse box in the engine compartment near the expansion tank. There are two there, and the one you want is the grey one.

 
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explorer0863

Member
A new contract at work and the fact that I am very frustrated with the Disco II prevented me from working consistently on this issue. So, let me update this thread.

As of today, it's still not running. The same: crank, but it won't start. The fuel pump is good and I have good PSI. The new crank position sensor didn't solve the problem. Current at the spark plug wires was "weak", so I replaced both coil packs and wires. That didn't solve the problem either. The current it's still weak.

I was thinking replacing the engine computer, but it is my understanding that if I replace the computer, it will require reprogramming. Is that true?

More than one person here mentioned a fuse box. Last year I replaced the interior fuse box (with a used one) because it wasn't sending current to the A/C blower motor. After I replaced it, the A/C came back to life and everything was working fine. I still have the original interior fuse box (the one that made the A/C motor blower inop). Before I spend and waste more time and money, I am going to re-install it this week and see what happens.

A friend of mine told me today that he had a similar problem with his Disco II last year. After a lot of work, and testing different components, he ended up replacing the engine compartment fuse box and that solved the problem. I guess that I may try that as well if replacing the interior fuse box doesn't work.

If nothing works, it looks like this is going to be a parts car very soon...
 
jymmiejamz

jymmiejamz

Founding Member
Callsign: KN4JHI
explorer0863 said:
I was thinking replacing the engine computer, but it is my understanding that if I replace the computer, it will require reprogramming. Is that true?
Click to expand...

That would most likely be a waste of time and money. IIRC, even the workshop manual says that the ECM is the most unlikely component to fail.
 
jymmiejamz

jymmiejamz

Founding Member
Callsign: KN4JHI
Another thought... are you sure you installed the CkPS correctly? The spacers go on after the sensor.
 
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explorer0863

Member
jymmiejamz said:
Another thought... are you sure you installed the CkPS correctly? The spacers go on after the sensor.
Click to expand...

Yes. 100%. When I installed the new sensor the first time and the engine didn't start, I removed it and re-installed to verify that it was done correctly. I also double checked that the plug was connected correctly.

Not a fun job, but after the 1st time it gets easier and you can easily cut the time it takes to do it in half.
 
MountainD

MountainD

Technical Excellence Contributor
I usually pull a lead off a spark plug, plug a spare in, and ground it to the engine block and check for spark. If you have spark, it is most likely a fuel issue. No spark, most likely coil pack or something typically to do with the CPS... I know you just changed it, so that would be rare.

It is a simple way to check for fueling...
 
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explorer0863

Member
Final report and outcome: the problem was the interior fuse box.

I re-installed the old one that I had removed last year due to the A/C blower issue. Had to reset the alarm and it started on the first attempt. I don't have A/C again, but at least the engine is running fine.

Many thanks to all of you for your help and suggestions, especially to jymmiejamz for the suggestion and instructions on how to diagnose the interior fuse box.
 
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