[Samurai]

Originally Posted by '72 Bullet

Wanted to know, do they also have these in yellow (or is it possible to find a yellow filter for them) as it will offer better visibility and penetration in fog. If yes then Samurai-san should probably have a set of normal and a set of yellow (like he had before with the round ones).

Originally Posted by beejay

He also has a similar one in yellow. Will try to get a picture.

I asked about that since Sachin wanted Yellow ones. I was told that unless we need 24 pieces (one carton), they can't order the yellow ones.

But, why do you need yellow lights? The fog lights need not be yellow. I found out about that last year during my research on fog lights.

Do Fog Lights Really Work?, Alaska Science Forum

Look for images of fog lights from Warn, they are all white.

[wanderhermit]

I am pretty surprised by these findings. I always thought that yellow had more penetrating ability in fog and snow. May be on a clear night, it has no additional value.

Lemme try these and give a feedback. And thanks for all the info, and descriptive night shots of the spread pattern of the fog lamps.

Just one query, a traffic cop has told me that it is not mandatory to cover the fog lamps as long as they are installed below the car headlamps. Anything above the height of the head lamps can be challaned.

Is this info correct?

['72 Bullet]

I was under the impression that yellow lights offer better penetration and visibility in fog as well

That said, I know that WARN, Roo lights, Lightforce etc. mostly have clear lenses, but then they also offer coloured filters for them. What are they for? My guess is:

• Red : To preserve your natural night-vision
• Yellow/amber : Better penetration in fog
• Blue : I have no idea, maybe for signalling / rescue

Does anyone know why they have the filters?

[Samurai]

Originally Posted by '72 Bullet

Yellow/amber : Better penetration in fog

There is no scientific proof for that. Try finding one on the web.

[smsrini]

Originally Posted by Samurai

There is no scientific proof for that. Try finding one on the web.

One explanation could be that yellow light reflects less than the bright white when it falls on a thick layer of fog, so while it may not enhance the visual depth, it certainly will help in allowing the driver to adjust better to the surroundings than with the white/fog lights or no lights. at a minimum it will allow you to see the tail lights of the vehicle in front.

That's why you see the Delhi taxiwala's switch off their headlights and drive with only the parking lights on in fog ??

[Samurai]

Originally Posted by smsrini

One explanation could be that yellow light reflects less than the bright white when it falls on a thick layer of fog, so while it may not enhance the visual depth, it certainly will help in allowing the driver to adjust better to the surroundings than with the white/fog lights or no lights. at a minimum it will allow you to see the tail lights of the vehicle in front.

Please look at the link I have provided few posts back. Scientists have not been able prove that until now, despite 100s of studies. I have read another thread by a scientific source which says it was a big goof up where a early fog light maker mis-interpreted the science and started selling yellow lights as superior fog lights. Even after 80 years, that perception still remains.

Originally Posted by smsrini

That's why you see the Delhi taxiwala's switch off their headlights and drive with only the parking lights on in fog ??

I can believe that. I just drove through two stretch of heavy fog. About 15Kms in Sampaje ghat and about 20Kms between Madikeri and Somvarpet.

The primary headlights was creating a white wall in front of me. So I switched off the headlights, and turned on all the 4 work lamps which now play the role of fog lights in my Jeep.

It worked beautifully I get only 20mts of good illumination, but I can see through the fog and clearly see the borders of the road. I have never been able to see through fog this clearly. I could drive as if there was no fog.

I am typing this from the homestay in Somvarpet. The Bang bros on a 11 vehicle convoy in still on the way, they must be closing on Hunsur by now.

Sachin and I reached Somvarpet around 10:45PM. My Jeep is having a small hickup, it is switching off if I stay in idle. Even while driving, if I come to neutral at a stop, and be in idle for few seconds, the engine switched off. Sachin says idle setting is low, it can be fixed in the fuel pump. Gotta find out how to do it, in the morning.

[DirtyDan]

Samurai is quite right. The theory used to be that long wave length yellow light penetrated water molecules better than other light of the visual spectrum. But, in fact, tests show that water vapor reflects all light equally, yellow is not better. An easy common sense test....fog is more-or-less white (clouds are white)...white is the color which reflects ALL wave lengths of the visual spectrum.

Driving in the mountains in the monsoons where I am means driving in thick clouds sometimes. Taxis and commercial vehicles here use their yellow marker lights and "four-way" lights simply to save money on bulbs and to cut down on glare that full headlights give to oncoming traffic. The blinking seems also to get attention better from other drivers. In other countries, motorcyclists often install an oscillator in their headight(s) to make them blink rapidly just because other drivers on the road pay attention to blinking lights, giving motorcyclists some margin of safety.

Most manufacturers of yellow fog lights use a tint of some kind over the lens in front of existing white light bulbs or they tint the bulbs themselves. The effect is to block light, wasting about 20% of the light produced. So, the use of yellow light does not help you see better and expends energy to no purpose.

[Samurai]

Originally Posted by Samurai

Sachin and I reached Somvarpet around 10:45PM. My Jeep is having a small hickup, it is switching off if I stay in idle. Even while driving, if I come to neutral at a stop, and be in idle for few seconds, the engine switched off. Sachin says idle setting is low, it can be fixed in the fuel pump. Gotta find out how to do it, in the morning.

This turned out to be a much bigger problem. At first, if I stay in idle for few seconds, the engine switches off. I started noticing this on my way to the Somvarpet event. When the fuel tank is full, it only happens after few seconds of idling, as in a stopped Jeep. But as the fuel level drops to say 2/3rd tank, the symptom becomes serious. Then the engine will switch off if the rpm drops to idle even for 1-2 seconds while down-shifting. Say I am braking and down-shifting from 4 to 3 or 3 to 2 in a corner, the engine switches off in the brief state of idling. It can be dangerous if there is a vehicle behind you. I almost got hit by my cousin's Gurkha once because of this.

Another symptom is I start losing power while climbing a hill. Say I am climbing in 2WD 2nd gear, normally the torque of my Jeep can take me flying up that hill, but I start losing power and stall the engine. And I am unable start even in 1st, despite using toe-heeling. This happened on the way to Pushpagiri Hills and back. I was forced to go 1st low in order to overcome the hill, on tarmac, at least 4 times. Then I took many incline roads (tarmac) in 2WD 1st gear instead of 2nd gear just to avoid the stall.

There were certain trails near Mallali falls and Beedalli where 4WD is required. I didn't encounter any trouble in 4L since the rpms remain high.

Since Sachin had shown me the way to increase the idle rpm, I decided to fix it while waiting in Beedalli, which is the starting point for trekkers into Pushpagiri hills.

Here is the Bosch fuel pump. At first I had thought marker A is the bolt I need to adjust. But that is a fixed bolt, can't be moved. After some close observation, I realized I need to manipulate marker B bolt. The marker D is the solenoid switch which died on me last month while coming back from Coorg.



So I loosened the bolt B and moved it along the curve and keep the idle at a higher acceleration. Notice the marker C bolt is mostly covered now.



After this I thought I had solved the low idle problem. But the stalling while climbing was still bothering me. I didn't think that had anything to do with low idling speed. That stalling was happening even with a floored pedal, it is accompanied with falling oil pressure. Generally the oil pressure should hit 4 bar when the key is turned, even before cranking. But here it was only rising if I start the engine and floor the pedal.

With the above problem in hand, I enter bisle ghat. Yes, I am a sucker for Jeep trouble. Bisle ghat is probably the most desolate and most pathetic ghat road of Karnataka. You might pass no more than 5 vehicles during the 30kms stretch during day. Don't know about night.

Since Bisle ghat consists of very very twisty roads, I started having this problem in every turn. Finally I stopped at the only section where I get signal and called Sachin and told him the problem. He quickly checked with the mechanic and then asked me to check the oil level, which was normal. After the rebuild, the electronic fuel pump had been misbehaving, probably because it was idle for 4.5 months. Even the Coorg mechanic had complained about having issues with it. Later the Udupi mechanic too found it defective and finally replaced it with EFP from a FC truck. Now Sachin+Mechanic concluded that EFP must be the culprit again. In other words, it is not a grave problem, the vehicle can be driven although in a limp mode. I was advised to pull, push and drag it back home somehow. Not a challenge for a Jeeper, so I managed to drag it 175kms in 5.5 hours with lots of drama and reach home. Gory details will be covered in the OTR report.

After refueling at Subramanya, I didn't have any stalling problem for first 100kms. After that it started stalling again very 5-6kms or so whenever I slow down to downshift. Now I started improvising, instead of stopping, I used to fully press the clutch and then release it, achieving a jump start. After a few times I took mercy on the clutch and started stopping again after every stall.

The only silver lining to the whole episode was, I could start in 2-3 cranks after every stall.

Now for the dumb questions:

1) Why the heck do I have a electronic fuel pump?
2) Can't the Bosch FIP do the whole job?
3) What should I do to throw away the electronic fuel pump?

I have been told that the FIP needs to be recalibrated, etc. But I want to understand the full function of the diesel Jeep FIP, and how it works, and why it needs the crutch of EFP sometimes.

[JeepCaptain]

Originally Posted by Samurai

This turned out to be a much bigger problem. At first, if I stay in idle for few seconds, the engine switches off.

----------------------------------------------------------------

I have been told that the FIP needs to be recalibrated, etc. But I want to understand the full function of the diesel Jeep FIP, and how it works, and why it needs the crutch of EFP sometimes.

Samurai, Dont know whether you have tried this. Please try the steps in bullet points below if you haven't.

I had encountered exactly same issue with one of my Ex-MM540 with XDP4.90 engine after a full body rebuild and painting where the Jeep was parked for about 2 months during heavy monsoons.

Same hiccups like your Jeep and engine stalling at irregular intervals and occassions.

Tried everything possible and never resolved it.Finally the culprit was identified. Which was very simple.
A clogged Fuel tank, clogged fuel line and clogged fuel filters which was restricting fuel to the FIP. I cleaned it as mentioned below and the issue was resolved immediately.

• Drain the fuel tank completely and blow high pressure air into it to blow away any traces of solid deposits and water which got leaked into your tank due to rains.
• Replace the full fuel line from tank to fuel filter with brand new one
• Replace both primary and secondary fuel filters with brand new ones

Fill fresh diesel and start the engine. Sounds silly but worked for me.
Shibu

[sreerajunnithan]

Samurai,

May be dumb questions, and you might have already tried these.

1) Is the Jeep stalling all of a sudden or after some misfires and Jerks?
2) Did you notice any excessive smoke from Exhaust just before stalling?
3) If yes, what is the color of smoke?
4) When did you last changed your Diesel filter?
5) Is your oil pressure gauge dropping suddenly, or gradually?
6) Did you try connecting the pump directly without the solenoid?

FIP calibration is a good idea if you haven't done it already. But only after checking everything else i mentioned. Some DIY.

1) Remove the disel filter bolts, and check if you have dirt in Primary and Secondary filter. Replace with brand new filters.
2) Remove the fuel line banjo Joint from Diesel filter side.
3) Remove the fuel line from Diesel tank side.
4) A strong Blow from the the diesel filter side and fix it back
5) Clean the tank as shibu Mentioned.

Thanks
--Sree--

[ex670c]

Hi Sharath,

I faced a similar problem while driving back from AKC/EXAMM.

Though it was not as frequent as yours.

There are 2 culprits
i) Pump Switch (Solenoid)
ii) Fuel Filter Lift Pump and Cover (has a one-way Valve).

I replaced the lift pump in Hubli and managed to reach Chennai, where I changed the Fuel Filter Assy.

The very next day I had to change the FIP pump switch.

Regards,

Arka

[Jaggu]

Samu get the pump and injectors calibrated proper. Replace the filters and do a clean up of full fuel line. If you can remove and bring it to BLR, nothing like Vijaya diesel for the job.

EDIT: They will check everything and set it up proper, you just need to carry it back and install.

[svsantosh]

Sharat - I got my FIP re-caliberated/serviced at a Bosch authorized center in my town near Bangalore. It cost me 2K. In my case, though the mechanic was able to install back the 4 inj's and FIP ASAP, he could not get the idle right, even the black smoke was still present. I drove back to the Bosch guy and the chief engineer came and within 2 minutes tuned the FIP to perfection. While the 2-3 nuts need to be properly adjusted for Idle, the whole FIP itself needed proper alignment to be fit correctly into the mount. Please check with the autho Bosch person, the mech can Only get it half right.

[DHABHAR.BEHRAM]

Dear Sharath - the screw "A" can be moved a little to change the idle speed by unlocking the nut with a size 10 spanner. Moving bolt "B' achieves the same thing but not recommended. From all the data, I understand that your FIP is not of CJ340 but from an FJ/FC vehicle with XDP4.90 engine. If so, it is necessary to put the original one back and after it works properly, to just leave it alone. I totally agree with Santosh's opinion. Let Bosch handle it in totality, otherwise the vehicle will not run properly. Also, please check the integrity and cleanliness of the fuel system. A little bit of water in the fuel will cause all sorts of problems. I have been fortunate to be able to conduct such tests by actually adding some water in the fuel system and the results were very similar to what you are experiencing.

Best regards,

Behram Dhabhar

[tsk1979]

Some modern vehicle have sedimenters to separate water from fuel. Maybe with your kind of usage, and fuel quality, it may be a good ideal to spend money on such an sedimenter.