Archived Help: fuel pre-heater wires caught fire

[Hootguy]

came home tonight to find a small fire under the hood. .

The fuelpre-heater wires had caught on fire,,luckuly i was ableto put it out with some snow,,,i hate to think what would have happened if i'd gone in and to sleep. . probably would have burned the whole truck down.

Anybody ever had that happen to them...

Any idea on a cause or a fix. .

I'm starting to think these Dodges aren't worth all this aggravation,,,,the Duramaxes are starting to look real good. .

Seems these things always have the same problems,,,is Dodge ever going to build a good truck,,,seems they haven't been able to build a good truck since 1993. .

sorry for the rant,,,but this is getting very old very quick,,,theres always something going wrong with these trucks. .

Are the 2003 any better????

Thanks

 

[Crowhurst]

Welcome to the club! My worst CTD moment was having the cab fill with smoke from these wires catching fire. The wiring is a simple series circuit through a thermostat and a heater element. There is a relay on some models, and this is up on the firewall next to the fuel solenoid. If the plug-in connector to the pre-heater gets corroded, resistance and heat can build up to cause a fire. My local Cummins dealer said that the whole heater/thermostat/wiring should be replaced as a unit, as the cause of the fire usually lies in the heater/thermostat. Others on this list have just replaced the wiring. You will find part numbers and other good information on this link https://www.turbodieselregister.com...adid=33109&highlight=fuel+heater+part+numbers

I ran for a while with the wiring disconnected, but used the block heater overnight in cold weather. I found it simplest to remove the whole pre-heater/filter assembly from underneath, and do the work on the bench, making a nice job of cleaning the pre-filter at the same time. Good luck. Nick.

 

[Hootguy]

Thanks for the help.

Any ideas on a cause for the fire,,,i meen,,if this thing is supposed to be able to be on for a long time when it's cold out,why would it burn up the wires like that,,???

And if i replace the wires,,,how do i make sure the new wires dont burn up too??

I just want to be sure not to fix it and then have it burn up again.

Should i replace the relay?? and everything together??

Funny,,i just had the ignition recall done,,,and now this///,,could the dealer have srewed up sometinh to cause this wires to get too hot?

Thanks

 

[Crowhurst]

Without seeing the bits on the bench, I can only make a guess, so the following could be total BS. The two wires attached to the pre-heater are the live feed and return from the simple series circuit through the thermostat switch and the heater element. The element has to generate heat, so the element has a resistance, and this creates a drop in electrical potential (voltage) across the element. This means that there is a voltage difference between the two wires at the connector, so given the opportunity, electricity will want to flow between the two contacts in the connector (a short circuit). This would be less likely if the feed wire entered the pre-heater on one side, and the return wire came out on the other, three inches away. Unfortunately, the two wires are close together in the push-on connector. This should not be a problem if the inside of the connector is clean, dry, and away from oxygen. So we put the connector down low on the engine, and run the vehicle through puddles of water containing salt and other chemicals. Then we warm up the whole system, because it's by the heater element and the hot engine. The hot salt water is a very efficient conductor of electricity, and some minute amount of this seeps into the connector. A current flows between the two wires in the connector (a short circuit). This causes corrosion, and thus internal resistance in the connection, heat, and eventually smoke and a fire. This can be prevented in 3 ways: 1. a re-design of the heater and its wiring, which is impractical for us. 2. disconnecting the wires, taping them out of the way and relying on the block heater and winter fuel to avoid waxing. (Not for those up North, I expect) or 3. Using dielectric grease on the connector. Dielectric grease does not conduct electricity. It can be used on the metal parts of light bulbs, light bulb holders, fuses and their holders, and any electrical connectors. It seems strange to coat surfaces you wish to connect electrically with a grease which prevents electrical contact, but the grease is pushed aside at the actual point of contact, and the grease keeps out oxygen, water, salt etc, thereby preventing corrosion (e. g the green surface and disintegration of bulb holders). This prevents short circuits and the resulting heat. I would take the pre-heater/filter off the vehicle, and replace any burnt wires and connectors with new. I would fill both connector ends with dielectric grease (after ensuring they are clean and bright), push the connector ends together, and smear more grease over the join in the connector. Dielectric grease is available at auto stores in small tubes for a few dollars. I have read that Vaseline is dielectric, but I don't know for sure. I suspect this is the likely cause of your problem. It could be in internal short in the heater, but you can establish this when the heater is on the bench. I do not see any point in replacing the relay. Just test it to see it functions. Even if the relay had failed in the "on" position, the heater circuit should be able to cope with long-term operation. Just my humble amateur ramblings, but I know you can feel a bit lonely when the smoke is pouring out from under the hood. Good luck. Nick.

 

[Hootguy]

WOW,,Thanks a lot,,,

This is exactly the type of information i can use. .

Plenty of good details. .

This group is awsome at helping out...

Maybe you guys should run your governent,,,,probably would be a hell of alot more efficient.

Is it possible to just remove the heater parts of the system or do i have to take the whole lift pump out. ??

Thanks

 

[Crowhurst]

It's not a lift pump, just a pre-heater and filter. You will see a picture of it and a description of how to service it at http://www.dodgeram.org/tech/dsl/filter/pre-filt_clean.htm

(The parent site, dodgeram.org is great for clear explanations of regular service items). This is an important item to keep clean. When I bought my used CTD it had 78k miles on it , and the pre-filter was half choked with sediment. I doubt it had ever been touched. The wires at the top of the unit are for a fuel temperature sensor , which are hopefully undamaged. The wires to the heater element are the lower ones to the left. With a struggle, you can pull this connector off, and replace the burnt wiring with the new section and connector, using dielectric grease. If the connector on the heater is damaged, you will have to replace the heater element, which incorporates the thermostat. This can be withdrawn from below when you service the pre-filter. When you unscrew the hex at the base of the filter, the next section revealed is the heater assembly, and this is withdrawn downwards. The dodgeram.org link describes an allen key bolt that may be installed in yours, and which will need to be withdrawn. It's awkward, of course! In my 98 service manual, the picture and instructions are at section 14-98. That manual is the best $100 I've ever spent on my CTD. With the element on the bench you would be able to check the element and thermostat with a meter, and clean up the connector. Good luck. Nick.

 

[Hootguy]

Thanks for all the help Nick

BUT,,,,, i have a new problem now...

i decided to clean the fuel heater sediment filter screen and bowl. .

I got evrything appart cleaned up and put back in,,,i didnt remove the heater element...

BUT,,i must have done something wrong,,,because when i got the truck started i went one block and it died like it ran out fuel...

Towed it back to my house,,and proceeded to check everything i could,,still no start,,checked the bowl,,,no fuel,,,checked the fuel filter and it was half full. ,,

Tried cracking the injectors,,no fuel,,still,,filled the fuel bowl and filter back up,,,,still no go,,

THEN,,i noticed that when i removed the fuel heater bowl,,the elemnt had come loose,,,so i might have been cranking on the starter for an hour,,,and filled evrything with air... .

Now i dont know what to do anymore...

Does this mean a tow truck ride to the Cummins shop????

Or is there anything else i can do to prime the system. .

I tried pumping the plunger on the lift pump... but it doesnt seem to work,,,i give the strater a crank and try again,,still no pump,,,...

That new Duramax is strting to look real good right about now,,,I'm starting to wonder if these Dodges are worth the aggravation. .

 

[Crowhurst]

The sequence for bleeding the fuel system is on pages 14-86 and 14-87 of the service manual. The all-important sequence is:-

1. Bleed the low pressure system by loosening the bleed bolt on the top left (as you look from the streetside) of the fuel filter, while pumping the push-button primer on the fuel transfer pump. (below the fuel filter). Tighten the bleed bolt.

2. Bleed the fuel injection pump by cranking the engine for 30 seconds at a time to allow air trapped in the injection pump to vent out the drain manifold.

3. Bleed the high pressure fuel line. Bleed one injector at a time by loosening the high pressure line fitting at the injector, and cranking the engine for not more than 30 seconds at a time (2 minute rest inbetween). When the engine starts, again bleed each injector until the engine runs smoothly.



If you still have the problem after this, I suspect you have a leak in the heater/pre-filter from the re-assembly, particularly if you re-used the old seal. I would re-assemble it with a new seal. If that doesn't work, there will be someone on this site with the experience to get you through. Good luck. Nick.

 

[R.ebel]

Hooter69,

It sounds like your lift pump is not working. Mine went out at 113k. As long as the prime is maintanied a 12 valve truck will run fine without a functioning lift pump. I changed my fuel filter and started to pump the lift pump but could never get it to prime, a new lift pump solved the problem.



When I recently replaced my lift pump at 113K I noticed that the plug connection for my the fuel heater had gotten hot enough to slightly melt the connector Close examination of the of the metal contacts showed a sever case of oxidation which causes a high resistance connection, once this process starts it only gets worse. I choose to not remake the connection to the fuel heater to avoid a fire and/or melted wire loom. If the proper anti-gel fuel treatment is added to the fuel during extreme cold weather IMHO the fuel heater is not needed

 

[Hootguy]

Well guys,,thanks for all your help.

I did everything you suggested...

I removed the heater element assembly and wires. . i left the burned up sensor part in the top housing. . and simply re-installed the bowl without the heater part as someone had suggested. . \

Good news ,,it works good now,,,i guess air was sucking in threw the element plug. .

I did have to use the air in the tank technique to get it primed as the manual plunger doesn't work anymore.

If my lift pump is bad,,,why does the truck still have lots of power??

I will make sure to always throw antigel in the fuel next winter.

I currently use Howes Cleaner Power formula all the time.

Thanks again for all the help