Engine/Transmission (1994 - 1998) Fuel heater

[RWorth]

About a month ago I noticed a wire burned into going to the fuel heater. I spliced the two wires together after checking for problems. Well today after looking at a friends truck I noticed the wiring was different. What was different was it seems that the burnt wire was from a temp sensor located on top of the lift pump. Is this item a thermostat or some type of temp sensing device? Can this item be purchased seperatly along with a new wire harness? Any advice would be appreciated.

 

[illflem]

As far as I know the temp sensor is in the heater. All the parts for the heater are available separately from Cummins but not the dealer.

 

[Cooker]

I just replaced some of these parts on my truck.



The temp sensor is mounted in the top of fuel strainer/heater housing. It is part of (directly wired into) the wiring harness that plugs into the fuel heater (I can take some pics when I get a chance an email them to you if you'd like).



As illflem mentioned, the harness is available separately from Cummins. If I remember correctly the harness was around $35.



Keep in mind the harness melts many times from a problem with the fuel heater. It may need replacing also. Does the plug into the element leak fuel when unplugged? Do you have a loss of prime issue? The heater element is also available separately for ~$40.



Hope this helps,

Ryan

 

[Missouri Mule]

RWorth

Yes, the sensor on top of fuel heater takes tempature readings of the fuel. I don't recall exact temp when it turns the heater on (thru pcm) but shuts heater off when fuel reaches 80 degrees.



The relay for the fuel heater relay is located next to the fuel shut off relay. If you ever need to check it out.

 

[Dan_69GTX]

When I bought my truck, the wires to the heater were both burnt at the connector.



The heater turns on at 40 degrees F.



Having a bad contact at the plug will cause the wires to melt. The heater has a very low resistance, this means if you have any resistance at the plug, it also becomes a heater.



To solve my problem and not purchase a new wiring harness I cut and soldered the wires together. The fuel heater works fine and the wires do not get hot. Yes if I have to take it off I will have to cut the wires, but I'm willing to do that for reliability issues (soldering is easy!).



Dan

 

[RWorth]

Thanks for replying.



I Southern Plains Cummins in Tulsa to see if they had the temp sensor and wiring harness. They got their service manual out but it did not show the ability to purchase the wiring harness sensor or the heating element. Cooker do you have the part number of the temp sensor and harness? Does anyone know what the resistance value should be on the heating element? Mine shows open.



TIA

 

[Cooker]

The Fleetguard part number for the wiring harness with thermostat is3843722S. I was invoiced $49. 39 for this part.



The heating element, should it need replacing is part number 3907766S. This was $35. 18.



I hope this helps,

Ryan