When the temperature drops to minus 10f or colder I am having problems. I use the block heater and the engine starts right up but will not maintain fuel pressure. I am using Amsoil cold flow improver in both my truck and Jetta TDI. The TDI runs fine but the truck does not. It starts well and runs about 11 psi of fuel until I start to drive, then the pressure drops to zero. The lift pump is only two years old and maintains nearly 10 psi when it is warm. I suspect the fuel heater. How do I check the heater? Any other ideas would be appreciated. -25 today, the truck started but had to drive the TDI.

 

You are not saying what do you have for the fuel pump. Stock? Aftermarket? Did you use an anti-gel? I don't know what you are referring to when you mention a fuel heater.

 

Thanks for the reply. I have replaced the origional lift pump with a Carter lift pump which is a direct replacement for the OEM. It usually runs at 12 psi at idle and drops to about 7 psi when under a load. The Amsoil cold flow improver is supposed to be an antigel. I did get to check the electrical connector to the fuel filter housing to verify that the fuel heater, located in the upper part of the filter housing has power. I do not know how to check the temperature switch or the heater element.

 

The heater element should be in the fuel filter canister. There is a sensor for the WIF and the other is the heater.

I'll check my FSM for it.

Try a bottle of Power Service 911, red bottle if you think the fuel is gelling.

 

The fuel heater is the top connector on the front of your filter canister, the plug should be facing upwards.

Its my guess that the ECM controls this item and runs it when the temps drop below a certain point.

I could not locate a code for a fuel heater issue, I suspect there is also a fuse for it under the hood in the fuse panel behind the drivers side batttery.

 

Thanks for the help, if it ever gets all the way back up to freezing I will look in the fiolter canister for the heater. I did buy a copy of the service manual which is a lot of help. It shows that the connector on the filter housing includes a thermostat that should turn on at 40 and off at 70. It also states that the resistance of the heater should only be 1 ohm.

 

fixing the truck in freezing weather bites....
when was the last time the fuel filter was changed?
just bump the starter to get the lift pump running and then try bleeding off some fuel at the last valve before the IP.
lastly... have you checked for codes?

What happened to your signature?

 

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