How do you test a WUR?

[Blue83Cab]

Hi Guys, I wanted to find out how to test a WUR to see if it is good or not. I have searched the treads and people refer to checking the resistance as well as other things. Are there directions for this and or documented in any of the books what the values should be? Also, if a rebuild is needed, who would you go with?

Thanks.

[914efi]

There is tons of info around the web on these. If you have it out of the car, yes, measure resistance across the electrical connections just to be sure the heating element is in one piece. You could take the cover off and see it it actually heats up with 12v applied. You can clean passages also, there is sometimes is a filter screen that can get gunked up.

Be warned, taking it apart is minor league tricky, there is small pin that must be put back in correctly. A dab of grease to hold into its 'cup' works well.

After that, it is pressure testing, best done in-car unless you have a way to apply fuel pressure to it.

[RarlyL8]

We take care of rebuilds for WUR's and Fuel Heads.
As Art stated it is easiest to check WUR function using your car. Inspect the unit first for any dirt in the passages and give it a good douching with mineral spirits or carb cleaner. Install in your car with a gage set in place and record the pressures and length of time it takes from cold to warm when plugged into the harness.

[boyt911sc]

Originally Posted by Blue83Cab

Hi Guys, I wanted to find out how to test a WUR to see if it is good or not. I have searched the treads and people refer to checking the resistance as well as other things. Are there directions for this and or documented in any of the books what the values should be? Also, if a rebuild is needed, who would you go with?

Thanks.

Blue,

There are two (2) sides to test in your WUR, namely electrical and mechanical. For the electric side, you need to measure the heating resistance (Ohms) of the heating element. For the mechanical, you need a fuel pressure gauge to measure the control pressure versus temperature or time. The condition of the bi-metallic spring is very critical and cleanliness of the micro screen. The test could be done with the engine running or just the FP. HTH.

Tony