M151A1 Fuel Pump

[kerogane]

I have a question regarding the electric fuel pump on my M151A1. I have a new in tank pump and replace the non working one that I had in my Mutt. I thought I might check the new pump to make sure I didn't have the feed wire Possibly touching a ground inside the connector. When I checked it showed that the pump wire was grounded. So I disassembled the unit and everything in the connector looked ok, So I checked the positive wire that is made with the pump and it checked that it was grounded inside the pump. Is this normal for a M151 pump? I checked the old pump and it checked the same way (rust killed the old one not a short) I just don't want to fry a new pump, there too expensive! THANKS!

[Rickf]

The pump is a magnetic coil so if you are just checking continuity on the wire going into the pump to ground it will show up as a direct to ground. If you check it with an Ohm meter you will see a resistance reading that would correspond to the coil in the pump. Sorry, I have no idea what that reading would be.

[Kurt Lesser]

This is actually a common problem with people who don't understand electrical systems and electronics. Motor windings, coils, solenoids, and light bulbs all have very low resistance values when checked with an ohmmeter and if the ohmmeter is set to a high resistance scale (>200 ohms) they will show up giving the uninitiated the appearance of a short. For most mechanics the lowest scale on the meter is where you want to set your range switch for electrical tests. Leave the higher ranges for the electronicers. 99.9% of us will never see some of the specialized meters used to measure extremely low resistance to locate shorts in circuit boards or megohmeters to test electrical breakdown of insulation so your average Radio Shack / Home Depot / Ebay will meter will work just fine.

Kurt
KG6KMJ

[kerogane]

You guys were right. It works fine. THANKS! Mike

[Rickf]

We are ALWAYS right, except when we are wrong and that never happens, just ask us.