M38 Fuel Sending Unit--Douglas Connector

[Z]

If discussed already, can I get help locating the thread. I've searched and searched. I need a sending unit but my all my wiring is original and has douglas connectors. The new 24v units are not compatible for douglas type. Thanks for any help.

[skyjeep50]

Buy Packard connectors at your jeep parts dealer of choice and switch the wiring to match the sender. No, its not original to the jeep but it is original military.

[Z]

Thank you. Are you saying to change the entire wire from the sending unit to the gauge? I'll need to change the gauge also or can I just change the connector to Parker type on the tank end?

[RonD2]

I believe that's "Packard" connectors......(helps with the search function)

Good source for Packard and Douglas connectors at https://www.eriksmilitarysurplus.com/coandte.html

And fresh Prestolite mil-spec vehicle wire https://www.eriksmilitarysurplus.com/prwimse.html

Happy hunting!

[kenperkins]

https://sep.yimg.com/ay/yhst-5952369085 ... 44-3-6.jpg

this is all you need, remove douglas shell from fuel sender wire and replace wit this

[mdainsd]

I have found those NOS with Douglas connectors on eBay and at meets.

[4x4M38]

Make sure you are buying an M38 fuel tank compatible sender. The A1 tank is different. But yes, if you find a good sender, just change the sender end of the wire to a Packard connector.

[Z]

Thanks for the input, all.

[wesk]

Were you missing a sending unit or did you determine your sending unit was bad using the M series gauge troubleshooting Bulletin TB 9-2300-228-20 ? http://www.willysmjeeps.com/v2/modules. ... tit&lid=46

Keep in mind when troubleshooting the M38's Gauge systems that grounds make all the difference. A half century of corrosion and a half dozen paint jobs leaves the corrosion hidden under the layers of paint and the layers of paint inhibit proper grounding. Remember, The gauge itself must be well grounded to the instrument cluster & the dash to function. Yes a current goes thru the gauge and on to the sender for grounding as well but the motor action of the gauge requires the gauge itself be grounded. Failure of the gauges to ground their own cases thru the instrument cluster panel and on to the dash are usually half the gauge problems. Grounds cannot function as grounds if they are insulated by layers of paint. The second most prominent grounding issue is the gas tank to the body. Again layers of paint or corrosion are the problem.

A search of your ORD 9 for the M38 has the correct sender listed on page 163 as ORD# 7524909 or AC# 1517375. You should then see if that sender is listed in TB ORD 479 Standardization of Ordnance Vehicles Electric Instruments in case the Army has already listed a substitution for it: http://www.willysmjeeps.com/v2/modules. ... _album.php

The Packard and Douglas waterproof electrical harness connectors have been around for 75 years. Packard connectors slowly replaced the Douglas connectors in production vehicles starting in the late 50's. The wire and pins used with them are the same. To convert one to other just swap the connecting insulating parts. On the back of an early gauge or sender that uses Douglas shells just remove the shell halves and install the corresponding Packard halves or vice-versa.

Review my M Series Electrical Photo Sub-Album: http://www.willysmjeeps.com/v2/modules. ... _album.php

[Z]

Thank you!
The float weld broke on the unit. Gauge is good. And unit works (though a bit pitted) and is solid. I have the tank pulled with sending unit and pickup removed. Plan is to coat the inside of the tank and changed the paper strainer to metal strainer. If another small weld will hold on the original float, I'll reinstall the original pickup. However, I'm planning on replacing if required.

[Z]

Meant to say...if the weld holds on the float, I'll install the original sending unit."

[wesk]

I would suggest you thoroughly research paint on in tank interior coatings versus a proper interior cleaning.

There are a couple of coating processes which start with a proper interior cleaning that when applied with proper treatments professionally seemed to last many years. However with steel tanks I prefer either plating or chemical conversion coatings which won't peel.

You'll run across dozens of personal testimony's on how well it worked for Joe Smith and etc however those are based on only less than a year or 2 of service with those coatings. It's 5 to 10 years later that the peeling coatings start clogging filters and carbs. My experience working on all these classic vehicles since 1960 is 8 out of every 10 of these coated tanks I came across have started peeling and usually at the ire of a second or third owner, not the original applicator/owner.

[4x4M38]

And if your float is brass for Heaven’s sake solder it, don’t try welding thin brass. Cleaned and tinned properly and using flux, it should be easy to solder the joint back together

[Z]

Of course, weld term used loosely. It is brass and intend to solder with hopes it holds. It is still fully enclosed but need to tack back to the arm.

[skyjeep50]

For my M38 I adapted a M151 fuel tank sender by shortening the float arm and what I call the blade that holds the float arm at the base. Very easy to do. The resulting sender is identical to the original M38 sender in size and configuration and is electrically the same. I have a M-series gauge in the dash and it works well with the sender. The mounting holes in the sender also match the fuel tank. The only difference is that the M151 sender has the rubberized electrical connector rather than metal shell. And that just requires changing out connector at the sender.