willysmjeeps.com

Had a few fuel problems recently

Ok so took the fuel pump off and partially stripped it
There seems to be a significant amount of oil within it - is this normal?
( I'm thinking not)
If not then any ideas why and how to resolve it ?

Will post pics when I work out how to from iPad
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Do you have a fording ventilation system installed?

If so, did you find traces of oil in the fittings going
into the fuel pump? If you did you might check your
distributor for oil as well.

One of the suction lines to the fuel pump comes off the
bottom of the crossover pipe, goes through the distributor,
then on to the fuel pump.

Another vent line comes from the bell housing and transfer
case on the later ventilation system.

Otherwise it may be oil trapped in the lower portion of the
upper body that is addressed my a modification described
on pages 162-163 of your TM9-8012 Operation Manual.

It is free on this website in the Downloads section.

I doubt very seriously if you are sucking any oil down from the oil batch air cleaner or the tranny/transfer fording plumbing. Failure of either diaphragms (fuel or vacuum) inside the pump will cause oil ingestion into the pump and/or fuel ingestion to the oil sump of the engine.

Erroneously running for long periods with the fording valves closed (this pressurizes the engine crankcase) will result in oil be forced into the fuel pump. If your engine is not equipped with fording valves the sticking of the PCV valve can cause overpressure in the crankcase and oil being forced into the pump.

Early M38 fuel pumps had issues with the middle oil filled section of the pump and the Army and Carter provided a TB 9-804-11 to modify the center body of the fuel pump drilling a new oil return port so oil forced into the pump housing had an escape route.

Its an m38a1
It does have fording valves, which are set to open but i will double check that it isnt stuck
Would the oil in the pump cause starting problems? -jeep can be reluctant to start & sometimes needs fuel sprayed into carb to achieve a good start

carb has been stripped, cleaned & re built.

a bit reluctant to drill holes in fuel pump but as its in an official manual then i am a bit happier

can any one advise how to attach images/ jpg files/pictures?
i click on the "img" button but that just puts "img" into the text

again many thanks for the help

Insert photos from your photo pages like this:

type

Wes,
That procedure is almost word for word without the photos of the TM9-8012
reference I posted. Guess they decided to make it official.

The manual says the mod I'd for the m38
Is the m38 fuel pump the same as th A1?




Ref the pics - do they have to be on a url?
I just have them saved to my device as a jpg file

Are you trying to put them on a post or your photo page?

You have to have a photo page here on this site before you can attach those photos to a post from the photo page.

You cannot insert a photo directly into a post from another device.

OK, Let's not confuse the discussion here so far we lose the thread.

Pocker's, You must have your photos preloaded to any host web site. The site you have them loaded to must allow no password required for visitors access by our web site so it can retrieve the photo and add it to your post.

All you need to post a photo here is carefully explained at these links. If you decide you would like to host your photos right here on Mjeeps then just request a album on the photo album issues board near the bottom of the forum board index.

Here's your album:
If you decide you want to host your jeep photos on mjeeps then ask for an album here: http://www.willysmjeeps.com/v2/modules. ... wforum&f=9

Here's the rules:
http://www.willysmjeeps.com/v2/modules. ... opic&t=498

Here's the tutorial for loading your album:
http://www.willysmjeeps.com/v2/modules. ... _album.php

Here's the tutorial for posting your photos:
http://www.willysmjeeps.com/v2/modules. ... pic&t=8670

Now with that cleared up let's get back to fuel pumps.

Are they all the same? NO

Do all 13 part number pumps work on either jeep? YES

With a half century of service and repairs there is no telling who installed which part number pump on which jeep. You will need to read the last 4 digits of the part number on the pump's mounting flange. To determine if an early M38 pump has been modified per the TB you will have to open up the pump.

here's a copy of a research chart I put together a few years ago:

The AC fuel pump numbers on the flange are the last 4 digits only of their full AC number in the ORD 9. Don't ask me why AC did it that way.

As for a chart. Here is a beginning for one:

No hand primer:
9917 = 1539917 Pg 72 of M38 ORD 9 and pg 29 of M38 ORD 8 ORD# 8330132
9585 = 1539585 Pg 72 of M38 ORD 9 and pg 29 of M38 ORD 8 ORD# 7375380 {This pump is also listed TM 9-2320-208-20P (M38A1 Org Maint Parts List as FSN 2910-547-7769 ORD# 8720569)}
2659 = 5592659 Pg 73 of M38 ORD 9 ORD#
2147 = 5592147 Pg 73 of M38 ORD 9 and pg 29 of M38 ORD 8 ORD# 8329527
With hand primer:
2655 = 5592655 Pg 29 of M38 ORD 8 ORD# 8332073
3209 = 5593209 Pg 29 of M38 ORD 8 ORD# 8333104
3249 = 5593249 Pg 29 of M38 ORD 8 ORD# 8720569
4260 = 5594260 Pg 83 of M38A1 ORD 9
4260JJ I think the JJ is a mod level or alteration stamp on a basic 4260
4069 = 5594069 Pg 82 of M38A1 ORD 9
4535
9810 = 1539810 Pg 82 of M38A1 ORD 9
9997

The basic assumption is the fuel pumps with the built in hand priming levers were stock only to the M38A1/M170. In daily practice whatever pump the supply system sent was used on the jeep.

Would the oil in the pump cause starting problems?

Usually not unless it finds it's way through a damaged diaphragm or if it hydraulicly locked the diaphragm to prevent the diaphragm from making adequate pressure.

Finally do not ignore the proper mounting spacer. The military M38/M38A1/M170 fuel pumps require the 9/16" thick spacer PN ORD 8329708, WILLYS 800361. The civvy fuel pumps use a thinner spacer. Wrong spacer or missing spacer will equal flow and/or pressure issues.

Thanks

Number on the flange is 4660
Which I think puts it within the m38a1 ord 9

There was a significant amount of oil within it so I'm thinking hydraulic lock of the diaphragm may well have something to do with it

My question is - will the modification as described be appropriate on my pump?


Thanks

As I said in my notes, the 4460 pump may have had issues which necessitated a mod to the 4460JJ configuration. Let me wade through my fuel pump data to see if I can find a reason for the upgrade.