M38 fuel pump modification

Post by **wesk** » Tue Apr 12, 2022 11:02 am

The damage that can be done is currently unknown. Probably because you have the first AC fuel pump I have ever seen without the last four digits of it's part number on the flange. If I was in your shoes I would carefully compare the behavior of both of your fuel pumps with the two different arms installed while not bolted to the engine. Specifically the results of different travel limits of the two arms and their associated linkage internal to each pump. I seem to recall a very significant difference in the angles of those two arms. Does the troubled pump have the AC trade markings on it?

horse · Post by **horse** » Tue Apr 12, 2022 12:44 pm

Yes it is a perfect copy of the one in your photo with all the AC markings but no serial number. It has a manual primer lever also.
As you said there is a significant difference in the angle of the two arms especially the foot which can be seen in the link with the article on rebuilding the pump in the downloads.
In the M38 reference guide page 65 there is a good photo of both.

Post by **wesk** » Tue Apr 12, 2022 7:48 pm

If it is a complete correct parts M38A1 manual hand pump style pump then it may be safe to assume it should use the late lever 5593764.

horse · Post by **horse** » Wed Apr 13, 2022 12:07 am

Thanks for confirming that. I will get the parts on order and go from there.

horse · Post by **horse** » Sat Apr 23, 2022 12:53 am

I have now received the new arm 5593764 also pin bush and other associated parts to fit the pump arm.

I have looked through the rebuild manuals and not sure if you can just replace the arm without splitting the pump completely.

Has any body done this swap and would confirm wether you need to open the full pump or not?

Thanks.

Jonathan