Posted: Tue Sep 07, 2010 1:15 am Post subject: M38-A1 FUEL PUMP REBUILD PROBLEM
I haven't found this topic in the archives, but, then, there are a lot of them. If there are articles on this, please point them out.
BACKGROUND: I live overseas, so couldn't go to a reputable USA supplier like Then and Now, so I locally bought a rebuild kit for my fuel/vacuum pump and followed the instructions in the TM 9-1828A manual, but am unable to get the vacuum section to function. The fuel side works great. Although it is impossible to see inside the pump, I think that I have not been able to engage the vacuum link to the vacuum diaphram pull rod. Although I have held the unit over my head, etc. as instructed, I don't get any positive engagement noise. I admit that I did not make the special tool to hold the vacuum diaphram level with the body, but I don't believe that is relevant to this problem. PROBLEM/SYMPTOMS: 1. almost no vacuum at the wipers; 2. pump is hard to install because the rocker arm is spring-loaded into contact with the cam and 3. there is engine oil in the vacuum cover.
Is there some trick to engaging the rod onto the vacuum link? Thanks for the help.
Then the vacuum diaphragm is not functioning or is torn or cut.
Quote:
2. pump is hard to install because the rocker arm is spring-loaded into contact with the cam
This is normal but can be made easier if you place your finger against the pump drive cam and rotate the crank until the cam is as high as it can be.
Quote:
3. there is engine oil in the vacuum cover.
If you have engine oil there then the diaphragm has failed,
The special tool is for insuring the vac diaphragm is unloaded when the cover is installed. It is at this point that you may have damaged the vac diaphragm.
If you followed the pull arm attachment paragraph correctly you should have seen that the arm properly engaged both links before installing the cover. Did you confirm this visually?
Was your fuel pump kit an old surplus NOS kit? If so the diaphragms won't work well with todays gas.
At this point you must pull the pump and open the vacuum section up. _________________ Wes K
45 MB, 51 M38, 54 M37, 66 M101A1, 60 CJ5, 76 DJ5D, 47Bantam T3-C & 5? M100
Thanks, Wes, for the quick reply. I really coulldn't (and still can't) see anything in the area where the pull rod should link up to the vacuum link. Even without the spacer in place, the rocker arm obstructs the view.
I expect that at this point I have ruined the pull rod oil seal since I have extracted and reinserted the pull rod numerous times.
I believe that the kit waas not NOS because it had black, single layer, diaphrams of rubber, not rubberized canvas multi-layer like I removed during the rebuild.
At this point, assuming that the diaphram is damaged, I think that my best bet is to install the civilian pump (without the spacer) that I have and then get the genuine pump to Then-Now the next time that I am stateside. Does that make sense?
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