Mr4btTahoe
Active member
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Hey alls...
Just buttoned up the rebuild on my MEP-003a injection pump (Ambac M50) and documented the process. Member "jamawieb" gave me a write up on the tear down and it was very straight forward.
I'll post his write up in steps with pictures from my rebuild and some details on what I had to do.
--
Removed from engine
![44527274640_d0e490c3bf_k.jpg 44527274640_d0e490c3bf_k.jpg](https://www.steelsoldiers.com/data/attachments/514/514997-d62a5759099436331d991dede6e9db31.jpg)
On the bench ready for disassembly. Be sure to MARK the pump body and housing as far as orientation goes!
![46306598202_c50c835dde_k.jpg 46306598202_c50c835dde_k.jpg](https://www.steelsoldiers.com/data/attachments/515/515112-77e26cf375e2409f17953c829df8ad70.jpg)
Step 1 - Take the throttle linkage out (take the flat head screws out and then it slides out). Mine was stuck pretty good so a couple flat screw drivers and a bit of prying was in order.
![46357426841_d9dd9945dd_k.jpg 46357426841_d9dd9945dd_k.jpg](https://www.steelsoldiers.com/data/attachments/515/515113-dc369b9021daa33b8fd18f86acab2f1c.jpg)
Make sure this little piece came out with it. It sticks in the end of the throttle shaft.
![45444960055_83d737fb13_k.jpg 45444960055_83d737fb13_k.jpg](https://www.steelsoldiers.com/data/attachments/515/515117-d6836aa18be6bf2044bc6490ef22280f.jpg)
Step 2 - Back the inlet and outlet adapters out or take them out completely. (I removed them)
![44540678240_5330b81e0e_k.jpg 44540678240_5330b81e0e_k.jpg](https://www.steelsoldiers.com/data/attachments/515/515114-964166b4e5a95b4a60c5b2b1d0fd26f4.jpg)
Step 3 - Take the 4 allen screws off the housing and then push the pump out of the housing. (On mine, this took a bit of effort. I used a thin putty knife and tapped it between the pump and housing at the lip where the 4 clamp screws held it in place. Then gradually worked it up taking care not to damage the housing.)
![45634446994_0e6dfc38bb_k.jpg 45634446994_0e6dfc38bb_k.jpg](https://www.steelsoldiers.com/data/attachments/515/515115-e9e2b6dc355b83a80e4732811d30f8f7.jpg)
![32485448178_d2eb1ad1eb_k.jpg 32485448178_d2eb1ad1eb_k.jpg](https://www.steelsoldiers.com/data/attachments/515/515116-14479f3cee8e853898b8848481663a05.jpg)
Step 4 - Remove the big c-clip off and separate the pump, you'll have the gear set in one hand and the ports for the injectors in the other.
![32485401368_9055f6c95c_k.jpg 32485401368_9055f6c95c_k.jpg](https://www.steelsoldiers.com/data/attachments/515/515118-1cb344b7f4cc736ed6c66c308d0345e1.jpg)
The gear set will have the plunger sticking out of it and if you look at the end, that the plunger is protruding from, you'll see a flat piece, that is the plunger guide. The plunger guide will be broken in half or it will be rounded off, where the plunger will just spin.
Step 5 - take the cap off the end of the gear set. (Pry it up with a flat blade screw driver carefully. Just an o-ring holding it snug). When you take the cap off you'll see the button under it.
Step 6 - There is a little clip that holds the button in place that has to be removed. I use a little pick to pick it out but be careful because it will fly off and you'll never find it. (I placed the entire assembly in a gallon ziplock bag and used a pick to work the clip loose. When it popped off, it was caught by the bag.)
![31418110477_bb44e799b4_k.jpg 31418110477_bb44e799b4_k.jpg](https://www.steelsoldiers.com/data/attachments/515/515119-6ff76d04eb2d40feff5266da610c40c6.jpg)
From let to right... Cap (tappet), wire clip, timing button.
![46357346691_f21b5b546f_k.jpg 46357346691_f21b5b546f_k.jpg](https://www.steelsoldiers.com/data/attachments/515/515120-80b3f523b7c5d4c4fa95ace40e84bd17.jpg)
Step 7 - After you remove the button. You'll see the end of the plunger under the spring. It's held in place with 2 half circles (best way I know how to describe), you have to depress the spring and get the half circles out. This is the hardest part of the whole thing. I have a pair of need nose vice grips that I cut the nose off of to make them flat. Then set them far enough apart to go around the plunger so I can put the plunger on a hard surface (Like a desk) and depress the spring with the vice grips to get the half circles out. (This is setup just like a valve spring/retainer. I just used some needle nose pliers to push down on the retainer while the plunger was held in a vice with soft jaws. Then a magnet to pull the little clips up out of the retainer.
![45634375214_b8760470ad_k.jpg 45634375214_b8760470ad_k.jpg](https://www.steelsoldiers.com/data/attachments/515/515122-a1c5d75feb5e2d1d5c321271f211b92f.jpg)
The little clips are on the right. Spring/retainer under the tappet and to the left of the spring/retainer is a spring shim (that is under the spring when assembled).
![31418088327_af5d710459_k.jpg 31418088327_af5d710459_k.jpg](https://www.steelsoldiers.com/data/attachments/515/515123-caed450711c8f08dc90d5ec80ba47a75.jpg)
Step 8 - Remove the spring, plunger and guide.
Plunger
![45634357694_a5328d6444_k.jpg 45634357694_a5328d6444_k.jpg](https://www.steelsoldiers.com/data/attachments/515/515124-3e733cb221b58a064cb36678190232a2.jpg)
Plunger guide. This is the item that likes to fail after the pump sits and gets gummed up. Mine was nearly rounded out in the center and cracked.
![31418100847_641e9fb242_k.jpg 31418100847_641e9fb242_k.jpg](https://www.steelsoldiers.com/data/attachments/515/515125-6e4164bf945573d1bc3eb620c3456a93.jpg)
Put back together with new plunger guide and everything clean. When I reinstalled the retainer clips, I placed them on top of the retainer. When I pushed down the retainer using the needle nose pliers, I nudged the clips into the hole and they worked themselves into place. Very easy.
![46357314231_4d6f30e087_k.jpg 46357314231_4d6f30e087_k.jpg](https://www.steelsoldiers.com/data/attachments/515/515126-6fb71f00a4a953cd5d3f1815ef65d01e.jpg)
New plunger guide in place.
![44540567030_f5220d43d5_k.jpg 44540567030_f5220d43d5_k.jpg](https://www.steelsoldiers.com/data/attachments/515/515127-be52b13d5476c537a4067ea730e106b7.jpg)
Timing button back in position with wire lock in place.
![31418050417_1137121088_k.jpg 31418050417_1137121088_k.jpg](https://www.steelsoldiers.com/data/attachments/515/515128-288ef2a43d65560788e4caa2f4c61cf7.jpg)
Tappet back in place.
![45634321894_981519590e_k.jpg 45634321894_981519590e_k.jpg](https://www.steelsoldiers.com/data/attachments/515/515129-775e6db78afea6433d1afd9fcc30b2c9.jpg)
Delivery valve components. Cap, Holder, Spring, Valve, and tiny spacer (orange piece).
![31418034287_ea13a689af_k.jpg 31418034287_ea13a689af_k.jpg](https://www.steelsoldiers.com/data/attachments/515/515130-de6ebef174561bae1efacd91c064afd2.jpg)
Just buttoned up the rebuild on my MEP-003a injection pump (Ambac M50) and documented the process. Member "jamawieb" gave me a write up on the tear down and it was very straight forward.
I'll post his write up in steps with pictures from my rebuild and some details on what I had to do.
--
Removed from engine
![44527274640_d0e490c3bf_k.jpg 44527274640_d0e490c3bf_k.jpg](https://www.steelsoldiers.com/data/attachments/514/514997-d62a5759099436331d991dede6e9db31.jpg)
On the bench ready for disassembly. Be sure to MARK the pump body and housing as far as orientation goes!
![46306598202_c50c835dde_k.jpg 46306598202_c50c835dde_k.jpg](https://www.steelsoldiers.com/data/attachments/515/515112-77e26cf375e2409f17953c829df8ad70.jpg)
Step 1 - Take the throttle linkage out (take the flat head screws out and then it slides out). Mine was stuck pretty good so a couple flat screw drivers and a bit of prying was in order.
![46357426841_d9dd9945dd_k.jpg 46357426841_d9dd9945dd_k.jpg](https://www.steelsoldiers.com/data/attachments/515/515113-dc369b9021daa33b8fd18f86acab2f1c.jpg)
Make sure this little piece came out with it. It sticks in the end of the throttle shaft.
![45444960055_83d737fb13_k.jpg 45444960055_83d737fb13_k.jpg](https://www.steelsoldiers.com/data/attachments/515/515117-d6836aa18be6bf2044bc6490ef22280f.jpg)
Step 2 - Back the inlet and outlet adapters out or take them out completely. (I removed them)
![44540678240_5330b81e0e_k.jpg 44540678240_5330b81e0e_k.jpg](https://www.steelsoldiers.com/data/attachments/515/515114-964166b4e5a95b4a60c5b2b1d0fd26f4.jpg)
Step 3 - Take the 4 allen screws off the housing and then push the pump out of the housing. (On mine, this took a bit of effort. I used a thin putty knife and tapped it between the pump and housing at the lip where the 4 clamp screws held it in place. Then gradually worked it up taking care not to damage the housing.)
![45634446994_0e6dfc38bb_k.jpg 45634446994_0e6dfc38bb_k.jpg](https://www.steelsoldiers.com/data/attachments/515/515115-e9e2b6dc355b83a80e4732811d30f8f7.jpg)
![32485448178_d2eb1ad1eb_k.jpg 32485448178_d2eb1ad1eb_k.jpg](https://www.steelsoldiers.com/data/attachments/515/515116-14479f3cee8e853898b8848481663a05.jpg)
Step 4 - Remove the big c-clip off and separate the pump, you'll have the gear set in one hand and the ports for the injectors in the other.
![32485401368_9055f6c95c_k.jpg 32485401368_9055f6c95c_k.jpg](https://www.steelsoldiers.com/data/attachments/515/515118-1cb344b7f4cc736ed6c66c308d0345e1.jpg)
The gear set will have the plunger sticking out of it and if you look at the end, that the plunger is protruding from, you'll see a flat piece, that is the plunger guide. The plunger guide will be broken in half or it will be rounded off, where the plunger will just spin.
Step 5 - take the cap off the end of the gear set. (Pry it up with a flat blade screw driver carefully. Just an o-ring holding it snug). When you take the cap off you'll see the button under it.
Step 6 - There is a little clip that holds the button in place that has to be removed. I use a little pick to pick it out but be careful because it will fly off and you'll never find it. (I placed the entire assembly in a gallon ziplock bag and used a pick to work the clip loose. When it popped off, it was caught by the bag.)
![31418110477_bb44e799b4_k.jpg 31418110477_bb44e799b4_k.jpg](https://www.steelsoldiers.com/data/attachments/515/515119-6ff76d04eb2d40feff5266da610c40c6.jpg)
From let to right... Cap (tappet), wire clip, timing button.
![46357346691_f21b5b546f_k.jpg 46357346691_f21b5b546f_k.jpg](https://www.steelsoldiers.com/data/attachments/515/515120-80b3f523b7c5d4c4fa95ace40e84bd17.jpg)
Step 7 - After you remove the button. You'll see the end of the plunger under the spring. It's held in place with 2 half circles (best way I know how to describe), you have to depress the spring and get the half circles out. This is the hardest part of the whole thing. I have a pair of need nose vice grips that I cut the nose off of to make them flat. Then set them far enough apart to go around the plunger so I can put the plunger on a hard surface (Like a desk) and depress the spring with the vice grips to get the half circles out. (This is setup just like a valve spring/retainer. I just used some needle nose pliers to push down on the retainer while the plunger was held in a vice with soft jaws. Then a magnet to pull the little clips up out of the retainer.
![45634375214_b8760470ad_k.jpg 45634375214_b8760470ad_k.jpg](https://www.steelsoldiers.com/data/attachments/515/515122-a1c5d75feb5e2d1d5c321271f211b92f.jpg)
The little clips are on the right. Spring/retainer under the tappet and to the left of the spring/retainer is a spring shim (that is under the spring when assembled).
![31418088327_af5d710459_k.jpg 31418088327_af5d710459_k.jpg](https://www.steelsoldiers.com/data/attachments/515/515123-caed450711c8f08dc90d5ec80ba47a75.jpg)
Step 8 - Remove the spring, plunger and guide.
Plunger
![45634357694_a5328d6444_k.jpg 45634357694_a5328d6444_k.jpg](https://www.steelsoldiers.com/data/attachments/515/515124-3e733cb221b58a064cb36678190232a2.jpg)
Plunger guide. This is the item that likes to fail after the pump sits and gets gummed up. Mine was nearly rounded out in the center and cracked.
![31418100847_641e9fb242_k.jpg 31418100847_641e9fb242_k.jpg](https://www.steelsoldiers.com/data/attachments/515/515125-6e4164bf945573d1bc3eb620c3456a93.jpg)
Put back together with new plunger guide and everything clean. When I reinstalled the retainer clips, I placed them on top of the retainer. When I pushed down the retainer using the needle nose pliers, I nudged the clips into the hole and they worked themselves into place. Very easy.
![46357314231_4d6f30e087_k.jpg 46357314231_4d6f30e087_k.jpg](https://www.steelsoldiers.com/data/attachments/515/515126-6fb71f00a4a953cd5d3f1815ef65d01e.jpg)
New plunger guide in place.
![44540567030_f5220d43d5_k.jpg 44540567030_f5220d43d5_k.jpg](https://www.steelsoldiers.com/data/attachments/515/515127-be52b13d5476c537a4067ea730e106b7.jpg)
Timing button back in position with wire lock in place.
![31418050417_1137121088_k.jpg 31418050417_1137121088_k.jpg](https://www.steelsoldiers.com/data/attachments/515/515128-288ef2a43d65560788e4caa2f4c61cf7.jpg)
Tappet back in place.
![45634321894_981519590e_k.jpg 45634321894_981519590e_k.jpg](https://www.steelsoldiers.com/data/attachments/515/515129-775e6db78afea6433d1afd9fcc30b2c9.jpg)
Delivery valve components. Cap, Holder, Spring, Valve, and tiny spacer (orange piece).
![31418034287_ea13a689af_k.jpg 31418034287_ea13a689af_k.jpg](https://www.steelsoldiers.com/data/attachments/515/515130-de6ebef174561bae1efacd91c064afd2.jpg)
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