Fuel Injection Pump Slow Drip -- Anything to Try Before Removing the Pump?

[texas-alex]

Howdy!

New owner of a gov planet USMC M1151A1 that runs and drives great, but has slow fuel drip when running. This is the first HMMWV I've ever owned, so I've been learning a lot as I go. I changed all the fluids (geared hubs, diffs, transfer case, trans, engine oil, coolant, and power steering) and have been adding the 'street legal-ing' pieces like windshields and license plate holders and such. It fires up first try every time, never studders or stalls, but I notice small drips of what appeared to be diesel dripping from below after the motor runs.

Troubleshooting lead to the engine valley drain, which in turn appears to be getting filled up by drips coming off of the Fuel Injection Pump.

Here is where the drip is forming (drip in center of frame, about to fall into engine valley), as viewed from the back passenger side of the engine valley. Worth noting is that there's a hose clamp sitting right under the Injection Pump, and I can't find a hose nearby that's missing one.




The passenger side of the Injection Pump looks like it may be corroded. I didn't see any drips from there, but possible the fuel is leaking out here and just running down to the bottom of the pump.




Has anyone seen this before?

Any things to check for before pulling the Injection Pump?

 

[nairb]

That seems to be pretty common, mine was rusted in the same spot after sitting in Georgia with water in the engine valley for who knows how long. Afraid you’re in for a pump rebuild.

 

[patracy]

Yeah, unfortunately it needs to be rebuilt. You can try stop gaps like adding some oil to the fuel to thicken it up. But there's nothing that will fix a dried up/leaking seal.

 

[Retiredwarhorses]

Advance servo plunger…there is an o-ring that fails, but the steel plunger is rusted out, the plunger should be able to move, its frozen now.
folks have replaced that piece and had some luck, I have maybe some pumps in the shop that it could be removed from, but generally I would replace the pump With a rebuild or new pump…I only buy my pumps from HPG, this way they are warranted.

 

[texas-alex]

Thanks folks! That's what I was afraid of, but figured it was worth asking. I'll plan on replacing with a new/rebuilt pump.

@Retiredwarhorses Good tip on the HPG warranty. I'm not seeing the part number (DB2831-5079) that this pump has on it on his site, do you know if there are other models in the DB2831 family that would have the same connections and on the 6.5L turbo?

 

[Retiredwarhorses]

There are several other pump models in the evolution of the pumps, best is to call Dave and he will help you out.

 

[cwc]

It's not that bad of a job to replace the seal, and a lot less expensive, if that matters. I would consider it if the pump is otherwise operating OK. See thread "Weepy Injection Pump". You would want to make sure it is actually the advance plunger leaking and not the front shaft seal (which will drip from a weep hole at the front bottom of the pump). It would be a good idea to also replace the plunger and the o-ring. Note that the seal and the O-ring have GM part numbers (22530034 and 15529637). Also, it is not necessary to grind the whole wrench as thin as shown in the TM, just at the bottom where the clearance is tight.

 

[texas-alex]

It's not that bad of a job to replace the seal, and a lot less expensive, if that matters. I would consider it if the pump is otherwise operating OK. See thread "Weepy Injection Pump". You would want to make sure it is actually the advance plunger leaking and not the front shaft seal (which will drip from a weep hole at the front bottom of the pump). It would be a good idea to also replace the plunger and the o-ring. Note that the seal and the O-ring have GM part numbers (22530034 and 15529637). Also, it is not necessary to grind the whole wrench as thin as shown in the TM, just at the bottom where the clearance is tight.

This is excellent, thanks for sharing. Definitely makes sense to try this first if it is the advance plunger seal leaking. "weepy" is a good word (I had searched for "leaking" and "dripping" but hadn't stumbled on that thread, thanks for passing the info along)

I'll see if I can wash some of the gunk off and get a better camera angle to confirm that the leak is coming from this plunger and not that front weep hole, and then give this a shot.

 

[texas-alex]

Feel pretty confident it is that seal now. I had the epiphany that if I parked with the front right side of the vehicle on a slight decline, that would prevent the forward weep hole from running back to where it was dripping and could rule that out. I cleaned and let dry the engine valley, then positioned camera carefully and recorded when the engine started. Almost immediately leaks out of the pressure advance seal, and with the slight right angle the drop now accumulates on the bottom of the pressure advance plug.


Two min video showing leak, engine starts at 42 seconds in: https://www.veed.io/view/7ec09f96-7192-4b78-8b04-d09f9060cbe2?panel=share

in case video doesn't work, right before starting

and ~10 seconds after the engine starts and the PA plunger moves outward, with a drop of diesel already forming:


The pump is working fine other than this, so I reckon it's worth trying. Now if I could just find these seals in stock somewhere!

 

[Mogman]

Feel pretty confident it is that seal now. I had the epiphany that if I parked with the front right side of the vehicle on a slight decline, that would prevent the forward weep hole from running back to where it was dripping and could rule that out. I cleaned and let dry the engine valley, then positioned camera carefully and recorded when the engine started. Almost immediately leaks out of the pressure advance seal, and with the slight right angle the drop now accumulates on the bottom of the pressure advance plug.


Two min video showing leak, engine starts at 42 seconds in: https://www.veed.io/view/7ec09f96-7192-4b78-8b04-d09f9060cbe2?panel=share

in case video doesn't work, right before starting
View attachment 886219
and ~10 seconds after the engine starts and the PA plunger moves outward, with a drop of diesel already forming:
View attachment 886220

The pump is working fine other than this, so I reckon it's worth trying. Now if I could just find these seals in stock somewhere!

Good video, yep that confirms it!!

 

[87cr250r]

Diamond Diesel sells OEM seal kits for the DB2 pumps. They're about $100 for a kit. I don't know anywhere you can get individual parts, maybe John Deere. They used a lot of DB series pumps on their engines.

 

[texas-alex]

Thanks! I'll check Diamond Diesel. I had seen a few kits from Stanadyne, like this one that looks like it's got all the seals and o rings. https://altamontediesel.com/shop/ols/products/stanadyne-db2-rebuild-kit-oem-gaskets-and-seals

Only thing is it doesn't look like it's got the plunger or the plug (which might not be necessary to replace, but do look a bit rusty). Maybe Diamond Diesel would have those? Haven't had any luck finding either plunger or plug in stock anywhere, but will do a bit more digging and then likely end up just getting a kit and just cleaning the plunger as much as possible

 

[cwc]

Adventure Accessories shows the plunger in stock: https://adv4x4.com/5740647.html

If you go to "Fuel system parts" on the website, they have a part 5742445 that looks like the plug, but it could be for the opposite side of the pump, in which case the hole would not go through. HPG has a listing for 5742445 also and lists NSN 5340-01-439-6455. Website wbparts.com crosses this to what looks like a Stanadyne part #28458, but then if you search that it appears to be a reamer for oversizing the advance piston, not the plug.

If you search Stanadyne 28474 for the plug, you'll see a listing on finditparts.com reasonably priced. There has been a lot of discussion here on SS about scam websites. I have no knowledge of this place, but they do have a physical address that maps to what appears to be commercial office space, an updated blog, etc. Please let us know how you come out on the parts. I would try very hard to locate a new plunger given how it looks.

 

[nairb]

I ordered these same parts from finditparts ebay store last summer and had no issues with them. Mine was rusted just the same, maybe worse. Ended up getting a new rebuilt pump because the old one turned out to be unsalvageable.

 

[jaredsalinsky]

hey man! great video. I'm in the same boat - leaky injection pump. I chose to just buy a new IP; I feel like if I just fix 'this one thing' then in a couple months i'll be dealing with some other issue I should have just dealt with while I was there! Also my vehicle is a 'for sale' vehicle so I just want everything tidy'd up for the new owner. (in classifieds check out humvee bug-out vehicle - I just put it on SS the other day) It's been a few months and i've been a little hesitant to try to change the IP myself; so its actually going in today at a nearby diesel mechanic shop for the change! I'll let you know how it goes!

 

[texas-alex]

Hey all, sorry to resurrect a dead thread, it took me a little longer than I care to admit to get around to doing this seal replacement and figured I’d share a few more pictures for whoever stumbles onto this next if nothing else.

Getting the seal and plunger out was actually a lot easier than I expected, while it’s not exactly spacious in there, there is enough room to do the swap without too much finagling.

I did need the ‘ground down’ 1” wrench, I just hit it with a grinder and tried to match the angle of the engine valley as much as possible so that I wasn’t weakening it by taking off more material than needed. Here’s a picture of how much I had to take off.

Hands down the hardest part was those little retention clips that go on the pivot pin of the servo arm. Those fly off very easily and are hard to track down. The thing that helped me the most was having two different lengths of locking tongs. I used these two McMastercard tongs and they were immensely helpful
https://www.mcmaster.com/5383A35/
https://www.mcmaster.com/5383A44/

Since they lock I was able to use them to grab the retention clips by the backside and press them on.

The new seal works perfectly. Been driving it a few weeks now and not a single drop! This was also the last leaking thing on the vehicle, so it was a great feeling getting it done.

Hope this helps anyone else considering this job.

 

[texas-alex]

Also a huge thank you to everyone that contributed and shared info, docs and links for parts!

 

[Gastrap]

I'll be changing this on mine soon with the pump in place, good to see the plunger isn't very long. This advance is a different design from the Deere spec DB2 pumps I usually work on, those don't have an external light-load advance lever and plunger. My valley was full of water when I got the truck, drain tube has since been cleared and chunks of rubber from the old hood support removed.

I have a neat little tool for small e-clips, It's a spring-loaded plunger with a hook that extends from a 6 inch tube to hold the clip. Not any good for removing them, but great for installing!