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+--- Thread: Yet another gear pump fuel leak..... (/showthread.php?tid=8038)
Yet another gear pump fuel leak..... - SquareOne - 02-10-2022
CM2350, so yep the fun fuel pump. Seeing if anyone has experienced this issue...
I recently noticed the fuel pump at the very back had a slight wetness across the bottom. After cleaning and hunting, it appears there is a 'weep' hole (at least that's what it reminds me of) at the rear of the pump on the engine side. It can only be seen with a mirror. Doesn't appear to be serviceable. This leak is on the same component on the pump that the 2 main fuel lines are connected. It is on the engine side of that block. Has anyone experienced this issue? Is there a fix or is it strictly a replacement. Quickserve only shows one o-ring for this which doesn't seem to be what would fix it.
Literally just put a head assembly on not too long ago, so that would be a pain to have to purchase the entire pump for this leak.
RE: Yet another gear pump fuel leak..... - JMBT - 02-10-2022
I had a leak between the main fuel pump and the gear pump on my 2250 at about 600k. I had not update the original 3 cyl fuel pump yet, it still had the ceramic plungers,. I went to get a gasket, and Cummins said they were no longer servicing the old style pump. So I updated the whole thing. New pump, new lines, (required for the new pump) and the gear pump came already on it for $4800.00. $4800.00 to fix a fuel leak! WTF! I would say the oring or a gasket should fix it on the 2350, as you probably already have the new style 2 cyl. steel plunger pump.
RE: Yet another gear pump fuel leak..... - SquareOne - 02-10-2022
Yep, it’s the new style 2cyl and everything’s been replaced just recently as I know the history of these bombs.
My issue is that I start to think, ‘why would there be a weep hole?’ Im wondering if the hole is there to release the fuel the seal begins to fail (much like a water pump). If that’s the case, it may not be serviceable or repaired with just the oring.
Damn PITA fuel pumps !
RE: Yet another gear pump fuel leak..... - SquareOne - 02-10-2022
So digging wayyy down into the ole interwebs, it appears that yes the entire pump would have to be replaced as the fuel out of the weep hole is an issue with the front seal on the low side of the gear pump...great......
I also noticed where now it may be possible to get just that low side pump....now that would be fantastic! I'll keep you guys updated on this saga.
RE: Yet another gear pump fuel leak..... - Rawze - 02-11-2022
(02-10-2022 )JMBT Wrote: I had a leak between the main fuel pump and the gear pump on my 2250 at about 600k. I had not update the original 3 cyl fuel pump yet, it still had the ceramic plungers,. I went to get a gasket, and Cummins said they were no longer servicing the old style pump. So I updated the whole thing. New pump, new lines, (required for the new pump) and the gear pump came already on it for $4800.00. $4800.00 to fix a fuel leak! WTF! I would say the oring or a gasket should fix it on the 2350, as you probably already have the new style 2 cyl. steel plunger pump.
If you got 600k miles out of a set of ceramic plungers.. you should have counted your lucky stars!. Even the newest steel/titanium plungers have to be replaced every 400k miles (8,000 hours) of use.
RE: Yet another gear pump fuel leak..... - SquareOne - 02-11-2022
Just to add a little info...
After plenty of hunting and loads of calls, I finally (fingers crossed) have the low side of the fuel pump on its way. I ran into a $hitload of businesses claiming it was in stock, but when I would try to purchase they would tell me it was on backorder...(wtf?). For those that are interested, these are the part numbers:
- 4307482RX - Pump - yes, it's a Cummins reman, but good luck finding new. I think the new ones are saved for the entire pump assembly. Quickserve will also show part number 4307438 for that particulat image within the parts diagram, but apparently it's either been superseded or it is invalid.
- 4903514 - Oring between the low / high side pump. Probably a .20 cent oring Cummins wants to charge $25 for....helluva markup right!
Total cost is just over $900 with tax. No fun, but much better than a 5k pump assembly!
I'll update once the parts arrive.
*** This is what the low side looks like. It's attached to the back of the high pressure fuel pump assembly. The small hole you see is the 'weep hole' which fuel will pass (when the shaft seal fails) in order not to be pushed through the seal of the main pump thus mixed in the engine oil. The side you are viewing would be the engine side. The 2 fuel ports on top would be viewed from above for reference.
RE: Yet another gear pump fuel leak..... - SquareOne - 02-15-2022
For anyone who may go through this in the future, here's a little info I came across...
- The new (reman) gear pump arrived today and I was surprised and a little pi$$ed they sent me the wrong part. I gave them very specific instructions and they still got it wrong...or so I thought. After some digging, I realized there was a TSB Cummins issued on this matter. It is TSB130044 (New fuel pump gear pump w/ revised fuel line locations).
Apparently there are older versions of the gear pump (3 cylinder and some early 2 cylinder) which have the 2 fuel lines located on the bottom of the low psi gear pump. During the reman process, the lower port pump cores were plugged and machined with new ports at the top for the most current design. Upon first inspection you may assume you have the wrong part, but it will be the correct one. However, if you have an older design, you will have to purchase the correct fuel lines to be used with the new pump as well. The TSB will break down the different items you will need for your particular application.
Below are pics of the remanned, lower port pumps. You can see on the bottom where the old fuel locations once were are now plugged.
RE: Yet another gear pump fuel leak..... - SquareOne - 02-24-2022
It's been about a week and I have around 3k miles on the replacement pump. It appears to be doing what it's supposed to do. I'm always skeptical of reman, but sometimes you don't have a choice in the matter. All in, the cost of the pump was just over $700 once the core was returned. The prices I had received on this pump were $3-400 different depending on where I looked. It pays to shop around.
Labor wise, other than being a little bit of a pain in the a$$ because of the truck (Cascadia), this is quite literally a 45min to an hr job once you have the part painted and ready to be installed. That time is including clean-up as well. The truck you're installing this in will most likely be what determines the length of time. One thing to note, be ready for some lube oil to come out once you break the low side pump free from the high side. Just have a catch pan ready.
* - A few interesting things to note.... When the old pump was removed and inspected, I could feel the endplay in the pump shaft. It was def more than the reman. Also, when turning the shaft back and forth, I could hear a metal to metal sound (think the same sound as a wore U-joint on a much smaller scale). This sound or feeling was not present on the reman pump. The old pump was certainly leaking fuel from the weep hole as some drained out when it was on it's side. It had about 550k miles when removed.
Lastly, something I didn't expect was the absence of that weird harmonic 'hum' these fuel systems produce. If you own one of these (cm2250 or 2350, not sure about the newer models), you know the sound I'm talking about. Occurs around 700rpm - 850rpm or so and is annoying as hell. Sounds like a damn brass band trying to hit a note to get in tune... (I believe there was another post on here where Mr.Hagg had mentioned the cause.) Regardless, it's an aggravating sound. Once you hear it, you'll wait for it at every time you drop back to low idle. This week, I haven't noticed that sound one time and without a doubt it had been present prior to the pump replacement. In fact, that sound became much more frequent within the last few months. Where at one time it would come and go, lately it seemed to be staying for longer periods without a break.
PM me if anyone needs any help with this. Again, it's simple and relatively cheap job considering this WILL put you on side the road if the seal completely fails. If your fuel milage is slipping, maybe check that weep hole for a leak. At nearly 4 bucks a gallon and climbing, I don't want any fuel escaping the path it needs to be on.