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Discussion Starter #1
Anyone here replace the engine mounted mechanical lift pump with an electric one? If so what specs does that pump have?
Thanks in advance.
 

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Need more info - P-pumps and VE-pumps have different fuel pressure requirements...
 

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Electric pumps are notorious for failing, leaving you dead in the water. You are much better off running a genuine Cummins mechanical lift pump. A p7100 needs a bare min of 25psi under load. More psi is better. The one I run pushes 50psi at 2000 rpm. Better throttle response & performance.
 

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Like Mark said. The mechanical pump is very reliable. Occasionally, might want to check the intake side to be sure the filter screen isn't clogged.
 

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Discussion Starter #6
Mechanical would be great, but this is a marine 4BTA-250 and I have had zero luck finding one. My ESN is 45719493. I have been in contact with a number of Cummins dealers on both coasts and have been told they are NLA. I can't even find an image online. Can't find it on Quickserve. If that is the case my only option is electric. Pictures show what it looks like, thanks for the input.


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Got ya. I believe your style is mechanically driven off of the inj pumps cam. I would check with a certified Bosch dealer & see if they can rebuild the fuel pump. Show them the same pictures. Short of that, yes, you don't have room for the normal mechanical lift pump on side of block, so a 95gph FASS electric would be your only other bet. Good luck.
 

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This is sort of strange. That part you have in the orange circle I've never seen before. The fuel lift pump is normally mounted on the side of the block below the injection pump and driven by a lobe on the cam shaft. Are you sure that is the lift pump? Looks more like some type of regulator valve or check valve. I don't see any source of power that would drive it. I went through every part on Quick Serve and didn't locate a fuel lift pump of any kind. The normal lift pump looks like the one in the photo below.
 

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Discussion Starter #9
Yes that's the lift pump. You can see the primer button towards the top of the circle and the fuel lines in and out. It looks an awful lot like the 6CTA pump. I mean identical to it but can't get a confirmation on that.
 

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With Nascarmark on this, a lot of Bosch inline pumps use similar type lift pumps. It is a plunger style so may just need seals. What is the problem with the current pump?
 

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I see what Mark is talking about. That is one weird lift pump arrangement. I suspect that part may be from Bosch since it's attached to injection pump itself. The marine P7100 is Cummins part 3393633 and Quick Serve doesn't show any parts breakdown. Don't know if a Bosch service center would have any info on that lift pump or not. If you can read the pump ID plate it would have a Bosch number for the whole assembly. Have you contacted someone like Seaboard Marine? They may have a clue. They probably stopped making the 250 HP engines in the late '90's.
 

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Yep, as mentioned, head to a genuine/certified Bosch rebuild shop. Cummins is useless in 90% of cases if you don't have a # for them, as I find they are lazy & won't dig into nothing. In most cases, I've had to stand at the parts desk & go through their books myself to find what I'm looking for.
 

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Discussion Starter #13
Thanks guys. Char I did check with Seaboard but no joy. If I could only find a part number somehow maybe that would help. Nascar, I will look for a Bosch shop, not easy to find here, and especially now I can't even go to the boat as we are in lockdown. Blackduck, I am at my wits end with a hard start issue. Went through the fuel system last year and could not find an air leak. Before I go deeper I want to try a couple of other things, like the fuel pickup tube in the tank, and even pressurize the system to see if there is a leak.
 

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You don't need to get to the boat at this point, just take those pic's of the pump to a Bosch shop.
And your better off pulling a vacuum then pressurizing to check the fuel system, as generally air leaks in & fuel doesn't leak out. Plus seals can seal a leak when pressurized, when the seals are meant to be under vacuum. Hope that makes sense.
 

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Have you checked your overflow valve? Pretty common culprit in p-pump hard starting.
 

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Discussion Starter #16
Nascar, I tried last season to find a vac leak and want to try again this year before I get deeper. I have been looking for a Bosch shop here and have a few more to check.

Yoder, I replaced the overflow last year with a Torkteck (spelling?)
 

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Nascar, I tried last season to find a vac leak and want to try again this year before I get deeper. I have been looking for a Bosch shop here and have a few more to check.

Yoder, I replaced the overflow last year with a Torkteck (spelling?)
Should be good there then, those toktec ofv's are a piece of quality.

That lift pump looks a lot like the one used on a lot of Bosh A and MW pumps in John Deere and International applications. Maybe even the John Deere P-pump as well although I've never worked on one of those.
 

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I did a little looking on the Cummins injection pump part number 3393633 and found reference to a Bosch part number 0 402 744 806. I even found reference to a newer Cummins number 4020189 but not sure about that because these were also some references to Case part numbers for the same pumps and those do not exist. I did find someone who has the 4020189 for sale for $5927.02 but like I said not sure about that one. If that Bosch number is correct, a Bosch service center should be able to bring up an exploded view of that pump and its parts. Someone mentioned the overflow valve as a possible issue. Over time, the spring in those units relaxes and ends up venting most of the fuel back to the tank. That part you should be able to replace easily if necessary. It is located near the front of the pump on the side facing the engine block.
 

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Discussion Starter #19
I did a little looking on the Cummins injection pump part number 3393633 and found reference to a Bosch part number 0 402 744 806. I even found reference to a newer Cummins number 4020189 but not sure about that because these were also some references to Case part numbers for the same pumps and those do not exist. I did find someone who has the 4020189 for sale for $5927.02 but like I said not sure about that one. If that Bosch number is correct, a Bosch service center should be able to bring up an exploded view of that pump and its parts. Someone mentioned the overflow valve as a possible issue. Over time, the spring in those units relaxes and ends up venting most of the fuel back to the tank. That part you should be able to replace easily if necessary. It is located near the front of the pump on the side facing the engine block.
Thanks Char, I will dig into that also. I replaced the OFV last season. Can't get much done now since we are locked down, not allowed out to the boat, this area is like a ghost town.
 

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Yes, recreation at the moment is sort of on the out. I go out at lunch each day to buy food. Go through the drive thru which was my normal way before this plague. Come back home and sit in the truck to eat. Not other extra traveling at all. Did drop by the pharmacy to pick up a prescription yesterday but that was drive thru too. May need to buy fuel in the next week or so but hoping diesel prices will drop some. The rest of the country is sort of living my life style now.
 
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