Cummins replies to liit pump problem

[Todd T]

this is the reply I got from Cummins after asking about the lift pump problems.



here goes;



Summary: lift pump failures

Solution:

Thanks for your E-mail message. We apologize for our delay in responding.

Cummins newest “Midrange” engines (5. 9L and 8. 3L) are electronically controlled and use electric fuel “lift” or “transfer” pumps. The pumps are used in conjunction with Bosch fuel injection pumps to pump fuel from the fuel tank to the fuel filter. Cummins has developed a new high-pressure CAPS fuel system that will eventually be used on all Cummins Midrange product line.

The ‘lift’ pumps are powered by 12V or 24V DC (depending on the electrical system of the truck) and are controlled by the Engine Control Module (ECM). The pumps are centrifugal vane-style pumps, with free-floating vanes that ride in a circular rotor that is offset from the center of the pump chamber. The rotor is turned from below by the motor, and fuel is forced through the pump because of the volume change as the rotor turns and the vanes slide into and out of the rotor, following the walls of the pump chamber.

The electric transfer (lift) pumps have a pressure relief valve that keeps the pressure at roughly 10-12 psi. The ECM can duty-cycle the pump (i. e. , turn power on and off very quickly) to let it produce a fraction of the regulated pressure (i. e. , 5-6 psi during engine cranking).

Earlier mechanically-controlled engines used positive-displacement lift pumps mounted to the side of the block. The lift pump’s plunger follows a dedicated lobe on the camshaft, alternately filling and emptying the pump. The check valve on the inlet closes when the plunger is compressed, forcing fuel through the outlet check valve. The outlet check valve closes when the plunger extends (pushed by an internal spring), allowing fuel to be pulled into the pump chamber. These pumps are not equipped with a pressure relief valve (or regulator), so one had to be installed elsewhere in the fuel system.

These lift pumps are purchased from an outside supplier and they are continually working to improve the quality of their product. There have been several part number changes over the years that represented improvements to the pumps. The supplier receives warranty information from Cummins on pump failures so they can take the appropriate action to make improvements and modifications where necessary.

Thank you for your interest in Cummins power or products. Please let us know if you need assistance in locating the nearest Cummins-authorized distributor or dealer. Please feel free to use our International Dealer Locator: (http://www.cummins.com/partserv/intro.html) found on the Customer Assistance page of the Cummins website (www.cummins.com).

Let us know if have other questions, or if away from your computer, feel free to call us (toll-free, from North America) at 1-800-DIESELS (343-7357), or 1-812-377-5000 (toll call, worldwide, ask for 800-DIESELS).

Regards,



maybe we should all burn down the phone lines with questions, and see if they can "improve the quality" a little faster.



I also asked about recalls or upgrades once a fix is derrived at. they seemed to miss that point though.



this CAPS system they spoke of anyone heard of it?

 

[jqram35]

It does not say anything about what we can do right now, sounds like the run-around to me!

 

[Todd T]

huh, I thought it was just me



I have replied back to them and will keep you posted.

 

[Ron Bissett]

Originally posted by Todd T

this is the reply I got from Cummins after asking about the lift pump problems.



here goes;



Summary: lift pump failures

Solution:

Thanks for your E-mail message. We apologize for our delay in responding.

Cummins newest “Midrange” engines (5. 9L and 8. 3L) are electronically controlled and use electric fuel “lift” or “transfer” pumps. The pumps are used in conjunction with Bosch fuel injection pumps to pump fuel from the fuel tank to the fuel filter. Cummins has developed a new high-pressure CAPS fuel system that will eventually be used on all Cummins Midrange product line.

The ‘lift’ pumps are powered by 12V or 24V DC (depending on the electrical system of the truck) and are controlled by the Engine Control Module (ECM). The pumps are centrifugal vane-style pumps, with free-floating vanes that ride in a circular rotor that is offset from the center of the pump chamber. The rotor is turned from below by the motor, and fuel is forced through the pump because of the volume change as the rotor turns and the vanes slide into and out of the rotor, following the walls of the pump chamber.

The electric transfer (lift) pumps have a pressure relief valve that keeps the pressure at roughly 10-12 psi. The ECM can duty-cycle the pump (i. e. , turn power on and off very quickly) to let it produce a fraction of the regulated pressure (i. e. , 5-6 psi during engine cranking).

Earlier mechanically-controlled engines used positive-displacement lift pumps mounted to the side of the block. The lift pump’s plunger follows a dedicated lobe on the camshaft, alternately filling and emptying the pump. The check valve on the inlet closes when the plunger is compressed, forcing fuel through the outlet check valve. The outlet check valve closes when the plunger extends (pushed by an internal spring), allowing fuel to be pulled into the pump chamber. These pumps are not equipped with a pressure relief valve (or regulator), so one had to be installed elsewhere in the fuel system.

These lift pumps are purchased from an outside supplier and they are continually working to improve the quality of their product. There have been several part number changes over the years that represented improvements to the pumps. The supplier receives warranty information from Cummins on pump failures so they can take the appropriate action to make improvements and modifications where necessary.

Thank you for your interest in Cummins power or products. Please let us know if you need assistance in locating the nearest Cummins-authorized distributor or dealer. Please feel free to use our International Dealer Locator: (http://www.cummins.com/partserv/intro.html) found on the Customer Assistance page of the Cummins website (www.cummins.com).

Let us know if have other questions, or if away from your computer, feel free to call us (toll-free, from North America) at 1-800-DIESELS (343-7357), or 1-812-377-5000 (toll call, worldwide, ask for 800-DIESELS).

Regards,



maybe we should all burn down the phone lines with questions, and see if they can "improve the quality" a little faster.



I also asked about recalls or upgrades once a fix is derrived at. they seemed to miss that point though.



this CAPS system they spoke of anyone heard of it?

Don't know for sure but ,Think its the Commenrail system Bosh has on some eng or some thing like it. We will not get it retro fit you can bet ,

 

[JEMOORE]

Thanks

Thanks very much for the post, Todd T, its helped me with my thinking and concerns on this problem.

 

[DHawthorne]

Sure sounds like Cummins is dancing around the question. I known electric fuel pumps do real good for pressure. I put one on one of my diesel trucks many years ago. They usually don't make 100k before they have to be replaced. My 2000 3500 has 50K on it now and so far I've not had any problems. Its still stock also.



I'm a boat guy. We have two 6BT's at 350HP in a 32ft Prowler in Cape Canaveral, Fl. Nothing in the port can catch it. The new version is 370HP, with our truck engine. They don't use electric pumps on them. Make plenty of fuel pressure to hold 2600 rpm for hours. Might be slightly differant kind of pump, not sure. If I have problems with mine, I gonna check out the mechanical one and see if it can be used. I need to look and see if there is a removalible plate on the engine first. All this talk, without researching it. Anyway just thought I'd throw it in the hat. Oh yeah, also the 6bt used as a generator prime mover at 50KW has a real time life of 35-40 thousand hours before rebuild. Constant

1800 rpm generator.



Dave

 

[Steve St.Laurent]

DHawthorne, the mechanical pump from the 12v won't work without a lot of hassle. The lobe on the camshaft to drive the mechanical pump isn't there. You'd have to swap a 12v camshaft into your 24v - not sure if that would work or not though. Also, the 12v pump puts out WAY too much pressure for the VP44. Already thought of that and canned it .

 

[EMDDIESEL]

Everybody should start saving there broken lift pumps and then all at once, we should mail them all back to them. They will be overwhelmed with them.

 

[Evan A. Beck]

Send 'em COD to boot! heheheh

 

[JSoloman]

We need to keep hammerin on this, til something gets done about it.

 

[JohnE]

The CAPS injection pump has not been an easy nor inexpensive development process for Cummins. Several customers of the 8. 3 or ISC series with CAPS are still getting the pumps replaced under warranty.



The nice part about the electric lift pump is the saving of a sore thumb after a fuel filter change. Instead of pressing the plunger you just cycle the power (ignition) key.



Cheers;

John

<font size=1>I am not affiliated with nor employed by Cummins, Inc. </font>

 

[Mopar-muscle]

well that was a nice tutorial on how and what the lift pump does , not that i know the question , but i'm sure it was not even mentioned ...



steve s. , what do you consider to much pressure for the VP44 ???

 

[Bigsaint]

Todd, thanks for sharing that with us, talk about a lack of response, other than stating that the pumps are manufactured by an outside vendor, who is constantly making upgrades, WTF.



Scott W.

 

[Bigsaint]

While I'm at it, what jacka$$ came up with the great idea of a forward mounted lift pump, DC or Cummins? Seems that's at least half of the battle right there, in fairness to Carter. I have to wonder how long ANY lift pump would survive in THAT location.



Scott W.

 

[TDickerson]

We understand.

These lift pumps are purchased from an outside supplier and they are continually working to improve the quality of their product.

Well lets face it, it all boils down to how much is Cummins going to pay for a lift pump. I'm sure someone out there can make a very reliable one that won't crap out so early, don't you think. But again, it's all about money and profits.

 

[Todd T]

actually it has probably more to do with Cummins not wanting any of thier hair hanging off the truck. what i mean by that is they dont want DC to be responsible for the placement of their ( cummins) pump on DC's truck and then who's lines would they be in between?



you see, that, is why the pump is where its at now. I have been wondering why they dont put a pump submersed in the tank.

 

[John Berger]

Typical Cummins response

Just like the response's I've received from them. Long winded and full of information that tells you a lot without answering your question.

 

[John Berger]

Originally posted by EMDDIESEL

Everybody should start saving there broken lift pumps and then all at once, we should mail them all back to them. They will be overwhelmed with them.

This could be fun. The only bad part about it is that we wouldn't be there to see their faces. I'm in if we can get it organized

 

[Ron Bissett]

Why not a Accumulator in the line to keep min pressure at all times and lesson the need for pump to run all the time? any one ? Just as asever . Ron up and running in Louisville KY

 

[JEMOORE]

Accumulator?

Not sure what you mean by the accumlator? Off the top of my head I don't think it would work. I drove my truck to Lex. Ky. today, first time on trip since installing fuel pressure gauge. If you have read my few previous posts you will know I have just started trying to do my on research on this problem, so please forgive me if I am behind on the subject or repeat simple things you all already know. Again , my lift pump is working fine at this time. On cruise 65-75mph pressure, post- filter, (new filter) for the most part 11psi, light accel. 8-9psi. The electric transfer pump or Lift-Pump runs all the time when the engine is running. I can't see any way to change this. If the fuel will siphon out of the tank when the fuel lines are cut (you guys that have installed pusher pumps will know the answer to this, I don't know but I think I read that it would?) then it would seem to me that the load on the stock pump would be minimal. We will just have to wait and see what you guys find when you examine your failed pumps. At this point it really seems to me foreign material entering the pump must be the problem. Unless its just a bad batch of pumps? Maybe we should do a poll to see where and when our trucks were assembled? Mine was St. Louis, MO 11-98. So far I have not been able to find out what type of screen or filtering device (if any) is in the line between the tank (or in the tank) and pump. What's there guys? I know some of you know. We will figure this one out with time, this part of the system is to simple not to be able to!