CUCV electric lift pump options and some help on understanding?

[hodgeb]

I've perused the forum and done a fair amount of web searching to find the 'ideal' answer to this question, and I've come across a couple prevalent recommendations for electric lift pumps for the CUCV:

* Get a "universal Carter" lift pump. Nobody I have seen on the forums has posted any information about which specific model they've used.
* Use DELPHI #HFP905, which is the lift pump from an 88-93 era C/K diesel truck (or van, in some cases). This appears to put out 10-14psi.
* Get an Airtex E8153, also a 10-14 psi lift pump.

I'm a little confused by this information/recommendations, because the only universal Carter pumps I'm seeing are the P4389 (rotary inline, 4-6 psi), P4603 (12-14 psi) and P60504 (3-4 psi). There are probably others, those are just the only ones I've looked up. This is with additional understanding that the DB2 wants (iirc - can't find the spec right now) 5-6 PSI at the inlet (though not too much of a problem because whatever doesn't get used just recycles to the tank - as long as the electrical is pumped) and that the OEM mechanical lift pump puts out 7-12 PSI (again, IIRC based on the last time I found that info, can't find it now).


Basically what I'm trying to understand is this: what's the ideal lift pump rate for the 6.2, and does it really matter if you're running an electric lift pump exclusively without the mechanical pump in the loop? My understanding is that a higher PSI than the mechanical, with the mechanical pump still in place, will potentially result in the electric pushing things out of place which should not be pushed out of place.


I will add that I've got a G30 with a 6.2l; I put a Carter P60504 (4psi max) on at the recommendation of a friend who appears to have the identical pump on his CUCV. It worked well until the mechanical pump died, at which time I bypassed the mechanical pump and it still works well (or at least, it has in the 2500 miles, including 1800 trip miles, since). However, 4psi is supposedly less than the IP needs, per my understanding.


Could someone help clear this up for me?


Much appreciated!

 

[panzerwillie]

Both of my 6.2 are running electric pumps with out the mechanical one im using a 96 6.5 stock GM pump the other a of the shelf pump universal type they being running for a few years hope this helps

 

[southdave]

The pump preasure was a concern for me too.. but you have to look at how everything is put together. The pump psi for mech. is delivery preasure. the electric is the out put..
there is a preasure drop at the filters. I belive the stock filters are 10 or 15 microns. also dont forget the pre pump diesel screen/filter needs to be installed if electric pump is to be used..you will be fine using 10 15 psi pump..

 

[hodgeb]

The pump preasure was a concern for me too.. but you have to look at how everything is put together. The pump psi for mech. is delivery preasure. the electric is the out put..
there is a preasure drop at the filters. I belive the stock filters are 10 or 15 microns. also dont forget the pre pump diesel screen/filter needs to be installed if electric pump is to be used..you will be fine using 10 15 psi pump..

Well, like I said, I've got a 4 psi MAX pump (the Carter inline pump) running on my G30 van, now. It seems to do OK with the winter thickening of the fuel, and I've got a friend who's been running his identical pump for 5? years now (over 100k). So I'm sure whatever PSI will work; but what's ideal?

I'm leaning towards picking up the Carter rotary 10-15psi pump if I can't find the stock 6.5 electric pump anywhere.

 

[MarcusOReallyus]

Because the fuel that isn't used will recirculate, I doubt that it matters much, as long as you don't get too carried away. For example, if you had a pump putting out 50 PSI, I suspect you'd cause some problems!

But, based on all the comments I've read about people using different pumps with different pressures, I'd say anything reasonable (Say somewhere in the 4-14 PSI range) should work just fine, and you should find the best deal on a quality pump, and just go for it.

Beware of analysis paralysis!

 

[chevyCUCV]

I use a 10psi walbro pump.

Any more and you get close to affecting transfer pump pressures inside the ip and therefore the timing.

 

[DriverSideImpact1008]

Might as well go with the higher pressure. Better to have and not need, than need and not have. You want a good flow of fuel to the injector pump. You definitely wont hurt anything by having 10-15psi.

I have the airtex in my M1009. Got it from SummitRacing for around $50. It has worked well so far. The smoke is a little darker colored when it cold starts now, probably a combo of more fuel to the IP and timing advanced a little.

I can't speak to the other brands. I think I put a Delco or Delphi pump from Napa in my old M1008. The guy I sold to said there were no probems with it a couple years later.

 

[grantcourtney]

I have a Walbro FRB-5, about $150, on my Blazer and bought it online from Leroy Diesel, they specialize in the 6.5 and 6.2 and were very helpful to me. It is the closest to pressure compared to the mechanical pump and many people use it to pump waste vegetable oil. I recommend putting a 25 - 30 micron filter between the tank and the pump to protect the pump. I put a water separator 25 micron filter and mounted it under the floorboard directly behind the transfer case to protect it. The pump fits well between the frame and body rail just behind the passenger door. With it mounted on the outboard side of the frame it is protected from the heat of the exhaust since this is where the muffler is. On the inside of the frame the 2 metal fuel lines break and are connected by a short length of rubber hose. I just tapped into the steel fuel lines and went to the fuel filter and then to the pump and back into the steel line heading toward the motor. You can remove the mechanical pump and just put a short length of rubber fuel line to bypass the mechanical pump. A fuel pump delete cover for a 350 chevy will cover where the mechanical pump is mounted. You should put a relay very close to the pump to protect it electrically. One wire is connected to the battery, one to the ignition and one to ground. Hope this helps! It is working out very well for me.

 

[DXTAC]

I have the Airtex in my 1009 running off a separate switch and NOT the ignition. I did this primarily because I use a spin-on filter and this makes it VERY easy to prime the filter after a filter change. I haven't had a problem and that was about 10K ago??? I removed the mechanical pump and installed a block. May have gained a 1/2 horse or so?!?! J/K