HVLP lift pump

[RedD250]

Has anyone put on the Cummins HVLP pump? If so, what's your impression of it? The store I got it form claims all kings of things, like more power, lower EGTS, better fuel economy, less smoke and such.

I'll be doing a few performance mods in the near future, so I figure that I might as well make sure my lift pump can keep up. All stock now except for a high flow intake and 4" turbo back straight pipe.

 

[Ozymandias]

From what I know the factory installed liftpump is the Gold Standard.
We are all crying about that loss in the generations that followed after yours.

 

[RedD250]

Well, it's a genuine Cummins part, so hopefully that means it's up to their high standards. I got it put on today. Took about 4-4.5 hours. I forget exactly what time I started. What an absolute nightmare! So much stuff in the way. But I finally did get it. If anybody is considering this, I used this video as a tutorial:

Some additional tips for anynbody considering this:

1. That video makes it look like there is loads of clearance and everything is right there. No. Not at all. Intercooler pipe, master cylinder, brake booster, brake lines, hood hinge... all right in the way lol. You will mostly be working blind.

2. That insulation that needs to be cut... don't ask me how he did it with a razor. It's made of cast iron. I needed a serrated blade to saw through it.

3. Be sure to install the pump with the hard line in place, but slightly loose. It'll make your life much easier, because good luck getting the threads started once the pump is bolted in place. I had to cobble together 3 extensions and use my cordless ratchet to get the firewall side bolt to start. Not ideal, but I had to keep the bolt spinning while I wiggeld the pump around in order to get the threads to bite. Thankfully it didn't cross thread. There is absolutely zero clearance to work. Very poor design. If I had the hardware laying around, I'd have put in a stud and nut instead of a bolt to attach it. That would make it so vastly much easier.

4. When you install the pump, use some masking tape to hold the gasket/spacer sandwich to the pump body so it's not constantly faling off and onto the floor while you thread the hard line up through all the wires.

5. The hard line was off by just a fraction of a hair... just enough to make getting the banjo bolt in a miserable PITA. I finally had to pull the plastic clip that holds the throttle cable in place out of the metal bracket so I could get a socket on it. I had to put a few of those tiny, thin rubber bands and a washer inside the 17mm socket to make a super shallow socket. The bolt is very short, and there's only about 1/4" of threads sticking out to screw into the bolt hole. Since it doesn't quite line up, you can't start it by hand, at least I couldn't, and the shallow socket I had wasn't shallow enough. The bolt kept sliding back into the socket, and the back washer would fall out and it wouldn't bite. The modified socket worked great. I was able to hold the line in place with my left hand and apply enough pressure to the socket with my right. Use a nut driver (I think that's what it's called... a screw driver looking thing with a 1/4" drive on the end instead of a screw driver). It'll make it a lot easier.

By the time you get it on, you will be completely drenched with sweat, your arms and back and legs will be sore as hell, and you will have neologized some creative new profanity.

Now I have 17 PSI at idle. The store I got it from claimed 14. 17 is right at the limit for a stock VE pump, so hopefully I don't have any problems. 18 is the max inlet pressure for these things, according to my research. And that was 30 years ago when they were new.

The main reason I put this pump on was because I was having some problems with my fuel pressure gauge. The gauges I have (GlowShift) are designed to flash the backlighting when signal is lost. I've been back and forth with their tech support for about 3 months now. During that time, everyting has been replaced. Banjo bolt. Snubber valve. Sensor. Wiring harness. The gauge itself. No matter what I do, the thing still flashes randomly while under light load. I know it's not a ground issue, because the gauge is daisy chained to the rest of my gauges, and they all function correctly. I know it's not the daisy chain cable or the daisy chain port on the other gauges, because I have swapped the position of the fuel pressure gauge with other gauges that work, but the problem follows the gauge. The only other thing that could possibly cause loss of signal is a bad lift pump. So I am hoping that this works. Before, my pressure would flutter around between 4 and 4.5 PSI at idle, and my tach (Isspro) would flutter around by about 50 RPM every time it did that, which leads me to believe that there may indeed have been a fuel issue. The tach would also usually flutter when the gauge lighting flashed. I haven't driven it yet, but there is no fluctuation in pressure at idle now. Steady 17 PSI.

 

[Ozymandias]

Thanks for the write up, yeah Gen1 is for sure a pain because it was never meant to install that engine from the beginning. Later Gens came from the drawing board with a proper install.
It's an interesting read how that small team of cummins engineers developed and installed that engine and all the surrounding parts into a vehicle that was built for a V8 gas motor. To say it was thight is a slight understatement.

 

[RedD250]

Well, since it's an inline engine, some things are easier than with a gas V8. It's really not much bigger than the leaning tower of power in the base D150s. The last fuel pump I did was on my '79 CJ5 with the 258. That was a breeze, 10 minutes start to finish. It practically fell out lol.

First impressions of this new HVLP is there is possibly slightly better throttle response. I didn't notice any difference in EGTs. Still 650-700 going up hill maintaining 55 MPH. I took it out for a 50 mile drive in the country (rolled over 200k) and no gauge backlight flickering so far. I typically average around 19 MPG with a peak of 21.5, so hopefully the claim of increased MPG will hold true. I topped off the tank tonight, so I'll know in a week or so. The fuel pressure was stable at 17 PSI when I first cranked it after the install, but now it flutters around between 16 and 18, even while moving with my foot off the gas. Give it gas, and it holds steady at 17. WOT is a steady 17 too, no drop. No increase in boost, still 15 PSI max flat out. No fluttering when under load. I guess fluctuations in inlet pressure must be normal for these engines? I just hope my injection pump doesn't start leaking with that much inlet pressure. I suppose Cummins would not have designed a pump for the VE engines that supplies too much pressure? Time will tell.

 

[AH64ID]

Unless your old LP was starving the motor for fuel it’s unlikely you’ll see any EGT, power, or fuel economy change.

Are you able to adjust the pressure at all? When the VE seal fails from too much inlet pressure it pushes fuel into the crankcase. 3 psi is the minimum for a VE, so if you can turn it down that would be advisable.

 

[RedD250]

No, there's no way to adjust it. It's just a mechanical pump. I will just keep an eye on my oil. I usually check it a couple times a week anyway. If I need to get a built pump with better seals, so be it.