internal injection pump pressure

rallydiesel · Post by **rallydiesel** » Thu Dec 13, 2007 8:38 pm

I am talking about the replacing the internal transfer pump, not adding a lift pump. The inlet pressure is pretty much constant without a lift pump isn't it? The only ways I can see to increase the internal IP pressure would be 1) increase fuel viscosity 2) decrease the size of the outlet orifice 3) increase the efficiency of the internal transfer pump (by getting new vanes/stator/etc.) 4) adjust the internal pressure regulator thingamabob.

I guess my question is: what is the main cause of low internal IP pressure?

A1-2-A3 · Post by **A1-2-A3** » Thu Dec 13, 2007 8:47 pm

Low internal pressure?

#1 Air in the fuel system
#2 Shaft seal leaking
#3 Vanes or stator worn from water contamination in fuel

Would have to take a survey?

But thats my final answer..

maybe

tawney · Post by **tawney** » Thu Dec 13, 2007 9:02 pm

I think if it's pressure you want, then adjusting the thingamabob with a punch and hammer while a pressure gauge and tachometer are attached is the way to go; it's quick and simple. I've seen several old pumps that could easily be adjusted to specs for pressure so long as the vanes aren't stuck. You should probably also check flow rate while you're at it; specs given previously in this thread.

coke · Post by **coke** » Sat Jan 26, 2008 11:13 pm

This has been made a sticky so I can continue to read and find it.

coke · Post by **coke** » Sun Jan 27, 2008 6:04 pm

Well I adjusted tonight but in an effort to get another 4 psi, I pounded a little too hard and got around 50 at 500 pump rpm, which is increasing too much. So I gotta remove the regulator and pound it back down

coke · Post by **coke** » Sun Jan 27, 2008 8:14 pm

Just to verify my own concerns, to decrease pressure, remove the regulator, grab a punch and put it in the small opening in the bottom of the regulator and pound down which decreases the pressure, same as process for increasing, correct?

libbybapa · Post by **libbybapa** » Sun Jan 27, 2008 9:28 pm

Yes, and go easy next time.

Andrew

coke · Post by **coke** » Sun Jan 27, 2008 9:44 pm

*laugh* Yeah, im going to use a smaller hammer next time. It definitely effected the dynamic advance, I can tell when accelerating. I really can't wait to get it adjusted properly and see what my gains are.

coke · Post by **coke** » Thu Jan 31, 2008 12:44 am

After setting to 43.5 at 500 pump rpm, per spec, my initial results are 47mpg highway/city mix (90%/10% respectively) A huge improvement over the 38 I was getting. Anyone have any other ideas to increase economy some? I have the dreaded AWY so this has some play, and I do have 35psi in all four tires, free rolling wheels, no brakes sticking on.

libbybapa · Post by **libbybapa** » Fri Feb 01, 2008 9:38 am

I have to note that a 23%+ improvement in fuel economy resulted from the adjustment which after acquiring a method of testing the internal pressure is a free adjustment. Fantastic!

Andrew

tawney · Post by **tawney** » Fri Feb 01, 2008 9:12 pm

Just for anybody else with an interest in fuel economy who might be following this topic, I thought I would confirm that my results were similar to Coke's. I got about a 19% improvement in mileage simply by adjusting the internal pump pressure.

The equipment to check it only costs about $50; it will pay for itself many times over if the little diesel is your daily driver.

coke · Post by **coke** » Fri Feb 01, 2008 9:26 pm

I might note that I also increased my tire PSI to 35, and before, some of them were as low as 26 psi, so that probably played a bit in the fuel economy as well, but I attribute the increase mostly to the pressure increase device.

rallydiesel · Post by **rallydiesel** » Fri Feb 01, 2008 9:41 pm

How are you guys spinning the pump and does anyone have a step-by-step on building the pump top tester?

libbybapa · Post by **libbybapa** » Fri Feb 01, 2008 9:47 pm

I think most of us are using the force of the burning fuel to turn the pump via the timing belt. I don't know of a pump pop tester. I have used an injector pop tester, tho.

Andrew

coke · Post by **coke** » Fri Feb 01, 2008 9:54 pm

I know tawney had a pile of scrap pumps he was spinning with a drill. We dont use a pop tester, we use a pressure gauge hooked somehow to the return fitting on the pump to get a pressure reading from inside the pump. This way, we can adjust the pressure while watching it on a gauge, and then verify that at 1000 pump RPM, we have the desired reading as well.

It can be installed as a permanent fixture if desired.