internal injection pump pressure

Quantum TD · Post by **Quantum TD** » Mon Jun 30, 2008 12:33 pm

So, I'm gonna pull this thread back from the dead. I was just wondering what kind of increase in MPG anyone has seen by setting the IP pressure this way? And, the second question: has anyone bought the tool posted on pg 10 from Thompson diesel, or do you all just hit the pin with a punch?

Thanks guys.

coke · Post by **coke** » Mon Jun 30, 2008 1:14 pm

Hit the pin with a punch. My mileage went from 40 to 48. Since the internal pressure of the pump is what operates the dynamic timing advance, in theory your engine will be more efficient if your getting the correct amount of advance throughout the RPMS.

Quantum TD · Post by **Quantum TD** » Mon Jun 30, 2008 3:31 pm

So, was that a consistent 40 MPG to a consistent 48 MPG? What I'm asking is, what that your average before and after, or just the average before, and then the reading after? You see what I'm getting at? I've had cars that got 42-44 MPG all day long, but sometimes I'd take a long trip, and get some good gas, and my MPG figures went from 42-44 to 48-49 with the only differences being 1)windless days, 2) possible higer cetane fuel and 3) more highway driving.

I'm not being incredulous, but I'm just wanting to see what type of increase I can get by fiddling with it.

Another question I had was in regards to static vs. dynamic timing. I'm going to assume that one has nothing to do with the other? In other words, my static timing set with a dial indicator (or by ear/trial+error) with have zero effect on dynamic timing? So, I can leave my pump setting and just adjust the pressure pin to acheive higher MPG? I'm probably gonna build me a pop tester and rebuild my injectors soon. Hopefully between the two, I should get closer to 50 MPG.

Op-Ivy · Post by **Op-Ivy** » Mon Jun 30, 2008 4:55 pm

I didn't really see any change at all. I'm still pretty consistant at 44MPG IMP.

coke · Post by **coke** » Mon Jun 30, 2008 5:28 pm

Your static timing is still important, because in the long run, the advance starts from there. Thats why if your engine is quiet, and you rev it up through the gears you shouldn't hear any valve noise, but if you advance your static timing, your dynamic timing is also going to advance.

Whats supposed to happen is giving the static timing spec, the advance is supposed to fall inline with calibration from that point forth. If you advance your static timing, it is my understanding your dynamic also advances, but if hte pressure inside the pump isn't where its supposed to be, you'll only get so much dynamic advance.

What I noticed was, I had no valve noise above idle but after messing with the dynamic advance, I had some. I was running my engine slightly advanced.

Caddyman · Post by **Caddyman** » Tue Jul 22, 2008 5:38 pm

Quick questions;

I drilled my out bolt and tapped it for 1/8 npt and installed a pressure gauge as a temporary pressure fitting. Max pressure is about 30 psig but it pulses. I'm assuming that the pressure is supposed to pulse with injector timing?

Also I want to adjust pressure to the specification. This can be done in pump without damage to the regulator? From the looks of things the best way to adjust is to get a long bolt and two nuts and jam them together for a pre determined adjustment amount. How much should I press the plunger in the housing to get about 13 psi (1 mm)?

Op-Ivy · Post by **Op-Ivy** » Wed Jul 23, 2008 12:18 am

Caddyman wrote:Quick questions;

I drilled my out bolt and tapped it for 1/8 npt and installed a pressure gauge as a temporary pressure fitting. Max pressure is about 30 psig but it pulses. I'm assuming that the pressure is supposed to pulse with injector timing?

Also I want to adjust pressure to the specification. This can be done in pump without damage to the regulator? From the looks of things the best way to adjust is to get a long bolt and two nuts and jam them together for a pre determined adjustment amount. How much should I press the plunger in the housing to get about 13 psi (1 mm)?

The pulse is normal. I'm not sure if it is from the vein pump pressurizing the pump or, like you said, the small loss of fuel getting spat out into the injector line.

To adjust the regulator you simply tap the inner section downwards. This can be done with it still on the pump. However, if you go to far and the internal pressure is too high, you have to take the regulator out and tap it the other way.

Adjust in very small increments. I would say to adjust for 13psi it would be much less then 1mm. Probably not even noticable. It really is hard to say though.

Tap soft and check often. Trust me.

Post by **Fatmobile** » Wed Jul 23, 2008 1:09 pm

Probably more like .005"
Seems like once tap breaks it loose,... it's been sitting at that setting for a long time, the pressure moves alot with very little movement.
I saw the factory tool for this over on GTD forum, it slides under the lip on the outside of the weird bolt and allows you to turn a screw to press it downward.

libbybapa · Post by **libbybapa** » Wed Jul 23, 2008 2:32 pm

The Bosch tool is also shown on page 10 of this thread.

Andrew

libbybapa · Post by **libbybapa** » Fri Aug 22, 2008 6:57 pm

Here's a perfect place to permanently place a fitting for a gauge (where I installed the little aluminum allen head plug), assuming your car is not an automatic:

Andrew

Post by **Fatmobile** » Fri Aug 22, 2008 11:54 pm

isn't it great they put that there for us?

I was messing with my 4 door project and couldn't get any internal pump pressure unless I revved it to about 3000,... then I got 20psi.
I removed the regulator and the lower o-ring was all messed up and letting uel bypass the regulator. New o-ring and problem was solved.

florigolf · Post by **florigolf** » Sun Aug 24, 2008 7:24 pm

hi,

I found that by setting the pressure as per Hagar's recommendation, it was vastly too much advance and caused a tremendous amount of valve clatter above idle. So i backed it down again in stages, using a dial caliper to measure the depth of the cylinder between taps with the hammer. I may have ended up with a little more pressure than stock, but not much more. I think there is a big difference between Hagar's pump/engine and mine (1986).

just a comment

Op-Ivy · Post by **Op-Ivy** » Mon Aug 25, 2008 1:51 am

florigolf wrote:hi,

I found that by setting the pressure as per Hagar's recommendation, it was vastly too much advance and caused a tremendous amount of valve clatter above idle. So i backed it down again in stages, using a dial caliper to measure the depth of the cylinder between taps with the hammer. I may have ended up with a little more pressure than stock, but not much more. I think there is a big difference between Hagar's pump/engine and mine (1986).

just a comment

I noticed that as well. If you read through a few pages back I explained the same thing.

I think it's best to go as far as you can without getting the "marbles".

Bubba1 · Post by **Bubba1** » Mon Sep 15, 2008 5:26 am

Now this is at idle?Is there a safe way of doing this without a tach?Is it true to be linear throught the rpm range?So if i set my idle press. at say 40psi then my dynamic advance will go with it?Im wondering if a "w' SIGNAL tach will work properly for this.

rabbit_man · Post by **rabbit_man** » Mon Oct 06, 2008 2:53 pm

"Pressure in pump MUST be 43.5 Psi at 1000 RPM engine "
"Pressure at 2000 Rpm -about 75.4 Psi"

Those PSI numbers change with perty small RPM changes so I sure wouldn't do it w/o a tach.

Former VWDieselParts.com Forum

internal injection pump pressure

my experiences with adjusting this

Re: my experiences with adjusting this