Tuning 1.6 NA pumps?

[TylerDurden]

The clear lines only need to be from the filter to the IP and about a foot after the IP... like windows to see what's inside the lines.

Air does indeed get trapped inside the IP and whipped around like in a blender making tiny bubbles that get into the injector lines, but eventually they are pushed out the OUT line as a fine "mist" of bubbles.

It is so easy to put a bit of clear lines and verify that the fuel is solid. It is the very first in the order of operations.

Until air is eliminated, you can fiddle with the lever orientation and not get any improvement. Air in the IP body gets in the injection lines and delays and/or prevents injection.

[bc]

So let's say air is trapped in the IP. How does one go about getting it out of the pump?

[TylerDurden]

Air should purge from the pump when the engine is running. The IP circulates much more fuel than the injectors burn, so if the system is sealed from air infiltration, the air in the IP eventually goes out the OUT bolt and back to the tank. It takes a couple of minutes to purge itself.

But if the air fails to clear from the return line, it means that air is being sucked in from somewhere like a line fitting or the input shaft seal.

It's common to prime the IP by using a hand vacuum pump on the out line, to pull fresh fuel from the tank/lines/filter into the IP and out the OUT bolt... this helps ensure the engine will start quickly, provided there are no leaks letting air in along the way.

[bc]

Well, based on that, the air should be purged out of the pump. I've addressed all other places that air might be coming in. So I don't think air is the problem. I think the issue stems from me taking the top off to replace the seal. Everything was running fine until I did that.

[greg lousy]

I'm not as air focused as some others here. often, I have different ideas while others point to air. That being said, I've got a clear line going from the pump. since this is the end of the line as far as fuel getting to the engine goes, I know at a glance whether I have air problems, and air does cause problems... 100% non debateable - when I ran on vegetable oil with a looped return line (cutting out the air purging capacities of a normal return line). It happenned all the time, with symptoms ranging from rough running to non running. Every time I would shore up any possible weak connection and the engine would run fine.
All this being said. If i suspected that top seal on the IP... the FIRST thing I would do would be to look at the air. If there's no air going into the pump, but air in the return line, that points to a bad seal in the pump or injector return lines, and since that top seal is the last touched, most questionable area, you'd have a good idea of whether thats the problem after some quick testing. (I'd also look for fuel leaking out of that area).

If that seal is bad, your pump will also have trouble building pressure which would definitely affect fuel delivery and performance.

You've basically "ruled out" air being a problem, then point to a culprit where the clearest and easiest to detect symptom would be air in the return line.

the bold part of Tyler's explanation is key

The IP circulates much more fuel than the injectors burn, so if the system is sealed from air infiltration, the air in the IP eventually goes out the OUT bolt and back to the tank. It takes a couple of minutes to purge itself.

if it is not sealed from air infiltration, it will never purge itself, and you WILL have problems.

good luck

[bc]

Thanks for the info, Greg lousy. I guess I'll have to put clear lines on this thing.

[bc]

So, I Installed a clear line on the outlet banjo bolt. I noticed the super fine misty bubbles in it but they eventually cleared out and I no longer see any bubbles coming from the pump. So that means there is no air in the pump, right? My last resort option is to take the pump to my local diesel repair shop and have them put it on their test stand, but I'm trying to avoid spending almost 2 hundo to have that done. To recap, the problem is low power and excess exhaust smoke, no matter how much I fiddle with the idle screw and the fuel screw.

[Fatmobile]

It's common to have a few small bubbles for awhile after you open the fuel system.
Glad to hear there is no air,.. even though we would know for sure what the problem is
Have you tried retarding the timing a little?
My buddy had the same problems until I timed it with the pulse detector, his was slightly too advanced.

[bc]

I have had little success timing pumps with a dial gauge. So it's running by me tuning it by ear. Does this sound like a timing issue? Once it's warmed up it sounds good!?

[TylerDurden]

If the problem started when the seal was changed, it is unlikely timing will fix it.

I'm guessing some of the guts are not in the right place, the accelerator linkage being the first likely suspect.

[bc]

that's kind of what i'm thinking. so i guess my goal here is to get some advice on getting the insides back where they should be. like i said before i've tried all different positions with the fuel screw, idle screw, stop screw as well as the linkage at the pedal, all with no luck.

[Fatmobile]

Have you tried putting the accelerator lever on a different spline?

[bc]

There's basically, from what I can tell, three different settings for the accelerator arm on the governer shaft and I've tried all positions where the line on the arm lines up with the notch on top of the governer shaft. Sound right?

[Fatmobile]

Yep, sounds like you've tried that too,..
Hmmmm?

[bc]

Strange huh, fatmobile. I might have to just take the pump in to my local diesel place and have them get it back to where it's supposed to be.