How do I adjust an SD22 inline injection pump to make it run richer?

SD diesels were widely available in the US in the 1981-86 Datsun/Nissan 720 pickups, and in Canada through '87 in the D21 pickup.

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waynosworld
Posts:519
Joined:7 years ago
Location:Vancouver Washington USA
How do I adjust an SD22 inline injection pump to make it run richer?

#1

Post by waynosworld » 1 year ago

How do I adjust an SD22 inline injection pump to make it run richer, I have heard people call it turning it up, how does one do that?
Is it as simple as adjusting the smoke screw, or do I need to do something inside the pump?

Back story, I helped my friend turbocharge his SD22 powered 720, once done we drove it, I was not impressed, I drove it and it seemed like once the pedal was down so far there was nothing left, we have plenty of boost(seen over 15psi once).
OK, this is hard to explain but I will try, the way I route the injection pump vacuum and vent line is that the stock vacuum line is left stock, so under boost if the vent line is vented the injection pump is basically floored and the engine tries to run away when driving it but when I let off the pedal it cannot get enough air so it just pukes black smoke with a very high idle, to fix this issue I pipe the vent line to boost also, my SD25 engines run great this way, but I figured out from trying to fix another issue that if I put a tee in the vent line pipe how I described above and connect a valve to that tee that I can open that valve a little and bleed off a little of the boost in that vent line and it allows the injection pump to move to a slightly richer position because of more boost on that side of the diaphragm, there is a point where if I remove the valve from the end of that line on my engines that it almost tries to start running away, it just has that feel like when I let off the pedal it hesitates to slow down for a moment.
Well I put a tee in his vent line and I can barely tell the difference, but when I removed that line from boost it did try to run away, so this is why I am trying to figure out how to turn up the injection pump on his SD22, the controlled leak in his vent line is not enough.
I was told by LarryV that he had the SD25 injection pump turned up on his SD25 turbocharged engine before I bought it from him, the SD25 turbocharged engine in my 521 kingcab also had a turbocharger on it when I bought it from the kids that inherited it when their father died, so they knew nothing other than it was a diesel engine, all I know is that turbocharging this SD22 engine didn't impress me, there has to be more power there somewhere.
By the way my 720 turbocharged engine has no smoke screw anymore, it does blow quite a bit of smoke if I give it a lot of pedal, but I rarely ever use more than half the pedal anymore as it goes plenty fast.

How do I turn the SD22 injection pump up to a richer position?
I know the voices are not real,
but they have some really good ideas.

plenzen
Posts:869
Joined:13 years ago
Location:Cochrane Alberta Canada

Re: How do I adjust an SD22 inline injection pump to make it run richer?

#2

Post by plenzen » 1 year ago

Usually it is just as simple as winding "IN" the smoke screw. I know it seems counter intuitive but mine ( it is a VE pump however) in is more and out is less. If your getting boost and no power I would suggest that it's running out of fuel. Too much fuel can however increase your EGT's so be wary of that.

Not sure how the vacuum diaphragm works on those so you may have to wait for Al to chime in and tell you. There are a number of threads on here I am sure that deal with it but I cannot recall where they would be.

Good luck and let us know.

P
Retired Pauly
Problem with being retired is that you never get a day off.
1987 D21-J SD25 KC
KJLGD21FN

waynosworld
Posts:519
Joined:7 years ago
Location:Vancouver Washington USA

Re: How do I adjust an SD22 inline injection pump to make it run richer?

#3

Post by waynosworld » 1 year ago

I went thru several pages looking for something on this subject and found nothing, I already thought of the smoke screw and the guy had already plated with that in the past.
I was wondering if there was something that could be adjusted on the inside of the injection pump somewhere that turns it up.
The guy came by yesterday and looked me in the eye and said it had more power as it didn't bleed off speed like it used to on the hills at freeway speeds, there were a couple of other issues one of which was taken care of buy him which he said helped at lower RPMs, that one was leaking where the piping connects to the top of the throttle body which could account for no power at lower RPMs, the other issue needs the intake manifold removed.
I found what appears to be another turbocharger like the one on my 521, but someone could have beat me to it, I am waiting for a response.
I also have been looking into small diesel engine turbochargers, not so many for the 2.2L, but 2.5L are easy to find.
The one that LarryV had on the engine I bought from him was modified to make it more like a diesel turbocharger, but it was too big of a modification as there was too much boost at freeway speeds that could not be dealt with while the stock turbo he started with works alright, nothing like my 521 turbocharger, but still has good results on my 2.5L diesel engine, the guy drove my 521 and now it is hard for him to forget about my results, he keeps talking about the TD27 now.
I know the voices are not real,
but they have some really good ideas.

plenzen
Posts:869
Joined:13 years ago
Location:Cochrane Alberta Canada

Re: How do I adjust an SD22 inline injection pump to make it run richer?

#4

Post by plenzen » 1 year ago

I think that Phillip had some postings about the vacuum diaphragm some years ago. You will have to go way back I think. I believe that there is something internal on the inline pumps that can be adjusted, but just not exactly how to go about that as I have always left injection pumps to those that deal with them. My experience with adding more fuel has been limited to the smoke screw.
If your getting black smoke your getting fuel. Something I think, is going on with the boost your supplying,,,,,,,,,,,, I think.
The flap in the intake is opening, or not being forced shut from the boost is it ? Can't recall how your set up on that one.

I take it the guy was p[pretty impressed with your 521

I will try and look back at some of Phillip's old postings and see if I can find a thread on it. Dealing with my grandson ( 5) on nearly a daily basis now and "they" can be time consuming.

P
Retired Pauly
Problem with being retired is that you never get a day off.
1987 D21-J SD25 KC
KJLGD21FN

waynosworld
Posts:519
Joined:7 years ago
Location:Vancouver Washington USA

Re: How do I adjust an SD22 inline injection pump to make it run richer?

#5

Post by waynosworld » 1 year ago

He drove my 720 first and the 521 a few weeks later I went to a Datsun show and stopped by his house on the way home, the 720 has way more power from letting out the clutch, but the 521 has a specific power band, letting out the clutch it appears to be about stock power wise(maybe a little more power), but once I get into 3rd gear that engine is a different animal, as we entered the freeway with him driving, he was quiet so I asked what he thought, he just said "we are already doing 70mph", it was a uphill on ramp and we were not even on the freeway yet, his truck would still be trying to get to freeway speeds while entering the freeway.
He was impressed, the 720 is great but doesn't really like RPMs above 2500rpms, I have to start putting my foot into the pedal to get to 70mph, but it gets there fairly fast, the 521 comes off the line like it did without the turbo, but once that turbocharger kicks in I cannot get thru the gears fast enough and the rpms just keep on climbing, after 70mph I do have to start putting my foot into the pedal to maintain them speeds, 75/80mph is around half the pedal on the 521, the 720 needs three quarters of the pedal to maintain 70mph, but 60mph only uses the top 3rd of the pedal if that, to get above 2500rpms in the 720 I have to put my foot into that pedal.
Keep in mind that my 720 is turning 3.3 gears in the rear while the 521 is turning 3.5 gears in the rear, even with that gearing in the 720(3.3), the 720 has more power off the line than the 521, but the 521 will leave the 720 behind after getting in third gear and the 521 is WAY MORE freeway friendly and that is why I turbocharged them, around town was fine, but on the freeway both these trucks were lacking.
I believe I got very lucky when it comes to the 521, what I did was repeatable as I figured out the 521 first, but the turbocharger on the 521 is awesome, it appears to have some lag but makes up for it in 3rd, 4th, and 5th gears, fact is it reminds me of my first motorcycle, I bought a 2 stroke KH400 off the show room floor, when that power band was hit I had to hang on and move my weight forward.
The 720 has a 2002 VW Passat turbocharger, the 521 has a 1985/86 Subaru XT turbocharger, they are totally different turbos but both work on my SD25 diesel engines, both increase the power on my engines, but the 521 is way more fun to drive, I have not driven the 720 out of town since turbocharging it my way, the 521 has went on several 200+ mile trips without any issues except pre-filter issues and that started within 10 miles of getting home but I did make it home.
I would never drive another SD series powered vehicle without a turbocharger, I likely have close to 50,000 miles on them without a turbocharger, it drove me crazy every time I came to a hill, a pass was a nightmare being floored and dropping gears, since turbocharging I cannot recall being floored except to see what would happen, and nothing did happen, there is a point where there is no more power so it is pointless to push the pedal down any farther.

If you find the info/thread about the internal adjustment on the inline injection pump let me know, there has to be more power there on my friends SD22 engine, but I have not drove it since he left here after turbocharging it, it may be better now.
I know the voices are not real,
but they have some really good ideas.

plenzen
Posts:869
Joined:13 years ago
Location:Cochrane Alberta Canada

Re: How do I adjust an SD22 inline injection pump to make it run richer?

#6

Post by plenzen » 1 year ago

It wasn't internal adjustments I was referring to was how the whole vacuum diaphragm thingy etc worked. That may be your limiting factor here. But....I'm not sure.

The 521 sounds like a hoot to drive. Pretty sure I have a shorter RE gear than you do in both your trucks. About 100 kph (62 mph) is about all I drive this little guy at because it sounds like it's spooled too high above that. Sometimes I let it go to 110kph but it seems to sound best around 90 to 100. I still have the 14 inch wheels and OE size tires on it too. 195/75/14. If I went to a taller tire I think I would lose some of my mechanical advantage as to climbing hills,merging etc. It's pretty slow as it is. I've just decided that if I take the truck I ain't gonna be in a hurry. Rolling 500 k soon. (320,000 mi) I've often said that all it needs is about 5 or 6 lbs of boost and it would be fine, but at this stage of its life I think it's fine the way it is.
Retired Pauly
Problem with being retired is that you never get a day off.
1987 D21-J SD25 KC
KJLGD21FN

waynosworld
Posts:519
Joined:7 years ago
Location:Vancouver Washington USA

Re: How do I adjust an SD22 inline injection pump to make it run richer?

#7

Post by waynosworld » 1 year ago

I drive faster than you do on the freeway, I am often 120 to 130kph, but that is with 3.5 gears which works out to right around 3000rpms in 5th gear(I have a tach), I normally only run it up to 2600rpms in 1st thru 4th gears as any higher rpm sounds too high, but if 5th it doesn't sound too bad.
With the stock 3.9 gears these little diesel trucks came with, 110kph works out to 3000rpms with the tires you have(same as my tires), I have found that is the line for the most part, any higher and it sounds revved out, and one has to put their foot in it to get any higher rpm in 5th gear, it just likes 2400rpms or less for the good fuel mileage which you appear to likely get.

I kinda understand the vacuum throttle now, there is a spring pushing the diaphragm to the floored position, the vacuum from the venturi in the throttle body pulls the rack back to the idle position when the butterfly valve is closed, boost created can cause the rack to move to the floored position, so I put boost to the vent line also so they cancel each other out and the venturi works properly again, now I do not fully understand how the venturi works under boost pressures but it does as when I let off the pedal it does not blow black smoke out the tail pipe and the engine acts like any normal engine acts.
So that above said I figured out that if I put a bleed valve in that vent line I could bleed a little of the boost in the vent line off(less boost) and it allowed the rack to move slightly to a richer position, not rich enough for the rack to be floored and try to run away, but enough to get a little more HP out of the engine, to get the rack to even a richer position now I will need a larger valve and hose to bleed off more boost in the vent line, but there is a fine line here, I need some boost in that vent line to keep it from running away, as when I vented that line the rack was just floored all the time when it had boost and it blew a black cloud out the tail pipe but it could not get enough air when I let off the pedal so it eventually would quit trying to run away when the boost dropped off.
The 720 was not derivable on the street with that line vented, so I gave up and made the it a draw thru as you read in that 720 thread, remember when I was talking about hitting a wall where it would not go over 65mph, figuring out how to make that draw thru setup richer is how I figured out how to make the blow thru work properly, and that happened because I talked to the guy on here with that red turbocharged engine in the photo on the home page, he did it another way to make his work, but he made me think about it in a different way and I figured it out because I talked to him, the draw thru worked but that way had a major issue that only a special type of turbo would fix, as the draw thru was sucking oil thru the seal of the turbo into the intake, in theory one could empty the oil pan on a long down hill grade where one is coasting without ones foot on the pedal.
I know the voices are not real,
but they have some really good ideas.

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