To start, I'm definitely new to most of this. As a heavy equipment mechanic, I'm comfortable around engines, but never really messed with the injector pumps.

I have a 94 12v cummins with minimal mods. Boost and pyro on A pillar. Dead cat. Disabled wastegate. K&N filter in factory filter housing.

I'm reading on here that it could be bad to run at full boost? I'm maxing out at 27 pounds of boost.

I have little to no smoke upon acceleration and feels really sluggish until I get to about 15 pounds of boost. I have read that adjusting the starwheel on the pump can fix this problem, it's just a matter of finding the happy medium between power and smoke.

Also at about 2500-2600 this thing falls on it's nose. Boost falls off and I have to shift. Is this normal? red line isn't until 3000.

I guess my questions are....

1. Is it possible to adjust the pump too much? Can I cause more problems than I cure?

2. Where do I start?

3. is 27 pounds of boost about the max I should see on a normally stock motor?

I'd like to squeeze as much as I can without any major modifications. I love the power it has from about 2000-2500 RPMs, but am dissappointed in the low end power.

Thanks in advance
Nick

 

Nick,

I do know that if you have a 12V, ya gotta bomb it. Where is your timing set?? I think 15.5 or 16 degres is where a lot of guys are.... Have you slid your AFC housing any??
How about valve lash? adjusted lately? Have you considered a Governer spring kit, AFC spring kit?, fuel stop plate, and/or injectors??

Check some of the 12V links:

https://www.dieseltruckresource.com/...threadid=22849

You could also call one of the experts....Piers comes to mind....

 

Valve lash has just been set. This all started when I decided to do some nessecary maintinance. As of this weekend, I've changed the oil/filter, fuel filter, cleaned the K&N, and adjusted the valves.

Feels good to know it's all right.

As for sliding the AFC housing, no I have not. This is where I am unsure. Anytime in the past when I've run into a problem concering a pump, it's an R&R procedure. So I know nothing about how they work or what to do. But I am good at removing and installing one and setting the timing.

On that note, I have not set the timing on mine. Probably something I need to check as I have read here about it slipping.

 

Thats probably the best place to start. I assume you already may have the tools....but if ya dont SPX will have what you need. 3000 GSK will help too.

http://www.toolsfortrucks.com/

 

I don't personally own them, but can grab them next weekend from the tool crib. That'll be next weekend's project then.

How about the pump though? Is there any harm in removing the 8mm plug from the top and adjusting it?

Just don't want to kill a pump, more $ than I have to rebuild one right now.

 

These pumps are amazingly tough. Don't see you having trouble with adjusting what is on the truck at this point. My 95 has been adjust on enough that I have had to replace the AFC gasket and helicoil one of the screw holes. Only trouble I have had is a bad overflow valve and it was just a matter of a spring giving up while the truck was bone stock.

 

Thanks, in that case, I may do a little light adjusting today. I still got the hood up and really want to tinker, he he.

Besides wouldn't mind seeing a little black smoke when I'm under a load. Just seems like all diesels should smoke some

 

[quote author=Lil Mule link=board=7;threadid=23018;start=0#msg215692 date=1070135600]

Besides wouldn't mind seeing a little black smoke when I'm under a load. Just seems like all diesels should smoke some

[/quote]

Did someone call me?

 

Mule,

Check the post by Jim Fulmer on the following link....

https://www.dieseltruckresource.com/...threadid=23012

He runs some serious HP (700 horse, 1300 lb-ft tq) and knows what he is doing.

 

well, I learned today I may have to replace my lift pump before i do anything.

I turned up the pump a bit, and while I noticed a slight difference in bottom end, I lost another 200 rpm at the top.

This thing acts like it runs out of fuel at 2500 anyways.

So I turned it down past where it was originally and now it pulls to about 2800, but it's a bit more sluggish.

When I get into work monday I'll do a pressure test to be sure, but I'm getting the feeling my pump isn't doing the job it used to.

Thanks Guys.

Btw I printed out that response Dr Evil pointed me to. May just have to start there once I get this thingk up to snuff.

 

http://www.tstproducts.com/power_install.html you've turned it up some? what adjustments did you do?

the problem with your defueling is the stock governor springs. get rid of them! www.piersdiesel.com. piers has the 3000rpms governor spring kit available- hands down the best mod that can be done to the 12valve. it'll allow you to be able to hit 3500rpms+ in neutral (don't recommend trying that) and 2800-3200 under load depending on your setup. 3200rpms max is the safe zone where the 60 lb. valve springs aren't needed.

Tom

 

well I say turned it up. really experimented a little

What I did was remove the 8mm allen bolt on top of the AFC and play with the adjustment.

After reading the installation instructions http://www.tstproducts.com/power_install.html earlier. I realized I could possibly give her a little extra fuel. But when I adjusted it for more fuel all I did was loose rpms.

Feels like a similar problem I had with a clogged fuel filter on a trackhoe. Unfortunately my fuel filter is new.

 

If you want performance without bying anything take your stock fuel plate in your injector pump and slide it all the way forward torwds front of truck. I have done this to many trucks u will see a 70hp inctrease and crank that afc spring toward the motor so its all the way forward to. Believe me you will like the results sounds like your trucks beggan for fuel with all those air flow enhancements. 8)

 

[quote author=Captain Insane-O link=board=7;threadid=23018;start=0#msg215861 date=1070172239]
I have done this to many trucks u will see a 70hp inctrease [/quote]

70HP is actually a little high, it will really be more around 40hp.

 

[quote author=Lil Mule link=board=7;threadid=23018;start=0#msg215806 date=1070160416]
well, I learned today I may have to replace my lift pump before i do anything.
[/quote]

If you get a low reading when you check your fuel pressure, have a look at the overflow valve in your injection pump before shelling out money for a new lift pump. It's a pretty common problem. They vary in price. I got nailed $110CAN from Saskatoon Diesel here in town. (didn't even kiss me first > ) I've seen $55US from some vendors. There's an address in this link that's way cheaper. http://www.dodge-diesel.org/yabbse/i...6761#msg206761 Good Luck.