Okay fellas I need some help with my new (used) toy. I bought a 1992 W250 with a p-pumped 12v. Im having some issues with it. The truck has the following mods done to it. 12v P- pumped,no fuel plate or afc, Hx40 turbo, no waste gate,191 delivery valves, arp head studs, Big front mount IC, 50hp pod injectors, timing at 16*,cold air intake,raptor 150 pump,4inch down pipe to 5 inch stacks, The truck is hitting 42 psi of boost and 23psi of fuel presure. The problem im having is that it stubles with blue smoke at a low RPM then it smooths out after the RPMs get higher and blue smoke goes away. Fuel presure never drops below 22 at and RPM or throttle postion. Its seems to be down on power but this is my first 12v so im not to sure on how well they respond and perform. Any help would be nice. They orignal owner told me timing needs to be reset for cold wheather but im not so sure.

 

Cummins' pressure specs are 17-22 psi at idle, 25-35 at 2500 rpm no load,
Pressure should never drop below 25 psi under load

Sounds like a FP issue to start with. Find a plate and put the AFC back together as well. A street truck has no business running a gutted AFC, IMO. It'll be a lot more responsive with some AFC tuning. You may want to post this over in the 2nd gen performance section for more exposure since this is more of a VE pump forum.

 

Blue smoke means oil. Have you checked your valve lash? At lower rpms it may be that there's enough time for oil to get in somehow and burn, higher rpms may not allow enough time. I think G1625S is right about the FP and AFC too. It can't hurt anything, and if you don't like it just take 'em back out again.

 

Turbo seal leak till it get's warm and expands ?

 

Blue smoke can also be unburned fuel. Take a whiff of it-if it makes your eyes water instantly, it's fuel That could be a sign of low fuel pressure and/or slipped timing. run the revs up and the cylinders build some heat and the fuel burns better, so the smoke goes away. Definitely address the f/p issue first. They'll run pretty good with all kinds of messed up timing.

 

I thought unburnt fuel was white.

 

Can be both, I'm pretty sure.

 

Yes the smoke does burn your eyes and is very strong smelling (no oil smell). So timing or fuel presure is most likely my issue?

 

Getting any air in the supply side or the fuel system ? I don't know much about pee pumps but the fuel pressure sounds low from other posts I've read.

 

I can hear the grumbling already. You have the best truck, the best engine and the best injection pump, great set up!!!!

Don't worry about the fuel plate, but get an AFC back on that truck, it will be much more driver friendly, no AFC is tractor pull stuff not street truck.

P7100s are known for slipping timing if not done just right, get the timing checked. Don't know about those injectors, I did not know they made PODs for the P Pump, but PODs are know for haze at idle. Your fuel pressure is not low enough to be a problem, it would show up on the top end not the bottom anyway.

There is a valve on the overflow/return line, it actually screws into the pump right next to the head, they are know for going bad once in a while. Is it hard to start or does it hit as soon as you turn the key?

I will soon be in the same situation, 1st. Gen. truck, 2nd. Gen. pump. The P7100 is absolutley the best part of a 2nd Gen truck, added to a 1st. Gen and your cooking with gas, err maybe diesel in this situation.

 

My money is on the timing, set it around 15-16 dgrees an leave it. You might want to look into getting new injectors or atleast get them pop tested cause if the pressures are low you'll lose power an make smoke, theres really no telling what they are an how many miles they have on them. Once u learn how to drive it u wont need the afc just use ur foot

 

Dump the electric pump and put a regular 12 valve pump on. Replace or shim the overflow valve spring. Put the Afc back together with a #100 or a zero plate. Search for a thread on afc tuning and follow the instructions.

 

I agree with those who say to check the overflow valve. A friend of mine complained of his '97 with a power loss and bought a new lift pump to put in thinking that was the problem. Didn't have any blue smoke issues like the OP, but it would die on him sometimes once he put the trans into a drive gear. The idle seemed awfully low yet ok at around 500RPM though. Did some searching here in the 2nd gen section and found that the overflow valve is a common and the most often overlooked failure and cause of power loss. We weren't actually able to swap in a new overflow valve cuz he didn't have one nor did we have time to remove the old one and shim it somehow but threading it all the way out and back in again seemed to knock something straight and my friend said the truck seemed to come alive again.

 

Well got the pump in time (16*) changed fuel filter on lift pump and check for leaks. Now she runs like new with Loads of power. All the smoke that was blue is now gone. The white smoke is only there now when it first starts and only lasts for about 30 secs when its cold but if its warm it doesnt do it at all. Thanks for all you help you are all a great help.

 

I know my truck has the pump slightly retarded. It stumbles on no load until it reaches higher rpms with a bluish/white smoke. I hotwired the KSB and it took those symptoms away. Now put a load on her and she won't do it.