OS= Optical Sensor?

have you found a good way to check for air in fuel? I drained a bunch of fuel into a bottle the other day when I was setting the TDCO. It looks clean as a whistle with no water in it at all.

I still have to go in and pull the air-tex sending unit out of the fuel tank. I have brand new delco one on the self. I was waiting for the guy from leroy's diesel to come back so I can remove the sock and Install the remote WIX filter at the same time.

BTW thanks a million for all your help man!!!!!! I feel like I am slowly getting somewhere. Its like impossible to find anyone that knows anything about these motors locally. So I have been firing the parts cannon at this truck for a bit now.

 

Easiest way to identify air in the fuel is to replace the IP fuel return line with clear diesel rated line and with the truck safely parked and idling-watch that line for bubbles.
Bubbles indicate air entry pre LP.

So anywhere between the fuel level in the tank and the LP input are the possible leak areas.

A hole after the LP will result in fuel coming out,not air going in unless the engine is shut off.

 

So clear line from the IP back to the small steel rail just behind the T stat housing?

 

Ya the frt line on the IP that connects to the T line where the injector returns connect to.

 

So I got a chance to take my truck for a good ride tonight. I took my laptop with me and left it plugged in.

I noticed 2 times I gave her full throttle on some back roads, soon as I took my foot out of it she stalled. Few key cycles and she started back up.

Next I took her for a quick ride on the interstate...I got up to about 55-60mph nice and easy, then I hammered it and she starts to bog, pop, & skip! Even tho she was doing all that it continued to pick up speed. Around 70mph the check engine light popped on and I got a code 78- Wastegate Control Solenoid. When I took my foot out the CEL went right out.

So I went in to the wastegate control section and I set the desired duty cycle to 100. Once I did that I got back all over the throttle and she ran good. I then got of interstate and came to a complete stop then did a full throttle pull and she ran right up good with no issues. I noticed at idle the wastegate duty cycle is always around 60ish then when i hammer it drops to the low 50's. With it set to 100 it never dropped below 60. ANY IDEA IF THIS IS NORMAL?

other thing I noticed was that if I look at "fuel rate-throttle requested" and "fuel rate" the FUELRATE is almost always 8-10 lowered than requested when I am in the throttle. Even if I power brake her this is the case...

Any thoughts on all this jibberiesh? haha

I owe you bigtime for all this help!

 

Boost is load dependent when the ECM controls it.

Meaning you only get good boost when you really need it-hard acceleration and when towing heavy.

Might want to spray some WD40 in the boost solenoid vac ports to lube the bleed ball-they can stick without a bit of lube every now and then.

Boost solenoids also fail and have wiring problems as well.

Check the vac readings at the pump side of the solenoid and at the wastegate actuator at idle.
Min from pup is 24"
min at actuator is 18"

any less means you need to find the leaks or weak point.

If you want to take control of boost away from the computer for improved performance buy and install a turbo master from Heath Diesel-an aftermarket ECM tune would help with that a lot also.

The #'s you give don't mean a whole lot to me unless I was in the truck with you.

 

Ya I found a trouble tree in ALLDATA to diag DTC-78. Tomorrow night I will run thru those steps and see what I come up with.

I was thinking about going to one of those waste gate systems but I like to get the bugs worked out before I go nuts with upgrades. You said ECM upgrade... You talking installing a CHIP?

 

Yes if you should decide to go with a turbomaster then you could also order a custom chip at the same time from the same place-they work hand in hand but you don't have to.

 

So I am at my shop now. I just started checking out my waste gate issue. I have no vacuum at all at the waste gate. I pulled the lines of the control on the valve cover and I have less than 1" of vacuum coming directly from the pump.

I guess I need a pump


Can I use any replacement pump from NAPA, or should I get a delco pump?

 

The delco pumps last longer.

Most reports of aftermarket vac pumps have them lasting a year or less.

Might get by with a used pump from a wrecking yard for a while if it's not already bad too?