O.K. the truck I got is an 88 250 4x4 C-6 7.3 N/A 3.73 gears. I talked to a local mechanic thursday about getting more power out of it and he told me to advance the IP a little. Now I'm fairly new to the diesel world so I have a few questions about this.

#1 If I advance the IP, how much is too much?

#2 how do you advance the pump without unhooking the injector lines?

Right now the way the pump is set when I'm hard on the throttle it does'nt give any smoke out the pipe at all. Does this mean that I can turn the pump up one flat at a time til I get some black smoke with heavy throttle?

One more question. There is a piece on the IP on the drivers side that appears to me that it is some kind of throttle position sensor of some sort that meters vacuum to the modulator valve. If thats what this is for then I'm pretty sure mine is bad cause I'm not getting any vacuum at the modulator valve, but there is vacuum on the vac. pump side of this TPS. It has'nt shifted right since I got it. If someone could tell me what this is called I would sure appreciate it.

thank's
scott

 

#1 when it rattles really loud........

#2 With the "engine off", just loosen the 3 nuts on the IP flange. Turn top of pump 1/16" in pax fender direction for 3-4* advanceing, top to drvrs fender retarding. Tighten all nuts before starting engine, do not attemp to move IP with engine running. There is a square boss on the front of the IP body for a suitable wrench to aid in adjustments.

Visit http://www.members.shaw.ca/k2pilot/ for turning up pump info

That is the VRV vacuum regulating valve.........

How to adjust VRV posted by James.....

You don't have the engine running for the test, you need to apply 20" vacuum to upper VRV port and attach vacuum gauge to lower VRV port. The lower port is the one that goes to tranny, the upper to vacuum pump.
You have to maintain 20" througout this test. If it drops off you need to pump it back up.
Remove throttle return spring, cycle throttle lever 5 times from idle to WOT. Make sure 20" vacuum is maintained on upper port side.
Move throttle so it is 0.515" (33/64") from wide open (they make a tool for this). Vacuum gauge should read from 6-8" of vacuum. If incorrect adjust VRV to 7".
Again apply 20" vacuum, cycle throttle from idle to WOT 5 times. Return to idle. Gauge should read at least 13".

It says if you can't get the 7" or the 13" to replace the VRV. If VRV checks out maybe the diaphragm (modulator), line from VRV goes to the vacuum diaphragm I believe. Can't find any adjustment for the diaphragm but I think there is a little.

Basically all you need for the test is a vacuum pump (handheld type), vacuum gauge and a ruler to measure 1/2" or a 33/64" drill bit in lieu of the .515" tool. And a screwdriver for any adjustment needed.
Good Luck
James

 

thanks for the info plc7.3. I took the VRV off and hooked a vac guage up on the modulator side. I started the engine and turned the VRV by hand to simulate throttle movement and got nothing on the vac guage. So I can think that it needs replaced.