Ok, I finally got some time to work on the truck again. THe IP that I have put on is a #DS4-5068, and the one that I took off is a #DS4 - 5521. Is there anyway to change the programing(?) with out switching the pump?

LOL, sure, you just have to get a PROM for a '94 HD truck. Or, if you try moving the optic sensor, you could turn your 'mismatch' into a High Output pump and really make some power.

So basically, I'm SOL:D . Should I just send my old pump out to be rebuilt?

I just got through putting it all back together after replacing the PCM extended harness(homemade) and it ran the battery down trying to start. Kinda stuttered a little but it was doing the same thing before.

[QUOTE= you could turn your 'mismatch' into a High Output pump and really make some power.[/QUOTE]
Is this possible?

read this thread http://dieselplace.com/forum/showthread.php?t=24264

SOL? Seems more likely you've LOS, on this one - those 5068's are becoming scarce as hen's teeth.

So what do I do. Is there anyone that will rebuild my old one, or do I have to buy a rebuilt or new one from the Stealership? If the 5068 is valuable, to who? Thanks!

TDGuy and\or Diesel Pro shold be able to point you in the right direction for a hi-perf rebuild...........

Matter of fact - read joeyd's 92mm pump post, below - should get your adrenaline levels up................

I have the prom #'s you require to go into the dealer and get a prom for ~$40 for a 5068, autotranny. The dealer cannot reference this for you but this will work.


BJAX (code on ECM)

BPBN 1621 7103 (prom ID)
(GM pn#1624-4854)

How hard is it to switch the prom. Do you mean a 5068? Will the model year make a difference?

Yes 5068, '94 HD onlybut I agree with Tex. Open the lid and move the optical and leave the 5521 prom. This gives you a "hot" pump. We'll give you step by step, if you're interested.

Sounds like fun and not nearly as expensive. What do I need to do first, remove the pump? I'm on shift at the fire station today, so I won't be able to do anything till tomorrow.

Where in Tx is IP?

To move the optical requires getting to the top of the IP, removing 6 T25 screws, return fuel line, optical connetor, setting the lid on it's side and loosening the T40 (factory torqued) inside to move the optical pickup. After rereading Tex's posts I think you should bump it 1mm toward the drivers'side, lowering fuel output and going from there.
having a scanner that reads time and IP fuelrate will help.

That's exactly right, you have to de-tune a 5068 to make it work in a 5521 application.

OK that rally makes it sound a little more complicated especially since I don't have access to a scanner. I am real close to Wichita Falls in north Texas.

Once you do it, you'll realize how quick and simple this mod really is, and in this case you will REALLY enjoy the difference it makes ;)

Don't worry, David. Take it 1 mm and then restart the engine and drive it, if you have to rebump it, go another 1 mm. You're looking for as smooth an idle as possible with as little movement of the optic (to the right) as possible to achive that.

Quantum, are you talking about the present setup or after changing the optical? I have messed with the timing and it helped it idle but it seems like there is stuttering or starving out at higher RPMs.

Bring the pump to where the shutoff solenoid is straight up and down and then do the optic bump. Once the bumped idle quality is ok, setting the pump 2.5mm to the driverside will advance the time ~8.5*

Is the shutoff solenoid the tall round cylinder on top?

The scenario you describe is typical with a stock 5068 pump on a '95. Can you get to a garage that has a scanner? Bump the optic sensor to the pass side, what you want to get is a Low Idle fuel rate of 6-9mm(3) with engine fully warm. And you want to get a TDC Offset between -1.5 and -1.9. Without a scanner your really shooting in the dark.

And yes, thats tall steel cylinder is the ESO solenoid.

OK, what is the location of the optic sensor and what do I need as far as any special tools besides the scanner to occomplish this?

1/2" wrench for the strap between the turbo and intake, deep 5/16" socked for the hose clamp, 10mm socked for the upper intake bolts, Torx 25 for the top cover screws, Torx 40 and IN/LB torque wrench for the optic sensor hold down screw, and maybe a pair of pliers to remove the return line from the pump.

After you get the upper intake removed, unplug the optic sensor, remove the return hose from the return fitting and remove all 6 top cover screws.
You will only be able to move the top cover to the side, there is a wire tying it to the optic sensor inside. What you will see underneath, is a Torx 40 bolt, with a plate underneath and the body of the optic sensor under that. Before you move anything take a note of where it is. Also, know that the whole thing will easily move side to side, so you will probably need two screw drivers, one to hold the lockplate still, and one to push the optic sensor underneath. Loosen the bolt until its just free, place one screwdriver on the driverside of the lock plate to hold it still, and the other on the pass side of the optic sensor to slide it to the driver's side about 1mm. Retorque the T40 bold to 210 in/lbs, replace the top cover, ensuring the gasket is still inplace, and don't forget the ground strap.
After you get her all back together, run it for a while to warm the engine up and check for leaks, and hook the scanner up.
What you want to see is a Low idle Fuel delivery rate of about 6-8mm(3). Reset your TDC Offset to spec, adjusting the pump if necessary and try it out, let us know how she runs.

Pics?

http://www.dieselplace.com/forum/uploads/BZE_afterbump4.jpg

Here's Canadian Riggers pics.

http://dieselplace.com/forum/showthread.php?t=14231

Move it to the passenger side or the driver side?

I referenced the link above where Canadian Rigger did his and bumped it over. Then I lined the timing marks back up and tried to start it. It will start but is hard to and will not stay running. Is there anyway that the factory timing marks should not be lined up?

You should have done exactly opposite what CR did and bump it to the right.

BTW, I'm thinking I will put the 5068 back on and do exactly what you're doing with the optical, then once it's all together I'll be talking to diesel ryan again about a 99mm3 chip for the '94. Then I'd like some dyno numbers to say where I am in power. If I can pull anywhere close to 90mm3 I should be making near 300hp.

Just to clarify, I moved bumped it toward the passenger side. I also moved the timing back to where the shutoff selinoid was straight up instead of on the timing mark. Now it will startr and run but with lots of dark grayish-white smoke and futs out under throttle. DSo I need to bump the other way on the optical or mess with the timing?

Dave, you have to go backwards of what we have to tell the other guys who do this because you have the 'wrong' pump OK?
You need to move the optic sensor towards the driver's side just a touch. ESO straight up and down is a good place to get a baseline for setting TDC Offset, but you will need the scanner to walk you in to get it where you want it.

Cool, I'll try to get it bumped back tomorrow afternoon and see what happens. Thanks for all the advice and the patience!

Bumped it back all the way to line up on the passenger side and I guess that it is too far. Won't start, bu sounds like it is trying like heck to. I guess that I'll split the difference from where it was and where it is now and see what it'll do. Think that I might be able to come with a scanner maybe!

You might want to buy this just in case:
http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&item=7967850791&fromMakeTrack=true

Bumped it back all the way to line up on the passenger side...All they way like you bumped it as far as it will go? Thats definitely too far, this is a very very slight adjustment. 5068 pumps are even more sensitive. Can you put the sensor back as close to its original position and get it to run? Then get us a scanner and tell us what your getting for Low Idle fuel rate, DES/ACT timing, TDC Offset and describe how the truck is running as far as smoke, noise, throttle response and we can walk you in where you need to go from there.

It's a drive but I'll help you get it timed if you're interested, David.

I finally had time to work on it today and bumped it back a little more toward where it was originally and it acts like it wants to start, but just won't quite do it. Diesel Mechanic, where are you located? I will try to get a scanner as soon as I can. Hate to drag this out, but my schedule is hectic. I'm a firefighter every 3rd day and work 2 or 3 part time jobs and try and have time for the family also. Thanks for your patience!

I live between college station and huntsville,tx.

I may be one of the people who's familiar enough with what has to be done to do it and I'd be happy to help.

Davidw,

What's the latest? My scanner should read your truck.

Don't want to make anyone have to come all the way up here. I think that I might just get another rebuilt pump and keep the 5068 to mess with later. Where is the best place to get a rebuild? I gotta get this thing going soon. I need it at the end of the month to tow to NW Arkansas!!!! Thanks for all the help.

What about SS Diesel?

Abilene Diesel (http://www.abilenediesel.com)