5521 Injection pump on 1994 HD

[NorthStarMN]

I have recently purchased a 1994 Chevy C3500 HD with 6.5L TD.
(94 Heavy Duty

[gmctd]

5068 was in production ~2years, immediately superceded, required eprom change for upgrade - 5521 is the current production IP replacement for your truck.

Because of the required eprom change, the engine would not run correctly with a 5068 IP

Replacement FSD should match the number on the pump, to get the current production version.

If the number is less than 34583, pass it up

[Mark Rinker]

Hello from a fellow Minnesotan...

Sounds like a nice truck! If you are concerned about the FSD failing, get a spare mounted underhood on a cooler, with an extension harness. That way you always have a ready swap if the pump mounted FSD fails when you are on the road.

For trouble free towing this summer, read the DP articles about de-bugging the radiator and between the oil cooler and tranny coolers. Updating your cooling system to a two thermostat system from the later years with a HD fan clutch will make a world of difference for an otherwise stock 6.5.

Mileage sound about right, maybe a bit low. Clean air filter? Any black smoke at the tailpipe under acceleration?

[NorthStarMN]

gmctd - Thanks for the good news - for the 5521 pump being OK for this truck! Thanks for the info concerning the right replacement PDM if/when I need one!

Mark Rinker - I have ordered both the 6.5 books from this site - the compilation of the articles and the trouble shooting guide. Should be in the mail today. Hopefully the DP articles about de-bugging the radiator and between the oil cooler and tranny coolers are in there.

I was thinking about updating the cooling system to a two thermostat system kit - (http://www.kennedydiesel.com/waterpumpkit.html) .

If I ran the truck without the cooling system upgrade - using the Stock Dash water temp gauge - at what temp would I know that I need the water pump kit?

Then - If I purchase the cooling system water pump upgrade, do I need to go with the HD fan clutch upgrade right away? Or would the budget $$ be better spent on the Oil Cooler/Oil lines upgrade kit - and not do the HD fan clutch upgrade? (The lines are leaking a little.)

I have not really tried any hard acceleration yet. Wanted to drive it for a while first. I'll check it out this weekend for the black smoke. Air filter is clean-newer K&N type.

Thanks again - this really helps!
I am in the Hutchinson area - and vacation by BigFork Minnesota (UpNorth).

NorthStarMN

.

[Mark Rinker]

If your oil lines are leaking, by all means fix that potential engine-killer first.

Most everyone here updates to the dual thermostat system AND the HD fan clutch simultaneously, if towing heavy.

I wouldn't trust the accuracy of the OEM gauges, but that being said, you wouldn't want to see water temps north of 210 for extended periods of time. 215 would be the 'peak' temp I ever want to reach, and that better be for only a minute or two while towing on a hot day, uphill, A/C on, etc...

You'll shave 20-30 degrees with the updates, they really work together well. JK's fan clutch setup rocks.

[MPrichard]

5068 was in production ~2years, immediately superceded, required eprom change for upgrade - 5521 is the current production IP replacement for your truck.

Because of the required eprom change, the engine would not run correctly with a 5068 IP

Replacement FSD should match the number on the pump, to get the current production version.

If the number is less than 34583, pass it up

I've got an "F" engine with an old 5068 pump and I have a good used 5521 to use with it. I'm rebuilding this engine to swap into a '93 454 equipped Sub. the donor vehicle had the VIN number 1GBHC34FXRE127224 (a c3500 truck) and the computer had the PROM code "4254 BMSD 0152". I'm having trouble getting the local GM dealer to supply the updated PROM as they don't seem to have a simple table to look up the replacement. Surely, if the 5521 is the current replacement for old 5068s (at least if serviced by the dealer), then they have a suitable replacement PROM to go with it, no?!?

Any ideas what the GM part # for this beast is? I know I can order a performance chip from Kenney and others, but I'd like to start with an appropriate stock chip, especially since it's around $40-$70 vs. $350. Plus, I'm going for fuel economy over power as even a bone stock 6.5TD will be a huge improvement over my current tired, oil drinking 375k mile stock 454.

Alternatively, can anyone with a 1994-5 "S" code engine, automatic trans and 4x4 (if that matters) give me their VIN number and possibly PROM code if they happen to have referenced it recently? The dealer should be able to source the chip with just a VIN number, I think. I just don't think I can simply swap the "S" and the "F" in my VIN to get them to find the right chip.

Thanks in advance.

[BobND]

How about this...

1994 K-1500

6.5 TD "S"

4L80E tranny

3.73 gears

Has a 5521 IP (I bought it used YEARS ago, with about 54,000 miles on it, so I am not certain what the original pump was. I could pull the 4-digit PROM iD with the scan tool, if that would help.

VIN... 1GCEK19S9RE182775

[MPrichard]

Cool! Thanks! I think that should be perfect. I forgot to mention the gearing on my truck, but it is also 3.73, so I'd think this would be a good matchup. I'll see what the dealer turns up. I would love to get that 4 digit PROM ID the next time you have the scan tool on the truck. I got a pile of service bulletin printouts from GM which reference this ID and that would likely help connect the dots...

Thanks again for the VIN.

[JohnC]

If you're swapping it into a '93 there's no reason to go with the electronic pump. You can use a '93 trans controller or an aftermarket one and be better off in the long run.

Bobby Martin's DS4 - DB2 conversion info would probably be helpfull as you need to deal with many of the same issues.

[MPrichard]

It's actually probably a lot simpler for me to stick with the DS4 since:

- donor truck was 1994
- cruise control and throttle pedal control are much easier to adapt with fly-by-wire
- adding 1997 cooling updates easier
- already have 5521 pump

I also imagine that the computer controlled pump will respond better to changing conditions and potential future veg. oil conversion (assuming relocated PMD).