1994 Chevy 3500 6.5 questions,,,,

[300stw]

hello all, bought new truck and have a few questions, have done a little searching but havent really found what i want,,,

this truck has a rebuilt 6.5 out of a 94, the injection pump is from a 97 i am told, the truck runs pretty good,
very touchy on the throttle, in low range it bucks like a mule, when i start it if you dont burp the throttle the motor revs sky high, it also smokes bad,
no boost or egt yet,,,

i have a mechanical pump from a 93 6.5, also the pedal, cable and injector lines, i would really like to change this truck to the mechanical pump setup for reliability in this ne montana country,

i have access to the computer and the under hood wiring harness,
i would like to hear from anyone who has actually done this swap, do i need to change out computer and wiring harness or just the pump and lines, should i upgrade turbo,,

i have a diamond eye exhaust and a new crossover sitting here as well as a k47 air box,

i had a 93 cummins for a long time many mods,,

any other thoughts appreciated,,

[300stw]

i spent some more time searching and found bobby martin guide to swapping the db2, seems pretty easy, turbo master for the turbo to control boost, what if a guy went to different turbo like a hw35 ,, how to adjust boost, thinking outloud,,

[john8662]

HX35 is wastegated, you adjust it's wastegate to regulate boost.

H1C is non-wastegated, what your 93 cummins had. To regulate boost on it you adjust fueling on the engine and match turbine housing A/R numbers to get it where you need.

J

[Robyn]

I see that your truck has the NV 4500 tranny, with this doing the mechanical IP swap is a snap.

Just swap in the IP and lines, do the throttle cable and your good to go.

Get the timing as close as you can by eyeball and then watch the EGT's to see where your at.

Bobby Martins info works well on the stick shift stuff.

The issues really start when you go for a swap to an auto tranny swap.

Get the DS4 off the rig and your issues will be gone for good me thinks.

The IP that works the best is the 4911

With the DB2 on the truck the computer will pretty much be left to do nothing.

The check engine light will be on, so just remove the bulb or ignore it.

The only issue will be to wire in the power Supply lines for the IP fuel solenoid and the cold advance/fasy idle.

I would say to use the original ++ feed that connected to the fuel shut off solenoid on the DS4, use this to power a constant duty relay, then feed the DB2 fule shut off and the fast idle/cold advance with the relay.

Install a cold advance temp switch from an early 6.2 in the RH head (rear side port) feed the power to the advance/fast idle through the temp switch and your set.

As soon as the ignition is turned on the relay will power the IP and the cold advance/fast idel and then once the engine warms a little the advance will shut off.

Pretty easy project.

Keep us posted

Missy

[Kennedy]

Odds are that the eprom is incorrect to match the pump. People get the notion that a DS is a DS so they start swapping willy-nilly and create issues like this. Tis is why I request the pump model number when doing a chip in an attempt to unravel as many mismatches as I can rather than sending teh chip twice.

It could well be a bad DS but the prom would be my first suspect.

[300stw]

thanks for the replies,,,
i have a 4911 pump if i remember right, i would like to have it rebuilt before i install, suggestions who to have rebuild it

i have a gm8 turbo, interested in upgrading it, what should i look for

do i need to do anything to fuel lift pump for longevity and reliability, in ne montana parts are few and far, help in the winter can also be few and far,

in the end i would like to get to the 225 250 horse power range to pull 3 mules and my trailer about 7000 lbs , i pull 8 or 10 times a year after that not much for towing with the truck

[300stw]

still searching and thinking out loud,


if i keep gm8 turbo with the 4911 pump, a turbomaster for boost control i assume,
if i change to a holset 35 or similar how to kep boost in check,,,

if and when i wreck havoc with this motor i was gonna get one of the latest models from tonys trucks to use as a performance rebuild,

[More Power]

I'd stay with the GM-8/Turbomaster for the mech conversion, at least for a while, to allow sorting out any nitpicks and give you some experience with how the engine/drivetrain perform. Once you've settled in, then consider some additional changes.

The Holset HX35W uses a boost pressure actuated wastegate. These normally produce, in stock form, a max of about 15-psi. With an intercooler, this would be OK on a stock compression ratio engine and close to stock 4911 fuel rates.

Jim

[300stw]

thanks for all the info from everyone, very helpful,,,

i see an electric fuel pump on the frame rail, should a guy change it out, if so what with, store the old one in the tool box for backup,,,,

[ccc]

" should a guy change it out, if so what with, store the old one in the tool box for backup,,,," I did..... but then I am having problems too. Not related to that though. There are a number of threads here that tell you what your output should be and some very knowledgable folk too. If it passes the test then it just depends on how much preventative stuff you want to do and can afford. Some of the experts can help out and tell you what fuel flow you should have. Good luck on your project.

[300stw]

finally got the mechanical pump installed,,,

some test driving today,, idles, great throttle response , turned the pump up 1/8th turn before install, wish i would of had the money for new injectors,,,

maybe next month or christmas,,,

no more computer controlled crap for me ,,,

ordered the turbomaster, running the vACCUM PUMP to the turbo right now
running 12 lbs boost 4 lbs at 70 mph