6.2 pump on a 6.5 will it work

[DrRoscoe]

I have a 1993 6.5 turbo with the pump[DB2-4911] taking a crap on me ,but i have a 6.2 pump new in the box what would i have to do to get it to work on the 6.5? or am i trying to do the impossible.

[JohnC]

As far as I know, all the 6.2 pumps are calibrated for a lower pop pressure than the 6.5's, so It may have trouble popping the 6.5 injectors. Also, the 6.5's have a higher fuel rate, although that's not insurmountable.

[DrRoscoe]

can the 6.2 pump be recalibrated to work? I've got a limited budget and just trying to save a few bucks

[Bnave95]

So, did you try it anyways? Then we all would know if it worked.

[Robyn]

Call (503) 232-1947 ask for Mark or one of the diesel shop guys.
This is the outfit I trust to do all my pump and injector work.
They can tell you for sure what you need to do. I think a quarter turn up on the HP screw will do it. Ask the pro's though.
Best to ya
Robyn

[Robyn]

Better yet Its a no cost call for me I will give them a ring this morning as soon as they open and get the straight scoop and post here later today
Robyn

[Robyn]

Sorry I got called out of town early yesterday and could not get to the shop boys. I will give it a go today though

[Robyn]

Correction on the tele # (503) 235-1947
talked to the guys today.
The 6.2 pump (DB2) looks the same and will physically bolt on but they say its not going to work right.
The inards are a lot different and thats the long and the short. I know this is not what you wanted to hear but thats the staight scoop.

Robyn

[dieseldummy]

The only difference between a 6.5 turbo pump and a 6.2 pump is plunger size, advance piston, and a few calibrations. In short a 6.2 pump will work fine on a turbo 6.5 with at least 1/4 turn of the fuel screw. It may have a different timing advance curve, but should run ok.

[Robyn]

I agree with DD
I talked with the owner of the rebuilder I use and he said the same thing. His tech guys are trained to use the canned NO it wont work to keep from issues with customers.
Just a quarter turn on the HP screw and a tad more timing and it will work fine. May not be perfect but it will get you up and flying.
Robyn

[dieseldummy]

I agree with DD


Thanks! Thats a first that anyone agrees with me.

[johnanc]

I put a 6.2 pump on a 6.5 and it worked fine. I was also using the injectors from the 6.2 though, don't know how well actual 6.5 injectors would work.

[Robyn]

The 6.2 pump can handle the pop pressure fine.
The 6.5 pump has larger plungers and a different advance piston and the adcance curves are different.
I am going to venture a guess here. IMHO I believe the advance thing is different and probably some of the other calibrations to meet EPA regs more than making the vehicle run well.
Remember when we used to order up a Banks kit for our 6.2 J engine.
Boy we were really doin it in tall grass when we had one of them.
The 6.2 and 6.5 are so very close in Cu.In so thats not an issue. The Banks kit had us tweek the fuel setting about a quarter turn to give us the needed extra fuel.
Hmmmm By Golly Oly I think It'll werk.
After talking with Mark yesterday at DFI he was quite sure it would run fine.
IMO many factory items can be swapped around and the end user will be quite happy with the way it works and so will the truck, its the engineering and emission regs that play a big part.

Hope this helps.
Good luck and let us know.
Robyn

[BILLYDIESEL]

injector pop of pressures different.
electronic pumps high pop of pressure
mechanical is lower

[Robyn]

Billy
This is true but the DB2 will also do the higher pop if you ask it to.
The early 6.5 turbo's were mechanical pumps and they were a bit higher pop than the 6.2.

[Robyn]

Just got off the phone with a friend that has swapped a 6.5 pump onto a 6.2 and it seems to be working. says it smokes a tad when ya mash it hard.
Thats seems about right.
Guess he got a great deal on the pump and his on the 6.2 was dead so all is well.

[gmctd]

The injectors set the pop pressure, not the Inj Pump - the pump will set the max fuel rate - plunger dia x stroke, determined by the camring.

In any case, the higher the pop pressure, the more stress on the rollers and camring - which is why S went to four - count'em = 4 - roller\plunger rotors in the DS4.

And one seldom seen DB2 with 4 plungers.

[Robyn]

I was not aware of that difference as I have never seen a DS series pump apart. Best thing they could do with that abortion is give it a funeral.
I had zero trouble with my 93 6.5 and the 94 and later Burbs are always causing hate and discontent.
Thanks for the info.
Robyn

[gmctd]

The DS4's have four 0.310" plungers, ceramic rollers, and the camring ramps are about half as aggressive as the DB2 ramps with 2 plungers - much less wear at the higher pressures available to the turbo engine.

Imo, 'they' spec'ed somewhat lower inj pressures due to IP warranty considerations - but, the camrings and rollers were still cratering until they began using the ceramic rollers.

DB2's also got the roller upgrades, and some 6.2 pumps were built using the sturdier 6.5 housing - but not all got that particular upgrade.

So - I still do not believe a shop can turn up the plain-jane...er, sorry - probably need to be politically correct, here.....plain-person 6.2 pump to 6.5 specs, reliably - maybe the upgraded pump, but the camring and head\rotor are still different than in the 6.5 pump.

And, I have read of noone who's even seen the mythical 4-plunger mechanical IP (listed under a DB2 p\n), even tho it's advertised on the Stanadyne site, which has caused much furor and gnashing of teeth.

[Robyn]

PLAIN JANE Hmmmmmmm thats me. When I am decked out I come with a grease smudge on my cheek. HAAAAAAAAAAAAAA
we dont worry about such things. Just to set your mind at ease I Dont subscribe in any way shape or form to the term Politically Correct.
That said lets talk pumps.
This is all very interesting. What was done to the 6.5's early 0n 92-93 when the turbos first hit the street's??
Lower pop pressure? The ealy ones had the DB2 pumps and I have seen many DS4's replaced with DB2's after the owner had had his/her (grin) fill of the DS4 failures time after time.
I had actually considered replacing my DS4 with a DB2 during the overhaul but ran out of time and $$$ and needed to get the rig back in service.
The DS4 with the SOL-D calling a tune to the pump is still working fine so I stuck it back on with no more than a wipe down with a rag.

It would seem that if the DB2 was not up to the task of fueling the later 6.5's what with all the swaps we would be hearing rumblings of some sort that the pumps were failing.

??????????
Lets keep this dialogue running a bit as it may give others some very useful information.
The local pump and diesel shop has done a metric buttload of swaps replacing the DS4 pumps that have failed and he says all is well with his customers. One fellow has a 96 Burb with a DB2 in it and a after market tranny computer and he is happy as a clam and has had it on the road now for about 3 years and I dont know how many miles. He pulls a big camp trailer though and uses the heck out of the truck.
**** One thought here****
Many of the rigs that are recieving the swap outs are high milers and the pop pressure has no doubt dropped off some with wear. Could be this is the reason they are lasting?????????
Oh if we could find one of those four plunger DB2 pumps were could hold it for the highest bidder :0)

Later
Robyn

[gmctd]

DB2's came in several flavors, not all of them intended for GM service - the IH 6.9\7.3 needed cw rotation, where the 6.2 needed ccw rotation, and we need not go into the Olds 5.7 situation.

The DB2 for 6.2 service has two 0.290" pumping plungers, and the camring is bi-directional - as indicated by a direction-of-rotation arrow on either face, can be used in cw and ccw pump applications by reversing the camring during installation.

The DB2 for the 7.3 has two 0.310" plungers for increased fuel rates, and the camring has one directional arrow indicating cw service - cannot be reversed to be used in ccw service.

All the aluminum DB2 bodies were cast with a narrow neck and small flange - fine for 6.2 use, but the greater fuel rates and pop pressures in other applications resulted in a much sturdier casting, required to stabilize timing and FR in those applications, incl the 7.3 IH\Ford.

For the '92-'93 6.5TD applications, S chose the heavier DB2 casting from the 7.3, with the 0.310" plunger rotor\head, and a camring marked only for ccw rotation - the 6.5 camring cannot be reversed and calibrated in the 7.3 application, and vice-versa.

All used steel rollers on hardened camrings.

Were other upgrades and changes involved, incl the advance piston and bore endcaps for timing and advance.

The '94 DS4 got an even sturdier larger body casting with larger rotor\head - required for the EFI solenoid and four 0.310" plungers - with steel rollers and hardened camring, also larger diameter.

A seperate IP for hi-output service - the 5068 - got a revised camring with more aggressive ramps and revised software with upgraded fuel rate and timing curves, but was discontinued by middle of '95 m\y, as the standard DS4 could meet all requirements simply by modifying the software in the PCM.

The early DS4 problems mainly involved the roller\camring interface, blamed partially on reduced lubricity - the rollers would disintegrate and crumble, which of course ruined the IP and loaded the fuel tank with metal particles.

'Course, dealer response was 'metal in the fuel supply, warranty void' to many of the failures, since, had the metal gotten there as part of refueling, the IP would have failed in the identical manner.

Imo, those early failures resulted in injector pop pressures being set lower than required for absolute efficiency - 1785psi vs 2125psi - the finer spray droplets result in easier ignition and more complete combustion.

Solution was ceramic rollers, along with several other improvements, and rebuilds with those enhancements were noted by a green tag on one of the top-cover screws - factory rebuilds and new mfr got the green tag, but evenutally a new blue S nomenclature label replaced the original S black label.

An upgraded DB2, with ceramic rollers and upgraded rotor\head - for 6.5 hot-start problems - also got the green tags, with blue labels eventually replacing the earlier black labels.

Should be lots more archival info on this site, if you're interested - JimB and Gomer's did several articles, early on.

[Robyn]

Very interesting.
Just a side thought here.
Had the big boys (GM) been using their heads, real time testing on a test track with Bubba out there beating the snot out of a truck would have revealed most if not all of the issues long before the trucks ever hit the streets and Jack and Jill public had to put up with all the failures and the resulting bad taste all this left in their mouth, not to mention the millions of $$$$$ it cost the factory to resolve these issues in the field.
The resulting loss of customers both current and future due to the bad reputation is also a point to ponder.
They never learn either the new Diaper max is no better as it has a host of issues that could have been resolved during a testing program.
Its no wonder they are losing millions every year.
Go figure. Ford and Chrysler arn't any better.

Robyn

[gmctd]

Story is - S wanted further testing, but GM needed to play ketchup to Dodge's 5.9 Turbo and Ford's 7.3 Turbo - GM won the discussion but GM-owners lost.

Anyway, as you can see, there is no problem with installing a DB2 on an EFI 6.5, long as you use the DB2-831-4911 equiv designed for the 6.5, with associated injector pipes.

To answer the orginal post - a 6.2 IP can be substituted for a defunct 6.5 IP, if the injector pipe fittings match - size and threads - those on the fuel distributor.

It will run lean with no throttle applied - what we call idle - and lean on the road - what we call fuel economy - so, it will get you by until you can get the correct pump, no harm done.

That's right, folks - Diesels run best when the ratio is lean - more air than fuel - exception being, no fuel in tank, but that more-air-than-fuel ratio is all air, like me...... :cool:

[Robyn]

All very interesting.
I have heard that GM and the "S" had issues over their technology and that is why we ended up with the PMD stuck on the side of the pump instead of lodged in a nice cool spot somewhere on the truck.
Can you shed any light as to the truth in this ???
I do know that the idea that the "cool fuel" running through the pump to keep the PMD cool was a joke for sure.
There simply was not enough testing done. Gm did this with the 5.7 and by the time they got it right the market was soured. They did it with the 6.5 and now they are doing it with the DMax. These guys have to be brain Dead.
Hell the boys at the Monster garage could do a far better job for sure

[gmctd]

Well - it's fairly well understood around here that the FSD should be mounted on the side of the injection pump - the internal fuel temperature is usually around 130deg, seldom gets above 140-150deg F with the PMD - as per GM and S instructions.

What 'they' forgot to include in the directive(s) was that, for extended PMD service life, the vehicle must be left running 24 hours a day 365days a year.:eek:

Someone apparently overlooked probability of incurred damage from heat-soak after the fuel stopped flowing, and the abrupt rise in underhood temperature after the coolant fan stopped forcing air-thru.

Simple oversight, but easily corrected, thanks to the good Mr. Heath and other Page contributors - GET THE FRIGGIN' THING OUTTA THE ENGINE BAY, PERIOD!

Sorry.....easy to get emotional about that prone-to-fail extra-cost not-an-option item, even after all these years.

I might also just add, that when the FSD\PMD on my truck failed back in ought one, I weighed the probabilities, then replaced the replacement FSD on the Inj Pump, as specified, where it resides, functionally, to this day as part of the R&D I was doing with my truck.

I do, however, take certain comfort in knowing that the wise engineers at S designed a special spot on the side of the IP to accept the FSD - that, and the spare FSD\heatsink\extension-harness combo I keep in the compartment behind the rear seat.

Ha!!! I might not of been born yesterday, but neither did I just fall offa some turnip truck, Diesel or not!

Anyway, that's my take on the matter, and that's my story - and I'm stickin' to it..........

[Robyn]

My first encounter with the FSD was back on 94 when I bought my first new body style dually (Im an "old" mid 80's body style lover)
The usual stuff was happening and the warranty fixed it, (For a while).
The truck never ran up to my expectations and when the warranty was about over I traded it off for a Dodge V10 and that is another story for another forum.
I guess we have answered fairly well the original question that was posted.
Yes the 6.2 pump will get the truck going down the road again.
I would however plan to get the original one fixed and reinstall it when possible.

Robyn

[gmctd]

Agreed - and, best wishes on your faux-hummer...................:cool: