DB2 and DS4

[jjw565]

I am considering replacing the DS4 pump on my 95 Tahoe with a DB2 (just tired of dealing with all the electrical gremlins and exploring the idea) and I had a question about the pumps (I already know I need to rig up something to control the 4L80E transmission and add a throttle cable etc.)

What I am wondering is, is it possible to get a rebuilt or new DB2 pump that won't eventually suffer from the no start on hot condition? The one I am talking about is when the old pumps are worn out they have too much space around the plunger and the hot thin fuel won't pump so you have to dump cold water on the pump to cool it down (my experience). If I understand correctly this was due to a dissimilar metal junction where the one metal shrinks/expands more than the other opening up too much of a gap around the plunger.

My understanding is the DS4 pumps don't have this problem (at least not that I have ever heard of) and I am wondering if anyone is rebuilding DB2s with a fix because I don't want to deal with this once the pump gets a few miles on it.

 

[ak diesel driver]

All pumps will eventually do it. It's all part of the wearing out process. Ds4s you don't hear about very often because they usually have something else fail first. As in pmd etc

 

[jjw565]

Thanks I didn't realize that, maybe having 4 plungers instead of two makes the problem less severe and less noticeable too, I think most guys with PMD problems hopefully know enough to not toss the IP but I guess there could be some optical sensor problems that take them out too.

 

[Will L.]

*IMO*. db2 is way better. Put it in, set it and forget it. Military still specs it for newly built hmmwvs. It takes more abuse and lasts longer. It handles dirty and dark fuels unlike a ds4. The only reason a ds4 was invented is smog laws required monitoring ability through the obd2 port. Gm was a little ahead of the game to beat out the competition on have bugs worked out for compliance. If you can ditch the ds4 I say do it.

I spoke to one of the 3 engineers that created the ds4 when working for the test fuel company. He hated the ds4 and was sure it and he pmd would be the downfall of gm in the diesel market. How many false ip swaps happened with the db2? Yeah, exactly. It will wear out. Keep it lubricated and it will outlast a ds4. Get one with the new material and coatings in it for multi fuel and it will keep you happy a long time. Setting time is a little harder because the proper tools are harder to find is the only downfall I see, so time it by ear.

Ok everybody can hit me with rocks now.

 

[ak diesel driver]

No rocks here

 

[Chevypoor]

*IMO*. db2 is way better. Put it in, set it and forget it. Military still specs it for newly built hmmwvs. It takes more abuse and lasts longer. It handles dirty and dark fuels unlike a ds4. The only reason a ds4 was invented is smog laws required monitoring ability through the obd2 port. Gm was a little ahead of the game to beat out the competition on have bugs worked out for compliance. If you can ditch the ds4 I say do it.

I spoke to one of the 3 engineers that created the ds4 when working for the test fuel company. He hated the ds4 and was sure it and he pmd would be the downfall of gm in the diesel market. How many false ip swaps happened with the db2? Yeah, exactly. It will wear out. Keep it lubricated and it will outlast a ds4. Get one with the new material and coatings in it for multi fuel and it will keep you happy a long time. Setting time is a little harder because the proper tools are harder to find is the only downfall I see, so time it by ear.

Ok everybody can hit me with rocks now.

I agree. Now that I have a DB2 I would not want to go back. A shame that GM only made them for 2 years on the 6.5 trucks.

 

[jjw565]

Thanks for the advice, that is the direction I am leaning, I just need to do my research on the throttle position sensor for the transmission and all that. I'll have to see if I can find one with the new coatings as you say

*IMO*. db2 is way better. Put it in, set it and forget it. Military still specs it for newly built hmmwvs. It takes more abuse and lasts longer. It handles dirty and dark fuels unlike a ds4. The only reason a ds4 was invented is smog laws required monitoring ability through the obd2 port. Gm was a little ahead of the game to beat out the competition on have bugs worked out for compliance. If you can ditch the ds4 I say do it.

I spoke to one of the 3 engineers that created the ds4 when working for the test fuel company. He hated the ds4 and was sure it and he pmd would be the downfall of gm in the diesel market. How many false ip swaps happened with the db2? Yeah, exactly. It will wear out. Keep it lubricated and it will outlast a ds4. Get one with the new material and coatings in it for multi fuel and it will keep you happy a long time. Setting time is a little harder because the proper tools are harder to find is the only downfall I see, so time it by ear.

Ok everybody can hit me with rocks now.

 

[WarWagon]

What are you running in the fuel to lube the pump now? Yes, every tankful needs it.

If you get the made in USA extension harness for the PMD and put it on the bumper you have solved 1/2 the battle with the DS4.

Going DB2 requires finding a good pump builder and is expensive. Kennedy Diesel is one place to look. Core charges are high everywhere.
Leroy Diesel in my signature sells a stand alone 4L80E controller. Bobbie Martin wrote a guide on how to do this without the controller. Some tuners may be able to retune the 1995 ECM to be trans only.

The DS4 with a 6 position, 6 tune, chip is an advantage when you are pushing the limits and hot rodding your diesel with huge turbo's, spool valves, cams, and other outside the box ideas. The 1995 ECM and glow plug control reprogrammed for longer glow time IMO is hands down better than the 6 volt plugs converted to 9 volt self limiting plugs the 1993 and older DB2's have to put up with now. The "newer" glow plugs don't get enough time to glow. Not easy to adjust glow time on 1993's and aftermarket controllers are immune to the resistor trick.

 

[jjw565]

I've been using Diesel Kleen lately and I have a remote mounted PMD, the reason I have been thinking about a DB2 pump lately is because of some electrical gremlins that have been giving me a headache the last few months. The truck had issues dying randomly even after replacing PMDs, going through the whole fuel system and all that I eventually just had to replace the IP which seemed to fix it for a while, then it started this new thing where it would not start after shutting down hot. Went through all the usual troubleshooting, PMD, trouble codes, fuel lines, filters, fuel shutoff solenoid, etc. Might have finally found it tonight, it typically would start after cooling down but the last week it got so bad that even after sitting for days it would not run properly (I shouldn't say wouldn't start, more like would only start with pedal down then would not idle and would die when put in gear). Today as kind of a last ditch attempt I swapped out the optical sensor for an old one I had and it started and ran. Will see how it does this week but hopefully that was the fix.

Anyway, the reason I was thinking about swapping out the IP for the mechanical one is the truck is almost twenty years old now and I am getting tired of its BS and as the wiring and sensors and crap get older it will only get worse and less reliable. We'll see the DS4 might live to pump another day but the next time I have to go through a bunch of debugging or if it ever needs replacing again its toast. I am hoping selling my two good PMDs and maybe a core charge on the couple of DS4s I have will at least partially pay for a good rebuilt DB2. I don't really tow anything heavy (its just a Tahoe) and the truck moves well enough for me when its running so I am not worried about performance just reliability at this point. For glow plugs if I do make this swap I'll finally get around to making a manual controller anyway. I should probably listen to my wife and stop fighting with an old 6.5L beater but its a disease I think haha

 

[NVW]

Any codes when it won't start? My 95 has an issue with the fsos fuse spade contact. fuse is good but on occasion the spades loose contact.

It would be code 13 IIrc.

 

[ak diesel driver]

I would be seriously checking the grounds on that. I'd also be looking for a different rebuilder of pumps.

 

[hookedup50]

X2 on the grounds. The ones on the intake bolt need to be moved to the next bolt/stud. I had same issues on my 97, even after cleaning them. The problem went away after moving the grounds.

 

[ak diesel driver]

yep the next bolt forward is a dry hole and grounds much better

 

[jjw565]

interesting, I'll have to look at that, I've had it apart so many times over the years I can't remember which stud I have the cable on anymore. For codes I had 17/18 and then some in the low 30 (EGR related or related to the turbo master I think) and then 35/36 which are the pulse width ones. I've had those ones many times in the past though after something as simple as an air leak so I don't think they are that great as an indicator of anything. 17/18 where new this time around though so they might have been pointing to the optical sensor.

The weird part though was how for months the truck would start and run fine cold but not when it was hot, I couldn't wrap my head around how that could be grounds or a fuel issue or anything but who knows I guess as things expand maybe the ground cut out or maybe the optical sensor was somehow affected by temp. I'll see if it still does it this week with the sensor replaced.

 

[WarWagon]

I've been using Diesel Kleen lately and I have a remote mounted PMD, the reason I have been thinking about a DB2 pump lately is because of some electrical gremlins that have been giving me a headache the last few months. The truck had issues dying randomly even after replacing PMDs, going through the whole fuel system and all that I eventually just had to replace the IP which seemed to fix it for a while, then it started this new thing where it would not start after shutting down hot. Went through all the usual troubleshooting, PMD, trouble codes, fuel lines, filters, fuel shutoff solenoid, etc. Might have finally found it tonight, it typically would start after cooling down but the last week it got so bad that even after sitting for days it would not run properly (I shouldn't say wouldn't start, more like would only start with pedal down then would not idle and would die when put in gear). Today as kind of a last ditch attempt I swapped out the optical sensor for an old one I had and it started and ran. Will see how it does this week but hopefully that was the fix.

Anyway, the reason I was thinking about swapping out the IP for the mechanical one is the truck is almost twenty years old now and I am getting tired of its BS and as the wiring and sensors and crap get older it will only get worse and less reliable. We'll see the DS4 might live to pump another day but the next time I have to go through a bunch of debugging or if it ever needs replacing again its toast. I am hoping selling my two good PMDs and maybe a core charge on the couple of DS4s I have will at least partially pay for a good rebuilt DB2. I don't really tow anything heavy (its just a Tahoe) and the truck moves well enough for me when its running so I am not worried about performance just reliability at this point. For glow plugs if I do make this swap I'll finally get around to making a manual controller anyway. I should probably listen to my wife and stop fighting with an old 6.5L beater but its a disease I think haha

Diesel Kleen isn't as good as 2stoke oil. Useful SPICER diesel lube study.

Good rebuilt IP's are hard to find. You have to pay for them and make sure they have a new head and rotor in them. The DS4 is sensitive to bad lift pumps, restrictions in the fuel line or tank sock and air. IMO the DB2 just looses power when the DS4 suddenly quits during fuel starvation. They can both loose power but again IMO the DS4 is more sensitive.

 

[Yachtcare]

I made the switch earlier this year. I tried a db2 pump I had on the shelf for a while, no good. Then I went thru two "rebuilt" 4911's from Pensacola diesel. Both were junk. Got the "Junior Moose" pump from Conestoga diesel in Pennsylvania. They do their own builds, whereas many just buy from a bulk builder and have 'em drop shipped. Cost was actually a bit less than Pensacola and some other builders were charging. I'm extremely satisfied. Truck has more giddy up, than it ever did with the DS4.

I made my own manual controller for the 4L80E. I had had intermittent trans problems for the past few years. Some say the full line pressure without computer control killed the tranny. Others say it was likely a torque converter gone bad, in combination with the line pressure that killed it. I haven't had the trans torn down yet so the jury is still out. I'll likely get the US Shift "Optishift" installed when I get the tranny replaced, or built.

As for the IP swap, get the "Junior Moose" from Conestoga, get a controller for the tranny, and don't look back.

 

[scottm]

Get one with the new material and coatings in it for multi fuel and it will keep you happy a long time. Setting time is a little harder because the proper tools are harder to find is the only downfall I see, so time it by ear.

Will, where can you buy a new db2 with hardened internals? The current production ds4 with hardened internals is DS4831-5521S, but I can't find new db2s.

 

[tanman_2006]

Not sure about hardened internals. Call Conestoga and pick their brains.

They do quality rebuilds, a lot of people get 100k and are still going strong on ford idi Forums.

 

[Burning oil]

I have done the swap to DB2 in an OBDII truck, used a TCM from a van. That was alot of work it took months looking at shop manuals depining OBDII and repining OBDI TCM. It was done without even cutting a factory wire, BUT!! i'd never do it again now that OptiShift is available http://leroydiesel.com/product-category/transmission/
I did the swap years ago before I had my business up and running. Knowing what I know now I probably would have just built a DS4 OBDI swap.

 

[Chevypoor]

I made the switch earlier this year. I tried a db2 pump I had on the shelf for a while, no good. Then I went thru two "rebuilt" 4911's from Pensacola diesel. Both were junk. Got the "Junior Moose" pump from Conestoga diesel in Pennsylvania. They do their own builds, whereas many just buy from a bulk builder and have 'em drop shipped. Cost was actually a bit less than Pensacola and some other builders were charging. I'm extremely satisfied. Truck has more giddy up, than it ever did with the DS4.

I made my own manual controller for the 4L80E. I had had intermittent trans problems for the past few years. Some say the full line pressure without computer control killed the tranny. Others say it was likely a torque converter gone bad, in combination with the line pressure that killed it. I haven't had the trans torn down yet so the jury is still out. I'll likely get the US Shift "Optishift" installed when I get the tranny replaced, or built.

As for the IP swap, get the "Junior Moose" from Conestoga, get a controller for the tranny, and don't look back.

I am happy with my Bull Moose pump so far. I agree on the power. I have had the ATT on a chipped auto 6.5 with a Walbro pump. I did not have the pocket ported heads or the diamond cups but T seems to run stronger and the throttle response also seems to be a bit better. The smoothness is what gets me- the Moose pump just flat runs better than any DS4 I have had.

Not sure about hardened internals. Call Conestoga and pick their brains.

They do quality rebuilds, a lot of people get 100k and are still going strong on ford idi Forums.

That is good to hear the Ferd guys are getting some good mileage from their Moose pumps.

I would do the conversion, the DB2 should give you simplicity and less electrical headaches over the long haul.