2ND Dtech bites it

[Yukon6.2]

Hi all
Just thought i would post that my second Dtech started acting up in my 96 3500 tow truck.
I can see how this series of diesels got their bad reputation.
Iv had this truck a little over two years and have put about 5000 miles on it since i got it.In those few miles i'v had more problems then any truck has ever given me,good thing i'm a GM die hard.If it wasn't a tow truck i'd probly sell it.There are no used tow trucks around here and i would have to get another shipped in.
To date the repairs have been
at delivery the turbo wasn't holding-new vac pump
batteries
PMD stanadyne quit,remote mount and Dtech
Head gasket,swaped motor form same year donar
optical sensor,swaped one from a questionable pump
front wheel bearing,replaced with new
remote mounted Dtech,replaced with known used stanadyne.
I think this time i'm going to try the new grey stanadyne.I got the first Dtech replaced under warenty,but i think i'm out of luck for warenty on this one.
Oh yah i'v still got some wiring issues that i'v yet to sort out,when any lights or load is placed on the truck while driving the tach jumps up to red line,even steping on the brakes causes the tach to jump.
Oh well the joys of an old truck,if i had the time i would convert it to a manual pump.I hate skinking computers,even have one in my 98 KW that has got an issue,nearest shop to read that one is 100 miles away.
Did i mention i hate computers
Anyhow just wanted to relay my luck with the DTech,they are not the great answer that the 6.5 crowd is looking for.
Thomas

[DmaxMaverick]

The D-Tech isn't your problem. They aren't dying, your electrical issues are killing them. This is common, with any brand of PMD and electrical issues. Fix your electrical, and it'll last. Pay special attention to grounds, all of them. When grounds are weak, the circuit will complete to ground in any way it finds. This is often through components, which causes them to fail.

[Yukon6.2]

Hi Dmax
Yea i figered there are other issues,still they are problems that the truck has.
I'v gone over the grounds on the motor ,batterys frame.
The Dtech started having the same problems as the first one,rpm swings on deceleration.That was the first,then got a couple of full throttle bursts.The last drive that i used it,the motor quit,threw a code,then started back up.
Unfortanatly i don't have any extra time to go serching for any other grounding spots.Building our house and have the business in limp mode,working there only two days a week so i allways have a plie to do on those days.I'll have to find a backup FSD and keep hoping to make it home when i go for a drive.
Thanks Thomas

[arveetek]

I've been pretty happy with my D-tech unit. I can't even remember now when I bought it....it's been many years back.

I know it outlasted the OEM style Stanadyne unit by many years.

I'll have to look in my records later to see how many years/miles I've put on mine.

Casey

[racer55]

There are several grounds on one of the rea intake manifold studs that need special attention paid to them,I would even go as far as to add a ground from that stack directly to the drivers side battery ground.

Also there were a bad batch of flight systems PMD's and the company is aware of the problem but not informing the 6.5 community of what serial #'s are involved.

Apparently they have even contracted outside engineers to further enhance the reliability of thier PMD's but at present I don't know of a way to tell the new form the old or the good from the bad.

[Yukon6.2]

Hi Racer
Thanks for the ideas
When i changed the motor i cleaned all the grounds and added extras under the hood,i added a complete ground from battery to frame,motor,cab.All were covered with dilectric grease.The first PMD went bad about 4 months after getting the truck,it was a stanadyne,and looked like it was the original to the pump,which was about 4 yrs old.
The symtoms of the secound Dtech mirrored the symtoms of the first.The motor would buck on deceleration somtimes quite violently.The last trip it stalled out and had a couple of throttle runaways.
I'm hoping someone has similer symptoms,and found the cause.
Thanks Thomas

[85-m1028]

just because the ground is cleaned doesn't mean the wires in the terminal have a good connection. I noticed on mine that the previous owner had replaced the original connector with a better quality one. "the one at the back of the engine block"

I always make connections with good quality connectors and then solder the tips of the wire to the crimp.

[Yukon6.2]

Yup
I don't like crimp on conectors.All my wiring gets soldered and heat shrink.iI keep crimp ons for emergancy use.I'v been around 18 wheelers most of my life.Up here we had gravel roads when i was growing up,calcium was used for dust control.Any exposed wire was reduced to green fuzz after a couple of years.Used to watch truckers fixing their lights with crimp ons over and over.
I try to do my wiring once.
Pet peve those scotch crimps people use to add wires into an existing wire,Yukk
THomas

[Plowboy81]

I have had to bad Dtech boxs also, One cost me a motor and now the other has started something weird on my truck. So Dtech owners be ware.

[Yukon6.2]

Hi Plowboy
I'm not sold on the dTech's.I replaced the last one with a used stanadyne,and havn't had any wierd symptons.
I did have to change the ignition switch last week,wouldn't start no mater what,pluged in the block heater,extended glow times,in deperation i disconected the glows and tried starting fluid,no go.I did a little more diagostic and could feel the shutoff solinoid clicking on and off,tried hot wiring the solinoid but no luck.Switched the switch and it fired right up.Starts way better now,i thought i had a fuel leak because the starts after sitting awhile were getting worse and worse.Hopefully no more gremlins for a while.
Thomas