1st Post
I have taken my 94 2500 6.5TD to several places with no luck but cost $$$. I have replaced the map sensor, computer, injectors, lift pump, pmd, all filters. Checked & replaced all the vacuum lines, checked wastegate, turbo spins free & is getting oil, replaced transmission sensor & OPS sensor, even replaced to timing chain & gears because one place said timing was off a tooth (wasn't). If I remember right it has a#9 chip in the pmd. I moved the pmd off the engine & installed a heatsink & fan. I marked the IP & have tried moving it alittle both ways to see if anything would be better. I put lots of money in & don't know what else to do, I'm even thinking about switching to gas motor. It will run good at 70MPH its just getting there. I have been told you have to take it to a dealer to do the timing adjustment & reset the computer. During the timing gear change I did notice the center set of intake ports had heavy black sut in them??. I'm wondering now if maybe one of the IP lines might be I the right place, I never moved them but I got the truck used. Any insight (http://www.dieselplace.com/forum/showthread.php?t=296341#) appreciated!!
2nd Post
Finally got a chance to work on my 94 6.5 Turbo S smoke & low power problem, I pulled the EGR & upper manifold. Boy was it gunked up, cleaned it up & checked EGR valve. Put a vacuum pump gauge on the valve it opened & closed & held a vacuum without problem. I checked the the 3 electric vacuum valves, waste gate, EGR turbo boost. They all did not hold vacuum, waste gate held along w/vacuum pump but w/engine running I couldn't get any reading at idle or higher.
So I am wondering if,
1st Can the vacuum pump on the motor hold pressure and still not work.
2nd, are the 3three vacuum switches suppose to close to seal.
I left the valves off, ran the vacuum line from the pump to the EGR & Map sensor. Although power is poor, it still smokes but I don't think as bad as it was. I guess I will have to replace all 3 valves and see what happens, but not sure on the pump its self. Again Thanks for any input Steve

Did you ever run down the diagnostics checklist? Its there to help us help you. Have you checked for vacuum from the vacuum pump?

Sounds like dead vacuum pump to me. Or bad wastegate solenoid. Leaning on the vac pump tho.

Yes, I hooked the gauge to the pump, sucked it to 15 and held 10min until I released it. But when I started the motor I did not get any reading at idle or fast idle. Thats why I'm not sure its working even though it holds vacuum. Waste gate moved back & forth with hand held pump also held 15 on pump

Yea, sounds like the pump is dead.

Loose the vac pump & get a turbomaster.

If you just sent vacuum to the MAP on the firewall and EGR then you arent getting any boost. You have to run vacuum to the turbo wastegate for it to do anything. The solenoid controls how much, but if you run it straight to wastegate actuator it will work.

You should be using a vac guage not pumping them with pressure and testing if they hold pressure. What vacuum is the pump producing at idle? Are you using a guage with negative pressure (vacuum)

If your wastgate actuater will move with vacume applied to it ,either with a hand pump or engine vacume pump, then the actuater is bad. Turbomaster would be a good fix[probly cheaper than the actuater] I would get rid of the egr. I just had the heads off of my 95 "s" and the intake valves had over 1/4 of crud on them and the intake ports were very clogged also. I put a "f" intake manifold on to compleatly get rid of the egr. Plugged the vac hose to the valve.

Yes, I hooked the gauge to the pump, sucked it to 15 and held 10min until I released it. But when I started the motor I did not get any reading at idle or fast idle. Thats why I'm not sure its working even though it holds vacuum. Waste gate moved back & forth with hand held pump also held 15 on pump

any chance the PO took the belt off and bypassed the vacuum pump? Quite simply, if while the engine is running, you measure vacuum at the solenoid from the pump and there is nothing, you've found the problem. TM or replace the vacuum pump are the options.

Quite simply, if while the engine is running, you measure vacuum at the solenoid from the pump and there is nothing, you've found the problem. TM or replace the vacuum pump are the options.

Get a Turbo Master. It eliminates the need for a vacuum pump and takes only a few minutes to install. Your truck will thank you.


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Get a Turbo Master. It eliminates the need for a vacuum pump and takes only a few minutes to install. Your truck will thank you.


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The original poster speaks of an EGR valve though. That means he has an "S" engine which does monitor vacuum and will throw EGR codes without the vacuum pump.

TM will also cause a loss of 1-2mpg. Not too big of a deal, but it does add up. If you have EGR (sounds like you do) then you are better off getting a new pump. The BEST way to fix it would be to put on a 4" exhaust, "F" engine intake, TM, and heath GL4 ECM. :D:D But that is $$$$. A simple $150 pump is sufficient to get it back up and running the way it was.

The TM can be used without losing MPG, the problem is that the vacuum can regulate it at cruise to a lower boost than you might get with the fixed spring amount if you adjust the spring to give you like 15psi max. So with vacuum setup I can get 15psi max on hills or acceleration and only 3-4psi at 65MPH, so low backpressure at cruise. If you adjust the spring so that it only gives 11psi max then the cruise boost will be in line with vacuum setup at cruise and not lose MPG. The TM is better at getting the right progressive boost for good acceleration though, and you dont get annoying vacuum issues causing power losses.

The stock vacuum system with PCM control is not going to give you what you want with max boost though. I get those numbers with an aftermaket chip designed to use vacuum system.

My mileage didn't change when I eliminated the vac pump

Mine dropped about 2mpg. Others have reported mileage loss too. Maybe it just depends on the truck , who knows.

I'm set to pretty much factory boost levels, about 9-10
max with no load

I'm set to pretty much factory boost levels, about 9-10
max with no load

Sounds to me that the turbo master is the way to go, along with an F upper manifold to eliminate the EGR & remove the check engine light. At this point a fix would be an improvement to the mileage I get now. I put the pump to the wastegate & everything else is disconnected, if the pump works at all it does seem to have a little less smoke maybe power also. Thanks Everybody for the insights.

Sounds to me that the turbo master is the way to go, along with an F upper manifold to eliminate the EGR & remove the check engine light. At this point a fix would be an improvement to the mileage I get now. I put the pump to the wastegate & everything else is disconnected, if the pump works at all it does seem to have a little less smoke maybe power also. Thanks Everybody for the insights.

Even an F intake will throw SES. In order to remove all EGR equipment (vacuum pump and solenoids) from the truck without throwing an SES, you will need a reflash/chip.