T\runs perfect for around 100 miles then if i hit a hill loose power and engine will not acceleate
it will get worse untill 15 mph is top speed if i stop shut off and wait a while then everything is fine for a short distance then same problem again. If seems if the injector timing is going extremely slow. when the slow n o power and no accelaration i get BLACK smoke that smells
of raw fuel.

 

how many miles on the truck and do you exhaust leak and do you have boost gauge first check air filter second do OPS and LP test to make sure LP pumping fuel to the injector pump and it also could be PMD going bad on you and is it still on the injector pump or front bumper also check make sure waste gate working

 

we have 270,000 and i don t have any exhaust leaks i can find. dont have a boost gage
have a new air filter what is the PMD how do i check the waste gate?

 

if your PMD is still on the side injector pump it may be going bad on you . you need get move to front bumper with heat sink

before we stay it bad PMD need do few test first to see LP (lift pump) working
here some reference material to read how test

Reference Material: Lift Pump/OPS
Here’s another one for the newbie’s out there.

After frequenting the boards for awhile, you’ll notice there seems to be a few things that come around, and around, and around again. One of those things is the Lift Pump, official title: Fuel Lift Pump. So, what is a lift pump, and why does it lift fuel? The lift pump is an in-line fuel pump mounted on the frame rail under the driver’s seat. This is a small electric pump that “helps” bring fuel out of the tank and up to the injection pump. This is to help prevent the expensive injection pump from having to “suck” it’s own fuel all the way up from the tank, which it can do, but can cause damage to itself and it's driver module - more on that in another section*.

Now, that’s pretty straight forward isn’t it? So, why so much fuss about a lift pump anyway? Only because it causes so many issues* when it’s not working.

Will my truck run without the lift pump? Yes it will. How well? Well, to some it will be very noticeable when it’s not working. Some may not even notice.

If I don’t notice that my lift pump isn’t working, I’m okay right? Not exactly. That means that your expensive injection pump is doing all the work in the fuel system. This is NOT a desirable thing. Plus you are setting yourself up for problems*.

How can I tell if my lift pump is working? Do the famous “lift pump test.” How do you accomplish this highly scientific experiment you ask? Very simple. Pop the hood - you’re half way there. Find on the front top of the engine the thermostat housing. You should see a little T-handle valve standing proud there in front of you. (If you have a van, you’ll have a schrader valve down deep behind the oil fill) That T-valve is calling your name saying “turn me.” Pay attention, ‘cause there’s a hose on the end of the T-valve. That hose should have diesel fuel come out of it when the engine is idling and you open the T-valve. When you open the T-valve and the engine is idling, and no fuel comes out, you’ll hear your engine cough, sputter, and die within 30 seconds. If it doesn’t cough, sputter and die with the T-valve open and no fuel coming out, something is plugged up in your fuel system between the fuel filter cannister and the t-valve, perhaps even inside the fuel filter cannister.

If the engine does die, it has emptied the fuel cannister and run out of fuel, so you will need to close the T-valve, then troubleshoot and repair the lift pump system, as follows in the text below.

Now, if you get a continuous stream of fuel out the hose, then close the T-valve and open the plastic air-bleed valve on the top of the metal filter cap - if fuel spurts out there, then congratulations! You are the proud owner of a working lift pump. Not everyone is as blessed as you are at this moment. If you're not, keep reading.

To those not as blessed, pickup reading here. You must determine why you have no fuel supply coming to your injection pump. There are two main culprits to the demise of a lift pump. Either it’s out to lunch, or it’s in the morgue. See, one means it still might work, the other means it’s dead. How do you tell? Check to see if it has power.

First, find the lift pump under the truck. With the engine idling along, pull the plug for the lift pump. You can either use a test light, or a meter to see if you have voltage at the pins. Make sure you get a good connection, otherwise you may condemn the wrong thing. Sometimes it is difficult to get a probe to meet up with the pins inside the plug, so make double sure you’ve got it.

If you have voltage, *chances* are you have a dead lift pump. Not always, but could be a dead lift pump. You may have voltage present under a "no load" condition. This means that voltage may be present when the lift pump is not attached to the circuit, but once the lift pump is connected, the load exceeds the amount of power the circuit can provide because the OPS contacts are creating a high resistance.

Now, if you don’t have voltage, you’ll have to verify upstream from there why there is no voltage present. What is upstream? The infamous OPS (Oil Pressure Switch), or fuse.

What does the OPS have to do with the lift pump? Doesn’t sound right does it to have oil pressure tied to fuel does it? Well, some think that it is a fail safe that in case your engine ever lost oil pressure, it would shut off the lift pump so that engine would stall. Guess what? If you read a little bit ahead of this paragraph, you’ll find 'dat ain’t so'. The real reason why this circuit even exists is because of an accident. In case you should be in a wreck, the last thing you would need is to have your lift pump going to town pumping out that precious, expensive, fuel all over the accident scene. After all, should you be bleeding and having a thumpin’ head - the last thing you’ll be thinking is “Hey, I just paid $2.50 a gallon for that, somebody get a shop-vac!”

Why would the OPS not allow my lift pump to work? Well, from time to time, or shall we say in the corporate world, from dime to dime, some decisions get made. Some for the good, and some for the good of the keepers of the money. The OPS has a set of contacts inside to power the lift pump. This set of contacts are not heavy enough to carry the pathetic amount of current to the lift pump. Sad, I know, but true. So, what ends up happening is your lift pump works fine, but the OPS gets smoked, and then it quits. You think the pump is bad, but it’s not.

Can I just eliminate the OPS? Well, be careful, it is a safety device in some people’s eyes, and to the rest of us, a pain in the rump. Eyes, rump, pick your part. Anyway. If you just “jump past” the OPS, then your pump will run all the time. Not just all the time, but ALL THE TIME. Christmas and Easter included. It will stop when your batteries are dead. Because, while you are grocery shopping, that pump is running. While you are down for a long winter’s nap, it’s pumping. Doesn’t matter if the key is on or off, it’s pumping.

You can make up another circuit and repower it some other way, but be careful how you do it. Some methods have kept the truck running after the ignition is shut off and keys in pocket.

Back to our little friend the lift pump.

The lift pump may fail in a variety of different ways. It may fail “open” meaning that the coil driving the pump no longer has continuity. It may fail mechanically where it is just frozen and nothing moves. It may even (not as often) fail to pump. This means, it makes noise, but doesn’t actually pump.

Does the lift pump make noise? Yes it does. The model year of your truck will determine if your lift pump is powered during the Wait To Start period. That’s the time where that light is on before actually starting your engine. '96-up OBD2 models pre-run the lift pump during WTS and during START, '94-'95 OBD1 models pre-run the lift pump only during START.

The lift pump is characterized by a kind of “purring” noise heard beneath the truck. That noise is quickly drowned out by the engine, once started. When you shut your engine off, you will hear that pump run briefly, maybe only a quick second or two. If you shut your engine off when cold, you will hear the pump run much longer, sometimes up to 30 seconds or more.

A loud clacking noise would indicate no fuel from the tank, or the lift pump is failing or failed - it will run without pumping fuel when the one-way valve(s) fail.

A faint purring or vibration when touching the lp body indicates it is running, but the internal valve-shuttle armature is stuck due to mechanical failure.

So what kind of problems will it cause if the lift pump isn’t working? Many. It will cause all sorts of fuel related issues*. It can be some of the following:
°Stumbling
°Hard Starting
°Lack of Power
°DTC (Diagnostic Trouble Codes) on the Computer
°Stalling

 

There are be other* issues too, but these seem to be a very (un)popular list.

Where do I get one of these? Some of our site vendors, or any of the popular auto parts stores, or the dealership. More often than not, the auto parts store is a good bet for Ineeditrightnow.

Diesel Place tip: Ask for the version for the '93 6.5TD truck - it is a direct-fit HD replacement that will supply increased fuel pressure and volume to the Inj Pump, which is a good improvement for the '94-up EFI trucks.
FYI: don't mention that you have a '94-up truck, or you will just confuse the parts guy\gal - just describe your truck and drivetrain as a '93.
The ACDelco or Delphi lift pumps are the best replacement, which you can get from O'Reilley's or NAPA , and some of the site vendors, such as Heath Diesel.
Also FYI: the parts-guy\gal may call it a fuel pump.

Are they difficult to change? No - loosen the tubing-fitting nuts on either end, remove and reinstall. Now, if it were only really that easy. Let’s get real here, no camera out-takes…. You’ll end up getting a Diesel bath. You see, depending upon how much fuel is in your tank, there will be fuel that wants to come out of the fuel line. Be ready, because your chances of a date after changing that lift pump dwindle a bunch, unless they are really into the smell of a Diesel cologne. J

After the successful fuel lift system repair you will need to refill the fuel filter cannister - after opening the air-bleed valve, which is the plastic nut on the very top of the metal cap, power up the lift pump, then close the air bleed when the bubbles stop and fuel begins spurting out - if you still get no fuel, you likely have a stopped-up fuel filter - no need to tell you what to do in that event, right?
FYI: after successful fuel flow out the air-bleed, the engine may take a while to restart and run as the Inj Pump begins to draw fuel from the filter, fills internally, then starts pump-up to 1900psi injection pressures.

This is at least enough to get you started on your lift pump journey. If you have any specific question, feel free to post them by starting another thread. We’ll be glad to help you out.

---AutoMerged DoublePost---

So where did your getty-up-and-go, go anyway?

The most famous part of the 6.5TD engine is the “TD.” That stands for Turbo Diesel. We all love the singing of that turbo under the hood. Some sing, some are of key, and some don’t sing at all. So, let’s dive into the common turbo issues.
One of the most common problems that comes around on these turbos are:

“I'm blowing black smoke”
“I don’t have much power anymore”
“My service engine light comes on”

So how does this macho piece of hardware work? Pretty simple actually. It is an exhaust-driven turbine motor driving a centrifugal air compressor. There are two “wheels” connected by a shaft. One wheel or turbine-fan is in the exhaust stream, the other wheel or compressor-fan is in the intake path. As the engine runs it pushes the exhaust gas out through the exhaust system. The turbine-fan wheel is driven by that exhaust gas. It in turn spins the compressor wheel. The compressor wheel pushes more air into the intake of the engine. More air, more fuel, more exhaust. More, more, more, which means more power “available” to be made. This increase of air is called boost.

What is a wastegate? The wastegate is a flapper-type valve that opens up on the exhaust turbine side of the turbo. This flapper will allow exhast gas to bypass and not spin the turbo as much. This will reduce boost pressure. This flapper remains closed under most conditions (idle, cruising, etc). It is designed to usually open up during high-load conditions, which causes high cylinder and exhaust heat.

So does more boost mean more power? Not really. It means that more power can be made. Boost is air. Air is cheap. If you want power, you have to pay for that at the pump. Power is fuel. More boost means you can burn more fuel. You can always dump in more fuel (to a point) but it won’t burn effectively until you have enough air to complete combustion.

So how much boost can I build? There seems to be ongoing discussion as to how much boost you can make. Some people like the idea of engine-splitting boost pressures, others like longevity. Which ever you prefer will be the answer to your question. The fine folks at GM have said the 12 is plenty. You can run higher levels, but you better do some reading, and have some cash ready too. That will be spent on modifications to the engine, or modifications to the engine after it’s failure. You can run more than 12 psig of boost without blowing it up. How long will you get away with this? That’s a variable not yet established, but the event is usually marked with exciting noises and other fanfare.

So why doesn’t my turbo work? There is are some common failing parts on these systems that will put your turbo on holiday. They would be:
°Wastegate solenoid
°Vacuum leaks
°Vacuum pump


Wastegate solenoid - This little piece of s. . . Plastic, yeah, that's it.....plastic....is a small solenoid-valve that PCM pulses in order to regulate the vacuum supply to the wastegate actuator.
Wastegate actuator - this is the small gold canister on the side of your turbo that pulls the rod to the wastegate. It opens and closes the wg by vacuum on a diaphragm which creates thrust on the rod.
Wastegate - This is a flapper-valve on the exhaust turbine side of the turbo that allows exhaust gas to bypass the turbine fan, reducing boost pressure.
Compressor - That is the intake air side of the turbo. It pushes the air into the intake.
Spool-up - That is the spinning-up of your turbo.


So, with that covered, now we talk about what is going wrong with all this pieces and parts. When the turbo stops working, it is usually because the wastegate is open, or opening. The wastegate is used to regulate the amount of boost coming into the engine. Why, you ask? Well for some very simple reasons.

How do I check to see if I have wastegate problems? A quick test would be, at idle, see if the wastegate rod is pulled up into the actuator housing. If it is, that is a good start. Now, pull on the rod, and see if you are able to move it. Pulled in means there is vacuum. Suction is good, but how much? If you are able to move it, then you may not have sufficient vacuum to maintain boost.

To really test the system you should get a vacuum gauge to verify readings - with engine idling you should have 26"hg at the vacuum pump and 15"hg at the wastegate, but the above 'pull-test' will show if you're in the ball park.

The wastegate solenoid is the most common failing part in the whole system. Chances are if you have problems, this is it. Now, don’t just condemn it because it’s everyone else’s problem. Verify first that it is bad. How?

How do I determine if my Wastegate Solenoid is bad? You must see if there is vacuum before and after it. Locate the solenoid by tracing the vacuum line back from the wastegate actuator. You will need to determine if you have vacuum after the solenoid. You’re looking for about 15” of vacuum. Many refer to this a pressure. It’s not really pressure, but suction. Notice I did not say 15 psig, but 15”.
This little valve has three ports. Only two of which you hook vacuum lines to. One is the vacuum source (to the vacuum pump), the wastegate actuator, and vent. Vent, is not something you hook anything to. Why a vent? That is how it regulates the amount of vacuum going to the actuator. There is a little steel ball inside the valve that switches back and forth between vacuum and vent. Here lies the problem. That ball will rust. When it rusts, it won’t roll anymore, so your engine power no longer rocks. Thus, you ain’t rock’n’rollin’ anymore. When the ball doesn’t move, it will get stuck and not allow vacuum (usually) to the wastegate actuator, leaving it open all the time. This means a no-boost situation.

The solenoid can fail in a vareity of different ways. It can fail to provide no vacuum to the actuator. (most common) It fail to provide vacuum always (not as common, but possible), the coil could fail, or no power to the coil from the ECM. Sometimes the ball will “stick” causing erratic boost, where it will spike up and down.

Can you fix this? Yes, replace it. No repairs ever found really. You can “limp it along” by spraying something like WD40 into the port. This may help to free it up, but it won’t live forever.

Where can I get one? Usually it’s a dealer item. Local parts stores don’t seem to have this item for some reason. Check around, there are some on-line parts sources.

I have no vacuum before the solenoid? You should check to see if your vacuum pump is working. If you have no vacuum present before the solenoid, then you either have a bad vacuum pump, or a leak somewhere. Chances are if you have an EGR equipped engine, you’ll have EGR codes if you have no vacuum, because they are all vacuum driven.
Weak vacuum too will also cause problems. You should have around 26"hg of vacuum available at the pump.

Where is my vacuum pump? It is driven by the serpentine belt. Look here.

Don’t rule out vacuum leaks. If you have a leak, you maybe changing parts that work just fine.

I am blowing black smoke, does this mean I have a turbo issue? Sometimes it does, if you have gone through all of the above diagnostics, and everything is okay, then may need to check some other things.
Does my computer (ECM) indicate problems with my turbo? Yes, depending upon your year, will depend upon what codes you will get. There are two generations of computer, OBD-I, OBD-II. The first one can be checked with a paperclip. The second needs a code reader. 96+ vehicles have the second generation that needs the reader. Check the FAQ section of this forum for specific codes.

 

What if my vacuum pump is bad? Well, economically speaking, you’ll have to make the determination if you want to replace it, or go with a simple spring on your wastegate to regulate vacuum. Yes, you can eliminate the problematic vacuum system on your turbo if you would like. So, why doesn’t everyone do this? Well, there are some things you need to watch in doing this. Your computer regulates everything with the stock system. You eliminate that, you will have to take over being the “brains” of the engine in the boost department. DO NOT replace with the spring system unless you have a mechanical boost gauge to monitor the boost pressure. Aftermarket products are available for a turn-key spring system, or you may fabricate your own.

How do I know if the actuator is bad? Well, this is not as common a problem, but does happen. You can check this by providing vacuum to the wastegate actuator, and see if it holds. If it leaks, then you may either replace the actuator, or go with the spring/mechanical system.
What happens if I build too much boost? Then, that’s called over boost. This is where the computer takes evasive action to prevent from blowing up. Depending upon what your computer is programmed to do, it will either dump the boost, or go into limp mode (may limit engine to 2000 rpm, and no power) This will also set the Service Engine Light.

So I can have either too much, or too little boost? Yes you can. Either is undesirable. Too little will not provide complete combustion, and cause higher EGT (Exhaust Gas Temperatures). Too much boost will cause unnecessary stress on the engine.

Are there any other things that will effect this system? Yes, the air filter. If it is dirty, it will reduce the amount of air that the engine can ingest. This can make noticable engine power losses. Don't trust that little pop-up thingy to tell you when it's dirty. Open the filter box up and check for yourself.

Does the turbo work all the time? Yes it does, mostly. At idle, under load, etc, it's spinning, or supposed to at least. The wastegate opens to bypass some of the exhaust gas to reduce boost under high-load situations. There is no occurance where the turbo "shuts off" under normal conditions or at idle. It will always be spinning.

What are the drawbacks to this turbo system? Well, it performs well under the conditions it was designed for. If you begin to take it outside of those operating parameters, it becomes an expensive hairdryer. Turbo compressors produce heat.

What's wrong with heated air coming out of the turbo? Well, the heat makes the air less dense. You are wanting more density of air to burn more fuel. That's what a turbo is for. It's for jammin' more air into the intake. Once you heat the air, it becomes less dense, and starts to be counter-productive.

How can I overcome this? You must come up with some method of intercooling. That is a way of cooling the air charge before it enters the intake. Under high boost conditions, your intake air temperatures can rise to 200°+F. That's the INTAKE, not what's happening in the exhaust, or the clyinder, that's BEFORE it gets there.

How can I intercool my engine? There are intercoolers available on the market that uses air to cool the air charge. There is also water mist injection. There are posts out there on these topics, feel free to search them, with forum's search feature. You may also check out the FAQ's, or follow this link.

Do I need an intercooler if I don't do any towing or have any performance modifications? Well, it's up to you. The current stock setup will get pretty hot still. It's all in where you want to spend your money. Do some more reading on the subject and see if this is something that suits you and your budget. Of course we'd all like to have our engines as souped up as possible, but then again, we have other payments that are calling our names. . .

How can I put an intercooler in, and how does it fit? Check this link. Do a search, there are many others.
Hope this helps to you to better understand everybody’s favorite part of their engine: The turbo.

 

so this only happens on hills?

 

usually the first time it happens is on a hill that is steep enough for a down shift to happen.
after i get back on level or on down hill i can not accelerate much. until finally the truck will only run at 20 mph no matter what. it smokes black but has no speed it seems to have plenty of power at idle. It is almost like a super jake brake on it. once i stop let it rest for a few minutes and restart everything is ok for a few miles. this happens on the freeway at 60+ mph. once i restart i can run up to normal speeds. Usually I am pulling a
4000 lb trailer. I do not know if it will happen with nothing in tow.
I have also noticed that sometimes when the truck downshifts pulling a hill instead of more power i get a feel like i added several times the load .

 

I have a 94 half ton that did the same thing but not to the extent of only being able to go 20 mph. Whenever I would get on it going up a steep hill and downshift it would go into what seemed like " limp mode" and the check engine light would come on and the engine would de fuel and only pull about 6 psi boost. When I first got the truck the wastegate controller was bad and it pulled about 19psi and it went into this what I called limp mode often. After I turned he boost down to safe levels it doesn't do it as much. But all in all, it sounds like a wastegate solenoid is bad because you said lots of black smoke and no power = no boost. But checking the ip ops lp and Pmd would not be a bad thing. O and what codes do u get when It does this?

 

I don't get any codes and the light does not come on the light on mine is check electonic accelarator??? I dont have a code reader for the plug on the truck