I know this may seem like somewhat of an odd question, but I am curious what part of an IP goes bad when they do? Being someone who is interested in "why it works" as much as whether it works, I was curious about a little more details about what are the causes & effects of the IP going bad.

I took my 93 65TD to the diesel shop because it was smoking and hard start. They improved it quite a bit by replacing the lift pump, but it still smokes a lot and is really rough starting. The mechanic said the pump is on its way south, but that is probably not out of the question since I think this is probably the original pump with 185K.

My understanding of the IP is that it injects the fuel into the cylinder of the diesel based on how it is timed. Since this is a mechanical pump, I am picturing it in my mind as something similar to a gasser's distributer, except that it is sending fuel to the cylinder rather than a spark. Is this a fairly close analogy?

Thanks for all of you who are willing to share knowledge to rookies like myself.:D

Welcome to the forum Haulin65,
I'll let TDG or diesel pro explain how the pump works, but rough starts with alot of smoke could be glowplugs.

Hydraulic Distibutor is one small role of the injection pump.

Lots of moving parts in an injection pump.

Before it can just inject fuel, it has to be able to get fuel up to enough pressure to open the injector nozzles (~1700psi).

Rough start, white smoke, low power, pretty much listed the top 3 complaints with automotive pumps.

Transfer pump will need a set of blades and new liner.

Housing will have to be reamed to fit a new oversized advance piston.

Governor components like metering valve and thrust washer will have to be replaced.

Delivery valve maybe, spring and stop definitely.

And don't forget the face cam and roller, servo valve in the advance piston, vent wire, governor thrust spring on the throttle lever.

Its due for an overhaul sounds like. Then after all the worn parts are replaced the pump has to be calibrated and tested to meet/exceed factory specs.

Thanks TDG and QM,

I actually installed the glow plugs first thinking it might be an easy fix, but alas... I was not so lucky.

I am gathering from your post that there are quite a few manual operations going on within the pump. I wasn't planning on trying to rebuild it myself or anything, but just wondered what operations it controls. I see that it controls quite a bit more than fuel delivery (Timing, etc)

Does the IP have an "advance" like a distributor, or is it fixed in relation to TDC? Is the amount of fuel controled at the IP as well, or is that controled by either the lift pump or a pressure sensor? I have gathered that the wastegate is what controls the amount of turbo boost, and it is controlled by vacuum created by a vacuum pump. (which has little other use to this engine?)

I will throw in a little disclaimer here... I am a software engineer and not a mechanic, so my understanding of the internal combustion engine is somewhat limited to a theoretical knowledge. I would like to have at least that much working knowledge on a Diesel. Maybe I should just invest in a book... Anyone have good recommendations?

Thanks guys,

The pump has an internal speed advance and Light Load Advance.
Rotating the pump as you say is adjusting the Static or Base timing of the pump, your 0 point basically.

Fuel quantity is completely controlled by the injection pump. Governor controls the speed, all the time, from Low Idle to Red Line.

Wastegate on your truck is simply spring operated.

Spring tension vs. pressure on Wastegate itself controls boost levels.

'94-up turbo 6.5s are vacuum operated, solenoid controlled, PCM dictated.

Hmmm.... so it sounds as if the mechanical IP might be easier to work on/tune than the electronic version? I have read many things that say "do not try to replace this at home" but now I am wondering what the difficulty level of replacing the DB2 would be? I see that Walt @ SSDiesel has remans for $638, which is roughly $400 less than the shop was going to charge me.

Would any of you feel obliged to persuade or dissuade me on this idea????

I just replaced my 1st IP about 4 months ago or so. I've always worked on my own and friends cars or trucks gas motors, but never much on diesels. However I done my own IP, and it wasn't to bad at all. Like I said I've always work on my own and freinds so I the basics down on working on motors. If you do it youself take your time and make notes if you need to(pics even better). It sucks trying to remember which bolt goes here or there. If you need your truck back really soon may be better to take it to a good shop if you can find one or know of one already. Either way good luck.

I know this may seem like somewhat of an odd question, but I am curious what part of an IP goes bad when they do? Being someone who is interested in "why it works" as much as whether it works, I was curious about a little more details about what are the causes & effects of the IP going bad.

I took my 93 65TD to the diesel shop because it was smoking and hard start. They improved it quite a bit by replacing the lift pump, but it still smokes a lot and is really rough starting. The mechanic said the pump is on its way south, but that is probably not out of the question since I think this is probably the original pump with 185K.

My understanding of the IP is that it injects the fuel into the cylinder of the diesel based on how it is timed. Since this is a mechanical pump, I am picturing it in my mind as something similar to a gasser's distributer, except that it is sending fuel to the cylinder rather than a spark. Is this a fairly close analogy?

Thanks for all of you who are willing to share knowledge to rookies like myself.:D

Haulin welcome to the site, take a stroll over to FAQs, several links there for the how does it work, I gotta know types.

I'd never done an IP before, now i've changed mine 2 times in the last couple of months, no sweat if your mechanically inclined and can access this site, everyone here is great when it comes to helping a guy out!

I couldn't agree more with exactly what CR said!

Kewl... I may find myself tearing into this monster yet.... Already decided on a bigger exhaust, but that may well be the extent of my mods. It is only a work truck, after all... :-)

Thanks for the good words...

4911 mechanical pump on your truck is even easier than the electronic pumps.

Probably take a full day to do yourself, if you've never done it and aren't familiar with the job.

Before you jump head first into buying a pump and trying to replace it, why don't you describe more of what the problem with it is, just so you don't replace the pump and have the same problem.

What color is the smoke?
When does it smoke? Idle? Accelerating? Cruising?
Is the idle rough?
Have the injectors ever been replaced?
Replaced the air/fuel filters?
Have you tried advancing the timing?

Smoke is white, I believe. Smells like when dad used to start up the diesel tractor in the shed, not like when something blows up on a gasser. It smokes mostly when it is just started (cold), although the idle is rough whether it is warm or cold. Still runs fairly well, though, once it is warmed up on the highway.

I don't know whether the injectors have ever been replaced, but the lift pump was just replaced at the diesel shop and when I picked it up the guy there said that the IP was probably the original and would need replaced soon. I have replaced the fuel and air filters within the past 500 miles, as well as the glow plugs. I haven't made any adjustments on the pump because all of the books I have picked up thus far say "Don't try to work on this part at home". I have considered ordering the injectors as a preventative maintenance measure, but have a bit of a limited budget and don't want to do PM until the truck is running good to start with.

Speaking of books, the ones I have gotten are less than thrilling. What manuals are good for diesel-specific work on a 6.5?

A few more pump-specific questions. I used to hear of people turning up the pump on the tractors. Is this just advancing the timing, or is there a way to turn up the pressure going to the injectors? Also, since this is a manual pump, does one still need the same monitoring tools to set the pump correctly or is there another method of doing this?

Thanks!:D

Rough idle is one indicator that you might need injectors, 100k miles is about all you get out of them. They're likely due for replacement.

I would suggest advancing your static timing first and see how it does.

If you get a chance to look at the truck, there should be a line scribed on the injector pump housing and one on the timing cover, right in front of the top mounting nut on the injection pump. From the factory, they will be set line to line. With mileage, the timing chain will stretch, and you have to advance to pump or replace the chain to restore injection timing.

When people say they turned-up the pump on their tractor, what they actually do is turn the leaf spring in inside the pump. The leaf spring sets the limit of travel for the shoes/rollers inside the pump, increasing the travel of the pumping plungers which makes the pump deliver more fuel. Injectors determine pressure, not the pump.

Cool... I will try to take a look at that adjustment this weekend. To advance on this pump do you turn it clockwise or counterclockwise? Is 1/16th inch about a good amount to turn the pump?

I have not heard much mention of turning up the pump on these forums, so is this something that people don't do on this engine? If I end up replacing the IP, is it easy to turn up this mechanical IP a little? Do the chips for newer model 65td engines increase the pressure or what method to they use to create a 40HP increase?

I feel like a kid in school again... so many questions! :-) Thanks!

If you end up replacing the pump, just tell the shop you get it from to set it on the hot side, like 5 or 10% over spec. Takes all the guess work out and its a piece of cake for them to do on the test stand, then you know where you stand when you put it on the truck. Its a pretty common and well known practice on these trucks.

As far as advancing the pump, rotate the top to the driver's side of the truck to advance. If its line to line right now, which I expect it will be, try advancing it just a lines width at first. It should atleast improve the smoke problem if it completely remedies it then your good right there, if not, go another line's width, but not much more than that.

The chips your talking about can't change pressures anywhere in the fuel system, its a completely different electronic injection pump too. Basically, all they do is add duration time to Fuel Solenoid Pulse Width to get more fuel.

I took a gander at the ol' Chilton's guide on this truck and it has you removing the intake manifold and everything else under the sun to get to the pump. Should I be able to do this adjustment without taking all of that out? I am thinking that if I will be taking a bunch of stuff apart, I will probably order new injectors and replace those at the same time. Then if I have to do a new pump as well, I will have a bit of experience at tearing things down... or more importantly, getting them back together!:grd:

Good to know what the chips actually do to increase the HP. My brother-in-law has a 'stroke and has been talking about putting one in his. In some ways I wish I had a newer truck so I could chip it as well, but then I hear him gripin about his truck payment and remember I don't have one... :lol:

Hmmm. you know TDG.... the more I read, the more I think your comment about needing new injectors may have been dead on. Rough idle, Smoke at startup, usually worse when it has sat a while.... I think I see new injectors in my near future as well. If nothing else, this sounds like it would probably be a good maintenance item on a truck I just bought and don't know much about.

Now off to bed with dreams of injectors dancing in my head...):h

I took a gander at the ol' Chilton's guide on this truck and it has you removing the intake manifold and everything else under the sun to get to the pump. Should I be able to do this adjustment without taking all of that out? I am thinking that if I will be taking a bunch of stuff apart, I will probably order new injectors and replace those at the same time. Then if I have to do a new pump as well, I will have a bit of experience at tearing things down... or more importantly, getting them back together!:grd:

Good to know what the chips actually do to increase the HP. My brother-in-law has a 'stroke and has been talking about putting one in his. In some ways I wish I had a newer truck so I could chip it as well, but then I hear him gripin about his truck payment and remember I don't have one... :lol: a newer power stroke would have a different way of increasing the fuel than our 6.5L's

Actually the Powerjoke chips are similair in strategy to what the 6.5 chips do.

Powerjokes just have 8 poppet valves, 1 per injector, instead of 1 in the pump for 8 injectors. Same principle though, longer Pulse Widths keep the valve closed longer and deliver more fuel.