Hello all, I'm new to the forum and have a little issue with my 93. It's always started hard when warm, starts fine when cold. Lately it's been having power surges in the engine, by this I mean, it accelerates on it's own, then looses power, even going down the road with the cruise set, you can feel the throttle hunting. Awhile back, the water in fuel light came on, so I changed the fuel filter and cleaned out the housing, changed oil at the same time because it was due.

Since then, it seems to have gotten worse, now it will accelerate hard, like a gas 350 hard, then fall on it's face and die. It starts right back up, so I don't think it's air, but it does have a small fuel leak in the return line in the valley under the pentum.

I'm thinking the governer in the pump has gone south, which brings me to the rest of my question.

Will an I/P off of a 6.2 run on a 93 6.5? The pumps look the same, and I have a practically new 6.2 pump in a baggy in the shop.

Thanks in advance for the help.

A 6.2 pump will bolt right up, but it delivers too little fuel. The turbo (I am assuming that your 6.5 is a turbo model) allows the engine to burn lots more fuel, and therefore produce more power. A 6.2 pump would make your 6.5 run like a 6.2.

Thanks for the reply. Yes, mine is a turbo, I can adjust the fuel output of the 6.2L pump with an allen wrench on the leaf spring above the plungers, as long as timing isn't an issue.

I dont know if it is possible to turn the fuel up enough this way. Someone with more experience would have to chime in.
At any rate, the physical fit is not a problem.

Will the 6.2 work on the 6.5? I would like to know as well.

I forgot to mention that on startup and if I don't let it warm up before giving it any throttle, I get alot of blue smoke (likely valve guide seals leaking) The truck has approximately 150,000 miles and I don't believe the valve covers have ever been off.

Diesels generally do not have problems with leaking valve-stem seals, because there is no vacuum in the intake manifold - you're likely seeing the smoke because of -

dirty air filter

advance not working

return line blocked

IP cranked up

surging can be fuel supply - lift pump

I was thinking fuel system. Check lift pump is my advise.

I was thinking fuel system. Check lift pump is my advise.

I agree. If you are not getting enough of fuel it would do this also you said hard start when warm...hmmmm did you check your fuel cap lately?

I agree. If you are not getting enough of fuel it would do this also you said hard start when warm...hmmmm did you check your fuel cap lately?
x2, these fuel caps are retarded

Update. I went out yesterday and pulled the intake to investigate the fuel leak which I thought was in the return line...turns out it was in the supply line just behind the inlet to the IP. I replaced the line, while I had the line off, the filter just kept pouring fuel, so I checked the fuel cap and sure enough, lots of pressure in the tank. I imagine if the vent in the cap is allowing it to build pressure, it is stuck, and also allowing it to create a vacuum while running, which would explain the surges.

The sound of the lift pump changed pitch a few times while I was priming the fuel system, so it might be taking a trip as well.

I haven't got it all together yet, but will let you know how it turns out so far.

Thanks,
Chad

Yes Please keep us updated on this project.

We built a 6.2 to go on a 6.5 and the results were not to good and we had to take it off. You can't turn the fuel up high enough. It can be done with somewhat limited results if that's what your willing to accept.

Yep - DP, you already know this stuff, so talk amongst yourself while the rest of the guys get up to speed ;) : problem being the DB2-0829 6.2 version vs the DB2-0831 version - last two digits indicates the diameter of the pumping plungers - that's 0.290" for the 6.2 vs 0.310" for the 6.5 - makes a big difference when the turbo is honkin'............

Ok, that takes care of the question of using the 6.2 pump...not gonna do it.

I got it back together enough to start it with the tubo crossover off, reved it to about 1200 and let off the throttle....still dies on decel.

I'm thinking the turbo is about done too, it doesn't spin freely like to ones I had on any big truck I ever owned. It's not rough, but when I flick the wheel to spin the turbo, it makes about 1.5 turns after my finger is off of it, instead of gradually slowing down.

That's a good turbo, then - wiggle the shaft up-down-left-right-in-out - if the compressor wheel doesn't touch the housing at any point, yer good to go.

Dies on decel is probably the HPCA\Fast-idle system, at cold-start - if engine coolant is at operating temp, could be the idle adjustment on the throttle arm - crank it in a little, get rpms up to ~600

You can use the 6.2 IP - it just won't power-up the 6.5TD like the DB2-0831-4911 IP will - and no danger of damaging anything by running "lean", as you may hear (but not on this forum, eh?) - Diesels run best when running lean - a Diesel not running lean is blowing black smoke, really bad for the engine, and fuel economy - you just won't have the increased power capability.

Your injection pump is shot:( First sign of failure on a 4911 pump is hard starting when hot. Bad news is this means worn head and rotor, the most expensive part of the pump. Buying a rebuild doesn't mean you will get a new head and rotor, they are only replaced if bad. I once bought a reman 4911 pump and it only lasted about 75,000 before the head and rotor gave up the ghost. Next pump had a new head and rotor and what a difference.

I got her back together and took it for about a 20 mile test drive, found another supply line fuel leak, this time it was the bottom of the filter housing, got that taken care of, not as bad to start warm now, I noticed it was about 2-3 degrees advanced when I was putting the top back on the pump after looking at the governer, so I retarded it 2 degrees or so, now it sounds better at idle, not such a clatter as it's always had, seems to run better and is making good power.

I definitely have a problem with my lift pump though. When I was on the way to town, I shut off the bypass switch I have for the lift pump and after a few miles, it started to surge a little. As I pulled into the service station in town to turn around and come back home, it fell on it's face and died...I couldn't hear the lift pump running. I turned the switch back on and it still wouldn't run, so I smacked the bottom of the fuel tank and then the pump started. I guess I'll be putting in a lift pump.

I read a post having to do with the HO pumps from NAPA, maybe I'll put one of those in if they are worth the extra money.

Dies on decel > metering valve sticking or idle set to low.
Try some Stanadyne fuel additive and pour in the whole bottle.

I bumped the idle up a little, took care of the dying problem in most cases, except when the lift pump shot craps...The idle is actually a little high for my taste right now, so maybe the metering valve is sticking, I'll see if I can find some stanadyne additive. We've got a turbo shop in the next town north of me, maybe he's got some....and a price on a pump, and nozzles.

I.....
...... so I smacked the bottom of the fuel tank and then the pump started. I guess I'll be putting in a lift pump.

....
93's have pumps in their tanks? Guess I thought they were like the 95's, under the cab, frame mounted.

My 92 lift pump is under the cab, drivers side , next to the frame rail.

id go for the computer thats bolted on the side of the pump PMD i think its called. You can unplug it and weasel the harness out and plug a new one on to try it. Check for vacum at the turbo. Lift pump?

'93 doesn't have a PMD or vacuum wastegate.

Heck, I assumed the lift pump was in the tank, I never noticed one on the frame rail, I'll have to check that out...this job might be easier than I thought..there goes my killing 2 birds with one stone theory...I was gonna pull the bed off and put in a new 5th wheel plate and change the pump at the same time.

I think I got her figured out. I do believe it was mainly the OPS, in combination with a few fuel leaks, and the fact that the pump was advanced about 4 degrees. I've been driving it quite a bit the last couple of days, put $100 worth of fuel in it yesterday and some power service and it is running better than it ever has since I owned it. Friday I'm gonna hook the trailer up and go get a horse, so I will see if it pulls better than it did before, but I believe it's gonna be alot better. Empty it is like a night and day difference.

Now I just gotta get the wife to let me spring for a 3-4" exhaust and I'll have it made...at least for awhile..hehe.

Thanks to all who helped with the great information. I've worked on alot of 6.2's over the years, but it's been about 15 years since I've worked on one of those, and had forgotten alot.