I have a 91 Ford f-250 4x4 with a 7.3 IDI non turbo.
recently bought it as it is my first diesel, took it to my mechanic, for a good lookover, and he recommended that I replace the injection pump.... so we did, no it almost seems like it has no top end speed whatsoever?.... the truck was idling at about 850 before replacing the Injector pump, and then about 700 afterwards, its now blowing quiet a bit of white smoke on start up, (meaning it is burning rich I think) until it gets warmed up pretty good, then the smoke goes away quite a bit. however it seemed the truck was just " falling flat" so I had another acquaintance (who is a diesel mechanic) adjust he idle up via the injector pump....
my problem now is that the truck just doesn't have the power it should, or had before we replaced the injector pump....
for example, climbing a hill, I went from 65mph and 5th gear at the bottom of a hill, to 35, and 3rd gear at the top, it just fell flat on its face.

any suggestions?

 

Did you have the timing checked after the new IP was installed?

 

no sir, i assumed they would do that at this shop? when at idling speed, this thing is a massive monster, but at higher speeds (so far) it just falls flat on its face. Would the timing have an effect on this diesel with the white smoke (cold start this morning just to see what it would do, and the white smoke definately poured on out). being new at this diesel thing, i wasnt for sure if timing would effect how the fuel was burning, if it would burn it rich or lean?

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talked to mechanic today, he did not put a timing gun on the truck afterwards, however he said he checked the timing via glowplugs, and it looked petty good.
the truck started blowing some great black smoke this afternoon when the temperatures were around 50 degrees, and ran like a strong bull after some pooonahnee, however tonight going up the dreade hill again, it fell flat once again. was blowing white smoke, almost seems like it is losing compression ability at higher speeds..... it is literally the STRONGEST motor I have ever seen in first, second and third gears, and it starts losig alittle in fourth? but after that it feels like a blown up old 4 cylinder. never seen nothing like this??

is this oncoming signs of cavitational problems?

 

timing, get it checked and done by someone that knows what their doing. Go from there.

 

Why did he suggest replacing the IP to begin with? Did the truck run ok before it was replaced?

Does your mechanic have an actual timing tool for one of these motors? Most shops will just time them by ear which a seasoned IDI mechanic may be capable of, but some of the younger guys only speak electrical and not mechanical. A lot of times these guys will mark the IP and put the new pump in the old position. The stronger pump can change the injection time as can new injectors. A new IP can also wear out old injectors much quicker as well. It's usually a good idea to change the injectors and IP together although it's not necessary. It is also entirely possible you just got a bad IP, you would not be the first to suffer that fate.

 

It is necessary to replace injectors at the same time as the pump, as you do not know the condition of them. You want to put an even load on the new IP that just costed $500+ otherwise, you will cause it to become worn out. I would just line up the center marks on the pump housing, and the center mark on the filler neck cover, adjust a dimes thickness accordingly.

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But unless your truck was in dire need of a new ip, I would have stuck with my old one, what is the condition of it? How was it running before

 

the mechanic checked the injectors, we put on new fuel lines to everything at the same time, but the mechanic said the injectors looked good and open, we changed the IP because it would drive just fine and dandy, but immediately cut out with no response at times, sit for alittle bit, and do just fine and dandy for a few hours, then just cut out altogether again. the mechanic checked the fuel pressure coming out of the pump, and he said it was not running consistent, however fuel pressure was great to it, and a couple of other reasons, (rough idle, fuel leak, etc.) when i took the old pump back to get the core charge off of it, the salesman took a look at the old pump and said he could see where it was not functioning properly, being new at this diesel stuff, i didnt doubt him as he is an old seasoned diesel mechanic himself. I'm going to go ahead and take it to another shop and have them check the timing, if thats not it, i am not sure what it is...

Someone else told me though over the weekend that these IDI diesels with the non-turbo version aren't going to get much higher end speed than what i am getting out of it. I am serious when i say this thing is a MONSTER in the lower gears, (i know its a no-no, but i had to try it out, but i pulled off about a 60 ft long classic roasting burnout in it, and it wanted more) but when i hit the highway, 70-75 is just all she wants to do, and it makes it hard to be in normal traffic in my region, cause we have hills galore.
ANd yes syncostang, we did go through the "getting a bad Injector pump" scenario, had to get two pumps to get a good one to even begin with. got a lifetime warranty IP though, spent alittle bit on it, but got a decent chunk back with the core, plus i know the salesguy i bought it from, so he helped me out on it a bit.

any possiblity that this thing just isnt used to the absolute fridgid winter weather we have had this year?

 

Are you running larger tires, how about your gear ratio? Are you blowing any black smoke? What kind of EGT's are you seeing?

 

Just throwing this out there...Do you use diesel additive like your supposed to?

 

not sure on the Exhaust gas temp range, it is blowing some black smoke, but it also is blowing some white smoke on start-ups only,
and since I just bought the truck, I have been putting in diesel additives in the fuel.
Not sure on the gear ratio, pretty sure it's stock on the axle and tranny, tires are stock 31" or 32" tires....
how would the EGT effect losing speed and power at higher end speeds? being new at this diesel stuff... I'm just trying to learn, sorry if I ask a silly or seemingly stupid question, and the gear ratio would have nothing to do with the loss of power if I had established an already high speed, but lose it over time? correct?
is it in the 7.3 IDI's to just lose some *** when maintaining speeds up hills?