Injection pump & HP problems
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Injection pump & HP problems
My first diesel was a 91 F250 7.3 stock. The transmission was apperently geared lower than my current 88 F350 Super Cab. The 91 F250 never smoked once warm even under heavy load. My 88 F350 throws black smoke at low RPM acceleration. To the best of my knowledge the injection pump needs to be replaced. The HP seems drastically lower than the 91 F250. I had the compression checked and all cylinders were 400 or higher. Other than the IP what else could be causing a drop in HP?
Senior User
Joined: Mar 2003
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I *think* there was the ZF 542 and the ZF 547 for standard trannys in those years, however I may be way out to lunch...
I am not even sure the differences between those two, although I assume it is gearing.
Sorry, my post may be entirely pointless, just glad to be back checking the forums after swapping a few engines and trannys over the last 2 weeks....
I am not even sure the differences between those two, although I assume it is gearing.
Sorry, my post may be entirely pointless, just glad to be back checking the forums after swapping a few engines and trannys over the last 2 weeks....
Posting Guru
Joined: Sep 2002
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From: Northeastern Pa - USA
Is the 88 model truck powered by the 6.9 litre engine and the 91 is the 7.3 litre? Is the rear diff gearing the same in both trucks? Is there different size tires on the trucks? Does the newer truck have an aftermarket turbo system on it? These types of differences could add up to the way they feel while driving them. That is just a couple places to start looking for answers.
Posting Guru
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From: Northeastern Pa - USA
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Post Fiend
Joined: Nov 2003
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From: Nutter Fort, WV
The two manuals should have been either a 4 or 5 speed.
The two different ZF numbers are gas and diesel.
The diesel 5 speeds are all the same gearing.
The axle gearing may be different from one to the other.
Someone may have turned the fuel up on the 88.
The pump or injectors or timing could be off on the 88 causing more smoke and less power.
The last model year for the 6.9 was 87.
The two different ZF numbers are gas and diesel.
The diesel 5 speeds are all the same gearing.
The axle gearing may be different from one to the other.
Someone may have turned the fuel up on the 88.
The pump or injectors or timing could be off on the 88 causing more smoke and less power.
The last model year for the 6.9 was 87.
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Well guys, her's the deal. I put a rebuilt injection pump in the '88 F350 (5 speed 7.3) Thursday. It has made all the difference. It throws no smoke when it shouldn't smoke and little when you would expect it. I have so much more power than I did. Before it struggled with a 16' fiberglass fishing boat. Now I hardly know it's back there.
Both the '91 and '88 trucks had the 7.3 International Navistar engine with 5 speed manual transmissions. I know my current '88 F350 has the 185 hp engine. I'm not sure what the other had.
Does anyone know how I can increase power without paying out the nose.
Both the '91 and '88 trucks had the 7.3 International Navistar engine with 5 speed manual transmissions. I know my current '88 F350 has the 185 hp engine. I'm not sure what the other had.
Does anyone know how I can increase power without paying out the nose.
Junior User
Joined: Jul 2004
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From: Ione, CA
Also if you still wanted to get rid of some more smoke and ad a little power try running some injector cleaner (helps so much!) like redline 85+ (that is my favorite) or having the injectors inspected and rebuilt if need it. I have got my 89 with 300,000 miles to not smoke at all because I consistanly run injector cleaner very consentrated about every 4th tank and change the oil every 3,000 with 15-40 delo and a good flowing air filter like a k&n. Also try a full exhaust for some good power gains.
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I usually fill up each tank with 12 gallons. What is the concentration of injector cleaner per gallon of diesel? What other cleaners do you recommend if Redline 85+ isn't available in my area? I just changed my oil with Rotella T 15-40.