Solve this mystery!

[Neal J. Moran]

I have 2 idi trucks:

1. '93 Crew cab dually, automatic, 230,000 miles.

2. '89 Crew cab dually, automatic, 30,000 miles on Warren reman. engine.

Here's the mystery:
#1 will run circles around #2. Both run very well.
#1 idles quietly. #2 is louder at idle and has been timed recently by a large diesel shop.
#1 will pull my 33' camper with ease. #2 has trouble reaching 65mph w/camper attached.

What is wrong here? I cannot figure it out. I've been trying to for 10 years.

 

[WildWest]

Maybe rearend gearing?

 

[Neal J. Moran]

Identical trucks. 4.10 rear ends, same rpms.

 

[WildWest]

maybe the timing is off on number 2?

 

[suv7734]

What is the fuel mileage comparison between the two like? Does one smoke more than the other under acceleration/load?

 

[f350flatbed]

Underfueled?

Paul B

 

[The Warden]

#1 idles quietly. #2 is louder at idle and has been timed recently by a large diesel shop.

How are your injectors?

When I first got my truck, she sounded like a 6-71 Detroit. Replaced the injector pump after about a year and set the timing; no change. I finally pulled the injectors (they looked like they were original, after 200K miles ) and got them tested...they all opened too early. I put a set of reman injectors in...they were tested as well and were right on the borderline, but putting them in immediately quieted the truck down. I don't know how much they helped with power output, because I shortly thereafter tore the top end of the engine down and added a turbocharger but, I seem to recall it helping.

I'd suggest pulling them and testing them, unless they were tested recently and proven good. Injectors and pumps on these trucks seem to have a half-life of 100K miles...some fail far earlier, and some last far longer, but MOST are dead or dying by 100K miles.

Just something to think about...good luck! And, welcome aboard!

 

[69oiler]

weak IP vs new IP makes a world of difference as well.

 

[The Warden]

weak IP vs new IP makes a world of difference as well.

Rob's right. I assumed that the IP was replaced since he mentioned the truck being timed, but that could easily have been a bad assumption on my part...

 

[Agnem]

For most trucks, timing and pump calibration make a world of difference. If your "large diesel shop" did it by ear, it may well still be off. Worse yet, too far advanced.

 

[Neal J. Moran]

Thanks for all the replies.

I brought #2 to the diesel shop because I thought it needed a pump. They timed it and said that I had a supply problem. I put a new lift pump on it. No more power.

Regarding smoke: After timing it, the light smoke trail at the pipe while pulling camper disappeared. I do not think that Warren Engine had rebuilt the pump when I bought the motor. Furthermore, the timing was very retarded from Warren Engine. It started and ran fine, though.

I don't know anything about the injectors, except that it has always started and idled fine. I also questioned the capacity of the injectors for delivering fuel. I have never had them out for any reason. This truck gets 15mpg empty and 11-12 pulling the camper. I sold the previous 5th wheel camper because I could only run about 62mph with it.

What should I do next?

 

[f350flatbed]

Have you played around with the fuel screw? If it is a supply problem you should try increasing the flow.

Paul B