Hello all,
I am new to the forum have read alot of great information on this site but never posted before. I recently purchased a 92 dodge 350 x cab 12 valve 2 wheel drive dually. I had to replace the radiator and a few other things after the guy hit a deer. But got the truck cheap as he thought the auto trans was going out. Replaced a leaky oil cooler line and the truck runs like a top with a new alternator, turbo, and starter he put on. Problem is he said it should get upper teens to low 20's for mileage and i get 14 mpg. I have checked the compression on all cylinders and they were all around 370 psi. I tested the injectors and they are popping off at 2900 psi. I have also done a simple test on the turbo to see if it was spinning freely, matched the numbers on the turbo to make sure it was the right application. i took the air filter off and cleaned it and stuck my hand in front of the intake pipe and it sucked the boot in on the manifold side to make sure the intercooler wasn't leaking. I believe it is boosting and the thing runs very well. Starts good and verified it was shifting into fourth. As far as i know it has stock injectors, I am at a loss though as were to go from here. Thinking maybe timing or pump. It does run very well and doesn't smoke at all. Please help. I put a scanner on it so i could check the rpms. It will go up to about 2200 rpms and just stay there as the pickup gains speed. From what i have read in the other forums this is normal.

 

Have you changed the fuel filter? Check for leaks around the fuel pump?

 

Yes i have changed the fuel filter and i have looked for fuel leaks and haven't found any. Also this pickup does have 355 gears acording to Dodge and the VIN number,

 

your pump timing might be retarded by some chance...

 

does anyone have access to the timing procedure for a 92 dodge diesel other than just static timing

 

Just do an 1/8" bump on the timing. You ought to be getting around 16 in town and close to 20 on the highway if you keep the speed below 75.

 

the guy i bought it from said he had it turned up a little bit so i don't exactly know what they did and he didn't either. I am worried they might of already advanced it and need to get a baseline to start on

 

2900psi is a little low on pop pressure. How was the spray pattern and atomization? Getting it back up to the 35-3600range should improve things.

Valve adjustment may also be in need, and can help wonders.

Timing, fuel filter, air filter, and general pump condition can afect mileage.

 

the spary pattern and atomization was really good i did ajust the valves as well, forgot to mention that. 3500 really, they were all very close in pressure except the number one injector which was 2600 and i had it shimmed up to 2900+ to match the other ones. Was also wondering if anyone could tell me what KSB stands for, and if maybe it could be stuck open advacing the timing all the time instead of just when it has power. It starts really well even when cold, just touch the key, so i am thinking it is advancing or might be advanced all the time. It also never smokes like i would expect from being retarded. And also where is the best place to get a ksb solenoid. Also he said he had it turned up, and i have a question on the diamphram underneath the metal softcap ( i believe it might be called the afc star wheel), i have read or think i have read that you can turn the diamphram in the housing and this is the primary power turn up. I was wondering how it should be stock. I might be all wet in the head on the diampharm, if somebody could line me out i would appreciate it.

 

The KSB doesn't have anything to do with this problem. It advances the timing at low RPM after a cold start. If it doesn't work all you will notice is white smoke when cold.

There's loads of info on turning up the pump in the sticky so I won't get into that here.

 

Have you checked all your fuel lines from the engine all the way back? I'm wondering if maybe a fuel line got crimped when he hit Bambi. Also, is the thermostat staying open and the fan running all the time? It may be pulled down that way. Check the intercooler boots, as they may be cut and you may be losing air that way. Is the exhaust system crimped or mangled somewhere? You could have excess restriction. If the pump was turned up, then you should be seeing smoke on heavy acceleration. Heck all I’ve done is a smoke screw tweak and I get smoke from mine.

Just for reference, I have a '93 just like yours but with the Getrag. My average is 19.5 running mostly interstate at 70. If I run 65 on the interstate on level ground and unloaded I can get 21 and if I leave my foot in it I can pull it down to around 18.

 

In the sticky i read somewhere if the pump timing is retarded it will be slower,less smoke than stock!,and higher egts. Im pretty sure i read it on this site there was a chart of pro's and con's of retarded and advanced timing.

 

slow down. I get in the 20's if I keep it under 1750RPM(60-65ish) and drop to 15 or less running 70mph or faster. I just towed a dakota at 60mph and got 18 mpg which is better than I can do empty going faster.

 

Guys,

I am very happy to report that i bumped the timing a little over an 1/8 of an inch and in some cross country and a little in town driving i got 23.6 miles to the gallon, Truck smokes now, doesn't seem to have quite the low end torque it did, but still runs very good, might be a little quicker. Thanks for all the replies i am tickled pink