Lack of full power

[Archive]

I've noticed a power decline on my truck lately. I can't make smoke anymore under full throttle. Occasionally I can get full power, you know that extra boost when it's floored. I've changed the full and air filter. Any suggestions on where to look next. I can still get what seems to be full speed, however it takes quite a while to get there. Everything seems to run correctly, just not that wide open throttle feeling. When full power does kick in smoke comes out the exaust and I can pull like a diesel should. The rest of the time I have to down shift. Nothing bad found in the filter when I changed it. I'm stuck.

------------------
Stock 92, 5sp LE, 4WD, 4. 10 gears, std cab, 184K miles, 50 gal aux. ,more to come

 

[Archive]

Hey Mike you may want to check and make sure that the throttle is being fully depressed. By this I mean that you are getting full throttle when you mash the accelerator. Something could be in the way not letting it move that last little bit every time. You said that sometimes you get the "full throttle" feeling but not all the time. Also check all of the connections from the turbo to intercooler to intake manifold. I was having a problem I thought, with my milage falling off. I normally get 430 to 450 miles per fill up from my rig during everyday driving. I started getting only 380 to 350 miles per tank full for several tanks and thought something was wrong. I changed everything (oil, Fuel filters) but still no luck. Finally one day I was on the freeway and noticed that my speedo was working but not my odometer (sp). Doooooohhhhh I hate that!!!

------------------
92 Ext. Cab, Auto trans. , 3. 54 Non-LS, Isspro Tach and Pyro (pre-turbo), 210,000+ miles, straight pipe,old and abused but still running strong!!!!

 

[Archive]

Mike, I know how you feel. I have the same problem at WOT. I have changed my filters and checked the throttle linkage..... still have the problem. I have run out of suggestions so maybe we can find one here.
cody


------------------
91 4x4, 5 speed, 3. 54 gears, pw injectors, 12cm turbo housing, K&N air filter, "tweaked" pump, isspro boost and pyro gagues w/A pillar mount, straight piped 3' exhaust

 

[Archive]

Some readings from gauges would be helpful in diagnosing this proble... egts... boost
<blink><h4>100posts woohoo</h4></blink>
sorry, I had to celebrate somewhere

 

[Archive]

I wonder if your lift pump is not working properly. The service manual says there should be a minimum of 3 psi on output.
Gene
92 350 4x4

 

[Archive]

One other piece of info: I seem to have intermittent sticky injector(s). Every so often immediately after start up it will idle rough and some white smoke will come out. The roughness and smoke clears up within minutes and everything seems to run OK. Is there a "good" additive to clear up sticky injectors? Might this cause or add to the low power at WOT? I've done a visual on the throttle opening and it seems to go against the stop when depressed. There is a small spring that looks like it takes up some play and the throttle stretches it slightly. Don't know what else to add.

------------------
Stock 92, 5sp LE, 4WD, 4. 10 gears, std cab, 184K miles, 50 gal aux. ,more to come

 

[Archive]

I've had a fuel mileage drop myself. Thought it was poorer garde\fuel being distributed. Will keep sharp eye on this thread!

------------------
http://coffeewithJesus. homestead.com/web1.html 89 1-ton, Amsoil System 3000 5-30,K&N air filter, cleaned-up exhaust, Dynomax straight-thru, rebuilt pump, 12cm wastegated turbo, thermostaticly controlled twin 14" electric fans, intercooler, modified 518 OD transmission, Gear vendors OD controler, R-134, louvered fenders, 93 aftermarket smoothe grille; 78 35'Avion, 93 Lance 900 slide in with generator and power jacks. Jesus saves!

 

[Archive]

I'll share some gague readings from my truck. Boost at WOT is 30 lbs and EGT is around 700-800. Everything sounds normal, but I have lost 10 mph top end speed. My truck can run 100, but is only running 90. The lack of top end speed is been steadily decreasing for about 2 years. I don't know what is wrong... . new filters and throttle linkage is good. Injector or lift pump failing??

------------------
91 4x4, 5 speed, 3. 54 gears, pw injectors, 12cm turbo housing, K&N air filter, "tweaked" pump, isspro boost and pyro gagues w/A pillar mount, straight piped 3' exhaust

 

[Archive]

I'm bringing this back up because I'm really hopeing that someone out there has an answer. Very serious problem, but it has not been cured yet.
cody

------------------
91 4x4, 5 speed, 3. 54 gears, pw injectors, 12cm turbo housing, K&N air filter, "tweaked" pump, isspro boost and pyro gagues w/A pillar mount, straight piped 3' exhaust

 

[Archive]

Have you checked no max load rpm? If it is correct, 2825-2925, then maybe fuel quality is the answer. The VE pump will only deliver so much fuel at certain boost/rpm/throttle combination. Your pump may be delivering the exact same AMOUNT of fuel as two years ago but if the energy content is lower the max power of the engine will be lower. At intermediate throttle you naturally compensate with more push on the pedal or the cruise control does it for you, but mileage will go down since more volume of fuel is needed for any given power level.

If no load speed is out of spec, you can adjust the stop screw. This may mean the pump is wearing out or just the governor spring inside the pump is weakening.

 

[Archive]

Before the BD injectors, my old ones would stick, 1 in particular. I used some additive as a last ditch effort near the end. Its made by STP and said it was accepted by Cummins N-14 testing. So I threw it in and it helped a little. Kept it from hammering at startup. Now, I was cautioned by a buddy that this is not a good idea as the varnish it does remove all gets put through the injector and makes it worse. At that point I didn't care. AS for full load losses with the same boost #ad
.
Is the blowby(crank case venting) up any?

------------------
Lil' Mack - 89 D250LE 2WD 5 Spd 3. 54 Reg Cab. K&N,"tweaked pump", BD Injectors, Banks Pyro/Boost, 3. 5" Exst tail section straight. E&M Custom seats. Bosch H4, PIAA 80W/80W HdLites. 100W Drv,55W Fogs.
232,500 miles (372,000 Kms) 7700 Hrs. Cummins Power Booster member.
The Original Turbo Diesel

 

[Archive]

Hey guys, I have a little more information to share with ya'll about my problem. In 4th gear at WOT max boost is 30 lbs. , but in 5th gear WOT, boost is only at 20 lbs. Is this normal and does it have anything to do with my loss of power at top end? Just thought i'd pass this along looking for answers.
cody

------------------
91 4x4, 5 speed, 3. 54 gears, pw injectors, 12cm turbo housing, K&N air filter, "tweaked" pump, isspro boost and pyro gagues w/A pillar mount, straight piped 3' exhaust

 

[Archive]

I just tanked up with 76 #2 diesel, this is different from my usual (ASTRO). By the way, this was off Hwy 224 headed towards Clackamas and the price was $1. 799. I added some Cummins L10 tested/approved additive at the same time. Don't have many miles on yet so I haven't seen any change. I am going to keep track of how often I get sticky injectors at start-up. I will post the results. I have checked visual full throttle and it does push against the springs. My mileage at this last fill up was still 20 mpg. , this is no load/mixed driving.

 

[Archive]

One more note. In the morning when the truck is fairly cool, I seem to get full power. Smoke at 3/4 throttle and noticeble power boost. When I start the truck for the trip home, no smoke! Does the temp figure into this at all?

------------------
Stock 92, 5sp LE, 4WD, 4. 10 gears, std cab, 184K miles, 50 gal aux. ,more to come

 

[Archive]

Untill the truck is at normal operating temperature you will not feel the full power of the Cummins. Do not put the pedal to the metal when the Cummins is cold its not good for the diesel delivery system.

 

[Archive]

My milage dropped off by about 2mpg and it turned out to be the water drain in the fuel filter . It only leaks while running.

Julian Bell
Houston