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Selling if I cannot find out whats wrong

foxdenfarms

foxdenfarms

1994 C3500 6.5TD
Messages
31
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0
Location
Cherryville, NC
:mad2:pissed off. I have had my truck now for a few months and have done a few simple mods. I am very mad because it does not pull for shit (excuse my french) my truck has major problems pulling my 18' bayliner fishing boat. I put my featherlite all aluminum 16' horse trailet and 1horse and it has no power whatsoever. It shifts at weird times downshifts at weird times and just has no power. Hesitates at start and will not move with throttle depressed, will slowly pick up rpm until turbo starts to spool and makes rpm to move and at cruising speeds of 65mph I constantly shifts back and forth like I cannot decide because it doesn't have the power to maintain in overdrive with a light load of 6k or even 3800lbs max with my boat.

WHATS WRONG?!?!?!?!?!
 
Lets start with what is the fuel pressure and volume at idle, and what is the fuel pressure at hi way speed? How old are your fuel injectors?

Have you ran a compression test? How much blow by do you have?

With he constant up shift/downshift are you getting any codes?

Btw, is this the same power since yo bought the truck or did something happen and it lost power?
 
Truck is acts the same since I bought it. Fuel pressure is good at idle not sure at hwy speed. I haven't done a compression test on it because I runs so nice it just doesn't perform. The injectors I am not sure how old and there is very little blowby. Oh and also this truck gets 10mpg's empty. ...
 
Yeah... My friggin hummer gets 10.4 mpg. Something is wrong or worn out. Listen to WarWagon, he puts more towing miles on a 6.5 than you could want to.
 
looking at your sig couple of issues could be mechanical wastegate, and definetly the cone filter if it's not sucking outside air. should get way better than 10 mpg empty so I would suspect injectors are getting old. Might be a combination of things rather than 1 item causing issues.
 
Well it was all stock when I bought it and it was same bad mileage maybe 220miles to a tank of 26 gallons. ..that sucks. I did the few home mods. Hoping for results and got none I dont know what the 6.5 is capable of so I do not know how far off performance is. Its my first diesel so I am in the dark
 
Do the compression test. You said it runs nice, but it is low on power and wasting fuel to the point you are thinking about selling it.

Hook up a fuel pressure gauge and go for a drive. It sounds like it is needing more fuel under a load. The next thing would be pulling the injectors and taking them to a shop for testing or rebuilding. I don't know of 3
People who regretted rebuilding their injectors when they are tired. The fuel savings will pay for the rebuild and then you will have more power.

You have a cone filter, please elaborate, pictures help. Same thing with the mechanical wastegate. What is your boost pressure at cruising speed and at what rpm?
 
Clean the grounds, especially the ones by the trans dipstick. They are for the ecm, it may help the shifting and fueling.
 
Tank sock plugging, last ditch filter in FFM plugged, IP inlet screen plugged? High IAT's will cause a defuel. Over boost will cause a defuel. Defuel makes the truck feel like a limp noodle.

For the record, my K1500 can out tow a 08 5.4L F250 w/ 4.10's and get 12mpg. This isnt on hard grades or anything but grossing 15K in a 1/2 ton. It has a chip, 3" downpipe, custom weed burner exhaust, LP relay, dmax fan and HD fan clutch.
 
tanman_2006 said:
For the record, my K1500 can out tow a 08 5.4L F250 w/ 4.10's and get 12mpg. This isnt on hard grades or anything but grossing 15K in a 1/2 ton.
Click to expand...

Ummmm . . . Isn't that something like kicking a puppy? Shoot, I think even a 5.4L F150 can stomp a 5.4L F250 :hihi:

Back to the OT, agree with others that it is likely a mix of things and seems like primarily a starvation issue with many possible sources (air / fuel filter, tank sock, IP, injectors, etc . . .). X2 on Gauges as they will help with cutting down trial and error of what to go after; also when going down the modification path, we need them to keep out of trouble and help plan for the next upgrade.
 
JayTheCPA said:
Ummmm . . . Isn't that something like kicking a puppy? Shoot, I think even a 5.4L F150 can stomp a 5.4L F250 :hihi:
Click to expand...

Well its not a bad truck but yeah its a bit on the gutless side even with its Diablo tuner. Doesn't feel as strong as a child GM 6.0l but it holds about the same speed when towing loaded heavy.

Sent from: Source Unknown
 
The lift pump looks like the fuel filter in a gas truck and is mounted in the same location on the frame under the drivers door area. But before you change it I need your injectors you need to do a little bit of testing first. It is very easy to start throwing wads of money at the truck and regret it later. A $30 fuel pressure tester is a worthwhile investment you'll use it long-term, enough to pay for yourself to keep you from putting in a lift pump when you do not need one. Even if you change the lift pump maybe you have a restriction at the fuel filter manager like recently mentioned on the last-ditch screen and you wouldn't know what if you don't test it.
 
Well I know the limp mode. I had to install the 5k pot by the boost sensor to tell the computer it could takr more boost. I am running 13lbs all out loaded at shifting. Cruising it levels around 2-3. Whats the best way to remove the fuel pump? And if it is plugged would it be causing horrible mileage? I have come to peace with the fact it is no cummins, but I do feel like my 6 cylinder Oldsmobile can pull better
 
foxdenfarms said:
Well I know the limp mode. I had to install the 5k pot by the boost sensor to tell the computer it could takr more boost. I am running 13lbs all out loaded at shifting. Cruising it levels around 2-3. Whats the best way to remove the fuel pump? And if it is plugged would it be causing horrible mileage? I have come to peace with the fact it is no cummins, but I do feel like my 6 cylinder Oldsmobile can pull better
Click to expand...

The injection pump is the last thing I would check as far as being plugged, it is the last piece in the fuel system. FFM is easy to get at then I would blow compressed air back from the tank side LP connection (fuel cap OFF!) to see if the tank sock is bad.

Never used a 5K pot to "trick" the ecm, I still run vaccum. Personally I would lower the boost to 8-10 psi because you dont have enough fuel with stock tuning to use 13psi boost (that could be one factor in the mpg issue)
 
How much is the max boost pressure? In some cases, more does not mean it is better.

Sounds like the fuel system needs work.
Make sure the OPS is still working to turn on LP when engine is running.
Make sure fuel filter is good.
Make sure there is no leak in the fuel system (more difficult).
Make sure all electrical is in tip top shape, why? well, this truck needs a lot of electric.
For example my weak alternator caused the AC not to blow cold air, etc.
 
Well the thing is with the 5k pot turned at anything less than all the way it defuels and limps out. The boost will peak at 13 as if shifts, stays around 8-10 at 3800. My lift pump is on a switch so I know it is on and working. I did the fuel pressure check at idle and it is good. How fo I know if the filter needs to be replaced? And whats the best way to get the fuel pump out to check it and the sock?
 
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