| From | Message |
Clif Norton
Dodge Dakota
JOIN HERE
10/12/2002
12:34:22
|
 Subject: Loss of power and milage.
IP: Logged
Message:
About 8 - 10,000 miles ago I lost about 5 mpg and power on my 95 3.9 auto. (I now have about 113,000 miles on it.) Around the time I noticed the change I had just changed the distributor cap & rotor, the plugs, and added a camper shell. I expected the shell to make a difference, though I wasn't sure which way. (It's cab height at the front and rises about 6 in to the back so a negative impact on mpg could happen but 20%?) I swapped the plugs, cap and rotor back and didn't fix the problem.
Prior to the problem the fuel gauge would stay above the full mark for about 30 miles then hit the 1/4 marks at about 100 miles apart for about 420 miles per 22 gal tank. Now it takes about 15 miles to come below the full mark, reaches the 1/2 tank mark at 100 mi then takes 100 mi for the remaining 2 1/4s. If I fill up at 1/2 tank indicated it takes approx.8 gal. If I fill at 1/4 indicated it takes approx. 15 gal. Regardless of when I fill up I get from 14.5 to 16 mpg.
Fuel pressure tests at 41psi consistently through a tank and I get positive pressure on the plenum gasket test. Compression tests good on alll cylinders. Cylinder #2 has a slight oil smell. Looking in the TB the pan is a little dirty with a little oil. The PCV tends to buzz like a bee. I can hear the IAC hiss intermittantly for about 5 min during warm up.
Since the change the cat went bad and I replaced it with a carsound cat but no performance improvement.
Given the above what should I check next? Maybe the injectors? Or the fuel pump?
Any help would be appreciated.
Clif
|
jason
Dodge Dakota
JOIN HERE
10/13/2002
04:27:08
| RE: Loss of power and milage.
IP: Logged
Message:
my truck gas milage dropped off in my 1994 3.9, but it took a little longer to start, and it would stutter. it might be the fuel filter/regulator which is on top of the gas tank. it is a real pain to drop the tank, i would replace that. just my suggestion. hope its any help, and run some fuel treatment, and some injector cleaner through.
|
NF1988dakota
Dodge Dakota
JOIN HERE
10/18/2002
20:03:27
| RE: Sputtering and then stall
IP: Logged
Message:
Hi there. Can anyone offer helpful suggestions as to why my 1988 3.9l v6 Dakota occasionally sputters and then when you give it more gas, it will stall. If however you ease back on the gas, it will not stall and regain power.
Thanks in advance
|
cory
Dodge Dakota
JOIN HERE
10/18/2002
22:05:08
|  RE: Loss of power and milage.
IP: Logged
Message:
hey clif, before you drop the tank and all that other hooplah crap. try replacing your O2 sensor. that could make a difference and with that many miles on the engine if it has never been done before I would really suggest you go ahead and do that.
|
Clifton Norto
Dodge Dakota
JOIN HERE
10/19/2002
16:09:47
| RE: Loss of power and milage.
IP: Logged
Message:
Sorry it took so long to reply I lost my cable modem and had to replace it.
Jason, Thanks for the suggestion. I've been looking mostly at the fuel regulator like you said. If I replace it I'll probably replace the whole pump assembly since the guage indications are so weird. I'm thinking about using Sea Foam cleaner on it next weekend before trying the pump.
Cory, I replaced the O2 about 5k miles before the problem hit after the code pinged the maintenance light. I haven't gotten the code again but that was before my cat went out so there might be something wrong with it. Do you know how to test it? Thanks.
NF1988dakota, does an 88 have a carb? If you're running rich and dump more fuel in it might stall, while letting off the gas might lean it out enough to keep running.
Does anyone know if putting a high flow holley pump on an otherwise stock engine would cause problems? I also wonder if the injectors could have some thing to do with it. Or maybe its a combination of several things associated with more than 100k miles.
Clif
|
Charlene
Dodge Dakota
JOIN HERE
8/22/2003
12:45:28
|  RE: Loss of power
IP: Logged
Message:
I have a 88 Dakota w/ 3.9 V6. It started to run really bad no power etc so I replaced the plugs, cap, and wires, air cleaner etc. That only seemed to make it worse, so then replaced the distributor, and ran a code check, kept coming up with a 33 and this truck doesn't have A/C. I looked around your posts and then changed out the TB and coil, now I get codes 12, 13, 14, 33, 55. I can get it to start up but have to have the throttle wide open and it will not idle, it won't even rev up. The fuel smells very rich. Now after reading more of the posts here I am wondering if it could be the CAT, I am hoping someone might be able to give me some advice as this is becoming a real pain. This trial and error method is becoming very expensive not to mention nerve racking. Thank you in advance for any help you might be able to offer.
|
J and J Auto
Dodge Dakota
JOIN HERE
8/22/2003
21:48:07
| RE: Loss of power and milage.
IP: Logged
Message:
Could be a pluged cat
Also check your TPS if its bad and reading high
it will just pour fuel in and you will not get
a light for it.
.5 to .7 is normal. center wire and black to
a good ground and just turn the key on it don't
need to be running. move the throttle open and
close and be sure it comes right back down.
Had that happen to me one day what a pain trying
to drive with the throttle to the floor to give
it enough air to run the fuel it was dumping
Larry
J&J Auto
|
Charlene
Dodge Dakota
JOIN HERE
9/01/2003
11:18:40
|  RE: Loss of power
IP: Logged
Message:
Just wanted to say thank you for all your help with my dodge. After trying your suggestion and finding that wasn't the problem I had a neighbor come over and cut my exhaust to see if it was the CAT. Fired right up and plenty of power, once it is replaced I will be on the road again.
I just can't thank all of you and this site for the help and knowledge I have received. It has been wonderful having this resource being as I live out in the country without the many resources larger towns have. I still prefer to do things myself whenever possible even if it means going about them the long way around with lots of trial and error.
Once again thank you!
|
grumpy
Dodge Dakota
JOIN HERE
9/01/2003
12:32:35
| RE: Loss of power and milage.
IP: Logged
Message:
ive got a 93 3.9 mag. with only 80,000 on it, the past couple months ive had a power loss but maily when its cold. it feels like the air is on until you get to a certain rpm and then it takes off.also theres a slight hesitation when it shifts gears.Ive never had to replace anything on this motor but i guess its time to start.does anyone know whats causing these probs? so Ill know where to start.
|
jr
Dodge Dakota
JOIN HERE
9/01/2003
23:03:38
| RE: Loss of power and milage.
IP: Logged
Message:
grumpy: my brother had the same truck and problem he replaced the cat and the o2 sensor it worked great after that
|
grumpy
Dodge Dakota
JOIN HERE
9/02/2003
19:46:29
| RE: Loss of power and milage.
IP: Logged
Message:
I've got a cat gut,but havent checked sensor.ill try that.thanks man.
|
Shank
GenII
9/02/2003
21:50:25
| RE: Loss of power and milage.
IP: Logged
Message:
I suggest all Dak owners bookmark this site, It's very informative and useful when you have code problems.
http://dakota-truck.net/CODES/codes.html
As for the sudden loss of power, Sorry it's soo long but here goes........
Get a bright flashlight, remove your Air cleaner, open the butterflies on your TB and look down inside. If you see Oil that's a bad thing and likely the culprit robbing your power. It's called the bellypan gasket.
To replace the bellypan gasket you have to remove the intake assembly (plenum) which sounds harder than actually is to do. once you get the plenum off, flip it over, there is a large flat steel plate on the bottom. This is the bellypan.
Your Plenum is cast aluminum and the bellypan is steel. Both metals expand and contract at different heats causing stress & friction. The bellypan gasket is pressed paper type & usually only lasts about 60k miles.
Reason behind the Leaky Bellypan theory....
Bellypan leaks oil into the bottom of the Plenum, this is also where your Air Flow is directed after it passes the TB, A plugged PCV combined with a leaky Bellypan will leave about 1/8" of oil coating the bottom of the pan. Your engine warms up and the increase in Air is sucking this Oil/Air mixture into your cylinders and burning it off with the fuel mixture. This will cause bad readings when it hits the o2 sensors and they will continue to re-adjust the fuel/air mixture until the oil is burned off. The 1st couple minutes it's gonna run like $h1T.
IF THAT DON'T WORK...... test your fuel pressure, you might have a leaky injector bleeding into the intake. To check this without a gauge, start your truck and let it run for a min & turn off...
remove the pressure release cap on the Fuel rail. DO NOT put your face directly in the path, use a pen or other object to push in the needle quickly and release, Observe how much fuel sprays out. restart the truck and let it run for a minute & turn off again. This time let it sit for about 15 mins - 1 hour & recheck again.
If you notice a drastic amount less within 1 hr than you either have a leaky Injector or a bad fuel line check valve.
Reason behind the leaky Injector theory......
The leaking injector will leak the fuel equivelent of all the cylinders into 1. When you start the vehicle it will take a few extra turns to get the fuel pressure back up and pumping to all the cylinders..... in the mean time you have just overloaded the o2 sensor with a too rich reading followed by a too lean reading, In the mean time the 'puter is telling the Throttle Body MORE AIR MORE AIR..... I mean LESS AIR LESS AIR...... NO NO MORE AIR..... the whole time its making these adjustments your engine is running like horse turds.
I got a set of Bosch Design III 19lb injectors (green 1's) from www.fiveomotorsport.com delivered to my door for $189. Autozone wanted $212 for replacement OEM Junk!
New Injectors and replacing my badly leaking Bellypan made a DRASTIC improvement in my Dak! hope this helps also.
Good Luck,
Shank
|
jeff
Dodge Dakota
JOIN HERE
4/05/2004
14:20:42
|  RE: Loss of power and milage.
IP: Logged
Message:
I have a 1994 Dodge Dakota V-6 that was stalling and running poorly and subsequently diagnosed by a dealership as needing a new fuel pump. In addition, they also recommend a complete fuel system cleaning for $100 after the pump is changed. I have 2 questions:
1. is the fuel system cleaning necessary and if so why? What would it take to do this myself?
2. If I choose to change the fuel filter myself, how difficult is it to drop the gas tank? what steps/precautions should I take? I have a full 22 gallon tank of gas and am wondering what the best/safest way to remove the fuel is also.
If it is not obvious, I am a rookie mechanic so any and all details are welcome.
|
99DAK
Dodge Dakota
JOIN HERE
4/05/2004
16:56:46
| RE: Loss of power and milage.
IP: Logged
Message:
Clif (et al), the following is from a US Department Of Energy website:
At highway speeds, most of the energy needed to move a car down the road goes to pushing air out of its way. On the EPA highway cycle with an average speed of 48 mph, 54% of the energy required to move a car goes to aerodynamic drag. Because drag increases with the square of speed, more than twice as much energy would be required to overcome drag at 70 mph.
The addition of the camper shell could indeed account for the 20% loss. Even without the 6" rise in the back the shell would increase drag, the rise makes it even worse.
|
TOMZ
Dodge Dakota
JOIN HERE
4/05/2004
20:04:13
| RE: Loss of power and milage.
IP: Logged
Message:
Jeff, do yourself a favor and visit another dealer!
While you may actually need a new fuel pump or not is debatable. Fuel pumps in our trucks usually work or don't. If it's a stumbling, stuttering, stalling deal check out the O2 sensor first. It may be old and getting"mixed" signals which in turn causes the computer to richen or lean out the mixture.
As far as changing the fuel filter and cleaning out the fuel system is concerned. Yes to the filter and yes to cleaning your injectors. Since it's a 94 you might want to just jeplace the injectors, it will only cost a few dollars more. You can find places to get them from many of the posts on here but the best seems to be Five O Motor sport.
|
Jeff
Dodge Dakota
JOIN HERE
4/06/2004
10:21:08
| RE: Loss of power and milage.
IP: Logged
Message:
Tom, Thanks for the advice. I have my doubts about this dealer. They said they monitored the fuel pressure and diagnosed it as the fuel pump based on seeing a drop in pressure. Could there be another explanation for the drop other than the fuel pump? Also, do you know how to test the O2 sensor without a computer? It's a $95 part so I'd like to be sure before I buy it. I'd also rather not pay the dealer another 1/2 hour of labor to hook it up to their computer. Again, I'm a rookie so I apologize if these are obvious questions. Thanks.
|
dak-jak
Dodge Dakota
JOIN HERE
4/06/2004
11:48:20
| RE: Loss of power and milage.
IP: Logged
Message:
Could be bad EGR valve/solenoid
$ 60.00 to $ 70.00
Not likely fuel pump..
|
| | P 1 |
|
Post a reply to this message:
Username Registration: Optional
All visitors are allowed to post messages
|
