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Nathan Howard
Dodge Dakota
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9/20/2004
09:54:48
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 Subject: '93 3.9 running bad and getting worse
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Hello everyone. I have a delima. My truck''s performance and running ability has slowly been deteriorating. It's been to three different fixit shops with three different answers and a lot of money spent for nothing. Can someone help?
Truck:
1993 Dakota 3.9 v6
70,000 miles
New Parts:
Plugs, Wires, Cap, Rotor
Fuel Filter
EGR Valve and Sensor
Fuel Injectors (5.0 Motorsports)
Timing Chain and Tensioner
Water Pump
K&N Air Filter
Valve Cover Breathers
First Place told me the EGR was bad
Second Place told me the Fuel Filters were bad
Third Place, I can't remember but it didn't work
None of the places or changes improved the runnability of my engine and it's very frustrating. I'm done spending my money at repair shops for wasted fixes.
Any clues?
Symptoms:
Lumpy idle and hard starts after engine sits for a while (when engine is cold).
Poor acceleration.
Bad MPG
"Feels" like it's "missing" mostly when it's cold.
Backfires or Pops when decelerating and post-rev.
Nathan
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Me Too
Dodge Dakota
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9/20/2004
10:46:54
|  RE: '93 3.9 running bad and getting worse
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I'd get the cylinder compression checked and check for vacuum leaks.
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Me Too
Dodge Dakota
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9/20/2004
10:50:09
| RE: '93 3.9 running bad and getting worse
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I'd get the cylinder compression checked and check for vacuum leaks.
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Dan M
Dodge Dakota
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9/20/2004
13:09:05
| RE: '93 3.9 running bad and getting worse
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I 3rd Me Too's posts, get the cylinder compression checked and also check for vaccuum leaks. Could be bad gasket. when cold it contracts, you'd might notice worse drivability and when it gets hot, expands and you might see better drivibility. Does the engine knock? Have you checked the oil pump? For under $100 you can get a dealer to do a diag check on the engine - even if you don't have them fix it, they can tell you what all is wrong - should be able to get you a nice print out.
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Nathan Howard
Dodge Dakota
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9/20/2004
13:32:50
| RE: '93 3.9 running bad and getting worse
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Dan M: The second place I took it to put it on the analyser and they gave me the printout. That's when they showed me that the fuel injectors were going bad. I replaced them but it didn't improve anything. There was nothing else apparent from the diagnosis (unless they screwed it up).
I'm not sure if the engine is knocking, but I do hear a ticking noise which maybe sounds like a minor exhaust leak of some sort. I'm not sure.
I will try the compression test. I've tried to hunt for vacuum leaks, but can't seem to find any.
I wish I could take it somewhere, but I'm sick of wasting my money at places which can't determine anything or give me improper fixes.
I've also tried to check the distributor to see if the gears might be bad (cam to dist), but there is only minor play when twisting the rotor, which seems fine.
It's costing a lot, but the problem is getting worse and I'm starting to get really frustrated. ;-)
Anymore help is much appreciated! Thanks.
Nathan
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93Dak
Dodge Dakota
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9/20/2004
15:59:12
| RE: '93 3.9 running bad and getting worse
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I had trouble with injectors from fiveomotorsport.com Mine would run rough and eventually a check engine light came on.
I recommend buying new o-ring kits for your old injectors, and putting those back in.
Also, you might have a belly pan gasket leak and possibly and intake manifold gasket leak. At a minimum, I recommend getting a new intake manifold gasket set from NAPA. It comes with a new belly pan gasket and costs about $45. You could also replace the belly pan cover with a an aluminum aftermarket replacement.
Injector O-ring replacements are available at parts stores. I bought mine at Advance Auto Parts.
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Dan M
Dodge Dakota
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9/20/2004
16:29:39
| RE: '93 3.9 running bad and getting worse
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Sounds like you've had quite the time on this one! Definately do the compression check.
Bad gas milage could also be oxygen sensor.
When you say bad acceleration, is it just acceleration or do you also have problems when you running at various speeds? 30? 45 mph? 55? 65?
You can always take it to a muffer place have them do a free inspection on it, could be some issues are exhaust related. Cat maybe? bad oxygen sensor can cause cat to go prematurely.
Also, you can take it to a transmission place and have them do a free tranmission inspection. 70,000 isn't alot, but worthy of an inspection considering the truck is 11 years old. Ever had the fluid / filter replaced?
Both of these options will cost only time. I'm hoping other on here will have some more options for you.
- Dan M
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Wadak
GenIII
9/20/2004
17:37:00
| RE: '93 3.9 running bad and getting worse
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The problem could be , as stated above ,your Oxygen sensor, this will affect gas mileage and power. Another possibility is the distributor pickup, if starting to go bad it will affecting fuel sync input to the computer.
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Verde SAR Dog
Dodge Dakota
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9/23/2004
12:29:40
| RE: '93 3.9 running bad and getting worse
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Sounds like the symptoms I just corrected with my 94 v6 with 178k miles on it by replacing the fuel filter/presure regulator ... good luck
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dex
Dodge Dakota
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9/23/2004
12:45:23
| RE: '93 3.9 running bad and getting worse
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0nly 70K mileage after 11 years? That's about 6,300 miles per year - why so low?
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Nathan Howard
Dodge Dakota
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9/23/2004
15:23:51
| RE: '93 3.9 running bad and getting worse
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dex, I bought it from a retiree who barely drove it... and I drive it very little as well. I live only a few blocks from work and we travel with my wife's car.
This weekend I plan to check the compression and fuel pressure. I'll reply with my results. Thanks for all the advice. Hopefully I can get my baby running fine again soon. :-(
Nathan
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Nathan Howard
Dodge Dakota
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9/24/2004
01:18:35
|  RE: '93 3.9 running bad and getting worse
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I checked my fuel pressure tonight. It was 35psi with key on engine off and was 32psi engine on idling. Is this ok?
I still need to check my compression this weekend.
Nathan
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Verde SAR Dog
Dodge Dakota
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9/24/2004
17:37:51
| RE: '93 3.9 running bad and getting worse
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32# is on the low end,should be 35-40. With the engine off you can't tell if you're getting enough flow either. You can have good static pressure without having good flow. The factory manual for my 94 states a good fuel pump should put out at least 1 liter/ min. If you're not getting that it could be the filter or pump.....
The filter/regulator also has a check valve the is supposed to keep the fuel line pressurized after shutting-down the engine.
The filter regulator is about $75.00 dealer item the pump almost $400. The hard part is taking the fuel tank off - some of the factory bolts on the skid plate were put on from the top before the bed was installed, I welded nuts on the top of the bracket so next time I dont have to be Houdini to get it off.
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93dak4x4
Dodge Dakota
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9/25/2004
10:45:50
|  RE: '93 3.9 running bad and getting worse
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i got my fuel pump for a little over a 100, and i would check out your oxy sensor, i was getting less then 8 mpg and running rough about a month ago till i changed it. i would also check out your other sensors, i replaced all mine, 11 years on electrical equipment takes its toll.
93 Dakota 4x4 CC 3.9
v8 tb
flowmaster muffler
3923's
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Nathan Howard
Dodge Dakota
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9/25/2004
14:18:49
| RE: '93 3.9 running bad and getting worse
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Dan and Gang:
I just did a compression check, following the manual of letting the engine cycle 4 times for each cylinder check. I performed up to 4 rounds of 4 cycle checks on some questionable cylinders.
This is what I found:
# Cylinder | 1st round | 2nd round | 3rd | 4th
---------------------------------------------
1 Cylinder | 120-170 | 120-170 | 120-170 | |
2 Cylinder | 120-170 | 120-170 | 120-170 | |
3 Cylinder | 120-170 | 120-170 | 120-170 | |
4 Cylinder | 90-170 | 90-170 | 90-170 | 120-170 |
5 Cylinder | 90-170 | 90-170 | 120-170 | 90-170 |
6 Cylinder | 80-170 | 80-170 | 120-170 | 120-170 |
Though 4,5,6 had at least one check starting at 120, the other 2 or 3 checks started at 80/90. While the other cylinders 1,2,3 always started at 120. All cylinders maxed at 170, every single one of them.
Does this tell me anything, or is the compression just fine?
Nathan
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Nathan Howard
Dodge Dakota
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9/25/2004
14:23:24
| RE: '93 3.9 running bad and getting worse
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Please note my post right above this one, note the compression check and data found. I have an additional note:
On the day, (today/Saturday), that I was planning on doing the compression check, my truck got really hot and on the verge of overheating! I noticed one other day, last week, where it got pretty hot. Well today the heat gauge was maxed out and when I opened the hood I could smell, see, and hear coolant boiling out.
So, I let it cool, pulled all the plugs out and performed the compression check anyway. The results are right above this post.
I purchased a new 160 degree thermostat, which I'll put in soon. This is just another symptom to my problem, which I and noone else can figure out.
Nathan :-(
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Nathan Howard
Dodge Dakota
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9/25/2004
14:34:52
| RE: '93 3.9 running bad and getting worse
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In addition, I forgot to mention that while performing the compression check, after pulling the plugs I noticed that each and every plug looked pretty "white". Does that mean it's lean?
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Wadak
GenIII
9/25/2004
17:02:41
| RE: '93 3.9 running bad and getting worse
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If your fuel pump pressure is only 32 to 35 psi, it will run but poorly. Your fuel pump pressure should be between 40 and 50 psi. It looks like a fuel pump change is in order. Please don't take it to a dealer. I helped my soon change the fuel pump on his dak, the part at Napa I believe was between 200 and 250.00. The local Dodge "STEALER SHIP" wanted 600+ dollars, 300 for the pump and 300 to change it. If you don't want to do it yourself, find a local, reliable repair shop and get an estimate.
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Nathan Howard
Dodge Dakota
JOIN HERE
9/25/2004
17:27:15
| RE: '93 3.9 running bad and getting worse
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According to Haynes repair manual the fuel pressure (32 idle, 35 engine off) seems ok for 1993 model. My fuel sending unit is bad though, because my gas gauge always reads empty... even after filling it full.
Nathan
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Verde SAR Dog
Dodge Dakota
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9/25/2004
19:50:05
| RE: '93 3.9 running bad and getting worse
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Message:
The factory manual for my 94 dakota says 35-40# and at least 1 liter / minute flow. If it's low it might just be the filter/regulator, but then it could be the pump too. If I was you I'd replace the filter/regulator which sits on top of the pump first and see if that helps, if not then go for the pump. The sending unit on mine went bad too but I was able to make it work by messing with the contacts on the sender attached to the pump. Everything is in the gas tank ....
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Verde SAR Dog
Dodge Dakota
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9/25/2004
19:52:50
| RE: '93 3.9 running bad and getting worse
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running hot and bad could be a vaccume leak some where
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