1991 Dodge Dakota Acceleration Misfiring

Tiny
FOX_RACER627
  • MEMBER
  • 1991 DODGE DAKOTA
  • V8
  • 4WD
  • AUTOMATIC
  • 187,568 MILES
My truck seems to misfire under acceleration. Its like it isnt getting enough fuel or spark. It starts to miss/bog as I accelerate but when I let off of the gas it picks back up if I ease into it. Im pretty sure it isnt an electrical issue because I just put new plugs, wires, distributor cap, rotor, and coil on about 4000 miles ago. I just put on a new fuel filter and did a fuel system cleaner along with a new fuel pressure regulator and it still does it. I think it may be the fuel pump but im not sure. Please help, thanks.
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Tuesday, September 30th, 2008 AT 10:23 PM

10 Replies

Tiny
JACOBANDNICKOLAS
  • EXPERT
Hi
First, does the truck misfire or feel like it's running out of power? If it's a misfire, it sounds electrical to me. However, if the truck runs out of power, you may be right; it could be the fuel pump. Try driving the truck up a long hill where the engine has to work hard and use a lot of gas. If it starts to die, my guess would be the fuel pump.

When you say a misfire, is it a backfire. If so, is it through the exhaust or the intake?

Joe
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Wednesday, October 1st, 2008 AT 8:25 AM
Tiny
JACOBANDNICKOLAS
  • EXPERT
I forgot to mention. If the fuel pump is bad, the easiest way to replace it is to remove the truck's bed. I believe there are only eight bolts that hold it on to the frame. But, you will need some help getting it off the frame.
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Wednesday, October 1st, 2008 AT 8:55 AM
Tiny
FOX_RACER627
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Im not exactly sure what you mean when you say running out of power, but it does misfire/bog when going up a hill or when the engine is working hard. If I push the accelerator too much during this bog, then the truck will die. I did it one time and the truck wouldnt crank up for about an hour or so. Another time and it cranked right back up. And yet another time and it backfired but did not die. The backfires have been at the exhaust and not intake by the way.

(I have a 2 inch bodylift so dropping the tank isnt going to be very hard. But thanks for the suggestion anyways.)
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Wednesday, October 1st, 2008 AT 2:18 PM
Tiny
JACOBANDNICKOLAS
  • EXPERT
Hi again:

How many miles does the vehicle have? Has the oil been changed on a regular basis? Also, from your description, it really does sound like the fuel pump. I'm asking the other questions so I can eliminate other potential causes (burnt valves, low compression.)

You know the vehicle, therefore you know better than I do if the potential for internal problems exist. If they don't, I agree with you and would recommend that you have a fuel pump pressure and volume test done to be sure it is bad. If you need help doing that, let me know and I'll try to get the specs for your vehicle and tell you how to do it. Checking fuel pressure and volume requires special tools and could potentially be dangerous if the engine is hot, or you are around anything that could ignite the fuel.

Let me know, and I'll do my best to help you.

Joe
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+1
Wednesday, October 1st, 2008 AT 4:55 PM
Tiny
FOX_RACER627
  • MEMBER
Thanks for all the help, the truck has 187536 miles on it. I work at Jiffy Lube so I change my oil every 2000 miles with synthetic. Every service we offer has been done to my truck and has been done usually before it is needed. :) It burns about a quart of oil (valve guides) every 2-3000 miles and the motor has never been rebuilt or worked on (nothings ever gone wrong with it) other than the usual maintainence.

I have a fuel pressure gauge but you have to have a T fitting to check the pressure and autozone, advance, oreillys, napa, etc. Dont carry one. The manual says 14.5 psi by the way. I ordered a fuel pump today so ill see if that does anything when it gets in.

If you can think of anything else it could be, please let me know, thanks.
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Wednesday, October 1st, 2008 AT 8:35 PM
Tiny
JACOBANDNICKOLAS
  • EXPERT
Have you ever replaced one in a Dakota? If not, I recommend that you remove the bed rather than trying to get the tank out. The plastic tanks are very easy to crack, and the straps are usually so rusted, they are almost impossible to remove without breaking. There are 8 bolts that holld the bed on. Just disconnect the wiring for the lights, take the 8 bolts out, and have someone help you take the bed off. It's really easy after that. You have complete access to the tank, fuel lines and power. Just be careful when you disconnect the fuel lines. They may still be under pressure causing fuel to spray everywhere. Also, the plastic retainers are easy to break, so be easy with them. Finally, before you remove you old pump, clean the top of the tank or you'll have dirt all through the tank. It is a pain to try to clean it.

I woud like to hear how it goes for you. I feel confident you're on the right track. Email me back to let me know if it fixes your problem. If not, we'll go from there.

Good Luck and let me know if you have any other questions.

Joe
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Wednesday, October 1st, 2008 AT 10:04 PM
Tiny
FOX_RACER627
  • MEMBER
I got a whole new bosch/carter fuel pump assembly (float, filter, fuel gauge, etc) and put it in today. Took it out for a test run and it still bogs under heavy acceleration. The other day I was on a two lane road and needed to pass a car, so I gave it alot of gas and it started to cut out and then died. I put it in neutral and tried to start it but it wouldnt start so I coasted into a parking lot. I tried to start it again and nothing (it wouldnt turn over or anything). I came back after work about 6 hours later and it started up first try. Im stumped. Im runnin out of spare time and spare money. Please help!
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Wednesday, October 8th, 2008 AT 9:20 PM
Tiny
JACOBANDNICKOLAS
  • EXPERT
Now you have me confused. Since the vehicle wouldn't turn over or anything, it sounds electrical. I have to ask you a stupid question. Have you checked the vehicle grounds? Does everything look ok? I don't remember if I asked about any codes. When the truck dies and doesn't restart, does it ever turn over for you?

Let me know before I loose my mind along with you. This is a difficult one that not being there even makes harder.
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Wednesday, October 8th, 2008 AT 10:44 PM
Tiny
FOX_RACER627
  • MEMBER
Grounds are good and everything looks fine. Threes no codes. Its happened a couple of times and it turned over 2 or 3 times and then nothing the first time it happened. The second time it wouldnt turn over at all. I cant think of anything but maybe an injector?
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Thursday, October 9th, 2008 AT 1:34 PM
Tiny
JACOBANDNICKOLAS
  • EXPERT
If the starter is good, all connections are good, and everything seems fine, I think we need to consider the ECM. Just out of curiosity, have you played around with any of the relays?
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Thursday, October 9th, 2008 AT 4:00 PM

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