The truck I have is a Dakota. I posted this 2 days ago, in the first gen. Dakota section, but have got no response. I suspect it may be due to the only Dakota that used the o2 sensor, carb feedback system was the 87. 88 went to TBI. So its a very limited crowd over there that has worked on this system. Hopefully someone over here could give me some pointers.
Thanks for your help and below is the orig. post.


I have a 87 3.9 holley 6280 carbed motor. (factory) Anyways, for awhile now, it seems to be running out of fuel. I can take off, wind it up in first gear, shift to second, and about 3/4 way through second, it will start missing like it is running out of fuel. I can let off the throttle for a few seconds and then it will run ok provided I don't go full throttle, and if I do go full throttle, shortly it will start cutting out again. Also, if in 5th gear at 55mph or so, if I go full throttle it will be ok for a few seconds, then I have to let off, because it seems to be running out of fuel. Again, let off for a few seconds, go back to cruising and its ok.


Now, for a little history on the truck. It has 76,000 miles. At about 64,000 miles, 4 years ago, I replaced, cap, rotor, plugs, wires, egr valve, rebuilt the carb. new fuel filter, air filter, etc.


I figured that my problem was the fuel pump and since I plan to eventually put a carbed magnum 5.2 or 5.9 in it, I installed a carter p4070 external fuel pump. It is low pressure, 6psi. So I ran a new fuel line from the tank to the pump, and then to the carb direct. The pump does not require a regulator. I also ran 3/8 fuel line except for about 4in. at the tank and carb, where I had to convert to 5/16 for the fittings.


I installed a 3/8 fuel filter inline before the pump and I blew back through the fuel line into the tank to assure it was not stopped up at the strainer. It seems to be ok.


Also, I removed the needle and seat, seemed clean. So I put it back.


Any suggestions would be appreciated. My next step will probably be to take the carb apart, and check the float.


This truck has the computer controlled carb where it uses a o2 sensor for feedback. Oh, and the o2 sensor was replaced at the time I did all the other work.


Any suggestions are appreciated. Thanks

 

Does the temp of the motor make any difference? Will it do this at first start up?

 

It seems to start and run fine. I have not got on it hard when it was cold though.

 

I had that same problem....I changed the Coolant Temp Sensor and the problem stop....the sensor effects the TPS

 

someone help me with the speed control.. when set over 65 speeds up and then down...what can I do to stop that?

 

Quote:

Originally Posted by Jim1993Dakota

I had that same problem....I changed the Coolant Temp Sensor and the problem stop....the sensor effects the TPS

Mine uses a carburetor, so that would not apply to this case

 

It would be nice if people would read everything before posting.
I'm wondering if this is a vapor lock issue. Take the truck out right after you start it up and get on the throttle and see what happens. If it only happens after running the truck for a while (after it heats up) it maybe partial vapor lock. When you install inline fuel filters make sure they are vertical! If they are horizontal or on a 45 they can trap air.

 

The orig. filter connected to the mech. pump is vertical. But with the new electrical pump, I mounted the filter horizontal. I will reroute it so it is vertical and try it when it is dead cold. The problem is, where I live I have to go about 2 miles before I can run it hard. But I can go to a restaurant and let it cool for a hour or so and try it from there. I will do this Monday and get back to you with the results. Thanks for your help.

 

I'm wondering if this is a vapor lock issue. Take the truck out right after you start it up and get on the throttle and see what happens. If it only happens after running the truck for a while (after it heats up) it maybe partial vapor lock. When you install inline fuel filters make sure they are vertical! If they are horizontal or on a 45 they can trap air.[/QUOTE]



OK, I reworked the fuel line so the filter was vertical. Took it out of town, let it cool for 2 hrs. Drove it, and it did the exact same thing. Wind up first, by the time its half way through second, it runs out of fuel.


Buf for the good news. Reading again, in my FSM they suggest an improper float level. Well as I said, about 5 years ago, I put a rebuild kit in the carburetor but I reused the old float.
Now I know this is a hokie way to do this, but I decided to take the needle and seat out, and try to put a thin washer on it, so it would in effect change the float level. Well I could not find a washer that would work.


Flusterated, I slightly ground down the tip of the needle that sits against the float. I figured my next step was a different carburetor or put another kit and float in this one. So I didn't have a lot to loose trying it.
Well I put it back together and it runs fine now. My next step is to hook the mechanical pump back up and make sure its still ok. (that external electrical pump is noisy)
I don't understand how it ran fine for about 3-4 years after the rebuild and then started this. If the float was taking on gas, I would have thought it would have caused a flooding problem.
But as long as its running ok, Im not going to tear it apart. I still plan to put a 5.2 or 5.9 magnum motor in it this winter.
Moparite, thanks again for your help and suggestions.

 

The truck is running out of gas..pre fuel filter is probably stopped up..when you blew back through the line it may have blown the strainer off..check the filter if ok its the pump...ran across alot of bad fuel pumps from carter recently...