i have a 1990 dakota with a 3.9L in it and it has developed an odd problem. whenI wasdriving down the road and the throttle is held at one position it started to die out and if i hit the gas it will rev a little but its a losing battle eventually it wont move without killing it ( i know it sounds simple enough but it gets weirder) if i shut it off and then turn it back on it works for a while and then does it again and every time i restart it the amount of time it works right is decreased each time till eventually it just doesnt work at all. ive checked everything i can think of: fuel pressure and volume, the fuel filter, throttle position sensor, map sensor, fuel pressure regulator, idle control motor, injectors, spark,flushed out the gas and put new fuel in. it has a brandnew ignition system in it and its timed perfectly and it seems like this problem is not temp sensitive
so if anyone has knows whats wrong or has had this problem before please tell me what to fix

 

Fuel pump, has it ever been replaced? You say you checked the fuel filter did you change it?
You say you checked the fuel pressure and volume but cheching it with the hood up and driving it down the road might not be the same. Just throwing somethoughts out here........

 

well i have replaced the filter and the pump is new as well.I checked the pressure3 ways regulated, unregulated, andmaxed which is where you pinch off the return line for a short period of time. and i checked the pumps check valve. oh and its a manual tranny so i guess that there wouldnt be much difference between driving and parkedexcept for loadbut i dont know if that would make much difference.

thanks for your ideas
kahanabob

 

i think that it might be a problem with the computer and here is why, my adujstment motors wont stop adjusting, and the injectors dont seem to be pulsing properly but there both still good, and when the truck is restarted it seems to correct itself for about as long as it would take for the ecm to read that there is something wrong then it all goes to s#!t again

 

what code is the truck throwing? mine is doing the same thing and i get a code 52 which is O2 sensor stuck in rich mode and also a 34 which is the speed sensor(i dont know what the hell that one is, so if anyone can tell me how to fix that it would be appreciated) but i would check the O2 sensor and see if its bad

 

Steve.... I have no clue where you live.... and I might sound like an idiot by saying this if you live in the Southern U.S...... But by the sounds of it.... I'd say your problems are Ice in the fuel line somewhere. Put a bottle of water remover/fuel treatment in every time you get gas. Just had the exact same problems as you. After about 4 or 5 trips to the gas station and adding the water remover... it finally went away. All it takes is one tiny bit of ice to plug something up.. and it sends your computer outta wack and everything. With my truck... it seemed to run smoothly.... just was like it was idling, when meanwhile, I had the pedal to the floor.
Anyway.... That's my guess.... so what is the weather like where you are? lol.
Oh... and by the way.... I'm a Northern Ontario Canada Hillbilly. So my diagnosis comes from dealing with this kind of problem several times a year no matter what you drive. lol. Hell.... even my snowmobile suffers from this sometimes. It's the cold sunny days, the -25 at night that causes the inside of the tank to frost up. Keeping a close to full tank of gas also helps prevent this problem.

 

Sounds like your catalytic converter is plugged. Check out this link to test it....http://www.aa1car.com/library/converter.htm.

Gerry

 

well as for frozen gas i thought it could be that too cause it is about-15so i put it in my garage ( where it never gets below 20 degrees) andflushed out the gas and put newgas in with a fuel stabilizer and it still did the same thing. and as for the cat being plugged I have replaced the whole exaust with a high flow 3 inch tube system that doesnt have a cat but thanks for the ideas guy keep them coming there greatly appreciated

 

I had a similar problem twice not to long ago. Engine rpms would decrease then increase then repeat until at an idle it would die. Start it back up and ran great for awhile until the process started all over again. First time it turned out to be the ignition coil. Replaced it and ran great until about 3 months later, same exact problem. Hooked it up to an obd reader and this time the o2 sensor was acting up. I threw in 2 bottles of that fuel cleaner system (chevron techron stuff) and no problems since (almost a year now). I know you said you have a new ignition system in and all but just thought Id throw my experience out there. Good luck.

 

there is no check engine light on but i had the truck run its own code check anyway
and it came up with a whole lot of codes
code 12, 14, 13, 24, 15, 17, and 62 in that order and yet some how the light never came on for things like memory standby power lost, map sensor electric circut, map sensor vacuum circut, tps circut, speed distance sensor, engine is running to cold,and emissions reminder light not being renewed how is that possible or did the test not get done properly or what