300 i6 sputtering and barely idling

[That_4.0_ranger]

Recently my 1990 f250 with 300 i6 and 5 speed is sputtering really bad when driving and it gets worse the more electrical I turn on in the truck I replaced battery and alternator as well as battery cables and it’s still doing it dose anyone else have any other ideas?

 

[bobbywalter]

fuel psi?

 

[pjtoledo]

got a volt meter?

 

[North Idaho 5.oh]

I second that ^ … my 89 bronco plow rig has the inline 6 and it’s doing the same thing… new, cap and rotor, battery, 3G alternator conversion, plugs and wires, fuel filter, air filter… yet it misfires and sputters and gets worse when I use the heater, or anything electric… still runs and drives and pushes snow! Gotta give it to these old trucks!

 

[Josh B]

What kind of carberater you got? Mine used to get a couple loose screws on it sometimes and all it needed was cranked back down

 

[rusty ol ranger]

What kind of carberater you got? Mine used to get a couple loose screws on it sometimes and all it needed was cranked back down

90 is EFI.

Hows the various ground straps look?

 

[Curious Hound]

Need to get a voltmeter and find out what your system voltage is while running. Sounds like a weak alternator or loose/dirty connection somewhere. The more electrical stuff you turn one, the lower the voltage goes. Low voltage could be affecting fuel pump and pressure or spark.

 

[North Idaho 5.oh]

89 is also EFI …. I will throw a volt meter on it today and see

 

[That_4.0_ranger]

I second that ^ … my 89 bronco plow rig has the inline 6 and it’s doing the same thing… new, cap and rotor, battery, 3G alternator conversion, plugs and wires, fuel filter, air filter… yet it misfires and sputters and gets worse when I use the heater, or anything electric… still runs and drives and pushes snow! Gotta give it to these old trucks!

I have recently replaced all the same things and it still runs and drives but when it comes to hills it lacking in any amount of power but I thought it could be fuel but then when I realized that the more electrical I turn on the worse it gets so I’m am just stumped

 

[That_4.0_ranger]

90 is EFI.

Hows the various ground straps look?

I only have the cable going from the battery to the starter and then an additional wire going to the body

 

[That_4.0_ranger]

I

Need to get a voltmeter and find out what your system voltage is while running. Sounds like a weak alternator or loose/dirty connection somewhere. The more electrical stuff you turn one, the lower the voltage goes. Low voltage could be affecting fuel pump and pressure or spark.

checked the voltage and it’s charging at 13.2 at idle and when I turn all the common electrical stuff (heater,lights,radio etc) it will sometimes go all the way down to 12.5 but also whe. I unhook the battery completely it runs the exact same with all that on so I replaced the battery yet again and still nothing

 

[bobbywalter]

Your not charging correctly.


Does it have an external regulator?

 

[That_4.0_ranger]

Your not charging correctly.


Does it have an external regulator?

I have no idea honestly can go look real quick, what should I be looking for?

 

[Curious Hound]

I

checked the voltage and it’s charging at 13.2 at idle and when I turn all the common electrical stuff (heater,lights,radio etc) it will sometimes go all the way down to 12.5 but also whe. I unhook the battery completely it runs the exact same with all that on so I replaced the battery yet again and still nothing

13.2 is getting a bit low. Should be closer to 14.

 

[That_4.0_ranger]

13.2 is getting a bit low. Should be closer to 14.

Yeah that’s what I thought because every other rig I’ve had charged anywhere between 13.6 and 13.7 my old red ranger even charged at 14.1 (yes I know that probably to much but it never caused a problem so I didn’t touch it lol)