Batman33165

I have a 1988 jeep cherokee, 4x4, manual tans. dana 30, dana 35 for rear.

I was not sure what section this should have gone, modified or stock so here goes. I recently got my jeep inspected and where the ballast resistor is i have an in-line fuse with a 15 amp fuse. I figured it would not hurt having a fuse in that area plus gave me a piece of mind, when i went on a long vacation i could just pull the fuse and its not going anywhere.

Here comes the question, why would the (new) resistor smoke? My wife purchased me a resistor because it was the right way for electrics to be done. blah blah blah.... I plugged it in and probably a couple of second running i saw smoke coming from the resistor. I turned the jeep off, unplugged the resistor, connected my inline fuse and started it up again. No smoke or any problems, so whats up?

I read on some forums that it is possible the resistor is defective or that the fuel pump is drawing too much current. Could this be an insight of what could happen if i continue to drive the jeep, a bbq jeep?

97grand4.0

Can I buy a clue, is the resistor in line with the fuel pump or the ignition coil? Your wife purchased you a resistor? How thoughtful of her. I like her reasoning that it 'is the right way for electrics to be done'. As an electrician of 23 years I couldn't agree more, we need electrics done right.

I don't know if the resistance of the resistor matters, or the 'wattage' rating of the resistor, or even if there should be a resistor there at all.
Here are the relevant equations : E = I x R, where E is the electromotive force in Volts, I is the current flow in Amps, and R is the resistance in Ohms.
Also you will need this one, W = V x A, where W is wattage in Watts, V is voltage in Volts, and A is amperage in Amps.
Using the basic algebraic manipulation you learned in 9th grade, you can move these equations around to solve for any of the variables.
Hope this helps.

Batman33165

in line with the fuel pump...

you have a magic number im looking for?

97grand4.0

here is a helpful thread

https://www.cherokeeforum.com/f2/fue...esistor-29636/

Only guessing here, but like everything critical to jeep, OEM is the only way to go. If your resistor smokes, not good at all. Start with the right part for sure ..guessing like this post says is around 1.3 ohms, and as far as the smoking, if the resistor is not robust enough to take the voltage drop across the resistor it will smoke or just burn open completely. By robust I mean it has to have a high enough wattage rating, which you might find in the fsm but I can think of anywhere else unless it's stamped on the part. Since it is ceramic, that tells me they intended it to dissipate a lot of heat in the first place.
What would be useful is to know what the fuel pump current should be, preferably with the resistor out of the circuit, then insert an inline current meter and see what your pump is actually drawing. If it is within spec then your only task would be to find a high enough wattage rated resistor at the stated resistance of ...whatever t supposed to be...from the post above it seems about 1.3 ohms.
Would guess you need one rated at 10 watts....the higher the better, higher will run cooler and last longer.

cruiser54

Get rid of it. It's not there for overload protection. It's there to reduce voltage to the fuel pump so it's quieter.....

Batman33165

yeah i figured you would say that cruiser...

As for the electrical aspect guys i am a total novice, i am a total beginner. I am lucky if i can understand the multi meter for power, voltage, etc...

I guess this post was more curiosity than concern... i would have liked to stay OEM but with a 30 year old jeep there is always an update/ mod out there. I will probably use the inline fuse like i had before to drive around and piece of mind, and one day ill finally get a radio in the jeep and i probably wont hear the sound of the pump lol...

cruiser54

Is the pump that loud?

Batman33165

No, its not screaming.... you just can notice it, how ive read in other post. It makes noise that i can hear with the jeep idling