J4jeep

bought a 1988 jeep cherokee chief it wasnt running when i got it the guy said he bought a new fuel pump but it wouldnt come on , so i took the chance,heres what happened ,i cant get power to the fuel pump so i tried to bypass it and the system went screwy so i aborted that idea,next i replaced every relay under the hood and the crank position sensor, still nothing so in a last ditch effort i bought an external in line fuel pump and the truck ran perfect no fuel gauge but ran for 10 days no trouble then it just stopped so i figured the fuel pump went bad so i got another 1 and it still wont start so then i did a little research and found there were some grounding issues and i took the suggested repairs to all the grounds on the dipstick and to the firewall and the batt. ground im at my breaking point CAN ANYONE HELP PLEASE !!!!!!!!!! i dont want to buy a new computer and just be throwing money away

freegdr

check wireing to crank position sensor for burnt or bare spot grounding out

J4jeep

any other ideas just in case that doesnt work i pulled the brain out and tried to start it and it continued to do the same thing as when the brain was in just turned over without starting

highmileage

The blue box (sometimes grey or black) on the top of your steering column may be the culprit. They are about 20 bucks from anyone and have a habit of shorting out on the Renix. If one for your jeep isn't available you may be able to match one from a GM car or truck (same same?).
symptoms: no crank no start
crank no start
binding when turning key
accessories and headlights work barely sometimes if at all
smell of melting plastic (the bad one)

cruiser54

TEST your replacement CPS. They're known to put out insufficient voltage right out of the box.

Renix CPS Testing and Adjusting
　
　
Renix CPSs have to put out a strong enough signal to the ECU so that it will provide spark.
Most tests for the CPS suggest checking it for an ohms value. This is unreliable and can cause some wasted time and aggravation in your diagnosis of a no-start issue as the CPS will test good when in fact it is bad.
The problem with the ohms test is you can have the correct amount of resistance through the CPS but it isn’t generating enough voltage to trigger the ECU to provide spark.
Unplug the harness connector from the CPS. Using your voltmeter set on AC volts and probing both wires in the connector going to the CPS, crank the engine over. It won’t start with the CPS disconnected.
You should get a reading of .5 AC volts.
If you are down in the .35 AC volts range or lower on your meter reading, you can have intermittent crank/no-start conditions from your Renix Jeep. Some NEW CPSs (from the big box parts stores) have registered only .2 AC volts while reading the proper resistance!! That’s a definite no-start condition. Best to buy your CPS from Napa or the dealer.
Sometimes on a manual transmission equipped Renix Jeep there is an accumulation of debris on the tip of the CPS. It’s worn off clutch material and since the CPS is a magnet, the metal sticks to the tip of the CPS causing a reduced voltage signal. You MAY get by with cleaning the tip of the CPS off.
A little trick for increasing the output of your CPS is to drill out it’s mounting holes with the first drill bit that just won’t fit through the original holes. Then, when mounting it, hold the CPS down as close to the flywheel as you can while tightening the bolts.
　
Revised 11-29-2011

J4jeep

I am @ my wits end nothing gets power to fuel pump wut next please help

J4jeep

so here is the update i think i still may need help but it runs again for now. i pulled the brand new fuel pump out and guess what the power wire inside was melted and burned badly, so i took it back and got a replacement . so now to recap i've replaced the fuel pump, the ground wire to the chassis,the ground wire to the batt.,and the ground to the dipstick, i've replaced the cps, i've replaced the fuel pump relay and the fuel filter so cherokee people what is causing this wire to burn out will it happen again or did i fix the problem already oh yeah and anew ballast resistor someone has had to have had this problem before and fixed it please tell me how.........

cruiser54

You got a replacement pump or wire?

The ballast resistor or the elimination of it will not cause the wire to get hot and melt, but a poor connection at one or both ends of the wire will, along with a bad pump that's
drawing too much current..

J4jeep

I got a new pump and ballast resister i got a airtex pump last time and it when bad will it again

J4jeep

how can i tell if it drawing to much current

J4jeep

100 miles shes still running maybe 1 of the many other updated repairs i did helped the melting wire issue or maybe it the airtex fuel pump

cruiser54

So clarify something. You had an Airtex go bad, the wire was melting, and you replaced the bad Airtex with what?

FWIW, punctuation and capitalization helps us old guys understand you better.

J4jeep

I replaced it with another Airtex fuel pump, and guess what, i woke up this morning and went to leave for work and wouldn't you know it the damn thing wouldn't start lol so i ordered a Bosch fuel pump today will this problem continue with a different model of fuel pump, also take into consideration i've already

replaced all relays under the hood 5 in total
replaced all ground wires going to the motor 3 in total
replaced the cps
replaced the ballast resistor


and there are no bad wires on the vehicle other than the power wire on the actual fuel pump that is in the tank. please help me i just want this nightmare to end i'm pretty confident its the Airtex fuel pump but i've been fooled before lol

any help would be greatly appreciated

cruiser54

Replace the wire to the fuel pump.

J4jeep

its the actual wire in the fuel tank connected to to the enternal fuel pump inside the tank