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89 cherokee starting issue

Tyler0wnsy0u

NAXJA Forum User
Location
Jackson NJ
I have a 1989 XJ with a 4.0 that will not start without starting fluid.... Immediately after shutting it off and attempting to start again it will not start, 1 spray of starting fluid and cranks right over and runs fine... I was thinking a possible crank sensor, or maybe a back drain in the fuel tank starving the line for fuel?? Any ideas i would greatly appreciate....

Thanks

-Tyler

NAXJANAXJANAXJA
 
where do you spray the starter fluid at, throttle body I'd imagine? After it starts, do you put the rubber snorkel back on and it runs fine? I'm trying to figure out why starter fluid would make it start and it runs fine so the injectors are getting fuel and proper timing from ECU. Maybe bypass the ballast resistor located by air cleaner.
 
Sounds like something is not letting your injectors fire on "crank up" mode, only after it starts. Maybe a relay?
 
Different modes for fuel pump on Renix:

When the key is in the ON position, power is supplied to the fuel pump by the B latch relay bypassing the ballast resistor for 3 seconds.

When the key is in the START position, power is supplied to the fuel pump by the starter relay bypassing the ballast resistor.

When the key is in the ON position, and the engine is running, power is supplied to the fuel pump by the fuel pump relay through the ballast resistor.

When the engine is at WOT, power is supplied to the pump through the oxygen heater relay bypassing the ballast resistor.

Question: When you turn the key to ON does the fuel pump cycle for 3 seconds?

Question: When the engine is running is there power to and through the ballast resistor?

Question: When cranking the engine, is there power at the fuel pump itself?
 
I was thinking a fuel pump relay is on the "sprits" And I'm not sure about the TPS because on a tps malfunction the truck probably would have no throttle response, or feel as if the trans was slipping i would assume? I was thinking mainly on a Crank sensor, a fuel pump relay may be bad too possibility?
 
I'm not sure about the resistor, fuel pump does cycle, and I'm pretty positive that the pump is functioning correctly. Idk what the resistor looks like and such to be honest... I'm thinking it's a back feed problem.. The line is staying dry essentially and starving it for fuel... but i'm not sure.
 
I would put my money on it not getting power to the pump with the key in START (cranking). Test for that.

I doubt it is the TPS, unless the TPS is signaling the ECU it is at WOT and the oxygen heater relay is bad.

Mark, and then try switching around the relays.
 
Ok, thanks for the suggestions hopefully i will have a chance to get out to it tomorrow.. I'm at a total loss with it. Do you think the crank sensor is a possibility? I really have to get the scanner hooked up to it so i can see the fuel pressure with key on/cranking... I'm thinking as soon as i can get the scanner on it i will solve my own problem...
 
For fuel pressure you need a mechanical fuel pressure gauge to attach at the Schrader valve on the fuel rail, not a scanner. Pressure should be 30-31 psi with vacuum applied to the pressure regulator at the front of the rail, and 39 psi with out the vaccum.

As it just won't fire when cranking without adding ether, I would say there is a lack of fuel while cranking, but it runs after starting with ether, then the fuel pump must be operating to allow it to continue to run after the ether has been used up.

Concentrate on testing for voltage at the pump while someone is cranking the engine over.
 
alright here is the scoop..we changed the tps,the iac,plugs wire,starter relay,fuel rail,injectors,and other little things,you spray it with starting fluid it starts up then you can shut it off and maybe it will start back up..we have no clue..it runs fine this is the only problem as of now with it..the crank censor is good cause when the ignition was all retarted that was the way you had to shut it off was unplug the crank censor and it shut of so i don't honestly think its that.
 
alright here is the scoop..we changed the tps,the iac,plugs wire,starter relay,fuel rail,injectors,and other little things,you spray it with starting fluid it starts up then you can shut it off and maybe it will start back up..we have no clue..it runs fine this is the only problem as of now with it..the crank censor is good cause when the ignition was all retarted that was the way you had to shut it off was unplug the crank censor and it shut of so i don't honestly think its that.

slow down.

start from the beginning. year? problem before the work done? exact problem after the work done?

have you tested anything(ssensors, fuel pressure, spark) or did you just replace parts? the tps needs to be adjusted to specs.
 
alright here is the scoop..we changed the tps,the iac,plugs wire,starter relay,fuel rail,injectors,and other little things,you spray it with starting fluid it starts up then you can shut it off and maybe it will start back up..we have no clue..it runs fine this is the only problem as of now with it..the crank censor is good cause when the ignition was all retarted that was the way you had to shut it off was unplug the crank censor and it shut of so i don't honestly think its that.

Are you posting with "Tyler" or are you a new person with an issue?
 
when i got the jeep the kid who had it before me swapped the terminals we fixed all that up..it was kinda running horrible..the rpms were all funky we got that taken care of it was running rich now its kinda running better..it gets spark but the plugs are burnt up a little we looked at them yesterday obvs. needs to be changed..the tps was adjusted to how it is now..its getting pressure..its getting fuel through the fuel rail..we changed the o2 sensors.
 
Almost sounds like an old fuel injected Cadillac I had that needed spray start to fire up. It was the temperature sensor gone bad. Fuel injection computer needs to know that it is cold to enrichen the starting mixture, just like a choke on a carburetor.
 
when i got the jeep the kid who had it before me swapped the terminals we fixed all that up..it was kinda running horrible..the rpms were all funky we got that taken care of it was running rich now its kinda running better..it gets spark but the plugs are burnt up a little we looked at them yesterday obvs. needs to be changed..the tps was adjusted to how it is now..its getting pressure..its getting fuel through the fuel rail..we changed the o2 sensors.

what? my head is spinning trying to read this.

burnt plugs? burnt or do you mean black soot/carbon from running rich?

"tps was adjusted to how it is now", i dont understand what your saying. did you adjust it to specs using a multimeter?
 
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