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'91 XJ no start, not getting fuel

R

Rikkrott

NAXJA Forum User
Location
Tallula, IL
Got a puzzler here guys. It's not getting fuel for some reason. It will idle off of starting fluid. I've swapped just about everything, fuel tank, pump, filter, pressure regulator, fuel rail w/injectors, TPS, IAC, pump relay. It's getting fuel to the rail and has good pressure. I'm at a loss and close to giving up. Any ideas are greatly appreciated.
 
I would consider testing the "camshaft position sensor" which resides in the distributor. It is responsible for fuel injector timing as well as other things.

What you describe isn't a normal mode of failure for this sensor, but as you have replaced most of the usual suspects, I would sure test it with a meter as it doesn't take much time to rule it in or out.

If it will idle off of starting fluid, it probably isn't related to the ballast resistor. When they are bad, the engine will usually start and run for a few seconds, then stop when the key is released from the start position.

I suppose you also could have a flaky computer. If you get stuck on this, swapping in a junkyard one might be something to consider trying.
 
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Sound like the computer.
The computer does TWO things when it sees the cam sensor AND the crank sensor.
It must have both to do these two things.

1. fires the spark plugs in correct firing order
2. fires all injectors at the same time or randomly ('91 was different from RENIX)
once RPM's come up, it sequences the injectors to match firing order.

So if you are getting spark (runs with starting fluid), both sensors are most likely in good shape. (In my humble experienced opinion)

You now need to borrow a computer, if you were closer to me I could be of more help.

One last thing, in the last week, have you; got waterlogged, jumpstarted a car, drained your battery down, shorted battery terminals?
 
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Thanks for the info guys. Fortunately I have another '91 parts XJ so swapping parts is cheap, hence my long list already. I was suspect of the computer, I'll give it a try. Dennis, as far as the last part of the post, those are all no. I've never actually driven this Jeep, I bought it brok, assuming it needed a pump since it would run off starting fluid. I'll let ya know how it goes.
 
Test the synch sensor in the distributor--quick and easier than swapping out a good one.

If you had a $3 NOID light you would know already if the firing impulse was reaching the injectors.

There have been several threads where there was a problem with the fuel injection harness, back towards the firewall where the synch sensor wires take off towards the distributor.

Good luck.
 
joe_peters said:
Test the synch sensor in the distributor--quick and easier than swapping out a good one.

If you had a $3 NOID light you would know already if the firing impulse was reaching the injectors.

There have been several threads where there was a problem with the fuel injection harness, back towards the firewall where the synch sensor wires take off towards the distributor.

Good luck.
Click to expand...

Any voltmeter will work in place of a noid light.
Set it to a low scale and watch for a change from the key on-not cranking voltage. It works good enough that I haven't bother to build a NOID light with all the electronic stuff I have on hand.

The hard part is getting the connector off without losing the spring clip.
 
dennis461 said:
Any voltmeter will work in place of a noid light.
Set it to a low scale and watch for a change from the key on-not cranking voltage. It works good enough that I haven't bother to build a NOID light with all the electronic stuff I have on hand.

The hard part is getting the connector off without losing the spring clip.
Click to expand...

Most any DVOM or analog voltmeter can measure the supplied voltage.

As the ground is provided from the ECU/PCM to the injector measured in miliseconds, many DVOM or analog meters won't provide a visible indication of the injector pulse. Higher end meters might.

Good luck.
 
Well it was the computer. I swapped out the distro as the PO had broken off both screws that hold the cap on anyway. No luck there so I swapped out the computer and shazam! So, it's running now but like crap, missing really bad. Idles smoothe but misses when you give it some gas. I checked/cleaned all the plugs and compression, all good. Fuel pressure is steady. I'm gonna swap the TPS tonite, well maybe tomorrow, 9 year anniversary today so wife may not like that! Thanks guys!
 
ha ha, I'll see how that goes! I forgot to mention that the thing is running hot also, just a short trip up the road and it's close to 260 until I turn on the heat. Seems to be flowing coolant, both hoses and radiator are hot? I'm gonna pull the thermostat tonite also and see how that goes.
 
Thats why i'm not married.
As far as cooling goes, do a thorough check on all your components.
Radiator, Cooling fan clutch, condition of fluid (clean and 50/50 mix), Thermostat, and check to see if your e-fan works, at around 260 (wow BTW) that thing should definatly be spinning!!
 
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