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Spark+fuel=no fire

DansGreyMj

DansGreyMj

NAXJA Forum User
Location
Nuevo, Ca
Basically I was driving and all of the sudden the motor dies, so change out the cps still nothing. I get it home and change out the plugs and wired, I am get spark at the plugs and i am getting fuel at the rail. I checked the timing and it seemed fine (rotor is at 31 @TDC). So basically it should fire but it wont, i tried a little fuel at the TB, but still nothing. Has anyone ever had this happen? It seems like its about to fire but doesnt. I hope this makes sense, I'm kinda rushing around here. TIA
 
Weak spark? coil maybe?
timing-31 deg. BTDC just cranking or @ idle to high?
Cap and rotor?
I don't know, just some ideas.
 
Sorry i made a mistake, the rotor points directly at the number one position on the cap at TDC, not 31, i was in a hurry lol.
 
DansGreyMj said:
Sorry i made a mistake, the rotor points directly at the number one position on the cap at TDC, not 31, i was in a hurry lol.
Click to expand...

You can check base timing while cranking.
Just don't overheat the starter.
 
I put a new cap and rotor in and still nothing.
 
check compression? How many miles on the motor? Could have lost the timing chain I guess, but low chance of that. I'd bet on coil - how good was the spark?
 
motors got about 166k, but the coil is almost new.
 
DansGreyMj said:
motors got about 166k, but the coil is almost new.
Click to expand...

Still could be the coil.
Weak spark-orange
strong spark-blue
Could be jumping to ground somewhere, watch the ignition wires in the dark while cranking.
Sometime you can even hear a high voltage cross jump or jump to ground.

Have you checked fuel pressure?
 
Spark is blue and FP is at 35 psi
 
Check compression. I fiddled around trying to figure one out years back. Fuel, spark, good timing= no run. Compression got too low on the old beast for it to start. Fiero, not XJ, but still the same.
 
I'll have to pick up a guage, i just test it using the spark plug hole right? What is a good range, and if it is low how do i fix it?
 
Grab a $3 NOID light and see if you are getting a signal to the injectors, or pull the plugs and see if they are wet with fuel.
 
If you have spark, fuel, and compression it will run or at least try to. Could be a number of things in my mind.I have heard of the timing chain also jumping a tooth which would lead to similar problems. A compression check is a must in this case.
 
NEWYXJ said:
This tells me that it is a fuel or ignition problem.
Click to expand...

:laugh:

...as evidenced by the title alone.

X2 on a weak spark. I swapped out 2 coil MODULES and still got a yellow spark at the plug. Granted, they were JY modules. Bought a new module and got a snappy blue spark at each plug...I'm just sayin'

OTHER:
Your fuel pump ballast resistor may have something to do with this IF it tries to start (budddda,bbddda, vrummma, dabudabudah, blah).

If it just never gets to the point of starting (vrrrr, vrr, lemma, lemma, budda, voom, blah) then I'd look at the B-Latch relay here:

2426393_11_full.gif


I've read that it's the RENIX version of the ASD relay. If this relay was fully blown I don't know for sure if you'd get spark/fuel, but it's worth swapping it with a KNOWN good relay to see if that's your problem.

Otherwise, check the fuel pressure again. Once with the vac line attached to the fuel pressure regulator, and again with the vac line off.
You may want to even check it at the same time you're trying to turn it over and start, even if it doesn't start.
 
ParadiseXJ said:
:laugh:

...as evidenced by the title alone.
Click to expand...

LOL!
CPU Malfunction!!!
What I may have been thinking but not typing is that an engine will not just die while driving do to low compression. Or something like that.

I think I'll have a drink, maybe that will help?
 
NEWYXJ said:
LOL!
CPU Malfunction!!!
What I may have been thinking but not typing is that an engine will not just die while driving do to low compression. Or something like that.

I think I'll have a drink, maybe that will help?
Click to expand...

Never worked for me. :gee:
 
I swapped out the relay, no luck. I'll have to wait to check the injectors until tomorrow, BTW they are 19lb mustang injectors.
 
Well the injector tips were wet and they are all getting power, but for the hell of it I swapped out for a set of stockers, and when i first tried it out it seemed like it was about to start and then just went back to cranking.
 
If the CPS was bad would it still spark? The reason i ask is because the one i put in it was a spare that was for sure good but it may have gone bad over time.
 
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