Hey guys Im new to the forum. I have a 1997 tj on a 4in lift riding on 33x12.5 Mickey Thompson MTs mounted on 15in sidebitter rims, unfortunately she is currently a paper weight that doesn't run. So maybe someone has had a similar problem to the one im about to explain.
A few weeks ago i was driving when all of a sudden my jeep while going about 40 mph. Upon dying it would not restart right away (it would turn over just not fire). So about an hr later upon getting it home i tried to start it up for shits and giggles and what do ya know fired right up.... and idled for a solid 5 min gave it some gas and try and drive it and you could hear a misfire before dying again. So this lead me to start dissecting the jeep and realizing the jeep doesn't have and ignition coil spark after every-time it dies..
What I have done so far- Ignition Coil, ECU, Distributor, Cap and Rotor, Crank shaft Position censor, Spark Plug Wires,
If anyone has had the same issue and has a solution PLEASE share it with me im a few hundred in and no solution so far.
When it won't start, check for fuel pressure in the fuel rail. You can do that by removing the black plastic Schrader valve cap and pushing the pin in the valve to see if fuel squirts out. There should be fuel pressure inside the rail.
I suggest that because it sounds like your fuel pump may have died.
The below pic shows the Schrader valve located on the fuel rail on the driver's side of the valve cover....
You can also rent/borrow a fuel pressure gauge from one of your local auto parts stores to verify that there's enough fuel pressure present. The fuel pressure at the Schrader valve is supposed to be 49 psi once the fuel pump has pressurized it.
If you decide to change the fuel pump, do not (!!) install a store brand fuel pump and avoid the Airtex and Spectra fuel pump brands like the plague. Their reliability is abysmal and you'll end up having to drop the gas tank to change it sooner than you'd like it. My Spectra pump lasted all of 13 months.
The only brands I'll recommend any more are Bosch and Mopar. You can get the Bosch at a pretty good discount from Amazon.com and sometimes from RockAuto Parts Catalog
One last hint... if you don't get fuel pressure out of the valve, try cycling the fuel pump on 12 times by cycling the ignition switch on-off-on a dozen times to give the fuel pump a chance to refill the fuel lines. If you get fuel after that and the engine starts, that's a pretty good indication the fuel pump is toast.
Get the assembly which includes the fuel pressure regulator and fuel gauge sender, it looks like this...
What brand Crank sensor did you use? Your problem sounds a lot like a failing CPS. Parts house sensors like from advance, autozone, o'reileys etc. are known for being of bad quality. Sometimes even straight out of the box. What makes me think it's the problem is the backfire before it shuts down and where you said it has no spark after it dies.
It certainly could be a bad replacement CPS but when my last fuel pump failed, the Spectra, the engine backfired (or at least popped) a few times from the extremely lean condition it caused.
Well jerry I was out looking at the jeep and could not for the life of me find the scharder valve on the fuel rail in the I4 2.5l. I did the 12 fuel pump cycles and still nothing. I wish i could some how test the fuel psi before buying a pump but im thinking about buying one and just hoping for the best haha at this point ive done so much to it there arnt many options left...right? haha I riding on hope right now thanks again for youre time!
See if it'll try to start or starts with starter fluid sprayed into the air intake. If it does, that's a good clue it's a fuel problem.
I wouldn't have suggested the Schrader valve if you had mentioned you had the 2.5L engine, or at least I shouldn't have assumed you have the 4.0 engine.
Just spent 5hrs swapping out a hole new tank and fuel pump... And still the same problem. **** this is getting expensive and I'm out of ideas at this point..
That sucks, time to step back and go back to basics.
Check camshaft position sensor.
Check actual injectors for visual blockage, then see if they're pulsing.
Time to start testing for leak-down/compression.
What codes have you thrown?
Sidenote: I know you don't want to hear it, but cCould an ECU/PCM cause a no-spark condition?
If anyone has Any idea of a solution I'd be more than happy to listen...possible bypass the asd is considered an option but wouldn't really like to if I could figure out the actual issue.
Wisconsin and when it starts it doesn't misfire at idle it misfires when I rev the engine. If I start it and let it idle it will eventually just shut down once it gets up to operating temperature. Upon shutdown then there is no spark from the coil.
Have you verified 100% it's from the ASD system? Could be the ASD relay getting hot and shutting off (bad relay is possible). The battery temp sensor also affects the ASD system. Just some extra thoughts.
Many things within the ASD loop can cause failure, but then there's the ASD itself. I'd start checking for shorts (and excessive dirt) in everything from the MAF sensor to your upstream o2 sensor.
Although, the whole crankshaft (i know you replaced) and camshaft sensor angle is probably not valid because those failures tend to cause erratic idle right before engine shuts down.
The PCM controls the ASD relay and disables it when there's a problem somewhere. That assures things like the fuel pump won't run when doing so could cause a problem.
To me, bypassing the ASD relay as that yahoo did in the above link would be a big mistake. Reading that thread actually pissed me off since it was so full of fail.
Find the problem that is causing the PCM to not energize the ASD relay, don't bypass it.
Agreed. Seems like a good way to melt your jeep. I suppose if you bypass you might as well test the relay itself. I'd have to read on how to properly test one.
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