Another Engine won't start thread

I spent the last two hours searching but no specific answer to my question.
Engine won't start on a 88 XJ 4.0, Auto, 231, Optima battery.

What happened? Well,
Went wheelin' in some seriously slopply mud. My snorkle broke and sucked in a bunch of muddy water. My snorkle was routed through my existing air box and K&N air filter. It filled up my air box, caved in my K&N, and there is evidence of mud and water in the Throttlebody and in the cylinders.

What I've done...
Towed it home, dried it out the best I could, charged the battery, and started to fire it up. Wouldn't go. pulled the plugs, turned it over a few times, felt the air rushing out of the plug holes, regapped and cleaned the plugs, and got it to fire up for about 30 seconds. It died just as I was taking the battery charger off. Battery was still at 75% charge. I was leaning toward the alternator but I cannot get it to fire again.

I am getting plenty of Air and fuel to the cylinders. I've had to pull the plugs a few times due to flooding it. I am getting spark to the plugs. but I cannot get it to catch. It just keeps trying to fire, little pop here and there but I cant' get it to keep running. I checked the ceramic resistor, it's good, ohmed the CPS, good, the TPS didn't get wet and It's only a week old, I cleaned out the throttle body, and I spent alot of time looking at it funny...

Questions...
If CPS was bad would I be getting spark at all?
If the timing was jacked would it have fired and ran for 30 seconds as if nothing was wrong?
I know my Alternator may be bad but the XJ should fire and run off the Battery for a short while right?

You didn't say you pulled the dist cap and dried it.

Yeah, sorry, It was dry under the cap. I didn't get that deep in the water that it got the distributor wet.

Lets go back to basics, you need Fuel, air and spark to make the engine run.

With your rig getting wet you may of messed up some electronics. Here some things to do.

1) Verify you have fuel pressure, I had to buy a gauge at O'reilly autoparts to fit my 88 XJ. I think it should be 32 psi minimum.

2) Verify you have spark. Do you have a timing light you can hook up to make sure you are getting spark. You can watch the light and see if it stops flashing when the engine dies or if it still flashing when the engine is stopping.

3) If I was closer i'd hook up my test set and see what values all the sensors are reading in the computer. The problem with computer controlled vehicles a scan tool is becoming as essential as a 3/8 inch ratchet and being a Renix only the dealer or snap-on mt2500 sanner can read the computer. It might be worth it to haul the XJ to a garage and have them check out the sensors to see what is "bad".

With your XJ in the water you may have water/mud in the neutral safety switch. You may want to pull it off, clean & rebuild, then reinstall. There an article out there on the web about it. But that only an idea.

Overdriven said:

I spent the last two hours searching but no specific answer to my question.
Engine won't start on a 88 XJ 4.0, Auto, 231, Optima battery.

What happened? Well,
Went wheelin' in some seriously slopply mud. My snorkle broke and sucked in a bunch of muddy water. My snorkle was routed through my existing air box and K&N air filter. It filled up my air box, caved in my K&N, and there is evidence of mud and water in the Throttlebody and in the cylinders.

Click to expand...

There's a strong possibility that you could have hydrolocked the engine and bent a couple of connecting rods. Does the engine easily turn at least two full revolutions if you turn the crank by hand with a wrench? You might wanna find out.

I have already done the timing light trick. I'm getting plenty of spark.

I suspect I'm getting good fuel since I am flooding the cylinders. Although I can check it.

As far as the Nuetral safety switch... If it was not making contact would it even let the engine turn over. I thought the NSS disabled the starting circuit.

And for Hydrolocking... or any kind of water damage, I was able to get the engine to run for about 30 seconds (and run good as far as that). If I had done damage to the internals wouldn't it have prevented this? I will try turning it by hand tonight.

Everyone is being helpful but the answers I really need are the first that I asked...

If CPS was bad would I be getting spark at all?
If the timing was jacked would it have fired and ran for 30 seconds as if nothing was wrong?
I know my Alternator may be bad but the XJ should fire and run off the Battery for a short while right?

Thanks again.

Ok, this actually sounds a lot like something I did. Got way too deep in the water. After towing it home it fired up for about 10 seconds, idled like crap and died, wouldnt start again. I swapped out the alternator, computer, TPS, Distributer, plugs, and wires, and battery. Mine ended up just being the CPS. Dont know if that helps, my CPS cost me about 65 bucks, but it was my last hope. Good luck.

Luckily I work at O'Reilly part time and I ordered up a CPS just in case. I'll get it in tomorrow. I was just really curious if the CPS is bad would it still let you have spark... Cuz I'm getting spark but no fire.

I hope your right about the CPS. I'll find out tomorrow.

Yes, I still had spark at the plugs with a bad CPS.

Overdriven said:

Luckily I work at O'Reilly part time and I ordered up a CPS just in case. I'll get it in tomorrow. I was just really curious if the CPS is bad would it still let you have spark... Cuz I'm getting spark but no fire.

I hope your right about the CPS. I'll find out tomorrow.

Click to expand...

If the CPS is dead you will not have spark, if it is working part of the time you could.

mmarriottxj said:

Yes, I still had spark at the plugs with a bad CPS.

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Thank you for that answer. Now I am confident to replace the CPS. I wasn't sure at first if I was tossing money out the window on a guess here.

thanks again.

Overdriven said:

Thank you for that answer. Now I am confident to replace the CPS. I wasn't sure at first if I was tossing money out the window on a guess here.

thanks again.

Click to expand...

With the CPS it's a given it will fail, you can never do wrong having a spare.

I swapped in a good CPS today and It didn't fix the problem. I then took my ignition control module into work and tested it. Failed...

Now I've got that on order. Turns out I was getting spark just not at the right time due to bad ICM.
At least I didn't drop the $60 on the CPS before I snagged the ICM.

Well, I was wrong again. ICM didn't fix the problem. I'm back to square one.
Ignition control modul, TPS, CPS, IAC, are all good. I'm getting spark, air, and fuel but it will not fire.

What else is there?

ok, did you use a spark tester to see if you have good spark? How much fuel presure are you getting? Is your FP holding ( ie are any of your injectors leaking) Im no renix guy, but how did you test to make sure your IAC was good? they often dont come up as a trouble code. You said your cylinders were flooded? Did you pull the plugs and let them dry and try starting it on a clear flood?(pedal pressed to the floor). I only know of 1 thing that will cause a crank but no bang if you have fuel and spark and that is the IAC.

I'm going to jump in on this thread instead of starting another one -- if that isn't cool, let me know and I'll start one.

I have an 86 4 cyl that we just did a re-ring and bearing job on. We've also had problems getting it started. Here's what happens on ours -- we're looking for anyone else that has figured out this problem.

We get no fuel delivery via the standard harness wiring. It tests weak on the fuel pump end of the harness (10-11 volts) and the relays are clicking all the time that the key is on.

To try some fixes for this, we started with running a ground wire from the fuel pump/sender unit to the body, just in case it was a bad ground issue. (We also checked continuity on all the wires in the pump, and the pump spins well outside of the truck harness.) That did nothing for us, so in desperation we tried using a jumper wire between the battery and the fuel pump feed wire. This runs the pump fine -- we have good fuel psi at the throttle body.

The problem is that when we're running power directly to the fuel pump, it shorts out the coil circut and there is then no fire. Pull the wire to the pump, and the truck starts up until it runs out of fuel in the TB. Put the wire back on to pump fuel and no fire.

Anyone have a clue about what is happening here? Fried computer? That's the only connection that I can see on the wiring harness diagram in the poor book I have.

Thanks!

Overdriven said:

Well, I was wrong again. ICM didn't fix the problem. I'm back to square one.
Ignition control modul, TPS, CPS, IAC, are all good. I'm getting spark, air, and fuel but it will not fire.

What else is there?

Click to expand...

silly question.....what kind of plugs do you have?

Just for grins, put in a fresh set of Champion $.79 plugs and give it a try. I have seen too many plugs spark when they are not in, but not work under pressure, especially after being exposed to water or being fuel flooded.