No Start on our 88 4.0l

Apparently it was running fine, Karen stopped to pick up the kiddo at a friends house, then after sitting for a few minutes it wouldnt start back up.

I had a tune-up planned for it anyway, so I towed it home & replaced: Fuel filter, plugs, wires, cap, rotor, air filter. I suspected a clogged fuel filter or a bum CPS

Confirmed the following...Good spark, 1.8 Ohms across the ballast resistor, can hear the fuel pump prime up and quit when keyed on... On a hunch, I swapped the pump relay out of the MJ, but it didn't help any.

The 'good spark' part rules out the CPS yes or no? I may toss one into the mix on general principle. If it helps cure it fine, if not I'll have a spare. (everyone needs a spare CPS anyhow)

I wish I had a fuel pressure tester...since all I could do is depress the valve (got fuel... but not a powerful stream) should I test this while cranking the motor or will it maintain pressure with just the key on?

Hmmm what's the mising link here? I drove the Jeep last night after doing front brakes/UJs and it ran strong.

TIA

Woody

Does it start now?
Does it just not start when it's hot?

Hum not sure But I know on my Eagle Medalion witch pretty much runs the same renix system it would turn and spark but no start all becaus ethe bone heads who changed the trany broke the CPS. I have yet to have a proble with any of my XJs or MJ resulting from a bad CPS(knocking on wood right now) so it may be posible.

No start at all (hot or cold)

When I first got to it (warm engine) it started and ran really rough but cut off and hasn't fired back up.

So a bad CPS will still allow the coil to fire? Hmmm curious.

(I checked for spark first at the #3 cyl, then put that plug on the coil wire...fire at both spots) While the plug was out, I put my finger over the hole and it had compression-at least in that barrel.

Keep up the good advice!

OK just went out and probed the CPS for resistance (my book says looking for 200 Ohms + or - 75) and my DMM reads 1 - infinity.

So I am thinking I got one bum CPS in there.

Ahhh nevermind...I probed the dang computer end LOL something about working in the dark with a thunderstorm overhead.

Hers reading 240 Ohms...for reference mine is 188 ohms (both within spec.

:dunno:

Just for grins, I swapped the gas tank cap off my 89 and it didn't help.

Going to bed now...will work on it more tomorrow.

Woody

It sounds like you're focusing on a fuel problem rather than a spark problem. Therefore, I assume that your starter is still working, but the engine is not firing up. That would make me think it's a fuel problem too.
I had this happen once to me on my '88 and it ended up being a cable that had come off of a relay. I'm at work right now and don't remember the name of the relay. It's on the driver's side located right beside the air box. It's a white plastic relay that has two wires going into it - one on either side. When one of the cables came off, my XJ would not start - it sounded like it wanted to though.

Good luck...

Thanks RTicUL8.

that's the ballast resistor BTW. Mine ohmed out at 1.8 (same as one of the MJs parked next to it.) I may temoprarily bypass it to see for sure

1st thing this morning plugged in a new CPS. No help...

I also pressed the valve on the fuel rail and got a good strong squirt. (may hunt down a pressure tester to confirm with #s)

I dunno whether fuel or spark. (kinda doing the "shotgun" diagnostic...replace everything I can think of until I fix it)

:gee:

Please keep the good ideas/advice coming!

woody said:

Thanks RTicUL8.

that's the ballast resistor BTW. Mine ohmed out at 1.8 (same as one of the MJs parked next to it.) I may temoprarily bypass it to see for sure

1st thing this morning plugged in a new CPS. No help...

I also pressed the valve on the fuel rail and got a good strong squirt. (may hunt down a pressure tester to confirm with #s)

I dunno whether fuel or spark. (kinda doing the "shotgun" diagnostic...replace everything I can think of until I fix it)

:gee:

Please keep the good ideas/advice coming!

Click to expand...

Check the hard vacum tube that goes from you map sensor to the throttle body.. don't just look at it, touch it, wiggle it a little.. see if it has broke off right at the throttle body... be careful though you don't want it to break... I know on my 87 mine broke and the would not start.

Woody - did you ever get it running? Just curious...

I'm not the most technically sound person in the world, but couldn't it possibly be bad gas or possibly water in the gas. Woody, from what you describe it sounds exactly what mine did a couple of years back. After testing everything, I drained the gas tank and fuel lines (Conoco Gas), went and got new gas(Shell), and it started right up. Not saying that is what it is, but I always try to think more simple rather than too technical. Hope it helps.

"K9Cop?!" .....saaay, you wouldn't happen to have access to those police XJ chips, would you? hee-hee......ZOOOOOM!

Do you think that the dealership would look at you strange if you came in and asked for 5 cases of them? :laugh3:

Police XJ Chips? What gives? Hey Woody you want me to come up there and help you fix it? LOL! I would have to meet you at Uwharrie first though! LOL!

if your getting power to everything and the thing has all the spark in the world. Check the starter relay. Mine went south in Nov. I replaced everything in the world with nothing more but wasted money. So if you get a turn over rule this out, if you crank it over and nothing happens. Have it replaced.

Hey RTicUL8,
Yeah I think they may look a little strange at me, especially since we don't have any Jeeps in our inventory. We've got a few Blazers (Blaspheme) and a Bronco (Sac-religious), but no Jeeps. Too bad I ain't in charge of vehicles, because at least all the dog handlers would have Jeeps and those damn things would be decked out.
"Cry Havoc and Let Slip the Dogs of War"
William Shakespeare

The sheriff departments around here mainly use Durangos, XJs, and recently Grand Cherokees. The Superior, CO dept. uses Land Rovers...."Ah yes, would you care for a spot of tea with that ticket?"

Thread Hijack

No no luck do far :dunno:

"if your getting power to everything and the thing has all the spark in the world. Check the starter relay. Mine went south in Nov. I replaced everything in the world with nothing more but wasted money. So if you get a turn over rule this out, if you crank it over and nothing happens. Have it replaced."

By Turn over whaddya mean??? This one the starter spins the motor over...kinda weirdly though... Kinda a RuRuRu - Ror - RuRuRu - Ror (sorry, I'm stressed) Plenty of DCV and as I stated, the coil and #3 cyl sparked brightly when I keyed the engine

Last thing tried was had the 1 amp charger on it for 36 hrs, then pulled the nasty battery cables off...cleaned up the contacts on the main breaker well (fixed a loose ring-term) and replaced all the cables with good ones...also added a new 1 ga ground strap from the Batt - to the radiator support.

No luck hunting down a fuel pressure gage, but I think I will spring for one (and a compression gage) this payday. It was K&N + Airtube time for this one. dangit if priorities don't change up on a guy.

Some advice I have been given is to check if it has jumped time.
I think to do this, I need to pull #1 plug out, spin motor over until dist rotor is pointing at #1 cap-spot. #1 should be at/close to TDC and the timing mark on the balancer ought to be on the pointer...

Before that, I am gonna swipe the ECU from my MJ and swap it in to see if that fixes it...but then again, a bad ECU would mean no-spark...just like a bad CPS correct? Or will a bad CPS or ECU allow spark but no fuel???

Thinking to get ready to haul it off for a pro to examine, since it plainly has me whupped. I would like to have some compression and fuel pressure #s to compare with my XJ though.

Last I saw (Sat night) it had good oil pressure according to the factory gage...better than mine and the engine felt stronger/smoother running than mine. The Mrs owns up to no obcene noises or loss of power. It just quit.

Thanks

OK I started yanking the ECU, but boyogolly that was fun, so I quit and went back underhood.

I removed the distributor cap and the plug from the #1 (front) cyl and when the dist rotor pointed close to the #1 position...the piston isn't anywhere near TDC. Using the crude menthod (1/4" extension as a 'depth gage' and flashlight + the highly calibrated eyeball...) best I can tell #1 TDC is occuring when the rotor is pointing at the #5 spot.

It's a pain w/o a helper to run the key while I do the peering.

I 'think' each pair of 3 cylinders has a partner...share timing yes? Is the condition I described above normal?

So "IF" it jumped time...this means new chain & gears yes? or could it have been the gear on the distributor or cam?

I suppose if I am going into the front of the motor...this is prime time for a fresh balancer pulley, waterpump/thermo, lower hose...and what else (we did upper & heater hoses two weekends ago...) since the front end of the Jeep has to come off for access.

Only three little bolts holding in the ECU but it's tough to get your head under there. Only use the two easier ones when you put it back in. The ECU controls pretty much everything and probably any portion of it could fail; however, they seem to be very reliable. Just to be sure about the timing, check it with a timing light. If you're checking the distributor indexing manually, make sure you're on the compression stroke and not the exhaust stroke.