No Start on our 88 4.0l

[woody]

No timing light here

How does one confirm it's on the compression stroke?

TIA

 

[Eagle]

Woody --

It's a 4-stroke engine, so each cylinder has two UPs for one rotation of the distributor. One's a compression stroke, the next is the exhaust stroke. Firing sequence is 1-3-5-6-2-4.

Distributor indexing sets it up with the rotor tip PAST the #1 cap turret with the piston at TDC (0 degrees on the timing marks). You check for the compression stroke with a finger over the spark plug hole -- if it blows your finger off on the way up, it's the compression stroke. The next time around, the exhaust valve will be open so there won't be any pressure. If you're on the exhaust stroke, rotor will be somewhere between #5 and #6.

Jumping time is highly unlikely. The chain and gears are all steel. Being accustomed to AMC engines with nylon teeth on the cam sprocket, I got nervous and replaced my timing set at 204,000 miles. The old chain was so tight you couldn't tell it from the new one.

Get a "noid light" from Auto Zone and check to see if your injectors are firing. CPS and "the other CPS" (the CAMSHAFT Position Sensor) control both spark and injector pulse. You may be getting spark but your injectors may not be injecting.

Squirt some raw gas into the throttle body and see if it'll even kick with that. Just like priming that old Harley after it sat all winter. It may not run but it should at least fire and run for a few revolutions until it runs out of fumes.

 

[bockwho]

I had a similar problem with mine not cranking .. but yours now cranks right. water in silnoid.

If it dose not crank use the jummper cables to the starter trick .. to check .. black from block to battery post. this will determin if you have a bad cable .. I trouble shot a bad ground for 2 days .. digital volt meters will not tell you if you have a good ground or enuf of a ground to run a starter.

if it was your cps .. you plugs would of been fouled .. you would get spark .. but it would run really rich and you would only be able to drive 60 or so miles befor they finaly fouled out. and with out new plugs you would not get it to start.

these were
my expearance

kelsey

.. the computer is a good place to go if you have one laying around..

 

[Andy in Pa.]

Hey Woody,

I learned something from our local STROKER about a year ago when I was installing a temp gauge. If the factory temp sensor wiring at the front of the intake manifold is unplugged (or I would imagine, if the sensor is bad or the wiring is broken), the engine will not start. He told me this while we were working on my jeep up at my garage, and I did not believe him so I unplugged it on my 88, and sure enough....

This is a long shot, but take a look.

Andy

 

[XJ88NO]

Same problem

Hei! Ihad the same problem and i had a broken vacumhose on vacumtank in the front bomber.My be the same in your!
Good luck
Per

 

[jlittle]

no start

sounds similar to the problem i had, and i went out and yanked the c 101 connector on the firewall around alittle and started right up..does it once in awhile and i just wiggle the conn every time and it starts right up......jim

 

[sidriptide]

this is exactly what i am going thru on my 87 laredo..... im not trouble shooting it actively cause i have another truck in pieces right now but im gonna print off all of this to help out... i have a Q about the CPS though.. what about it goes bad? could it malfunction just by getting dirty/greasy and clean it and it works fine? or is it just a crap design ?

 

[old_man]

OK guys, lets approach this thing with some direction. He says he is getting spark, so have some one crank it while you spray a little carb cleaner or ether down the throttle body, if it fires and tries to start, it isn't the spark. If that is true then press in the needle on the schrader valve on the fuel rail with the key on. That will tell you if you have fuel pressure. It won't tell you how much but will let you know there is fuel there. If you have fuel and spark, then the computer isn't responding correctly. The most likely culpret at that point would either be the throttle position sensor or not as likely, the MAP sensor. You can proble the connectors for both sensors and each should have a ground and a +5v regulated line. The third line on each is the signal ouput. If I remember correctly, the TPS should have around .7v at an idle, but you should check that out.

There is one other possible issue having to do with grounding. Make sure that the grounding strap from the rear head bolt to the body is intact and making good contact.

 

[brien]

my '89 xj Sport 5sp. wouldn't catch when spun by starter -
rolling it down a grade & popping the clutch would have the
engine catch & run OK . Shut it off & it would not start.

This went on for 4 days - today it would not catch regardless -
had it towed in - & shop will call tomorrow ..........

 

[whosyourdaddy?]

have you pulled codes out of it. that seems to be the easiest thing to do. sounds like a tps to me.

 

[whosyourdaddy?]

in order for the cps to give correct output voltage the elongated hole side of the cps must contact the machined lip of the bellhousing. maybe while doing the ujoints you bumped it.

 

[skipc]

OK, lots of good info on what seems like a common no-start problem (mine does this once in a while). WHAT HAPPENED???

What was the final answer??? ;-)

Skip

 

[Rastus]

Same thing I want to know. What was the solution to this?

My daughters 87 XJ Laredo also has a no-start issue. Pour fuel in the throttle body and it fires \runs, then dies. It won't pick up the fuel from the tank. Filter has been changed, and it has fuel in the tank. Has fuel at the schraeder valve, but not sure of the pressure. Going to pull the tank shortly and se if I find anything there. I also plan on checking some of the things mentioned in this thread.

 

[wascobi]

update please!!!!!!!!!!!!!!! currently going through a good spark and lots of gas but no start! floods out almost instantly and it almost catches at WOT. I think mt TPS is doing it

 

[old_man]

OK, if you have been fighting this for a while, you could have gotten your plugs wet. This is a common problem. Pull the plugs, spray them with carb cleaner and let them dry, or just get a cheap set of Champions (my favorite plugs) Install them and have somebody crank it, leaving their foot off of the gas. At the same time, hold the tps in the WOT postion. Once it starts to catch let it rev just a bit and turn loose of the TPS. Putting the TPS in the WOT position tells the computer the engine is in a flooded contition and will restrict the gas through the injectors. The engine will run rough for a few minutes until you get it warmed and the plugs cleaned.

This condition has been the basis for more sensors being needlessly swapped than almost any thing.

 

[XJRubicon]

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.

Just to clear things up... If its cranking, (spinning the motor) then that Itself rules out it being the starter relay.

The starter relays job is to supply your starter with power when you turn the key. The fact that the motor is spinning proves the starter relay has done its job.



Right now, my XJ is also in nostart condition.

It fires off a single cylinder every 4 or 5 rotations, 3 or 4 times and then won't fire at all.

87' with a 96' motor, Plenty of fuel pressure, Nice Hot MSD Spark, fresh tune up, oilchange, all new sensors.

I had a problem before with the connectors for the engine harness, (drivers side, above master cylinder 1/4 bold in center) if I had someone crank the engine and I smacked the connector, it would fire right up! Then, While it was running, I again smacked the connector and the damned motor killed...

So I figured it was the connector and did not worry about it too much. I planned on cutting the connector out and soldering all the wires and then heat shrinking them.

Tonight I cut out connector, and resoldered everything thinkin I solved the problem. But it still tried but no fire.

While trying to figure out what the deal is, I noticed my ballast resistor is SMASHED! Its on the firewall in the same location as the harness connector so I'm hopin that is what I smacked to make it run better. I didn't see anything else over there other then the MAP sensor that could have recieved the vibration of me smackin it. No loose wires...

Let you know but my moneys on that resistor..

 

[woody]

My junk was laid up by a faulty wire connection... After letting it sit for 4 months, I bit the bullet and towed it to a local repair shop. $100 and a week later, I had a running Jeep. I was too disgusted to even ask him which wire. :dunno:

 

[TBLimited]

Hey Woody did you ever figure out what was wrong?

 

[Desert Jeepin]

I know there are atleast 4 of us still experiencing a similar problem.


Any updates?

 

[TBLimited]

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