94 z-34 won't start - timing chain?

[Millster]

My son was driving car and thought he ran out of gas. Running good before. Checked all the normal stuff I can - took it to 2 different mechanics (1 new little about the motor) and the answer I get is 'probably' a slipped timing chain (without spending a lot more money). Is there a check I can do to tell. Battery was disconnected and no codes show up now. New plugs - getting fuel - have spark. Fires when you first turn key for about 1 second but then wont start. Plugs are wet after try to start a few times. Wont fire with starting fluid. Timing belt looks good and is tight. Could a bad vacuum leak cause no start - flooding? Any help appreciated. Thanks!!! Russ

[3400-95-Modified]

There is no timing chain, just a timing belt, and when you say the "timing belt" is tight are you referring to the one on the alternator? because the cam timing belt is under a plastic cover on the passenger side of the motor... and yes you may have killed that.

[RedZMonte]

When my timing belt jumped a tooth it was tight but out of time.. the belt is recommended to be changed @ 60K miles. if your getting fuel, spark and no codes that may be a indication of the belt jumping a tooth and out of time. Pull the cover off the front cam cover (black plastic cover) and inspect the belt, i bet its pretty worn. If thats the case i would start there. a vac leak would most likely allow it to start but not idle or have a rough/high idle.

I would also do a fuel pressure test, just because your getting fuel to the rail doesn't mean you are getting enough.. Its an easy test to do. should be ~42psi to the rail... I would also pull the vac line of the passenger side of the intake manifold and see if it pisses out fuel, could have a bad FPR, mine failed and would not start, flooded the intake and engine with fuel.. if this is the case, do a oil change before driving (my oil level was WAY high cause it was filled with fuel as well).

Hope this helps,
S

[pocket-rocket]

There is no timing chain, just a timing belt, and when you say the "timing belt" is tight are you referring to the one on the alternator? because the cam timing belt is under a plastic cover on the passenger side of the motor... and yes you may have killed that.

Actually the LQ1 has a timing chain and a timing belt. The timing chain drives the intermediate shaft (think pushrod cam without lobes) that drives the oil pump and the timing belt.

I would think that if it's getting a good spark the plugs would not be wet when you pull them because the spark should create enough fire to dry them off. Have you checked your fuel pressure at all? Checking the timing without one of the timing tools (Kent Moore or aftermarket) will make it much harder to tell if it's out of time at all. The intermediate shaft doesn't care about timing, but it's the cams in relation to the crank driven by the timing belt that matter.

[Millster]

More info - thanks for your help

Some more info - the fuel pressure was checked and went to around 34lbs when cranking, someone else checked it so I trust they were accurate - the timing belt looked in fairly good shape, I had the covers off myself - a mechanic told me the the timing chain jumping a tooth throws the cam timing off because the timing belt is driven by the timing chain which is driven from the crank - the explanation for the wet plugs was because the timing is off the valves aren't open and closed at the right time so even if the plugs are firing there is not ignition which would burn the fuel completely. So ultimately I guess I need to invest in the tools to properly check the timing - if it is off then I need to fix it anyway. I was hoping there was some other cause I just was not aware of - I don't know much about the electronics, sensors and stuff - I'm old school - that's why my hotrod has a carb. Any other comments, suggestions are very welcome. Thanks!

[3400-95-Modified]

Actually the LQ1 has a timing chain and a timing belt. The timing chain drives the intermediate shaft (think pushrod cam without lobes) that drives the oil pump and the timing belt.

Shit your right, I forgot about that little sucker down there...


My bad...

[Millster]

Thats ok - I am learning alot about this oddball now that it needs to be fixed.

[3400-95-Modified]

All I know is I had to help with a timing belt on a friends one time, and not knowing anything about the engine and trying to lend a hand... man that was interesting... I also told him to wait for me to install the tensioner, he didn't and when started it wasn't tight so he slipped the brand new belt again.

Just note though, even though the belt slipped the thing still started and ran... I guess it didn't slip enough.

[55trucker]

With the front bank access cover for the timing belt removed...have someone crank the engine for you....and you watch to see if the belt is actually turning...the belt teeth can shear off on a section of the belt (not necessarily the entire belt)......and if that section is under the drive pulley on the end of the intermediate shaft you'll never see that and the belt will not move.

[d.o.h.c]

Is the MAF hooked up? There are only a few things that will cause it to not run. When did it stop running is the more important question. Was he driving and it died or did it just not start after being turned off? If you are getting 34psi of fuel psi and it HOLDS, the pump is good and injectors are not leaking. Then the spark, are you certain your getting spark? even on one set of coils (2 cylinders) the motor would still try to run atleast. If those both check out then I would check the MAF sensor and make sure its connected then go to the timing belt. If the belt slipped a tooth your in for one fantastic weekend. That belt is not an ordinary belt, and look to spending $250 in parts if you want it to run correctly again.

Mark-OEM

[Millster]

Is the MAF hooked up? There are only a few things that will cause it to not run. When did it stop running is the more important question. Was he driving and it died or did it just not start after being turned off? If you are getting 34psi of fuel psi and it HOLDS, the pump is good and injectors are not leaking. Then the spark, are you certain your getting spark? even on one set of coils (2 cylinders) the motor would still try to run atleast. If those both check out then I would check the MAF sensor and make sure its connected then go to the timing belt. If the belt slipped a tooth your in for one fantastic weekend. That belt is not an ordinary belt, and look to spending $250 in parts if you want it to run correctly again.

Mark-OEM

He was driving and turned into a driveway, then it stalled. The car was running good before. A guy came and checked the fuel pressure while I cranked it. He let the pressure off and checked it again 3 or 4 times. While cranking the pressure came up to around 33-34 lbs. We did not see any leaks. I towed it in to a mechanic and also had another guy come and he checked coils, plugs etc. I had all the covers off the belt and inspected - it was tight and looked in decent condition to me and is turning. The garage mechanic mentioned the compression being a little low and thought this was a sign of the cam timing being off - valves not closed during compression. A lot of the vacuum lines are cracked etc. I will check the MAF sensor. Thanks!

[savannaz34]

so.....................did you figure it out? i have had nothing but trouble with my 92 z34.same prob.have spark,good fuel,injector pulse,pressure,new icm,tps,ect,ect,ect.but something is telling the motor not to start.when you leave it for a few hours and try to start it.it burbs and farts(runs like shit)for a couple seconds then no start.my timing belt is fine.i removed most of the bolts for the front cover and gently pried it back to inspect the belt and pullies,belt is pretty snug,no missing cogs,ect.but thats not the biggest bitch.my 91 z34 just died on me yesterday.
i was turning a corner,then it was acting like i was out of fuel.tested what i could last night,and yup,same fricking thing as my 92.now because of the amount of people that have this problem,and i have 2 cars with this problem,it must be something silly,that is being over looked.is there a sensor anywhere else on this car that wont let it start?or ,if you have solved this problem.could you plz let me know.thanx and sorry for the long post.but im very upset about it.(i have no wheels)

[Millster]

Have not done any more on the car - may sell it if I could get $4-500 or still tear it down and check/replace timing chain. It is frustrating because I don't know for sure what it is and don't want to tear into the motor that far because it 'might' be the timing chain - lot of work if that's not really the issue. ????????

[RedZMonte]

I wouldnt suspect a timing Chain.. Belt, Yes... Chain, No.. If you look at how the chain is setup, i don't see how it could skip a tooth... it will stretch over time or even break but not skip... Timing belt will skip a tooth or a few teeth... Did you pull a plug, set it on metal and see if the plugs are actually sparking? if its craking and not firing i would say something spark related... Faulty Ignition modual (would not get any spark on any cyl), Crank Pos. Sensor (would also get NO spark).... OR timing belt... My t-belt skipped a tooth and ran like ASS... if its far enough off i would think it wouldnt start at all.

S

[savannaz34]

well,ive been reading alot of old posts about the same issue on this site,and i noticed people change every sensor on the motor,plugs,coils,but i dont see anyone saying they changed the plug wires.that made me wonder if it is possible to have spark,but not enogh spark.make sense?not really.but what the f***.so i spent $120 on some new plug wires,spent the most part of my day at work changing the plug wires,and the flippin thing fired right up..but like i said i had spark at every plug in the first place.i forgot to mention that when i had the wires off,i tested them with my multi meter and the old wires showed from 24 to 34 resistance.huh??????????i still had spark.the new wires resistance reading doesnt go past 4.BIG DIFFERANCE.so i just wanted to share that with you.hope this helps