hello i have a 1988 with a 318 fi. She won't start. I have fuel at the tbi spraying well and a yellow spark at the plugs. She did this while in 4 wheel drive and with a little cleaning of the distributor and checking the ignition coil by jumping the hall sensor she started after a few many tries with starter fluid and alot of stutering but then ran perfect. Next day she started right up, i hooked her up to the boat, went to crank her and nothing. I have since replaced the ignition coil with no change. She has spark and gas. What is the next step in my diagnosis. Any help would be greatly appreciated. Thankyou.[>:][:@]

 

So i decided to stop chasing the yellow spark hoping i could make it blue and solve the problem. Looking in side the oil inlet at the valve cover i can see that the cam is still turning with the crank and thus the timing chain is not broken. If the timing has jumped on the gears how would i diagnose this?

 

UPDATE: When the timing marks are at zero degrees the distributor appears to be pointing at the number one cylinder. I am not sure if this method will tell me if it jumped one link on the timing chain so i also took cold compression tests with the throttle wide open.
1-170
2-150
3-145
4-150
5-100
6-100
7-140
8-95

I know this engine is OLD (over 250k), but even those cold compression readings are so different could the lower reading in the back of the motor be from the dissolving of carbon deposits from gasoline and starter fliud sitting in those cylinders?
Are these readings indicitive of proper timing and no jump of the chain?
Even with these readings shouldn't she start?
I'm getting desperate I have to move at the end of this month and i need her to run 25 miles so i can move her... then i can put her on a stand a rebuild my first motor.

 

Do a wet compression test and see how your numbers look. Your timing looks to be ok with those readings. Another way to check it is to put number 1 at TDC and look at your rotor. If it is just slightly past where the number 1 wire would be on the cap then your timing is fine.

Another thing you might want to do is clean your injectors. Yes, it might look like you are getting proper fuel but it also has to voporize correctly for it to ignite. If there is just a slight restirction it might not allow that.

Your spark should be white or blue as you know. On those low compression cylinders you might not be getting enough spark to ignite the mixture. Another thing to look at is if there is too much play in the distributor. If you grab the roter and it wobbles excessively then you might have to replace that. It will turn back and forth a little but that's only because it is meshing witht he gear on the camshaft. There should be no movment side to side though, if there is then it is throwing your spark timing off.

Ok, let me know how all of that turns out and let me know. After those tests there are some others you can do but that will at least helpto tell whichdirection to go.

 

UPDATE:
cold and wet compression test-
1-170
2-180
3-170
4-165
5-155
6-165
7-165
8-170

The rotor appears to point to the number one cylinder at 0 degress tdc with no side to side play just a small (maybe 1/8th inch to 1/4") play back and forth.
I have purchased a timing light, cap and rotor, wires, and plugs to go with the new ignition coil- hoping that yellow spark turns blue.
The injector is vaporizing the fuel.
So again I ask- based on these compression tests my timing is good and even with the low cmpression dry indicitice of ring wear she should still start?
Tomorrow evening I will replace all those parts and check the timing- maybe she will start?
Anything I should chase and any advice

 

With those high of readings your timing is definitely on. See how it does after you install the new parts on it and let us know. If that still doesn't do the trick then check your fuel pressure at the TB. I don't know what the spec is for that year but you probably have that. Check it while cranking and also while you have the key on for 10 minutes with the engine off. If you have compression, spark, and timing, the only thing left to look into is the air/fuel side of it.

 

Update:
All parts new- ignition coil, cap, rotor, plugs, HALL effect sensor (pick-up).
My fuel pressure is good while cranking and with just the key.
I put a timing light on it and it is firing on time while cranking.
After replacing the Hall sensor it tries to run more now stuttering then backfire out of the intake a nice white cloud of smoke.
The only thing I can think of is the PCM.
I will lossen the distributor and try cranking it advanced and retarted.? AND check the firing order and wire locations again.
Thanks for listening and the advice Casper

 

Yeah, with that backfire out of the intake I would have to say your timing is off or you are getting way to much fuel. Cars that I have worked on did that to me for these reasons but way more often a timing issue than fuel. The timing that I was talking about above was the timing between the crankshaft and camshaft. Your spark timing could definitely be off though.

 

You may have a loose chain and gears. Try this...
http://www.misterfixit.com/chanslop.htm

 

Update: Got her to run like a dream for about 5 seconds. After cranking her a bit i unplugged the in injector harness and she cranked right up and ran with the risidual fuel in the intake. I am getting 10 psi at the on switch and 12 while cranking for my fuel pressure. The filter was a little clogged and got replaced. The resistance on the injectors is dead on and the signal form the harness is perfect using a noid light. I tested these after i noticed only one injector was spitting fuel. I have since removed the injectors and put them back in and am trying to get the fuel to stop. They both now spray but she doesn't run. I have tested every sensor and they all check out (except the colant temperature I get a resistance of 8000 ohms instead of 17000 at cold) and the one i couldn't check ( hall sensor) was replaced. I am going to keep chasing the injector thing but before i spend 80 bux each on new ones does anyone have another two sense to throw at me. Oh yea i noticed the vent line at the tank is not connected, gonna have to drop the tank trailer hitch and guard to fix that.