L98 won't start - HELP!
Thread Starter
Burning Brakes
Joined: Jul 2003
Posts: 873
Likes: 2
From: Whittier ca
L98 won't start - HELP!
91 L98 A/T - quick synopsis - replaced muffler brackets yesterday, started this AM, pulled down driveway and washed it. Did not open hood and no water in engine compartment. Spent some time with wife & kids and then tried to start, but it just cranks. And cranks. Checked for spark (with a screwdriver in the end of the wire and with an induction timeing light) and it checked ok. Checked fuel pressure with just ign. on and when cranking - 52# to 50#. I have about 1/5 tank of gas. Checked all the fuses - all ok. New ECM about 5 months ago. New dist cap, rotor, plugs (#5's) and wires 2 months ago. Have not replaced the coil.
So now I'm at a loss. Help. This is my daily driver so I've gotta get it running real REAL soon.
Thanks in advance
Subman
So now I'm at a loss. Help. This is my daily driver so I've gotta get it running real REAL soon.
Thanks in advance
Subman
Team Owner
Joined: Jan 2003
Posts: 20,275
Likes: 236
From: Summerland B.C. Canada
Re: L98 won't start - HELP! (subman)
Try and check to see if your injectors are getting power and ground. One side is always hot and the ground is controlled by ecm. Thats some high fuel pressure 
Good Luck
Good Luck
Team Owner
Joined: Dec 2000
Posts: 90,675
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From: SE NY
Cruise-In II Veteran
Re: L98 won't start - HELP! (subman)
You will likely need a test lamp across an injector to see if they are firing; or you could pull a plug an crank it to see if you smell fuel.
Thread Starter
Burning Brakes
Joined: Jul 2003
Posts: 873
Likes: 2
From: Whittier ca
Re: L98 won't start - HELP! (AGENT 86)
86 - Thanks for the reply - how many volts should I be getting at FI's. Using the multimeter, I got .03 Volts (I think).
I sprayed a little electronic parts cleaner in the plenium and it fired for a second or so. So I have spark. Me thinks A) fuel pump (9 months or so old) or B) ECM Your thoughts?
Thanks again
Subman
I sprayed a little electronic parts cleaner in the plenium and it fired for a second or so. So I have spark. Me thinks A) fuel pump (9 months or so old) or B) ECM Your thoughts?
Thanks again
Subman
Team Owner
Joined: Mar 2001
Posts: 54,124
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From: Cincinnati, Oh USA
Re: L98 won't start - HELP! (subman)
The spray into the MAF is a sure sign that your injectors are not being pulsed by the ECM and your engine is not getting fuel sprayed into the intakes. Put a low power 12v lamp across a disconnected injector plug and crank the engine. The lamp should pulse. The ECM receives pulses from the spark control module and grounds one lead of each injector for a short duration to get fuel to the engine. The other lead of the injector goes to 12v when the ign is on. A voltmeter is not an effective tool for checking out if the injectors are being pulsed. Check both injector fuses with an ohmeter. You would need an oscilloscope to determine if pulses are being sent from the distributor to the ECM. If they are, then you might have a dead ECM.
Thread Starter
Burning Brakes
Joined: Jul 2003
Posts: 873
Likes: 2
From: Whittier ca
Re: L98 won't start - HELP! (jfb)
Okay then - clipped onto the pos of the battery, the other end of the test light to the FI plug (pink wire from the ECM). In theory, only ECM side (ground) should pulse the test light, correct? both sides of the plug light up without a pulse. So now I'm looking for the receipt for the ECM I just bought some months ago. It would be nice if it's under warranty. Will replace tomorrow and let y'all know what happens.
Thanks for the help
Subman
Thanks for the help
Subman
Team Owner
Joined: Mar 2001
Posts: 54,124
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From: Cincinnati, Oh USA
Re: L98 won't start - HELP! (subman)
Yep, you did it right, but a better test is to use the 12v line from the injector socket! Since you have spark I doubt the reference pulses are missing from the spark control module, but it doesn't care what I think. And.....you could also have a dead ECM no matter when it was last replaced. Hope you get it fixed soon. 
[Modified by jfb, 11:50 AM 6/21/2004]
[Modified by jfb, 11:50 AM 6/21/2004]
Thread Starter
Burning Brakes
Joined: Jul 2003
Posts: 873
Likes: 2
From: Whittier ca
Re: L98 won't start - HELP! (jfb)
So the saga continues. . . . bought a new ECM, changed the chip and finally got it installed tonight (10:00ish - I had to bowl) Nothing, Nada, Zip. S.O.S.
Replaced the fuses even though that checked ok. Pulled the TPS sensor plug and turned the engine over to check the codes, if any. Got a 46, which is the VATS circuit. WTF? And no code 21 for the TPS. And no other codes. So I tried the wifes key. Still won't start. The fuel pump is hummin', still have good pressure at the Schreider valve, got spark, if I spray a little Electric parts cleaner into the plenium, it fires for a second or 2.
So, now I am at a total loss.
The good thing is I get to return the ECM no charge.
Any help, ideas, off the wall suggestions (short of selling my Vette, at which point you can kiss my ...whatever) would be appreciated
Thanks
Subman
Replaced the fuses even though that checked ok. Pulled the TPS sensor plug and turned the engine over to check the codes, if any. Got a 46, which is the VATS circuit. WTF? And no code 21 for the TPS. And no other codes. So I tried the wifes key. Still won't start. The fuel pump is hummin', still have good pressure at the Schreider valve, got spark, if I spray a little Electric parts cleaner into the plenium, it fires for a second or 2.
So, now I am at a total loss.
The good thing is I get to return the ECM no charge.
Any help, ideas, off the wall suggestions (short of selling my Vette, at which point you can kiss my ...whatever) would be appreciated
Thanks
Subman
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Instructor
Joined: Jun 2004
Posts: 138
Likes: 0
From: ronkonlkoma ny
Re: L98 won't start - HELP! (subman)
im not sure if vettes have it but ive had cars that wouldnt start cause the oil was low!!
but my brother has the same problem w/his88..the key chip alarm bugs out..
lock and ulock the drivers door from the inside and outside a bunch of times.it works for him...some time it takes a long time...
maybe check to see if the door light pin is working also,,it may have some effect on the door lock alarm ground
if no help find out how to bypass the cutoff
good luck
but my brother has the same problem w/his88..the key chip alarm bugs out..
lock and ulock the drivers door from the inside and outside a bunch of times.it works for him...some time it takes a long time...
maybe check to see if the door light pin is working also,,it may have some effect on the door lock alarm ground
if no help find out how to bypass the cutoff
good luck
Thread Starter
Burning Brakes
Joined: Jul 2003
Posts: 873
Likes: 2
From: Whittier ca
Re: L98 won't start - HELP! (subman)
Some additional testing produced something I think is weird. If I connect a tester to the neg side of the battery and connect the other end to the pos side of the FI plug, with the key on the tester lights up. It also lights up if I connect the other side of the plug. However, if I turn the key off, no light. With the key off, the tester connected to the pos side of the battery, both sides light up. A continuity test between FI plugs 1 & 3 on the ECM side show .3 Ohms. It show the same thing on the pos side of the same 2 FI plugs.
I can understand the .3 on the pos side of the plugs since they should be constantly "hot", but the ECM side is a ground and should be set to fire at different intervals i would think. So what's "normal"?
Thanks for the help
Subman
I can understand the .3 on the pos side of the plugs since they should be constantly "hot", but the ECM side is a ground and should be set to fire at different intervals i would think. So what's "normal"?
Thanks for the help
Subman
Thread Starter
Burning Brakes
Joined: Jul 2003
Posts: 873
Likes: 2
From: Whittier ca
Re: L98 won't start - HELP! (dannydoo)
Danny - just checked the oil and it's ok. I'll try the door lock thing. All the interior light seem to work in normal fashion including the 7 minute delay for radio and such.
Thanks for the reply
Subman
Thanks for the reply
Subman
Racer
Joined: Feb 2004
Posts: 265
Likes: 1
From: Irwindale Ca
Re: L98 won't start - HELP! (dannydoo)
Check the battery terminal. There is a B+ wire that gives juice to the ecm. Sometimes the battery acid rotts the wire and there is no volts to the ECM. Make sure there is a good connection to the battery. there aint no fuel squirting if you squirt start fluid in the plenum. 
Thread Starter
Burning Brakes
Joined: Jul 2003
Posts: 873
Likes: 2
From: Whittier ca
Re: L98 won't start - HELP! (jfb)
I just re-read jfb's posts and came across "spark control module" If this has taken a dump, could that lead to the ECM no firing the injectors? Just a thought.
Madmike - will double check the cables - thanks
Subman
[Modified by subman, 12:36 AM 6/22/2004]
Madmike - will double check the cables - thanks
Subman
[Modified by subman, 12:36 AM 6/22/2004]
Thread Starter
Burning Brakes
Joined: Jul 2003
Posts: 873
Likes: 2
From: Whittier ca
Re: L98 won't start - HELP! (dannydoo)
Danny - yep. Didn't lift the hood. No water in the engine compartment. Fired right up in the morning. Wouldn't start in the PM. Don't make a lot of sense, do it.
Instructor
Joined: Jun 2004
Posts: 138
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From: ronkonlkoma ny
Re: L98 won't start - HELP! (dannydoo)
it sounds like the bullsheet alarm system..somehow its on the fritz..even the moisture will make problems..not to mention what drips into fire wall onto who knows what..id post a question?anyone know?to bypass alarm?
most likely it will start in a day or two if it moisture...your getting spark but no fuel why?im not even sure if the alarm kills fuel or spark?are you trying these suggestions now??
most likely it will start in a day or two if it moisture...your getting spark but no fuel why?im not even sure if the alarm kills fuel or spark?are you trying these suggestions now??
Thread Starter
Burning Brakes
Joined: Jul 2003
Posts: 873
Likes: 2
From: Whittier ca
Re: L98 won't start - HELP! (dannydoo)
danny - done that - had it disconnected overnight - still nothin'. This s**t is really frustrating. I'm trying anything I can within reason at midnight. Will do a search on disconnecting VATS. Thanks for the input!
Subman
[Modified by subman, 1:05 AM 6/22/2004]
Subman
[Modified by subman, 1:05 AM 6/22/2004]