How JustAnswer Works:
  • Ask an Expert
    Experts are full of valuable knowledge and are ready to help with any question. Credentials confirmed by a Fortune 500 verification firm.
  • Get a Professional Answer
    Via email, text message, or notification as you wait on our site. Ask follow up questions if you need to.
  • 100% Satisfaction Guarantee
    Rate the answer you receive.
Ask Peter Bagley Your Own Question
Peter Bagley
Peter Bagley, Toyota mastertech
Category: Car
Satisfied Customers: 813
Experience:  master tech at Toyota dealer
Type Your Car Question Here...
Peter Bagley is online now
A new question is answered every 9 seconds

I have a 1987 Grand National 3.8 Turbo I have no spark when

This answer was rated:

I have a 1987 Grand National 3.8 Turbo I have no spark when cranking. When I let go of the key it starts right up. I'm not a Buick mechanic but I've been working on cars for over 30 years. The ICM has power while cranking and good ground.
JA: Will the headlights turn on? Is the battery fully charged?
Customer: Yes
JA: What year is your Turbo?
Customer: The turbo charger?
JA: Are you fixing your Turbo yourself? What have you tried so far?
Customer: I ran the test on the crank sensor and cam sensor. The ICM is getting pulse from both when the key is in the run position. I have not checked for pulse while cranking. The fuel relay is good. its not a fuel problem. If I put a timing light on #1 plug wire I can see that its NOT firing when cranking only. When I let go the key after cranking a few seconds - the engine fires right up and I can see my timing light start flashing.
JA: Anything else you want the mechanic to know before I connect you?
Customer: No

Hi, I'm Ron and I will be helping you today.
Stand by for a moment while I prepare your answer.

It sounds like your losing the power supply from the ignition switch. The run mode/on mode appears to be the problem.

Thanks, Ron

Customer: replied 12 months ago.
Power supply to what?? The ICM?? I already checked for power to the ICM while cranking and it's got 9.6 Volts

Okay, but it's supposed to have battery voltage.

Thanks again and please remember to rate me 5 stars and keep this mlink in case you need me again later on.


Customer: replied 12 months ago.
Wait a minute! There is nothing wrong with the "run" "on" mode. It starts and runs in the run mode. The problem is only when "cranking"!!!
Customer: replied 12 months ago.
Are you still there? Did you read my issue thoroughly?

I meant to address the crank mode.

You said that you checked the crank and cam sensors, how did you test them?


Customer: replied 12 months ago.
I tested them with an LED test light. I have pulse 18X and 3X when key is On. as I said - I have not checked for pulse while "cranking ".

Here's how to test them with a scope and how they should look. That test won't show us operation, just power in and out.


Customer: replied 12 months ago.
To my knowledge the crank and cam sensors are bypassed when first cranking the engine.
Customer: replied 12 months ago.
The engine won't start when "cranking" because there is no spark. Why does it not have spark when cranking??

That's wrong, then how would number one be recognized for timing and also synchronizing #1 for fuel injector synched pulses?

Thanks, Ron

Ill opt out

Customer: replied 12 months ago.
I can see with my timing light that there is no spark when cranking. As soon as I let go the key and it's in run position the engine fires and the light flashes indicating there is spark.
Customer: replied 12 months ago.

Hello and welcome to just answer, I see your having trouble starting whit key turned to crank? sometimes with these newer cars we forget the basics.remember what they refer to as reserve power? that's the voltage left in the battery going to the ignition while the starter is drawing to turn the engine. today's cars require a higher reserve then the older ones .The cause of not enough reserve can be, a weak battery. to much starter draw . The first thing to do is a load test on the battery to see if it will hold up under load , the next thing is to do a starter draw test and see what voltage is left for the ignition circuit. at least 10 volts Yoy see when your holding the key to turn the starter all or most of the power is going to the starter and as soon as you let the key off there is enough to start .

Customer: replied 12 months ago.
Hi Peter, Thank you for helping me on this Buick problem. I appreciate you reading about my specific issue and giving me a very straight forward answer. I have a load tester and will check the condition of the battery. I can tell you from my tests that I have 9.6 volts during cranking. The starter motor turns fast but is drawing power down to the ICM to 9.6. I tested it at the pink/black wire while cranking. It shows 9.6 on my meter. Is this not quite enough for this engine to produce spark? During cranking I have NO spark which I test using my Snap-on digital timing light.

what I would do is use one of those cheap spark testers, because I like to see what color the spark may be as well. if you can't get one at least take a spark plug out and see if indeed you have any spark and if it's orange or blue. I'll give you a pic of that spark tester so you know what I.m talking about, they are handy. The second one is good because you can actually adjust the air gap to match your spark plug gap. You can still be getting a weak spark that the timming light may not pick up that's why I'd use this or at least pull a plug and ground it. Don't forget to do that stater draw as well.

Customer: replied 12 months ago.
Hi Peter, I will get the spark plug tester you recommend. Good to have in my toolbox. Thanks for the pictures, that helps a lot.
I put my big battery charger on the car and after 30 minutes I gave it a try. The car started right up! Without the battery charger on it seems to turn over a little slower but it did start. I probably need a new battery. This Die Hard is about 4 years old. I want to check with you about the starter motor. When I test it if it draws down to 9.6 volts while cranking is that too much draw? If so, are you implying it may need a starter motor?

no not at this time you cannot get a proper reading with a tired battery so replace the battery first then if no problems good to go.I am one of those practical guy's that likes to save money , LOL

Peter Bagley, Toyota mastertech
Category: Car
Satisfied Customers: 813
Experience: master tech at Toyota dealer
Peter Bagley and 3 other Car Specialists are ready to help you
Customer: replied 12 months ago.
Gotcha! Thanks for your straight forward answers. I think I've got this resolved now. I really appreciate it. Thanks for taking over from the first guy. Unfortunately, he didn't help me at all. If I hit the thing at the top of this page with 5 stars will you get the credit?
Customer: replied 12 months ago.
If I want to talk to you some other time in the future how do I request you??