Darn thing won't start

[seandublin86]

I've got a 1987 GN that's giving me some trouble. It's turning over okay(shouldn't be the starter) but just refuses to start. The fuel system checks out fine. Just wanted to get someone else's ideas on where to check next. I was thinking maybe the mass air flow sensor could be bad? I've got a guy looking at it who wants to check the ignition system out(MSD), but I'm trying to save money. lol. Any help or ideas would be appreciated. Thanks

 

[fontana]

Mass air sensor is not used during starting.....

Wayne

 

[WIKEDV6]

Do you have spark? Is the power to the computer ok? No spark, You may have a crank sensor or module issue. Need more info.

Prasad

 

[QWK]

This site helped/is helping me.

GN Tech

 

[seandublin86]

Please forgive my ignorance (I'm very new to working on my car by myself, I know, shame on me, lol), but what is the best way to go about testing for spark? Or for that matter checking the power to the computer? Thank you for responding also. Glad to know I'm not alone out here.

-Sean

 

[Mad_Trbo]

I know for the longest time I was having an issue with my car starting. checked fuel, checked spark and a host of other things and it turned out to be my ECM. Are you getting the service idiot light on the right hand side of idiot lights when you turn the ignition on?

To check he spark you can simply pull th boot off the plug and put it next to the head and see if there is an arc.

 

[Squid4life]

One way is an inline spark tester. It looks like one of those cheap electrical test lights only for spark. One end goes on the plug, the other goes in the wire. Good tool to have in the box.

If you do not have the above, just pull the plug (or use a spare) and lay the plug with wire attached on a metal surface like a bracket or on the head (so it is grounding) and have someone turn the motor over to see if it sparks.

I am not sure of any problems this could cause with the ECM, I am used to old carb'ed crap that you can't hurt.

 

[Quick6'n'-K.C.]

Step 1

Turn key on, varify that the ses light comes on, aka check engine light should come on when key is on, this means power is getting to the ecm.
If not, orange wire at positive cable isnt getting power, cable can be corroded, no power to computer, reroute power to ecm, varify that check engine light works.....
Step 2
Check all fuses at fuse panel, may be bad fuse for fuel injectors, or.....

If you have a light, crank motor over, if no fire, unplug maf, pull hard pipe off to throttle body, crank over, if it blows air OUT toward your hand, then the timing chain has slipped.
Pull intercooler, balancer,timing cover, replace with new chain and good to go.
Step 3
post back before you pull the car apart
BW

 

[DMan]

Was the car running before?? What are the events that led up to not starting? How old/condition of car?

Keep your search simple. Then get complicated later.

No start - three basic needs are fuel, air, and spark. Oh and a good battery.

Fuel - no tools? Assuming tank has adequate fuel and fuel is good (not very old). At a minimum, turn key to on. Wait 2 seconds for fuel pump to stop (you should hear the pump - if you dont - problem). Then key off. Then unscrew cap on end of fuel rail. Press valve in rail with pen tip or screwdriver (keep a rag right there). Should spray out fuel. No spray - problem.

Air - assuming no blockages. Filter clean. Try cranking with throttle lightly depressed. NOT fully depressed.

Spark - get a spare plug, any plug, pull a boot, attach boot to plug, lightly visegrip the plug body to something metal for grounding and in a place where you can see it. Crank. Should see spark. If you don't - problem.

Battery condition/voltage?

If these simple checks find nothing, then your problem is more complicated and may involve electronic signals, mechanical timing of events and so forth. Report back and we can get more complicated from there.

 

[Quick6'n'-K.C.]

Was the car running before?? What are the events that led up to not starting? How old/condition of car?

Keep your search simple. Then get complicated later.

No start - three basic needs are fuel, air, and spark. Oh and a good battery.

Fuel - no tools? Assuming tank has adequate fuel and fuel is good (not very old). At a minimum, turn key to on. Wait 2 seconds for fuel pump to stop (you should hear the pump - if you dont - problem). Then key off. Then unscrew cap on end of fuel rail. Press valve in rail with pen tip or screwdriver (keep a rag right there). Should spray out fuel. No spray - problem.

Air - assuming no blockages. Filter clean. Try cranking with throttle lightly depressed. NOT fully depressed.

Spark - get a spare plug, any plug, pull a boot, attach boot to plug, lightly visegrip the plug body to something metal for grounding and in a place where you can see it. Crank. Should see spark. If you don't - problem.

Battery condition/voltage?

If these simple checks find nothing, then your problem is more complicated and may involve electronic signals, mechanical timing of events and so forth. Report back and we can get more complicated from there.

Excellent post there early bird :wink:

KISS Keep It Simple Stupid, i always try and treat everything broken the same, keep it simple and its much easier to figure things out the easy way.

BW

 

[seandublin86]

A little history on the car: I've owned it for three years and it is used mostly as a Sunday driver or trips to Tahoe (in the summer of course ). I think I've put a little around 5000 miles on it since I have owned the vehicle. Bought it from a friend I used to race with up at Sears Point. When he raced the car I now own it ran mid 12's just over 100mph. I have yet to take it to the track. Also, just installed a new battery. Aftermarket: ESP front mount intercooler, MSD ignition, TA-49 Turbo, Aluminum Headers, Green Stripe Injectors, K & N filter. So the car was running fine for a while, had an issue with a drained battery (probably from sitting too long in the garage with the alarm activated). Tried to smog it in July, but alas it is a gross poluter right now. Then, just about a week ago I started stalling a few times, but would fire back up. It started this morning and stalled after about fifteen seconds. Sounded kinda rough. So, it's geting fuel initially at least, and there's a spark.

 

[DMan]

So it has a new battery, but the battery died?

Did you charge the battery?

What chip do you have?

If the battery is fine, some suggestions:

0. Can you check for any stored trouble codes? Do you know how to do that?

1. hook up a fuel pressure gauge, and start. Watch the gauge as it runs and dies.

What does "tried to smog it" mean?

 

[Quick6'n'-K.C.]

Then, just about a week ago I started stalling a few times, but would fire back up. It started this morning and stalled after about fifteen seconds. Sounded kinda rough. So, it's geting fuel initially at least, and there's a spark.

Pull the up pipe off the throttle body, unplug the maf sensor wire connection.
Start the car if it runs like normal, revs and idles then you have a bad maf.
BW

 

[deadhorse66]

Pull the up pipe off the throttle body, unplug the maf sensor wire connection.
Start the car if it runs like normal, revs and idles then you have a bad maf.
BW

Good suggestion. Probably not the same, but I have seen the same type of symptom out of an 88 L98 corvette, and it worked out to be the MAF. Like the guys say, you need fuel, and you need to check it with a pressure gauge, and if you have pressure (should at least *start* on 20 lbs), you need to look to see if you have injector drive. You can do this with a small light bulb hooked into the connector for one of your injectors, or a noid light from any good tool dealer. Spark, I think has been covered well enough. Air--that should be clarified a little more. YOu need compressed air, like quick6 said, if it blows back at you, you have a valve timing problem. YOu can go deeper, and do a compression test, just pull all the plugs and stick the compression tester in one of the spark plug holes and crank it over. YOu should have somewhere around 100 psi or so, and all cylinders should be within 10% of one another. If it has all that, it should run, not necessarily well, but should run. Hope this helps.

 

[alvin87gn]

Isnt there also an oil pressure swithc that wont allow it to start till the engine makes a couple lbs oil pressure