Car starts but wont stay on

Rob Lyons

Member
Feb 10, 2018
41
2
8
36
San Francisco / San Jose
Hi everyone, just brought a new toy home and now I’m trying to figure her out. I just bought an 87 grand national with what looks like stock everything. I was able to get the car to finally start after doing a few minor tune up things like new plugs, maf sensor and coil and ignition. Now the car starts, but it wont stay on. Any suggestions.
 

SteveZ82

Member
Mar 31, 2019
72
10
8
37
Hi everyone, just brought a new toy home and now I’m trying to figure her out. I just bought an 87 grand national with what looks like stock everything. I was able to get the car to finally start after doing a few minor tune up things like new plugs, maf sensor and coil and ignition. Now the car starts, but it wont stay on. Any suggestions.
What do you mean it doesn’t stay on? It just dies? Does it start again? I’d check your fuel pressure and fuel filter. Check the pressure on the driver side fuel injector rail. Fuel filter is near the the rear driver quarter. Bad gas? How many miles? There are other things like the crank and cam sensor but do the simple stuff first.

Report back. Happy to help. Great community here so we’ll get you going.


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Rob Lyons

Member
Feb 10, 2018
41
2
8
36
San Francisco / San Jose
What do you mean it doesn’t stay on? It just dies? Does it start again? I’d check your fuel pressure and fuel filter. Check the pressure on the driver side fuel injector rail. Fuel filter is near the the rear driver quarter. Bad gas? How many miles? There are other things like the crank and cam sensor but do the simple stuff first.

Report back. Happy to help. Great community here so we’ll get you going.


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I’ve checked the fuel pressure had to be adjusted a little bit but it holds. Dropped the tank and cleaned it and put it back up, also powered pump while down to make sure it was running. The gas was piss yellow. Changed the plugs.
 

Rob Lyons

Member
Feb 10, 2018
41
2
8
36
San Francisco / San Jose
Was this "stock everything" GN sitting for an extended period? Like in years?
Any scan tools available?
Yes it was sitting since 2012. I took my computer with a powerlogger out of my running gn and am now using it to scan. If I keep my foot on the gas it will stay running and I did that for about a minute and it didn’t throw any codes.
 

GNRick

Retired member
Mar 21, 2004
5,083
208
63
60
Champaign, IL
Maybe a bad IAC valve? Are the iac and tps set correctly? You could also spray out the throttle body and iac hole with throttle body cleaner. Couldn't hurt.
 

ttypewhite

Well-Known Member
Oct 1, 2001
3,234
579
113
46
Toronto
Sounds like you already took off your air inlet pipe from the MAF to the turbo. Any air leaks in that pipe to the turbo will do that. Make sure the pipe itself is in good condition and that it is clamped down properly. Also verify that you plugged back in the MAF harness.
 

Rob Lyons

Member
Feb 10, 2018
41
2
8
36
San Francisco / San Jose
Could be the injs are sticky, and some may be sticking shut, to the degree, it won't idle on the remaining cylinders.
I was thinking about the injectors. I have some close to stock injectors that worked for me before I switched to bigger injectors on my other one. I’m going to switch them out today and see. I also think I will switch the iac out first then the injectors.
 

Rob Lyons

Member
Feb 10, 2018
41
2
8
36
San Francisco / San Jose
Sounds like you already took off your air inlet pipe from the MAF to the turbo. Any air leaks in that pipe to the turbo will do that. Make sure the pipe itself is in good condition and that it is clamped down properly. Also verify that you plugged back in the MAF harness.
The maf pipe is a chrome 3” so no holes. I have a reman ac delco from my warehouse where I always use to get my stock mafs. And they always worked. But, to make sure I put my translator to it with my ls1 maf and it started doing the same thing.
 

Boostrules

Member
Mar 16, 2013
131
14
18
64
New Jersey
HAPPY THANKSGIVING everyone. I’m thankful for this board and the next 4 days off to do what ever I wish to this car while the wife is busy with out oops i mean in-laws.
Reminds me of an old joke. What's the difference between outlaws and in-laws? Outlaws are wanted.
 

Rob Lyons

Member
Feb 10, 2018
41
2
8
36
San Francisco / San Jose
Hope everyone had a great holiday. Mine turned out not to be so bad after all. I got the car running and idling just fine now. Thru a combination of things and suggestions i was able to get everything going, let me explain.
First thing I did when I got the car home was put a new maf on it since I thought that that was the problem in the first place. Even swapped over my maf and translator to see if that would work it didn’t. So, I checked fuel pressure. It seemed to be fine a little low on the pressure side but held pressure fine. Raised the fuel pressure just a few pounds to get it at 43 psi line off. That didn’t do it it still stumbled out after a few seconds. Keep in mind I’m still using my maf from my reputable parts dealer. While releasing the pressure out of the fuel gauge I noticed the gas was piss yellow, so I dropped the tank. In doing so while trying to pump out the gas by powering up the pump I noticed the pump would ground itself out for some reason after priming. So, I cut out the hotwire kit and wired it up normal. And what do you know the pump started pumping when I powered it up.Next I changed the plugs and they were fouled out to the max. I then tried starting it same problem, it would start then stumble out with in seconds. As if the ignition was being cut out. I remembered there was an alarm in it so I went through the task of removing the alarm and reconnecting all the wires. While doing so I found a wire cut to the esc module. Reconnected it and tried again. Once again it stumbled. So, I got on the forum and threw out there what was going on. It was suggested to try my iac which was my next thing to do so i did it. This time after changing the iac the car stumbled but caught itself and tried to adjust. Did this for about a minute and died out. Then I got this great idea because I’ve seen these symptoms before to unplug my great new maf from my reputable dealer and what do you know the car stayed on smoothed out and idled like a champ. At this point, I threw my translator back in with new piping and it idled like a champ. Also threw my coil and ignition module on from my working gn before i did the spark plugs. Once the car got running I took it off to see if the original coil and module would work, turns out the ignition module was bad as well.