87 gn slow drain


Jan 14, 2003
i just bought this 80.000 mile car that’s been sitting for looks like 30 but they said 20 years in a barn. And it wasn’t driven or taking care of. It’s got stock everything even the chip. It’s got a horribly rough idle when it’s cold. My main concern right now it has a slow battery drain. I got rid of the never start battery thinking that was part of the problem and put a optima on it. It sat three weeks and I barely got it started. My question is can these cars sit with the battery disconnected until I figure it out? Any help will be greatly appreciated even on the idle. Thank you!
Yes it can sit with the battery disconnected . If it's been sitting for that long there are a bunch of things that need to be addressed before proceeding . Does it have fresh gas in it , if not drain it . Get a Turbo Tweak chip from Eric , the stock chip is no good for todays gas with to much timing ..... it will run much better . Check ALL vacuum lines . that's just for starters , others will chime in .
A 50 - 80 ma drain is normal with the battery connected .
Thanks will do. the gas tank has been cleaned (I was told) anyway. when driving down the road the car shakes even the rear view mirror shakes. it has new tires and tracks straight. Maybe it needs motor/ transmission mounts and possibly body bushings
Has it been sitting on those tires a while ?? If so they could be flat spotted from sitting in one position , or lost a wheel weight .
I was told they were new. But they had put wood blocks underneath the front bumper fillers to hold them up to. And I was so exited about getting another gn i didnt notice it had the wrong headlight bezels and marker lights. My fault totally


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Congrats on the car...now open your wallet...roll up your sleeves and start wrenching.

New fuel pump
New injectors and TT chip
New fuel filter
New stock spark plugs from the dealer
New thermostat
Remove radiator and clean it
All new vacuum lines
New timing gear set
New valve springs-981's
Inspect the brakes-Replace as necessary
Hotwire kit

Rest of you guys jump in cuz there's prolly shit I forgot.
Thank you. Coming from two guys who have went 10s on stock blocks that means a lot. You have to take the good with the bad. I haven’t owned a gn. Since 2009. The first car my 26 year old son drove was a grand national thank you
Run a compression check on it and see where you stand mechanically with the engine. These cars are lots of fun, but close enuf isn't good enough. Happy spooling!
I'd have the battery tested, Optima Batteries are NO longer Optima...they just carry the name, they are now Johnson Control batteries, and just don't last. I went thru 2 within 3 1/2 years, will NEVER buy one again
Fan delay relay is a good candidate for the battery drain. If it’s still connected go ahead and disconnect it. The delay relay original function was to run the cooling fan after shutting off the car and they have a reputation for causing issues like battery drain.
Go ahead and get a Battery Tender. The cheapies are no good and don't last. I tried Schumacher and it lasted about a year. The green Battery Tender works best. An everyday car will go dead eventually as well.

If it shakes going down the road, a bent wheel is very possible. Jack up the car and spin the wheels one at a time with a fixed pointer almost touching the edge of the rim lip.
Slow batter drain could be cause by radio from what I read on other posts. Don't recall all the details but maybe someone can tell which type of stock radio may cause the slow drain.