1990 ZR1 problems

[Randall1]

Hello all, I have a 1990 ZR1 with 32k miles on it that has been in storage for about a year. I have started the car every month and wamed it up. The last time I tried starting the car it stumbled and backfired and the SES light stays on. The car did start and runs but not with the power it normally has. I checked the vacuum line in the back (hard to get to} and made sure it was tight. Checked the plugs and they look good and when I turn the key on I here the vacuum pump go on and then turn off like it should. I bought a fuel pressure gage today and a new fuel filter and will check pressure and change the filter tomorrow. I was just wondering if any of you folks have any ideas before I tear into the car. The engine intimidates me a little but I am pretty handy with a wrench.

Thanks,
Randall

Randall, welcome to the group. More than likely you had a back fire from not holding the key over long enough while the engine was starting. You can take a flashlight and peek at the backside of the plenum and you will see the mao sensor. On the underneath side you will have an electrical connection and and a vacuum connection. The vacuum connection has more than likely come off at that point. Just reach under and reconnect.

BTW, check out our local group site www.pnwzr1.net

I also run a shop in Battle Ground and have a few guys that come down from the SeaTac area for service.

[Randall1]

Hello all, I have a 1990 ZR1 with 32k miles on it that has been in storage for about a year. I have started the car every month and wamed it up. The last time I tried starting the car, after many cranks it stumbled and backfired and the SES light stays on. The car did start and runs but not with the power it normally has. I checked the vacuum line in the back (hard to get to} and made sure it was tight. Checked the plugs and they look good and when I turn the key on I here the vacuum pump go on and then turn off like it should. I bought a fuel pressure gage today and a new fuel filter and will check pressure and change the filter tomorrow. I was just wondering if any of you before I tear into the car. The engine intimidates me a little but I am pretty handy with a wrench.

Thanks,folks have any ideas
Randall

[Randall1]

Thanks for the info. I did check the hose on the backside of the plenum and it does appear to be attached but will try to see if any cracks are in it using a mirror today. Last year it did come off and I re-attached it. The more I read the more I think the injectors may be a problem. I will check the fuel pressure and also buy a bottle of the injector cleaner (Redline I believe) and see if I can get it started and run it till warm.

Randall

[4DSZR1]

No problem running in northwest today Cold and sunny

[Sgreg]

If that gas has been in your tank for a year without a stabilizer, it may be contaminated with water. That will not help injectors. Just a thought.

[Randall1]

Ugh.......... it might be bad gas. No stabilizer for a year is not a good thing if the car has been sitting over a year. Live and learn I guess.

Randall

[Randall1]

Well, I spent a couple hours tracing all vacuum hoses looking for disconnections and found none. Should be getting my scout 2500 scanner in about 4 days so can pull the codes and see what is happening. The story gets better. After getting in my car and having it stumble and try to start I keep looking at the gas gauge making sure it has gas and it reads half full. I then decide the gas is bad and decide to drain and put new premium in. Total amount of gas to empty tank was about 3 quarts........EMPTY. I put 10 gallons of new gas in and tank reads full but at least I know I have enough gas and fresh. Try to start and stumbles coughs backfires and finally starts and after warm runs ok except SES light on and of course NO secondaries. The car does not want to start the next day but will if cranked for awile but I am not willing to risk burning the starter motor up so will continue my adventure. I did purchase a new fuel filter and will install today. Always open for suggestions.

Thanks,
Randall

[tccrab]

Dig out a paperclip and pull the codes.
We'll need to know what is triggering the SES code.
Remember, you only need three things for the car to start, fuel, air and spark.
It's getting air so that can be ruled out.
There's a fairly straightforward procedure to check the fuel pumps, and of course do change the fuel filter.
I doubt seriously that all your primary fuel injectors have gone south at once, but you never know......
And it would be very unusual to lose all 4 coil packs at once...
Bad O2 sensors will cause all kinds of fun stuff after the car goes into closed loop, but the engine should start correctly.

Pull the codes, work from there...

Randall, I'll be up in Seattle this weekend for the swap meet. I'll be dropping off a ZR-1 for a customer as well. I am willing to come by and check it out for you.