1989 SHO stalls

[dewey630]

Ok...here is a good one. my sho had been in storage for 4 years. when i went to start it, it would crank but acted as if no spark. I ended taking to the local tech school to let them try to see what it can be. They ended up replacing the power pack, and all was good till the next morning. I started it, backed out of the garage and it died. Cranked and cranked, but nothing. I tried it about 4 hours later.....took right off. The next day it made it about 5 blocks till i stopped for my coffee. Again died and wouldnt start right away. The shop checked it out and couldnt find anything, and then it ran perfect all summer. Then one day it died coming home from work. Towed it back, it started the next day, and died 1 mile further down the road. Currently its in the driveway. I tried it yeaterday, and wouldnt you know it, it fired up....so i let it run. But again it died after about 5 minutes of running, and wouldnt start again. Anybody got any ideas, its driving me nuts trying to figure it out. Thanks

[shorod]

You really need to determine if it is lacking spark or fuel when it fails to start. If you don't have access to a fuel pressure gauge or spark tester, then after cranking the engine over for a few revolutions with a no-start, pull a few spark plugs and see if they are wet with fuel. If so, you are getting fuel and probably no spark.

If you have fuel but not spark, the Crankshaft Position Sensor (CKP) has been known to fail on the SHO V6. The CKP is not easy to change and while in there, you should consider changing the timing belt and water pump. Often the water pump will start to seep/weep, dripping on the CKP and causing it to fail over time.

If you have spark but not fuel, then the fuel pump is likely weak and failing.

-Rod

[dewey630]

it has fuel....but if its the crankshaft sensor, how can it revive itself after some time of it just sitting there?

[shorod]

The same way a bad solder joint can make contact as it cools (contracts). When hot, things expand and wires / solder joints can go open circuit. Starter motors fail this way, electric fuel pumps fail this way, as do just about any electronic component that fails intermittently.

-Rod

[dewey630]

ok....i know that it had a leaking fuel pressure damper....do you think that may be the cause of the CKP giving a false reading?

[shorod]

Have you confirmed that the CKP IS giving a false signal? I don't see where you've confirmed that it doesn't have spark when trying to start it. Keep in mind though that even if it doesn't have spark, that doesn't CONFIRM that the CKP is bad, it could also be the ignition module and probably a couple other things as well.

-Rod

[big white bufflo]

lets start and give some code numbers the crank sensor will cut in and out at a wim so will the ignition moduel these cars are very hard to diagnous because the lack of code retention i the computers only if the trouble is constant will the code stay there do you have a check engine light on now next time it happens check for spark then go from there