Here are the conditions:

Doesn't always occur. It has happened 3 times in last month (about 15-20 times out with it). When it does occur it seems to happen only when the car is warm (not hot, coolant temp between 130-150 degrees), and after it has sat about 1-3 hours. The car cranks just fine, but seems to get no spark to get it started. After about 10-15 minutes, the car has started fine (kicked right over, just like it should). Car has started/restarted fine when it has been hot (temp around 200 degrees, like after filling it up with fuel, for example) and also when it is cold. The first time this occured was when I turned the key and immediately cranked, before waiting for the fuel pressure to 'charge'. After that incident, I've waited for the fuel pressure system to 'charge' before turning the key to start and it has repeated this situation.

Particulars: car has 149,000 miles and runs great (averages over 20 mpg for highway driving and has lots of pull when going full throttle), fuel filter is about 15,000 miles old, no fuel coming from vacuum line on fuel pressure regulator, coolant temp is around 130-150 when this occurs, spark plugs are about 5000 miles old, spark plug wires about 15,000 miles old, distributor and cap/rotor/coil are all within 15,000 miles as well, throttle body bypass is in play here, but it has been like that for 2 years with no problems.

The last time this happened, I disconnected the TPS and tried to start with it disconnected with no luck. I've heard that the ECM will 'default' to limp home mode with that condition and if that was the problem the car would start.

I'm about a 3 or 4 on a scale of 10 for mechanical skill, however, electrical problems are not my strength. Some of the problem is replicating the symptoms, it doesn't always happen.

I'm guessing some sensor is either not connected or is sending an incorrect voltage. Or a wire problem from a sensor that I haven't found. Any suggestions?

 

ttt

 

I'd say you are starting to see the effects of age on your injectors.
You can see if your ECM is in closed loop or open loop by grounding
the diagnostic terminal and starting the car (at operating temp).
Depending on how quickly your check engine light flashes, you will
see if you're in open or closed loop. I believe if it flashes three times a
second, it's open loop (should throw a code), if it flashes once a second it's
in closed loop. I supect your injectors are just getting old.. I'm sure you'll
notice the hard start condition when hot will worsen with time.

 

Well, its going into a shop, mainly for an alignment, but I'm going to have them take a look at the starting problem.

While taking it in, I received a low voltage warning light (11.4 volts). I think I have a bad connection at the battery and this may be the reason for the hard starting. We'll see.

 

I had a bad earth which caused slow cranking when hot.

I also had 5 crappy injectors.

 

I think I'd be suspecting a fuel problem. Bad relay or pump maybe... Try this: carry around with you in the car a short jumper wire. Loosen the fuel pump relay from the firewall (and leave it that way) so that you can get to the wire harness connector easily. Next time it Does it - try jumping the relay connector (power to pump) and see what happens. A pressure gage handy to hook up to the fuel rail would be nice too - but not really necessary, you can Hear the pump run from under the hood - if it does... I've had a bad pump relay do something similar to what you describe - before it simply quit completely (in the driveway at home, luckily). Jumping from the battery positive terminal directly to the pump wire at the relay connector bypasses everything else in the fuel pump circuit except the fuse, and the tank connector.

 

I agree with rons85 in that it is most likely a fuel problem, but doubt that it is the fuel pump or FP relay. They are often a cause of the problem you describe, however in your case you mention some conditions that cause me to agree with Unriced and suspect problems with the injectors.

If the pump or relays were at fault the problem would most likely occur at other times than just the limited conditions you describe for when it does happen. lf you have injectors that are just marginally leaking, then it takes time for them to leak enough that when you go to start the car it won't start. The amount of leakage is probably small enough that when the car is very warm the excess evaporates. If the car sits for 1-3 hours the leakage is enough after a few hours to flood the car so that at warm start it causes a problem.

You can test this theory out. The next time you know it is happening; stop cranking the engine and push the accelerator all the way to the floor. Hold it there for a second and KEEP it pressed all the way down, try starting the car. If it starts up pretty quickly then it is an injector problem.

When you start the car with the accelerator pedal all the way to the floor the ECM sets "clear flood mode" and cuts back on start mixture assuming the engine is already flooded. When my injectors started to go, "clear flood mode" would usually fire it up pretty quick.

It is also possible (though unlikely) that the coolent temp sensor is off. The 85 has 2 coolent temp sensors. One is connected to the Digi-dash and the other is connected to the ECM. It is possible to see accurate temp readings at the dash and have the ECM not seeing accurate readings from the temp sensor that counts. If the clear flood test doesn't point to the injectors, I'd have the mechanic check the accuracy of the coolant temp sensor to the ECM.

 

check the simple things first

 

My 85 did this. It was caused by leaky fuel injectors. At 130-150 degrees, the engine is still in the cold start mode. The injectors are leaking, so you have too much fuel in the intake to start with. Then the cold start injector kicks in when you try to start. Guess what? Too much fuel to start with, then extra added by the cold start injector. Now you have way too much fuel, and it won't start.

I fixed mine by adding a can of Techron to the next 2 tanks of gas. No more problem.

 

The dealer is telling me its a bad altenator and a bad lead from the battery to the altenator.

I'm skeptical on the bad altenator, since I've been told that the 85 altenator is darn near bullett-proof. I'm having him change the wiring lead from the battery to the altenator, then driving it home where I'll change the altenator ($255 plus 1.3 hours labor vs. $99 for the part and my labor) at my convenience if I feel its necessary.

I'll get it tested first at the local Autozone for a second opinion.

I'm leaning with the leaky fuel injector idea since my conditions matched Dave's.

Thanks for the replies and I'll let you know what the resolution comes out to be.

 

After changing the altenator, car has sufficient voltage, no more warning lite.

However, on Sunday, the car wouldn't start even when cold. I tried, with the key in the 'off' position, to hold the peddle to the floor for 60 seconds and tried to restart after that. No luck. Then I took the air hose into the TB off, held the TB blades open for another 60 seconds, reattached air hose, and it still wouldn't start. Through this attempt, there was the slight smell of fuel in the air.

I also unscrewed the fuel cap (without the normal hissing sound of pressure releasing) and screwed it back on.

After 6 hours, tried to start it and it fired right up.

I'm considering the route of pulling the injectors and sending them to Cruzin Performance in Big Rapids, MI. He's only an hour away from me.

Is there any way to find out for sure that they are leaking? Right now, all I'm finding are symptoms.

 

Resolution:

I'll post this so if someone finds they have a similar problem, they'll have another place to look.

The hard starting condition on my '85 was a result of a bad pick-up coil on the distributor. After replacing, the car fired immediately both cold and warm.

The Haines Manual (surprisingly) has a very nice and detailed section on how to test and replace the pick up coil. It is in Section 5-7. You should have infinite resistance on an ohm meter. If you do not, you need to replace. The test can be done with the distributor in the car.

Hope this helps someone in the future. I've been chasing this problem off and on for the last 4 weeks.

 

i agree , the pick up coil could be it !! good luck whatever you do !