Trouble starting when warm

JasonMiller94SC

Registered User
I've been trying to trouble shoot this problem for awhile now and I'm stumped.

If the car (94 SC) sits over night I can go out in the morning and starts it right up. However, if I drive it and get up to opperating temp then shut if off it dosen't want to start. It will crank and not fire. Sometimes I have to try it 4 times and it then starts or like the other night I tried about 12-15 times till the battery was dying and it never fired. I waited 10 min for my girl to come give me a jump and as soon as I hooked up the jumper cables it started right up.

I've tried replacing the cam position sensor, I've tried changing the position sensor as I thought maybe I had gotten it out 180 degrees. I've checked the wiring to the sensor.

I just took it for a drive and it runs great. Screams up to 6000 rpm. But, when I pulled back and in driveway and turned it off I took 4 tries before it would start again. Let it run 2 min and turned it off then tried again once and it's not starting again. I'm guessing if I wait a couple hours and go out when it's cooled off it will start fine again. (Edit: I waited 2 hours and tried it again and it started right up on the first try)

Any ideas?
 
Yea it's chipped. But, it's been running the same program it was dyno tuned on for 5 years.

I'd have to take it somewhere to have the program looked at since I don't have any tuning software and the closest tuning place to me can't do anything with the SC computer code I'd have to make a road trip somewere to get it looked and and I might not make it back if it won't start. :confused:
 
poss starter getting old and not taking heat soak well(drawing high current and drop voltage to ign) connections or even battery getting weak. maybe an inj stickingor not sealing well(can check that w press gauge and sea how long it holds pressure after you shut it off). hope you find it,
brian
 
Starter turned the motor over just fine untill I got to about 10 starts in a row the other day. then the battery started to drop off too much and then it cranked slow.

I do have a pressure gauge I can put on the fuel rail so I'll look into doing that.

Guy at work suggested it might be the igniton module. That sound like a possiblity? I was thinking of snagging the one off my girls ride and driving the car a bit to see if that gets rid of the problem.
 
Double checked the Cam position sensor today and I think I had it off by about 5-6 degrees. After setting it I let it warm up in the drive way, shut it off and then started it right back up. Let it run for a couple min shut it off and then started it right back up again.

30 min later I came out, started it right up and drive it to the store to pick up some stuff for dinner. Came out, took 4 tries before the damn thing would start. Got home, shut it off, tried once to start it and just cranks.

I'm really running out of ideas on what the problem could be and I hate to just start throwing parts at it.
 
Check the battery for a dead cell. I had the same problem on my F100, would start great cold, you drive 5 minutes or 5 hours and it would not start. I changed my whole ignition system and it still did not start until I changed my battery. Hope this helps
Jerry
 
I'm having the same issue. Mine seems to happen once reaches operating temp. Since been working 50+hrs a week hadn't tracked it down yet, though not much of issue for me usually since go to work and let it then sit for 10+hrs and go home and gas station is right next to work.
 
Thanks for the battery tip. This morning I stole the 2 month old battery out of my girl's 94 SC (exacly the same battery I have just 3 years newer). Started it up and took it for about a 5 mile drive.

Came back to the driveway and the same exact problem remains so I can rule out the battery being a problem.

Something else I'm thinking is could it possibly the crank position sensor? Sometimes when hot and I'm cranking it the motor acts like it hits a compression stroke and just stops cranking. Then if I release the key and try again it will start cranking again. Then sometimes when hot it will fire up and start so quick that you can hear the teeth grind on the starter cause I can't let go of the key quick enough before it starts. Then sometimes it will even backfire.

When I look at autozones website about the crankshaft position sensor it says:

" When not replaced, vehicle could experience no- or hard start, long crank time, misfire."

Anyone know a way to test the sensor or should I just get one for 20 bucks and see if it helps? I really hate throwing money at a car trying to fixed it but I'm not sure what else to try. And I'm really confused if the sensor is a problem that it only fails when hot.
 
It's such a P.I.T.A. to get to I think I'd rather just spend the 20 bucks.

After doing some reading about the crank sensor wouldn't the car just shut off if it failed while I was driving? It's never done that.

What's the best way to check for vacuume leaks? Run some propane around the motor while it's running and wait for it to stumble?
 
Just took the car for a drive and got it nice and hot. Came home and shut if off and just for the heck of it tried to start it. Fired right up. I hate trying to troubleshoot interminit problems.
 
Assuming its the same issue for us all we can rule out (because cover 89-93 and 94/95s).
1) Ignition Module
2) Crank Sensor
any thing else?
 
The only time I have ever had anything similar to what you're discribing is was my balancer was going or the crank sensor was on the way out...You have a BHJ on your car though right? I would assume so with the built bottom end...so kind of rules that out.

I'd try the crank sensor...its not to bad to get at from underneath.

-Tim
 
Had a similar situation on my car before it got tuned. I turned up fuel pressure and it helped. My starter was going too. I'd put my chips on the starter. The local auto parts store can hook it up to a machine.

On my previous car it was a bad battery ground, rotted insulation. Make sure it's not all gummed up at the engine block terminal.
 
Checked the fuel pressure today and it's good but I did poke around and I hear a small hiss coming from the underside of the upper inncooler tube where the top colar screws on. Next on my list to do will be to remove the upper tube and reseal it to see if that helps.
 
Checked the fuel pressure today and it's good but I did poke around and I hear a small hiss coming from the underside of the upper inncooler tube where the top colar screws on. Next on my list to do will be to remove the upper tube and reseal it to see if that helps.

I was just about to post that mine used to do the same thing when I had a leak on my collar nut. Tightened it up and it fixed it. Now its another problem on mine lol
 
Well the good news is I fixed the leak around the collar nut by putting a new o-ring inside the inner part the the nut screws to. The bad new is that it still did not fix the hot starting problem.

Drove it very easly to the gas station to put some fuel in it and took 3 tries to start. Pushed on it a bit on the 2 mile drive home (still pulls hard when you floor it) and got in the drive way and tried once to start it and it didn't fire.
 
Back
Top