Hot Starting Problem.......
12-27-2006, 03:05 PM
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Hot Starting Problem.......
Hey all, my 97 SSE has developed an interesting starting problem. Only when hot, I mean you pull into a store, run in grab something and come right back out (10-15mins), when I try to start it she spits and sputters shakes and coughs until finally reving up a little and the runs just like new. I know GM had problems with some of the older 3.0 V6'* with fuel boiling in the rails. I kind of think this is like that but it is getting worse and taking longer for it to clear. I have had no SES light. Plugs have about 30k on them and the wires maybe 10k. Overall the car has about 88k. My wife drove it a week ago and it did it to her and not knowing any better she kept gassing it and had to call me to get her. She had it so flooded that it took about an hour to get it going. Again.....once it smoothed out it was fine. Has anyone had this problem? Is there possibly a temp sensor that regulates how much fuel is injected that could be (going) bad? Cold starts are no problem at all.
12-27-2006, 03:13 PM
#3
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Try something for us.
Take the vacuum line off the FPR and see and smell for fuel in that line. It almost sounds as if a possibility is that your FPR is sticking open when warm.
Edit: I had thought of the cracked coil possibility too and agree that that should also be checked for.
Take the vacuum line off the FPR and see and smell for fuel in that line. It almost sounds as if a possibility is that your FPR is sticking open when warm.
Edit: I had thought of the cracked coil possibility too and agree that that should also be checked for.
12-28-2006, 08:34 AM
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Okay, I drove her into work this morning and pulled that vacuum line off of the FPR with the engine hot. I can smell fuel in the line. I did not see any though. I also checked over the coils the best I could without removing them.....they look ok!
12-28-2006, 10:28 AM
#5
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The coil testing procedure is in Techinfo. I'd suggest doing one test hot, and the other cold.
Keep in mind there'* an Ohio meet coming up mid-January. If your car can make it, we have a couple good guys that could take a look at it.
Keep in mind there'* an Ohio meet coming up mid-January. If your car can make it, we have a couple good guys that could take a look at it.
12-28-2006, 11:07 AM
#6
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Do you have a meter to check the coils with? You really need to do some diagnostics on this.
In the meantime, read this article I linked and excerpted below and follow the directions to check and see if your fuel pump is running when you try to start it hot.
link: http://www.misterfixit.com/fuelrlay.htm
In the meantime, read this article I linked and excerpted below and follow the directions to check and see if your fuel pump is running when you try to start it hot.
ELECTRIC FUEL PUMP RELAYS CAN FAIL CAUSING HARD STARTING
There are a zillion cars out there today that use the oil pressure sending unit as a dual function switch, the first function to send oil pressure information to the dash gauge or idiot light and the second function being to run the fuel pump after the car starts. During the start cycle there is a fuel pump relay that takes over to run the fuel pump. After the engine is running that relay turns off and the current for the fuel pump is supplied via the oil pressure sending unit If that relay fails then the car won't start until the oil pressure is up to three or four PSI.
The logic is that in a bad accident the engine would stop, the oil pressure would go to zero and the electric fuel pump would stop pumping fuel through a possibly ruptured fuel line thus preventing a disastrous fire.
When this relay fails the engine will start after the starter motor has pumped up sufficient oil pressure to send electricity to the fuel pump and run it. When you turn off the engine the oil remains in the galleys for a short period of time, typically several minutes for an old worn engine, to a few hours for a new motor with good tight clearances. Therefore, the engine will start up again shortly after shutting it off but typically will be relative hard to start for longer time periods afterwards when the oil pump has to pump the thin warm oil back into the engine oil galleys. When the engine is cold and the oil is thicker it doesn't take too long to generate oil pressure and the car will start up relatively easily, however not as easily as it would if the fuel pump relay were working. The test is to listen carefully when turning on the ignition key to see if you hear the fuel pump running - it'* in the gas tank so listen there for a humming noise. If you hear no humming but the car eventually starts and runs fine, then replace the fuel pump relay.
Bob Hewitt'* Auto Repair Page
There are a zillion cars out there today that use the oil pressure sending unit as a dual function switch, the first function to send oil pressure information to the dash gauge or idiot light and the second function being to run the fuel pump after the car starts. During the start cycle there is a fuel pump relay that takes over to run the fuel pump. After the engine is running that relay turns off and the current for the fuel pump is supplied via the oil pressure sending unit If that relay fails then the car won't start until the oil pressure is up to three or four PSI.
The logic is that in a bad accident the engine would stop, the oil pressure would go to zero and the electric fuel pump would stop pumping fuel through a possibly ruptured fuel line thus preventing a disastrous fire.
When this relay fails the engine will start after the starter motor has pumped up sufficient oil pressure to send electricity to the fuel pump and run it. When you turn off the engine the oil remains in the galleys for a short period of time, typically several minutes for an old worn engine, to a few hours for a new motor with good tight clearances. Therefore, the engine will start up again shortly after shutting it off but typically will be relative hard to start for longer time periods afterwards when the oil pump has to pump the thin warm oil back into the engine oil galleys. When the engine is cold and the oil is thicker it doesn't take too long to generate oil pressure and the car will start up relatively easily, however not as easily as it would if the fuel pump relay were working. The test is to listen carefully when turning on the ignition key to see if you hear the fuel pump running - it'* in the gas tank so listen there for a humming noise. If you hear no humming but the car eventually starts and runs fine, then replace the fuel pump relay.
Bob Hewitt'* Auto Repair Page
12-28-2006, 04:53 PM
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Lash, I do have a meter and I read through the testing procedure that Willwren suggested. I will probably not be able to do it until this weekend. She is due for an oil change and I will do the coil testing then. I will also listen for the fuel pump when hot. The article makes sense! Thanks a lot! I will report my coil findings asap.
12-28-2006, 08:09 PM
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Originally Posted by Bob Keyes
Hey all, my 97 SSE has developed an interesting starting problem. Only when hot, I mean you pull into a store, run in grab something and come right back out (10-15mins)
12-29-2006, 11:41 AM
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I think it had sit for about a 1/2 hour or so. I will check it again before I leave work today after she has been sitting all afternoon. So, I should smell gas or not?