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Randall C
Randall C, ASE Master Tech
Category: Chevy
Satisfied Customers: 11453
Experience:  ASE Master, L1, 32 years, Diagnostic / Electrical Specialist
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2002 Impala: 3.8L..engine, will not start until it has sat

Resolved Question:

2002 Impala, 3.8L, Loaded with everything
After driving sufficient distance to thoroughly warm up engine, will not start until it has sat for at least an hour or so. It turns over OK, and tries to start, but just won't. Let it sit for a while, it starts right up, Never dies while driving or idling, just won't start after warming up good and being shut off for a few minutes. Replaced the fuel filter, no help. Have purchased a new complete fuel pump kit ($300), but don't want to install it until I know for sure it will help. Seems to me that the "hot or cold" factor would point toward something electrical. Someone please give me some clue. Thanks
Submitted: 5 years ago.
Category: Chevy
Expert:  Randall C replied 5 years ago.
hello, are you familiar with the fule pressure test port on the fule rail on top of engine? looks like a large bike tire valve with black cap. lmk we will go from there
Customer: replied 5 years ago.
Yes, I'm familiar with the FPTP
Expert:  Randall C replied 5 years ago.
The best way to test for lack of fuel is: wait till you know the car will not start right up. Do not keep trying to start car, stop. Push the pintle on the test port. You should get a fairly decent spurt of fule. use a rag for safety. If you get a dribble, etc,, the fuel may have flowed back or the pump could be going bad. yes, a fuel pump is very much temp sensitive. Nearly 75% of all fule pump failures happen at the gas pump due to ice cold fuel from undergroung hitting a hot, weak fuel pump. As a pump sits, the temp of the pump actually climbs since no fuel going through to cool it. I am not ruling out an igniton problem but like you asked, you need to eliminate pump as the problem. You can also spray some carb cleaner into throttle body when sure of a not start. If car starts/stalls,. upon spraying some cleaner, most likely the pump is going bad. Ignition failures most common are : ignition module and crank sensor. heat affects both
Customer: replied 5 years ago.
Tracer2; I drove 20 miles to warm up engine, then wouldn/t start. Got good fuel spray from test port. Then started right up on next try. Tried over and over and started every time. I'm really puzzled now. Got any thoughts??
Expert:  Randall C replied 5 years ago.
It sounds like you maybe you removed an air pocket by letting pressure out. I am thinking a fuel pressure test would be the way to confirm. next time no start, carry a rubber mallet or similar and bang hard on the bottom of the gas tank . Try to start immediately. If it fires after just a few revolutions of engine, you need a pump. You could always get a fuel pressure guage at the local parts store. They really are inexpensive for the off brands. I am still leaning to fule delivery problem. Pump, regulator, air lock etc..
Customer: replied 5 years ago.
Remember, on this Impala, fuel pump does not mount in gas tank, so don't know what banging on the tank will accomplish. Maybe I don't understand exactly. Fuel pump mounts behind rear driver side wheel with access thru a cover plate in the trunk. Make any difference??
BTW, with ignition on, dash light alternates between battery and security. I think that's normal, but not sure.
Expert:  Randall C replied 5 years ago.

Starting with fuel pump. It is located in the tank through the top. i have no information stating otherwise. This is where GM has put the pumps for years now. It is a 1.8 hour job not including the4 drain and fill of tank. I have not ever seen the fule pump located behind wheel well. Sorry. here is the info. If I am wrong, I will opt out and let another expert jump in but... never seen one outside of tank and never heard of one outside tanks either.

 

graphic

Replacement procedures for the Fuel Pump/Fuel Sender Assembly can be found under Fuel Tank Unit, See: Fuel Tank Unit\Service and Repair

 

Customer: replied 5 years ago.
My bad, I didn't read far enough in the instructions printed out for me at AutoZone. Access thru the trunk is for replacing or removing the fuel sender unit. I will get a fuel pressure gauge and check fuel pressure. What PSI should I expect? Will also try the "bang on bottom of tank" procedure you outlined. Sorry, didn't mean to usurp your expertise. I'm enjoying the help.
Expert:  Randall C replied 5 years ago.

No worry :) I thought it was time to retire:) had me fooled. here are the pressure specs per your request

 

Pressure
Notes Fuel System Pressure
Key On Engine Off (KOEO) 53-59 psi

 

Customer: replied 5 years ago.
Just tested fuel pressure ten times and read 46 PSI every time. If key is left on, small black unit (sensor, relay ???) on air intake clicks irregularly, but continuously. Mean anything?? You said fuel pressure should be 53-59 PSI. Does the 46 PSI (slightly low)measurement really mean the fuel pump is bad?? Tests were made with engine cool. Should I drive it to put in no start condition and check pressure again??
Thanks.
Expert:  Randall C replied 5 years ago.
Factory specs are what i wrote. Unsure if the 46 psi is the problem. hav you had a chance to catch the no start and then use carb cleaner into t body to see if it hit right up? this would be very good sign of weak or bad fuel pump. let me research the clicking. I may be back this eve but for sure early in AM
Customer: replied 5 years ago.
Will try the carb cleaner in the morning. BTW, I drove around a while and engine wouldn't start. Immediately checked the fuel pressure, still at 46 PSI. But when leaving key on, no more clicking. Tried the ignition and started right up. With engine idling, fuel pressure is 48-49 PSI. Will let you know how the carb cleaner works tomorrow AM. Thanks.
Customer: replied 5 years ago.
Drove around a while this morning, but engine still starts OK. Having cooler weather here today; maybe that's the reason. Will still try the starter fluid in throttle body first time won't start. Out of town til Wednesday. Find out anything on the clicking? I'll accept and pay as soon as we pin this down a little more. JustAnswer opened this up to other experts, but really don't want to start with someone else. Hope you'll stay with me. Thanks.
Expert:  Randall C replied 5 years ago.
A "kind" expert will not jump in if they see the post going. JA has a timer so we need to keep any hello, going to keep the post open. LMK when you can and thanks for the heads up
Customer: replied 5 years ago.
Used carb cleaner in no start condition; started and continued to run just fine. What now? Did you get any info on the clicking?
Customer: replied 5 years ago.
Got an e from JA saying you needed more info with instruction to "click here" to see your reply, but it does not show on the JA post page. Says received at 6:33am this morn. Might just be part of JA's automatic messaging, but if you really need more info, please re-post. Right now, I'm waiting to here anything you learned about the clicking noise that occurs sometimes with key on when checking fuel pressure (after releasing the pressure). Thanks.
Expert:  Randall C replied 5 years ago.

Unsure of click . Is it located in pic? this is the complete t boday and airflow meter

 

graphic

Customer: replied 5 years ago.
Item 7 in the pic.
Expert:  Randall C replied 5 years ago.
That is the idle control motor. They can click from time to time as they wind in /out to reset the base idel strategy. If you had a no start, sprayed cleaner and it started up and stayed running. I am going with the fuel pump
Randall C, ASE Master Tech
Category: Chevy
Satisfied Customers: 11453
Experience: ASE Master, L1, 32 years, Diagnostic / Electrical Specialist
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Randall C
Randall C
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ASE Master, L1, 32 years, Diagnostic / Electrical Specialist