This topic contains 7 replies, has 3 voices, and was last updated by 
Don Phillip 2 years, 5 months ago.
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Topic
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Won’t start if outdoor temp is 85 degrees or hotter. No check engine light or codes recorded on tester. Already replaced temp sensor and Mass air flow sensor. Problem persists. Help
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You first need to find out what your missing to start the engine IE. fuel, spark, air.
T{ determine if it’s a fuel problem hook a fuel pressure gage up when problem happens or spray starting fluid into throttle body while cranking. If it fires you have a fuel delivery problem.
Thanks guys, did both tests. In failed mode engine started with starting fluid, So I did the fuel pressure test and had 60 psi. If outdoor temp is 80 degrees or less it starts reliably. Some electronics or sensor is failing. Last night at 87 degrees it would not start, so I plugged in the analyzer, of course…no codes. This morning at 75 degrees it started like normal. MAF and temp (coolant sensor) are new. When it starts it runs perfectly.
Any other tests or possible faults to check?Let me see if I understand you correctly.
When it fails to start:
You can get the engine started by spraying starting fluid. but you also show fuel pressure at the rail?
I would first check the flow of the fuel injectors when it doesn’t want to start.
If you can get it to fire up using starter fluid you must have spark at the cylinders.
Might also look at the fuel pressure regulatorSo now we know it is a fuel delivery problem. Fuel is getting to the rails but not through the injectors. It’s a good idea to check the regulator but I’m thinking electrical problem. Heat can effect electronics. I don’t know the schematics for this specific vehicle, but if you can find them you can test for proper voltage to the injectors. A mood light would be very helpful in this case. There is power supplied to each injector, then the ECM grounds that circuit to activate the injector. I’m guessing that whatever sourses the power to the injectors or supplies the ground is fairing when hot. With a stethoscope listen to the injectors while cranking during fault mode. You should hear them clicking as you crank. If you don’t, then follow the circuit that supplies power to the injectors. Then follow the circuit that supplies the signal to the injectors. You may find a bad wire or connector at these points. Pay special attention to the connector at the ECM.
A noid light would be very helpful in this case.
Thanks guys. Again your info is very helpful. When I get the next failure I’ll do the checks and run the tests.
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