Why does my car have to be revved to start, even though I have good fuel pressure and batteries fine?
Posted by Beeg__Cheeese@reddit | askcarguys | View on Reddit | 13 comments
1996 Buick Riviera supercharged, every other time I start it it'll crank but I'll have to rev it to get it to fire up. Gets worse when I have lees than 1/4 tank of gas, doesn't happen at all until I'm under 3/4ths. The battery is fine and I'm getting good fuel pressure
comfy_rope@reddit
MAF
ObviousAlias7@reddit
Is your check engine light on?
Flooring it during start on an EFI car triggers flood clear mode. If the car starts then, it usually points to a sensor issue such as a bad coolant or intake air temp sensor causing the vehicle to go pig rich on start. Disabling the injectors clears the flooded condition and allows start.
Might want to troubleshoot a bit for bad temp sensors or other issues
Beeg__Cheeese@reddit (OP)
No check engine light either
04limited@reddit
If it’s getting the correct fuel than your not getting air. By pressing the gas pedal you’re opening the throttle plate allowing more air to enter the engine.
I’d clean the throttle body first then go from there.
JCDU@reddit
Some EFI systems have a "flood clear" mode if you press the pedal all the way down when cranking they cut the fuel injectors off - this could be what OP is doing.
04limited@reddit
Correct. Leaking injector could be flooding the cyl.
Ok_Two_2604@reddit
Or idle control valve, if cars still have them.
dirtyforker@reddit
It's a 96
Blu_yello_husky@reddit
Youre getting too much fuel, its flooding during cranking and thats why it wont start. By putting your foot on the gas, youre putting it into clear flood mode, allowing for more air into the engine during startup. Check for leaky fuel injectors, check for fuel pressure loss after shutoff, remove the hose from the pressure regulator on the fuel rail and check for fuel inside the cylinder. Is the check engine light on? Look for rich codes or o2 sensor codes. How's your fuel economy? Does black smoke come out of the tailpipe when you rev the engine?
Youre getting too much fuel. Find out why and fix it, and you wont have to floor it to start the car anymore.
J-Rag-@reddit
Pull the throttle body and clean it. Replace the TPS and IAC to start with and fire it up. See if that changes anything
Longjumping-Log1591@reddit
10 bucks says a can of BG44k will alleviate the symptoms
One_Evil_Monkey@reddit
First thing I'd look into is stuff that's air related.
MAP sensor, MAF sensor, TPS. Throttle body. The AIC valve may be dirty but usually that will cause unstable idle as well after the vehicle is started.
Then possibly even though you say it has fuel pressure, could be an issue with pressure regulator. I had a similar issue on an '88 GMC 4.3L with TBI. If it sat for a day or two, it would crank and crank with no start unless you opened the throttle a little. The regulator on the TBI unit would leak down pressure, opening the throttle a little would make the ECM increase the pulse rate of the injectors and make it spray a little more fuel. Unusual because the regulator is spring/diaphragm. New regulator took care of that on that particular vehicle.
TeamFoulmouth@reddit
My guess is an air or MAP sensors going out..or went out, so its not opening the mix flap in your throttle body.