sometimes I have to crank for about 5 seconds or more before my car fires up.
and on another note, sometimes the cold start injector makes it "explode" right into high idle.
Im thinking that there might be something possibly clogging the cold start injector sometimes.
I have an adjustable fuel pressure regulator, and wonder if I should adjust the top screw in or out of the fpr assembly. (I might be a little low on fuel pressure after the fuel pump primes.)
the ignition works, I have an msd 6al, and I just checked, modified and re-gapped the plugs to take advantage of the more powerful spark.
Many times the fuel pump relay quits working and the fuel pump ends up getting power through the back up oil pressure switch. That results in a few cranks before enough oil pressure is there to turn it on.
Turn your key on and listen for the fuel pump. It will come one the first time you turn the key to on. It might not the second unless you wait at least 45 seconds. It should however come on for two seconds every time you bump the starter.
Many times the fuel pump relay quits working and the fuel pump ends up getting power through the back up oil pressure switch. That results in a few cranks before enough oil pressure is there to turn it on.
Turn your key on and listen for the fuel pump. It will come one the first time you turn the key to on. It might not the second unless you wait at least 45 seconds. It should however come on for two seconds every time you bump the starter.
You are asking if the fuel pump primes the fuel rail with pressure? Yes, it does, every time.
With a cold engine, check for 12V on the the tan wire on the cold start injector switch with key in "start" position. If no power, check for 12V on the purple/white wire on the cold start injector switch, key in "start"position position. If no power, check the fusible link by the starter solenoid for continuity.
[This message has been edited by olejoedad (edited 08-12-2013).]
With a cold engine, check for 12V on the the tan wire on the cold start injector switch with key in "start" position. If no power, check for 12V on the purple/white wire on the cold start injector switch, key in "start"position position. If no power, check the fusible link by the starter solenoid for continuity.
the car is my daily driver, I dont see why it would be the fusible link, it just cranks and fires up right away, and sometimes... not soo much.
but then again, my question, why is this issue intermittent?
You said sometimes it does this. Is it only when the car has been sitting for a short period of time after running it? If the car starts up really well when you start it for the first time in a while, but then requires quite a bit of cranking after sitting for a short while, it could be a leak in your injectors and you need to blow the unburnt fuel out before it will fire up.
My 86 GT had an intermittant long crank problem, swapped in known good injectors, cold start injector & switch, fuel pump (pressure was good) - all the usual possiblities - no change.
Found this thread (grounds) on adding ground straps (I ran two, one by the battery tray ground to the waterpump, one from the pump to the trunk hindge) - problem fixed! Starts right away every time, it seems to run smoother too.
My 86 GT had an intermittant long crank problem, swapped in known good injectors, cold start injector & switch, fuel pump (pressure was good) - all the usual possiblities - no change.
Found this thread (grounds) on adding ground straps (I ran two, one by the battery tray ground to the waterpump, one from the pump to the trunk hindge) - problem fixed! Starts right away every time, it seems to run smoother too.
I have the same setup, with the grounds. I even have more underneath...
and I KNOW EVERYTHING WORKS... its my daily driver... just... this intermittent problem has me stumped... ALTHOUGH... I could just for he heck of it... I could try swapping the relays.
I gave you the electrical troubleshooting proceedure.
Do with it what you want.
I did some thinking, and IF it was the fusible link that had popped, I wouldn't get good fire... EVER. but I do get a good fire sometimes. and my fuel pump primes every time I turn the key on.
something just doesn't fire the cold start injector sometimes. last thing I didn't check was the relay.
I did some testing on the oil pressure, and the engine fires as soon as the oil pressure sender registers pressure.
Have you tried replacing your fuel filter? Its only like a $10-$15 fix and it sounds like it might be your problem, thatd be one of the first places Id think to look and it probably needs replacing anyways
Have you tried replacing your fuel filter? Its only like a $10-$15 fix and it sounds like it might be your problem, thatd be one of the first places Id think to look and it probably needs replacing anyways
everything is about a year old, and no less, I cleaned the tank properly, and installed a replacement fuel pump.
HOWEVER, could the IAC and TPS have any effects?
I know my tps gives my ecm problems, and theres always been a hesitation on takeoff because of it.
I did some thinking, and IF it was the fusible link that had popped, I wouldn't get good fire... EVER. but I do get a good fire sometimes. and my fuel pump primes every time I turn the key on.
something just doesn't fire the cold start injector sometimes. last thing I didn't check was the relay.
I did some testing on the oil pressure, and the engine fires as soon as the oil pressure sender registers pressure.
The cold start injector circuit has no relay. When the starter solenoid is energized, power is applied to the cold start injector switch. If the coolant temp is below 95°F, the switch energizes the cold start injector.
Check the fusible link at the starter solenoid for a soft spot. It is possible for the link to be open (burned), but make intermittent contact, like a small break in a wire. Not common, but possible.
The trouble shooting proceedure I posted earlier will verify the operation of the circuit. If it tests bad, wiggle the wire from the solenoid to the injector switch to see if it will test good. If it tests good, wiggle it to see if you can get it to test bad.
Have you watched the fuel pressure on a gauge during a cold start when it starts hard? The pump check valve might let the fuel line drain back into the tank, the pump would have to fill the line then build up enough pressure to start the engine. It might take cranking a several seconds for full pressure.
Have you watched the fuel pressure on a gauge during a cold start when it starts hard? The pump check valve might let the fuel line drain back into the tank, the pump would have to fill the line then build up enough pressure to start the engine. It might take cranking a several seconds for full pressure.
There is no check valve in the fuel delivery system. Key 'ON' energizes the fuel pump for a few seconds to build system pressure for starting.
But, the question is valid.
Have you checked fuel pressure after key 'ON', but prior to starting?
There is no check valve in the fuel delivery system. Key 'ON' energizes the fuel pump for a few seconds to build system pressure for starting.
But, the question is valid.
The pump has a check valve built into it to keep fuel from siphoning back to the tank when the pump is off - otherwise the fuel pressure would drop to zero as soon as the key is shut off. When the valve starts going bad the fuel lines can empty back into the tank overnight, sometimes intermittantly. The only way to tell is to watch the pressure when it won't start.
The pressure may only rise to 10-20 psi when first turning on the key because it has to fill the lines - not enough to start the engine. Cranking opens the injectors, dropping the pressure a little more. After a couple seconds the pump catches up & there is enough pressure to start the engine.
I've had several GM pumps act like this at my shop over the years : the fuel line is empty, If you turn the key on/off a few times to fill the system & build up pressure, then crank it over & it starts right up.
quote
Originally posted by AL87:
Fuel pressure is as follows... during prime, pressure reaches 45psi, and stays there.
During idle, its 40
Fuel pressure looks fine key on/running but was that the pressure reading while cranking while it would not start?
If the pressure is 40-45 while cranking & it won't start the pump is good, problem is something else.
[This message has been edited by AL68 (edited 08-14-2013).]
I did figure out that the ground running from the block to the negative terminal has acid leaking through it, and that because of this the threads stripped from me trying to tighten them, also, I cant pull the bolt out that holds the cable.
I guess its time to break out the grinder, put a cutting disc on, and have at it.
I re timed the motor to the correct spec grounding the diagnostic terminals.
I checked the wiring going to the cold start injector, and no power, whatsoever through it while the fuel pump primed, or even during cranking. somewhere in the harness there is the problem.
I do not know where the cold start injector wiring goes from the injector harness.
when is the power supposed to be applied to the cold start injector, and for how long?
I read a thread a few months back where a member had increased the spark plug gap and claimed better performance, gas and mileage - he had gone from 0.40 to 0.60 (bear with me on this) 0.40 being the advised gap. this thread came with a bit of mixed opinion (I will try and find it and post it later) I decided to go half way and re gap my plugs to 0.50 just for curiosity and to play safe etc.
what I found is the car would fire up within 1 to 2 seconds - so this was an improvement to me because originally my car would take, like yours a good 5 seconds to start.
As you have re gapped your plugs I would look somewhere else.
does it still take a good 5 seconds to restart after the engine has been warmed up ?
jon
[This message has been edited by jon m (edited 11-14-2013).]
I chopped off half my electrode-ground finger thing... and increased the gap to .050, I'm also running the msd 6al system so I get a fatter/longer spark.
I don't know whats up with this, idk if its partly a tps problem or what... I chopped off the wiring going to the cold start injector, and everything seems fine now, starts up no prob...
[This message has been edited by AL87 (edited 11-14-2013).]
You said sometimes it does this. Is it only when the car has been sitting for a short period of time after running it? If the car starts up really well when you start it for the first time in a while, but then requires quite a bit of cranking after sitting for a short while, it could be a leak in your injectors and you need to blow the unburnt fuel out before it will fire up.
I agree, wonder if ti does this when cold started.
