Long start up on LT1
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From: Royal Oak, Mi
Long start up on LT1 Get ready for a long post(Important parts are bolded):
My friend has a 94 LT1 Camaro that has developed a long start problem.
I initially thought it was the fuel pump because pressure at the schrader valve would take a long time to build up and then drop rather quickly. I replaced the fuel pump with a walbro 255LPH pump, problem still there. I then figured it might have been the fuel pressure regulator, I tested that both with the car running and off, and the fuel pressure regulator is functioning as it should. I then checked fuel pressure at the schrader valve again, it was still dropping off to 0 with in a second or two of the key being turned to run. Then, the car developed a hesitation below 2000 rpm, so I believed it was the injectors. Today, I pulled the fuel rail half off and saw that the front 4 injectors are not leaking and working properly, the back 4 injectors where not tested. I did notice that the vacuum lines coming to and from the evap purge solenoid were cracked. I replaced the evap vacuum lines and the car no longer has a hesitation, but it is still taking a long time to start. I never replaced the fuel filter because I felt that the problem wouldn't happen just on start up, but could it have been that simple all along? Was there a return fuel line that I accidentally forgot to block off when I installed the walbro fuel pump?
The only two things left that I could think of that would cause the problems are : clogged fuel filter, bad evap purge solenoid(but I dont think this would affect start up).
Also, if the key is cycled 4 or 5 times, the fuel pump is kicked on enough that the car will almost start immediately, but the longer the car sits, the longer it takes to start.
My friend has a 94 LT1 Camaro that has developed a long start problem.
I initially thought it was the fuel pump because pressure at the schrader valve would take a long time to build up and then drop rather quickly. I replaced the fuel pump with a walbro 255LPH pump, problem still there. I then figured it might have been the fuel pressure regulator, I tested that both with the car running and off, and the fuel pressure regulator is functioning as it should. I then checked fuel pressure at the schrader valve again, it was still dropping off to 0 with in a second or two of the key being turned to run. Then, the car developed a hesitation below 2000 rpm, so I believed it was the injectors. Today, I pulled the fuel rail half off and saw that the front 4 injectors are not leaking and working properly, the back 4 injectors where not tested. I did notice that the vacuum lines coming to and from the evap purge solenoid were cracked. I replaced the evap vacuum lines and the car no longer has a hesitation, but it is still taking a long time to start. I never replaced the fuel filter because I felt that the problem wouldn't happen just on start up, but could it have been that simple all along? Was there a return fuel line that I accidentally forgot to block off when I installed the walbro fuel pump?
The only two things left that I could think of that would cause the problems are : clogged fuel filter, bad evap purge solenoid(but I dont think this would affect start up).
Also, if the key is cycled 4 or 5 times, the fuel pump is kicked on enough that the car will almost start immediately, but the longer the car sits, the longer it takes to start.
I have the exact same problems as described above and im pretty sure that the check ball is leaking on the return line so that is why the pressure drops off so quickly and takes a few cycles of the pump to build up enough pressure
Some people say that a hard start problem can be caused by the ICM. There is no need to block off any of the lines with the 255 swap. The yellow plastic container that your stock fuel pump was inside had 3 hoses in it One was the high pressure out to the fuel rail, one was the return dump The other is a breather.
You should have fuel pressure in the rail at startup. You have 1 or more injectors leaking fuel after the shutdown. Any leak in the system will result in the pressure in the fuel rail dropping and having to be recovered. I'd check the injectors next for leaking. It only takes one bad one.
Joined: Jul 2007
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From: Ringoes/Flemington, New Jersey
going to say pretty sure the one-way check in the feed line is in the pump... I had this issue with my old car, I would lose pressure fast and have a long crank. new pump fixed it. If its leaking real fast... that is crazy. if its the injectors youd be washing down the cylinders lol
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For pressure to bleed down that fast there are only four possible causes.
Leaking fuel pump check ball (integral to the pump).
Leaking fuel pump flex pipe.
Leaking valve/seat within pressure regulator.
Leaking injector(s).
Just because a part is new doesn't mean it is invincible and can't be faulty. Walbro 255s can go bad. I will agree that that is a LOT of pressure to bleed down from leaky injectors (I suppose it could be possible). How did you test the injectors? The best thing to do is to remove the rail and prime the system and visually look to see if any of them are dripping.
Also, since you had the pump out, if the flex hose was leaky and/or not sealed properly then that can cause a leak-down.
Leaking fuel pump check ball (integral to the pump).
Leaking fuel pump flex pipe.
Leaking valve/seat within pressure regulator.
Leaking injector(s).
Just because a part is new doesn't mean it is invincible and can't be faulty. Walbro 255s can go bad. I will agree that that is a LOT of pressure to bleed down from leaky injectors (I suppose it could be possible). How did you test the injectors? The best thing to do is to remove the rail and prime the system and visually look to see if any of them are dripping.
Also, since you had the pump out, if the flex hose was leaky and/or not sealed properly then that can cause a leak-down.
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From: Royal Oak, Mi
I will check the injectors again since I don't believe I had the system fully primed when I tested them. Also, the flex line on the fuel pump was replaced when I installed the walbro because the original one had a pin hole in it. How can I check if its a bad check valve in the pump? Think I should call Walbro and see if they will work with me?
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Joined: Mar 2009
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From: Clearwater
they will probably ignore you because in their eyes (and honestly it somewhat makes sense if you think about it) you are one of the thousands that installed a new pump on a 16 year old fuel system and have a failure. a local shop told me walbro won't honor returns because of an explosion of situations like this (don't know how true that is but i did see a box of returned pumps that they are stuck with). your options are find the answer here, pay someone to figure out the cause or replace pump till it works.
On The Tree
Joined: Dec 2007
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From: Paso Robles, CA
Got the exact same issue here as well. I have noticed though, that the more gas in my tank, the less time it takes to fire up. About 3 or 4 seconds of cranking on a full tank, 6 or 7 seconds when near empty... Don't know what that could mean.
Could any of the possibilities causing this issue mentioned above make a fuel pump fail prematurely?
Could any of the possibilities causing this issue mentioned above make a fuel pump fail prematurely?
Here are some things to think about. Try starting the car with your foot on the floor, this will shut the injectors off until the engine starts. If it starts faster this way, it is most likely flooding and you have a bad injector. I had the same problem, i replaced the pump and found out I only had one injector bad but it would drop the pressure immediately. All it takes it one drop of leakage from one injector to drop the pressure, especially if its hot out, the gas boils and the whole line to the tank is full of air. I believe gas boils at around 70deg, so it doesent take much.
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From: Old Bridge, NJ/Corpus Christi, TX
hey vinnie, just want to let you know that the car doesnt have a long start anymore, but it has a hesitation in 5th and 6th gear while cruising. any ideas?
