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Old 07-19-2008, 08:20 PM   #1
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Default why does my car take so long to start?

Ok, replaced fuel pump, plugs and wires. And recap - have replaced MAF sensor, TPS switch and new fuel filter with in the last month. Runs great and responds to acceleration great, that is once you get it started. Turn the key on and wait for the pump to build pressure and crank and crank and crank and then it will start, but sluggusly. Right when it decides to start you have to get into the peddle and rev it a bit and then it idles perfectly at 750rpm. If you don't give it gas right after it starts it struggles to stay running. It is like something needs to calibrate when it engines hits a higher rpm. ONCE it does, it runs great, it is just the starting that is bad. Is there something to with electronic timing that could be bad? Should be able to turn key and that baby fire right up so my guess with experience I have would be something to do with the timing but know nothing about this system. Is there something that that can be replaced that syncs (times) the coils are something to the effect. There are no codes other than the rear O2's cause no cats, and light is on for the radiator due to corrosion according to the forums. Any ideas from anyone.
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Old 07-19-2008, 08:47 PM   #2
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Did you replace the fuel pump only or the whole module? The module is the plastic bucket the fuel pump sits in.
There are a few things in the module that can cause the problem you're having.
One thing you can do to test the module is before trying to start the car turn the key on and listen for the fuel pump to run and shut off, then turn the key off and back on to let it run again. Do this four or five times, when the pump shuts of the 5th time turn to crank it, if it starts right up it's a problem with the fuel pump module. Usually the module bucket will never fully fill up when it's got a problem.

Here is some info on how the stock module works, from this site http://www.racetronix.com/RX-F99-FPKG-2.html.
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The 1999 & up LS1 F-body cars have a pump that is inside a plastic fill-bucket. The fill-bucket is equipped with two inlets on the bottom. The equalization checkvalve is used to fill the bucket when the level of fuel in the tank is greater than in the bucket. The equalization checkvalve does not allow fuel to exit the bucket. The venturi system's inlet is a combination checkvalve and powered suction system. The factory pump supplies pressurized fuel via a small tube which feeds a calibrated jet inside the venturi system. This jet of fuel shoots across the base of the checkvalve inlet thereby creating a suction effect which draws more fuel from the bottom of the tank through the filter sock. This venturi system keeps the bucket full all the time even when the fuel tank is almost empty. A full bucket keeps the pump immersed in fuel regardless of the tank level so that when the tank is low on gas and you are doing some hard cornering or acceleration the pump does not run dry and start aerating (air bubbles) the fuel. This happens as the fuel sloshes from side to side in the tank leaving the center low on fuel. This can cause detonation and possible engine damage. The 99+ F-LS1 cars with plastic tanks have no baffling in them so the bucket is very important. The bucket also allows the car to operate with lower fuel levels in the tank due to its scavenging effect. The fill-bucket improves motor crank-to-run time as the priming time is reduced under most conditions. The return line feeds the pressure regulator on the fuel module which diverts fuel back into the bucket so that the unused fuel also helps keep it full at all times. Keeping the pump constantly immersed in gas within the bucket can extend the pump's life by not allowing it to be exposed to open air. Open air within the tank contains moisture and in time will cause the pump to rust / seize up especially if left to sit for long periods of time without the tank topped-up (i.e. winter storage).
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Old 07-20-2008, 11:35 PM   #3
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tried the turning key thing and it didnt start right up i still had to do it 3times
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Old 07-21-2008, 12:09 AM   #4
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Put a fuel pressure gauge on it and see if one or more injectors are leaking down.
Assuming this is an LS1, it should go up to 58 psi when the key is switched on, when shut off it should bleed down very slow, it should actually hold for quite a while.

You could also try starting with the gas pedal to the floor, that activates the flood clear so it won't add more fuel during start up if some injectors are leaking down.

Doesn't really sound like an ignition problem to me.
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Old 07-21-2008, 12:46 AM   #5
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pull the fuel pump fuse and turn the engine over for about 10 full seconds. Then pop it back in, turn the key to "on" for about 2 full seconds before starting the engine, then go ahead and start it, see if it starts normally.
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Old 07-21-2008, 12:08 PM   #6
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My 98 does the same thing, ill stick the key into it to start it, turn it on it will just crank, turn it off and back on and it will just crank, turn it off and crank it again and it will fire up and idle like **** for 5-10 seconds, then its fine, ive have put a fuel pressure gauge on it and checked the pressure its a firm 58 psi, but when the engine is not runing it drops to zero immediatly, cycle the key on it will build up to 58 psi, the fuel pump will shut off and it will drop to zero again. No SES codes, runs great once its running.
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Old 07-21-2008, 11:30 PM   #7
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Originally Posted by 99NMB View Post
My 98 does the same thing, ill stick the key into it to start it, turn it on it will just crank, turn it off and back on and it will just crank, turn it off and crank it again and it will fire up and idle like **** for 5-10 seconds, then its fine, ive have put a fuel pressure gauge on it and checked the pressure its a firm 58 psi, but when the engine is not runing it drops to zero immediatly, cycle the key on it will build up to 58 psi, the fuel pump will shut off and it will drop to zero again. No SES codes, runs great once its running.
thats exatly what its doing ive tried the fuse and it still did the same thing
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Old 07-22-2008, 12:03 AM   #8
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It is not holding pressure once shut off. It is either a injector or the check valve in the fuel pump(or module).

I just know it needs to keep pressure in the lines. That's where my knowledge stops.
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Old 07-22-2008, 03:30 AM   #9
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ok today i noticed something when i was driving around to test it out i didnt floor it but i pushed the pedal down a bit and got up to 80 then slowed to turn onto the highway when i did this i was going about 20 then i started to push the gas pedal and it didnt wana go at all it was stalling out after a few seconds of the pedal being down it finally started to go again
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Old 07-22-2008, 08:27 AM   #10
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cool.
are you ever going to check the fuel pressure or anything?
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Old 07-22-2008, 10:27 AM   #11
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^^^^^
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Old 07-23-2008, 09:39 PM   #12
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Sounds like a fuel pressure regulator... to me... $0.02
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Old 08-07-2008, 03:23 PM   #13
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ok well fianlly got money to take it to a mechanic
this is what he said it threw 2 codes dont remember the #'s but Banks 1&2 were lean
then he said its because the fuel pressure reading was 18-20psi???
funny thing is we just replaced the fuel pump we got this one http://store.summitracing.com/partde...5&autoview=sku
now idk why it wouldnt fix it but anyway we ordered this one instead and are sending the other back since its still under the 90day warranty (had it 30days)
heres the one we ordered http://www.racetronix.com/RX-F99-FPKG-2.html
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Old 08-07-2008, 05:18 PM   #14
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Theres more to fuel pressure than the pump.

How much did you pay the mechanic to connect a $45 gauge?

If you had taken my free advice you'd have a new tool and know part of the problem plus have some money left over.
Theres a lot in the fuel pump module other than the pump that can cause low pressure.
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Old 08-07-2008, 05:35 PM   #15
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it was 65$ for hooking up to a computer and checking everything

but what elese could it be then cause he said it was a fuel pump
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Old 08-07-2008, 07:24 PM   #16
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This is why it may not be the fuel pump, from the link you posted: The fill-bucket improves motor crank-to-run time as the priming time is reduced under most conditions. The return line feeds the pressure regulator on the fuel module which diverts fuel back into the bucket so that the unused fuel also helps keep it full at all times. Keeping the pump constantly immersed in gas within the bucket

Sounds like your bucket is leaking down.

Just check everything real good while you have it out.

If you drop the tank to change it be sure to test the fuel pressure before you bolt everything up 100%
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Old 08-07-2008, 07:47 PM   #17
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Did you use the supplied fuel line that came with the pump? If so they are known to split and cause a lot of the problems that you are having. Low pressure and hard starts.
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Old 08-07-2008, 08:01 PM   #18
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ahhh beedo just answerd the most likely problem.. the little like fuel line you use that goes from the pump, to the connector is cheap. heres a pic of the line in question.

Click the image to open in full size.
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Old 08-07-2008, 11:29 PM   #19
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9000 - no i cut a hole to get to it but ill look it over
bee/jeff - no i did not i bought a new plastic one i did not use the rubber one because of all the complaints of it messing up
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Old 08-14-2008, 12:24 AM   #20
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ok guys thank you sooooooooo much slow mo the regulator was crap and we put a new one on it we got at orileys and it runs like a champ now
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Old 08-14-2008, 12:24 AM
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