Ok, I've asked about this before...about 4 months ago, and I still haven't gotten it fixed.

Problem:
When car is cold, it will turn over great, but will not start on first try, even if you hold it for 3 or 4 seconds. Then it will almost ALWAYS start on second try, usually pretty quick. I'm pretty certain it's fuel related, cause everything else has been changed(opti, wires, plugs, coil, starter, alternator, fuel filter too). I've been told "oh, your fuel pump's bad", but how in the world would it just not be able to start up, but then work fine at all other times? I think it just doesn't keep pressure in the fuel lines for very long, that's the reason it starts fine when warm. I just don't understand how the fuel pump could be just weak, cause it's a motor and I suspect it would eventually just quit, but it hasn't in 7 months.

Could anyone give me any ideas as to what to maybe check out that could be causing this, or is the pump the only thing possible? Also it ran lean on the dyno, so that's another clue something's going on. It just frustrates me whenever I try to start it and it takes 2-3 tries.

Thanks for any help in advance,
Kyle

 

It is your fuel pump. I know this cause my car is doing the same thing and I had the dealer diagnose it with a fuel pressure gauge. Here is what is happening basically. You fuel pump motor itself it probably fine. The prolblem is you have a hole in one of the lines inside the tank. So you car primes up the fuel pressure to where it needs to be, but as soon as the pump turns off, the pressure and fuel bleed out and therefore you will have extended crank time. Solution: replace the fuel pump with either a stock replacement or a racetronix (what im doing tomorrow) and it will come with the necessary hose to fix the problem. If your fuel pump motor went out your car wouldnt start at all and it would be immobilized till u replaced it. I am 99% positive if u put in a new pump your problem will be cured. I let u know. -Michael

 

Ok, see, that makes complete sense. Thanks for the help man. I never thought of the hose that's connected to the pump. I just had a lot of people telling me that the pump was weak, which wouldn't make much sense.

I know about the car not starting. My old IROC decided to die one time going through a toll booth. I started it back up, drove to my dad's shop, turned it off and after that it never started back up. Replacing the pump sucks, I know from experience. Looks like I'll be doing that then soon.

Thanks for the help, let me know how it goes,
Kyle

 

There is a check valve in the pump that holds the pressure. Very common for the check valve to fail.

 

I agree with Injuneer, I was having the SAME exact problem also and replaced all the things you replaced. It ended up being my fuel pump, the pump itself was fine, but that check valve was faulty. So when you would test the pressure on the shrader valve with a gauge it would pressurize fine, but when the jump was done priming it would drop to 0 instantly, it should hold pressure stedily. Change the pump, its 99.9% usally the problem when you replaced all the things you did. That or a leaking injector (not likley) But you can check that also.

 

Ok, now even more sense. This is a great big help guys, thanks. Either way, I'm hearing that it's the pump. I was just hoping it might be something a little easier. Looks like I'll be replacing it in the near future.

One more question. My car doesn't have much done to it and it won't ever have much done to it. Probably will never make 350 rwhp. If I replace the pump should I go with something like the racetronix new system, or would just getting an AC Delco one be satisfactory?

Thanks again for all the help,
Kyle

 

I went with a racetronix. The ac delco costs the same or more and the racetronix ive heard is a better pump (walbro). So, its really up to you.

 

I also went with the Racetronix setup. I am VERY satisfied with it, and install seemed fairly simpile. We went the cutting the access panel route. I ended up buying the kit for $250 from thunder racing, not knowing that i bought the unit that has the harness for the MSD pump booster, o well, guess I am ready in the future

 

When changing your pump do a thorough cleaning and inspection of the tank. In many cases the pump fails due to rust which is very common in the aging f-body tanks. Rust will make its way through the filter sock and into the pump where it will stick to the magnets etc. and degrade its operation to eventual failure.