I've got a 2001 gmc jimmy sls, 4.3, 320,000km. So far I've just delt with this the last year, but I'm over it and am lost on what to do. Upon cold starting after it's sat for at least a day, if you turn the key it will just crank and not start. Now here's the weird part, if you crank, and let off they key the moment it fires, it will sputter and die. If I do this crank/let off/fire/sputter cycle 5-10 times in a row, it will eventually start and sputter to life. Works every time. This only happens the first start of the day, after it's started once, it starts fine and normal all day. If I cold start it by spaying starting fluid, it starts up immediately no problem. Temperature does seem to make a difference, it's way worse in the winter then summer (less key cranks). I've replaced the fuel pump twice even tho I didn't think that was the issue (I've got 50-55psi when it's key on cold, and does not drop off when cranking, then 55-60 ish once running), the fuel pressure regulator is new, new fuel filter, new crank sensor (also didn't think that was the issue but put one in anyways), the fuel pump runs and primes with key on as it should. I am convinced this is a fuel issue but for the record the cap, rotor, plugs, wires, coil, distributor module are all less then a year old. Everything is ACdelco or Bosh or name brand, no Amazon or eBay parts here. I'm also convinced this is not a wiring issue cuz then it should start bad every time and temp make no difference. The only other symptom I have is every once in a while while driving, the thing with make a hard thud, like the engine shuts off for a split second. It only does this about once a week or two, not every time I drive it. It never doesn't start, runs smooth, no miss, never dies, no nothing once it's had that weird first start of the day. I'm out of ideas other then maybe the spider injecton unit itself? Any suggestions or thoughts would be appreciated. This is just my beater backup vehicle, I also have a couple parts Jimmy's I could rob off of, so don't be afraid to say try changing any sort of sensors. Thanks

 

I once had a random, infrequent crank/no-start situation. I found that the fuel pump relay had really burnt up contacts. Even if an unlikely remedy, I'd suggest swapping the relays for the fuel pump and one of the other systems, e.g., the rear window defogger, to see it it makes the problem go away. The relays are in the under-hood fuse/relay box.

If not the relay, perhaps someone else can help.

 

Thank you for the suggestion. My fault tho, I forgot to mention I have tried this already, as well as jump the fuel pump with 12v directly. No change

 

What is the leakdown pressure at 10 min after key on no start? You may be flooding some cylinders with leaking injectors.

Next time crank it with the accelerator at the floorboard for a few seconds then try again normally. This is flood clear mode.

Does it always start with starter fluid?

George

 

Yup, starts on the first try with starting fluid every time I do it that way. I'll check the leak down and try flood clear tonight.