Hi all,

I'm having some starting issues with my 98 Blazer LT that I just bought. If I let it sit for anywhere between a couple of minutes to a couple of hours, it will almost never start instantly.
I can hear the fuel pump run before attempting to start, and usually the engine will start, run for a couple of seconds and then die.

The strange thing is that when it has been sitting for a longer time (eg overnight), it usually does start right away. After some reading up I suspected a fuel leak in one of the injectors or the fuel pressure regulator. Unfortunately I don't have a fuel pressure meter (or I do, but not one that will fit the schrader valve) but I pressed the little pin to check if there was pressure and can't visually see any difference in the spray after letting it sit for a couple of hours. So it does not seem to be losing pressure quickly anyway.
I also checked one of the plugs right after it failed to start, I was expecting it to be wet, but it was bone dry. Of course it could be wet on the other 5 cylinders... But no excessive smoke from the exhaust once it does start. So all this leads me to believe that if it's a fuel problem, it's a lack of fuel, and not a leak causing too much fuel after sitting.

Suspect number 2 was the passlock system, because it behaves pretty much as if the system was active. I usually wait for the pump to prime and most of the lights on the dash to go off before turning the key to start. The security light does not come on while starting though, which is what's confusing me. It is almost as if the system becomes active after I let go of the key, but without the light.

Once it stalls on me, I have to crank a bunch of times to get it started, repeatedly cranking for a short time seems to work much better than cranking for a long time.
When it does start again it's usually right after turning the key and not after having cranked for 5 seconds. It behaves completely normal after once it does start, running beautifully with no sputtering or hesitating or anything.
If I turn off the ignition and start it again within a minute or 2, it will start right away without hesitation.

I have checked for error codes using a generic OBD reader, and it did not show any error codes.

Does anyone have any suggestions what I should be looking at next?
Can I "hotwire" the fuel pump to force it run even if passlock is active, just to check if that fixes the problem?
All suggestions are welcome, this is driving me insane!

Thanks in advance

 

Thanks for all the tips

A little update on the issue, maybe it helps someone else..
I'm 99% sure I found the problem now.. A faulty fuel pump, even if it was replaced only a couple of months ago. It runs but most of the time doesn't pump. Yesterday I noticed a change in sound from the pump right before the engine started, that was the final clue I needed to find the answer. It starts buzzing at a lower frequency or something right before it starts (when it actually starts pumping), the sound becomes a bit softer.
Apparently this is a relatively common problem with some aftermarket pumps. I have no idea what kind of pump was installed, but a new one is on its way so hopefully it will all be fixed next week.

 

i had the same problem with my 99 Bravada the first thing i would check is fuel pressure. you can rent a gauge from Autozone and its easy to connect the schrader valve is located on driver side fuel rail

my problem was a bad pump. be careful pulling the tank there is a small valve on the front of the tank with a rubber hose to vent for EVAP. if you break that nipple you have to replace the whole tank, those valves are not serviced separate. this is 98+, pre 98 had metal tanks and could swap them out i dont know why they changed it

my pump still primed but failed to start because it could not hold pressure. the gauge would jump to 55 psi then 0

would not be a bad idea to check spark and make sure throttle body is clean air/fuel/spark 3 things an engine needs to run and couldn't hurt to check

 

We don't have Autozone over here (Sweden), I ordered a gauge off ebay though but it probably won't be here until next week. I'll probably wait with the pump swap until I've checked the current behavior with the gauge.

The weird thing is once it gets going everything is just fine, it has never cut out while driving. Feels like it may be a little down on power in 2nd and up, but that might just be me thinking that a 193 HP car should accelerate faster, the car still a bit of a pig after all. But other than that no problems until I let it sit for a couple of minutes again.
So I'm pretty sure it's just the pump that's acting up. Once you know what to listen for, you can clearly hear the difference in sound when it starts pumping properly and the engine starts instantly at the next turn of the key.

Thanks for that tip on the vent hose!

I'll keep you updated on the progress

 

my Bravada did the same thing, alot of time i got in trouble for being late coming back to work cause i could not get the truck restarted. i replaced the pump over thanksgiving, it was kinda easy

 

Just out of curiosity, did you notice any power loss while your pump was like this? Or was everything OK once it started pumping?

 

you really need a fuel pressure tester and to get that done first. Pushing the schrader isnt good enough

 

I've asked around everywhere but couldn't find anybody that has a gauge or adapter that will fit. I ordered one though, hopefully will get here early next week. I think it's pretty clear that something is up with the pump though, but obviously doesn't hurt to confirm using a gauge before changing it.

I know just pressing the schrader isn't very scientific But that was as good as it was going to get without access to the proper equipment.. In my option if there were a leak somewhere that was big enough to cause it to be this stubborn, any pressure should've been long gone after sitting for about 4 hours.

 

one thing you check is remove the throttle body (where most carburetors go) take a flashlight and look unside under the plenum. Should be all black and ugly looking. any shiny spots would be a leak of some sort. Injector line, etc. not hard to do, basic tools

the first 4 minutes will show you how to remove it. its 5.7 but basically the same

 

It sounds like you have leakage in the system for sure. Your symptoms are consistent with any or all of these possibilities: a bad fuel pump (pressure leaking down inside the tank), a bad fuel pressure regulator (pressure leaking down either to the return pipe or dripping into the manifold plenum), or leaky injector nozzle poppet valves.

When there's no pressure in the system, the fuel pump will sound different when it first starts (no pressure, no load) than it will after a few seconds. That pretty much confirms you have a leak somewhere, but it doesn't tell you where. It's also not definite that the fuel pump is bad just from the noise.

Throwing parts at it will be expensive, and it will be the last part you replace.

If you think it's leaking in the plenum, try pulling the fuel pump relay before you shut the ignition off, and then shut off the key. Your fuel pump relay is in the fuse block under the hood (that started in 1998). Pulling the relay will stop the engine, after a few coughs and sputters. That will depressurize the system, and with no pressure, it usually won't flood if the injectors leak or if the pressure regulator leaks. When you go to start it, put the fuel pump relay back in, then put the key in, and cycle the key 2 or 3 times to prime it before you try to start it. I had this issue with my Oldsmo-Blazer a couple months ago, and I used that "workaround" to drive it, relatively problem free, while I was waiting for parts to arrive and for the time in my schedule to do the work. If that workaround helps, then you have leakage inside the plenum (dripping regulator and/or leaking injectors). That doesn't mean that your fuel pump is good, it could be bad as well.