98 blazer no codes random flooding

ok i am baffled. my 98 chevy blazer 4.3 runs perfect the majority of the time but every once in a while, and by every once in a while i mean like a month or two, it will suddenly start misfiring and from what i can tell...i mean smell..it starts flooding with gas and really reaks coming out of the exhaust pipe.It totally loses power and can barely get up and get to the speed limit...whether on the highway or street driving. usaully if i make it home or work and turn it off and let it sit for a few hours,then it magically runs perfect, except for the last time it fouled a plug and killed it. I am guessing this is fuel related..either the pump maybe taking a dump or maybe injector/regulator related since lack of codes.i just am pullin my hair out on this one. any ideas?

Welcome to AF
The best time to check it is when it does it.
A good engine capable scanner will show codes past present or history or pending.

Also check for codes after it does it before you turn engine off.
If you can get a code past present or history or pending post back code no.

ok heres an update.i changed the plugs yesterday and put in some high dollar fuel system cleaner with not much luck.i checked the fuel pressure when running normal. stays around 55psi idleing. it has started to be an everyday thing now with it running like crap and missing.i dont have access to a nice scanner and am stuck with the crappy free autozone scan.only shows cylinder one misfire,by the way the plug looked perfect,and a evap code that i have been hunting down.i checked the pressure when its running like crap and it is still above 50 around 55 like it should.it reaks of gas when its missing so i really figured it would had a drop in pressure if maybe if an injector was malfunctioning but still no luck on the culprit..I also noticed when it has been sitting for long periods of time its hard to start. so i checked the pressure this morning and before starting would only get to high 40''s.and when cranking on it the pressure slowly drops.Isnt the pump supposed to run while cranking? cuz i think it is not running when cranking. but after a few tries it starts and pressure jumps to 55. and if i turn it off and the pump delay is on it goes up to 60 like i figured it should.so anyways this is the degrading update. any ideas?this thing is killing me in gas with all ready horrid gas prices. any chance this might be the dreaded high dollar fuel injector spider acting up? i dont really know how a bad injector would act. :crying:

Have you checked for codes or engine running data.

You fuel pressure is to low.
You need 64-65 cranking and 62 /65 engine running.



The only true test on a fuel pump is to check the direct fuel pressure from fuel pump.
A quick test is to block off the return line and see if fuel pressure comes up to 75-85 lbs.
But do not run the pump at full pressure very long.
Also when testing fuel pump and pressure you need to tape a gauge to outside windshield or outside mirror and drive it on the road for 20 -30 minutes
until the pump gets has run a while to check for a pump fading out after hot.

Hard to start cold or hot and fuel pressure testing guide lines.
Check cold start fuel pressure.
Check engine running fuel pressure.
Check engine running on the road fuel pressure.
Then shut it off and watch for fast leak down.
Pinch off at rubber part or block off return line and check full pressure.
If pump has full pressure with return line blocked and low pressure without it blocked most usually the fuel pressure regulator is leaking or not holding pressure.
Later V6 and V8 gm engines should have 60-66 fuel pressure.
Cold start should be 64-65 lbs of pressure.
If you do not have full fuel pressure on a cold start the injectors will not squirt fuel.
Do not leave home without it.
Engine running should be 60-66 lbs pressure depending on engine load.
Full pressure with return pinched off should be 75-85 or more.
And if it has a fast leak down after shut off you have a leak in system.
Post back fuel pressure readings.

well another negative update...it is now gotten so bad that it will barely keep up with traffic with it floored. i did notice this morning that i could feel it surging and getting power in pulses then went straight to no power...its barely even drivable when it does this.its gone from a very random problem to multiple times a day..and is getting harder to start in the mornings. i noticed i could barely hear the fuel pump come on but after about 5 minutes or so of cranking and stopping sranking and stopping it finally started and when it was to that point, the pump was much louder. So either something is sticking open and no putting much pressure on the pump or a bad connection...but still doesnt make sense the way it feels only sometimes..anytime i had a pump go out before it was out. going to do the wiggle test while running on any part of the harness i can get my hand on ...after that i am stumped

HOLY CRAP I FOUND IT!!!!!!!!!you would never guess the culprit..somehow there is fuel pressure in the connector on top of the intake where the harness plugs in to the injector spider. the pressure behind the connector actually pushed a few of the wire/pins straight out of the connector. i started wiggling the harness starting there while running and it would either almost die or would rev up and smooth out. so i opened the connector cover and low and behold the pins with the little seals had been pushed out of the connector and when i jiggled them they started spewing fuel out. now i am hopefully sure fuel should not be there and am thinking either something is cracked inside or maybe the regulator is leaking. i have never been into a motor with the under intake injector spider.if any body has any advise on the cause or maybe even a repair.

You should have run the fuel pressure test.
That would have showed up on the leak down test.

Pull the injector plug off and clean out fuel.
Then prime up fuel pump pressure and look for where it is leaking.

It may be coming up around top of injector prong.
Let us know what you see there.
If just one injector prong leaking you can remove top cover and replace one injector at a time.

ok well i did numerous pressure test and only randomly slowly leaked down.if the wire harness was moved just right then it would leak passed the connector pin. ok now what i found was cylinder 1 injector prongs are leaking. it is coming through both of the prongs for that injector. so you mentioned that this is a single injector problem, as in i will not have to replace the intake or the whole spider assy? that shure would be great.i am just happy to find the problem. but need to repair it as cheap as possible. a local guy has the same motor with intake and all with a knocking rod and was going to see if he will let the intake and spider go for half of what he is asking for the whole damn thing,which is only 100bucks.so please let me know .thanks

ok well believe it or not it only cost me a couple bucks for carb cleaner. i took the injector that was leaking out, took it to work and put it under a micrscope for inspection and the leak was actually an oring that was around a torx screw that screws int the middle of the injector. so i had orings at work and put it back in with no leaks...but i still have a cold start problem. i hear the pump come on like it should but it will not start till after about 10 trys..i am going to see if i am getiing spark when first trying it.when it does finally starts it putters then slowly smoothes out.but it doesnt even try to start till after the 10th attempt.any ideas?

Run the fuel pressure test.
Post back readings.

ok when i first put the guage on it was on zero...but has been sitting for more than a day. i think that is normal..correct me if i am wrong. then i turned the key on but not start yet. pressure jumped to a little over 50psi. then i cranked it for a few seconds didnt start and pressure dropped a little below 50. so i turned the key off and it went back to a little over 50. then i turned the key forward again and it went to 55psi. i then tried it again and it almost started but didnt.with pressure right around 50. so iturned it off then back on and press was back at 55. about the 3-4 try it started. this has been the easiest start in a while. after running for a few secs..i cut it off and watched pressure..it jumped to about 60psi. then you could just barely see it falling,almost wasnt noticeable .so what do you think?

Your fuel pressure is to low.
This engine needs 64-65 lbs of fuel pressure for a cold start.

Run the full fuel pressure test as outlined in post no. 4 and post back pressure readings.

Be aware several things can cause low fuel pressure.
Weak fuel pump.
Restricted filter.
Fuel pump pressure regulator.
Leak in fuel system.
Bad voltage and ground to fuel pump.