S-10 Forum banner
Status
Not open for further replies.

gas dripping out of injectors when cranking ??

2K views 14 replies 5 participants last post by  Rhotpursuit 
#1 ·
hi guys,
well i got it all back together and it will not start.

now it ran before i changed motors and i hear the fuel pump come on right after i turn the key.
now have not checked the fuel pressure yet...

but besides the fuel pump , what else would make the injectors not spray??

now i rebuilt the tbi and its not my first time doing so.

92 s10 blazer , 4.3
 
#2 ·
You got it back together after what? You mean you just rebuilt the tbi or what? Been sitting a long time?
The only time my tbi ever dripped fuel out of the injectors I took them out and cleaned the inlet screen (on the side of the injector) and ran carb cleaner through while pulsing them. Hadn't had a problem since and this was 12 years ago.
 
#3 ·
This engine came out of a 89 1500 pickup as the s10 blazer engine has a bad piston. But the truck did run barely. So I got the pickup for the engine. I striped it and put some new parts on it plus replace all seals/gaskets. And painted it up. Dropped it in a few days ago and got it all hooked up. Trying to start it and would not. So I made sure the pump was working and it is. So checked the spray and noticed it's just dripping and not spraying. And I just rebuild the tbi. I have another tbi I just rebuild the other day so I took the injector pod off and put it on the tbi and it's doing the same thing.

Is there any sensor that could cause the injectors to not spray?
Remember the truck ran with the other engine so the pump was working and it's turning on now but it's just not spraying. And it will not start with the fuel just dripping.

Any suggestions. .. I could use some.
 
#4 ·
Are you doing something wrong on your rebuilds? It might be something in the fuel pressure regulator, which as you know is in the pod.
Did either of the tbi units work before the swap? Or did you rebuild them after the swap?

You might want to either take the tbi apart and recheck everything or check the fuel pressure. It could be the fuel pressure somehow bypassing the diaphragm and going right back out the return line.

The injector signal comes off the distributor, usually if it has spark it has injector pulse. But not if something weird is going on.
 
#6 ·
the tbis worked before rebuild.
but i alway clean them good and rebuild for peace of mind.
and have rebuilt a lot of them and carbs...

theres nothing to get wrong on a tbi regulator. its just a diaphragm and i make sure its seated and gasket is not cocked.
anyway i will still check ....

but i picked up a fuel pressure tester and a node light today.

so the injector run off the disy..... i know it all by the ecm but i know there has to be something to give the injectors power ( signal ).

it would be very weird if both tbi regulators are not working.. and have never had any problems after a rebuild..never. been working on cars for over 30 years.
but im not saying i know everything because i dont. thats why im asking as i never had a tbi do this.

now i will say the injectors were not replaced but cleaned up. as they worked before all this.


so first thing im going to check is how much pressure im getting at the tbi... if thats good then ill hook up the node light and see..


but i have another ?

on this truck it has a 3 wire o2 sensor and i do not have my y-pipe on, only the manifolds as i dont want to put it on and find out something is wrong and have to pull it.

so i was thinking well wander if its because the o2 is not hooked up..............
so i pulled it off my y-pipe and connected it to the harness..
then i got to thinking again... does it have to be grounded ?????? as in it being in the y-pipe.. as i just have it hanging but connected.

what do you guys thing?? and i know when the truck is cold its not reading the o2 as its in closed loop. but it still has me wandering.
 
#7 ·
is there a way to check fuel pressure after the regulator ??
there a cap on the top of the regulator body and wandering can a fitting be fitted ? would that read after the its regulated??

also whats the tank pressure ??

i know the tbi is like 12-13psi right ? is that whats going throw the injectors right?
 
#8 ·
Could be a blown fuse I guess. I don't remember. I think the injectors are pulsed on the ground side.

TBI pressure is 9-13. I've never owned a tbi s10 but I do own a tbi full size. On that I need to disconnect the line and put a test fitting inline. If your fuel pressure is good you don't necessarily have to check the return line pressure. If you have no fuel pressure you can check return line pressure to see if it's a regulator problem.

I've seen the screws get caught on the diaphram and twist it out of position. I've seen it twist a chunk out, that would send fuel pressure right back to the tank through the return line. I've seen a chunk of crap get stuck in the fuel line and end up in the regulator seat, again letting pressure bleed to the return side.

I've been working on cars since I was 12 too but to be honest the older I get the more I make little mistakes that make me wonder what the hell is wrong with me :dunce: I've screwed up things I've done 100's of times and didn't even screw up the first time.
 
#9 ·
heres a ? as i never had the digital dash...

ok i reused the pickup oil sender and when i had key on the gage was all the up showing high pressure.
well i put on the one that came with the s10 blazer and not when i turn key on all gages go all the way up for a few sec. and then it goes down to 0 . this is normal right ??

if so the the other sender was no good or was not right for the s10. not sure.
i had to pull the dizzy to get to it so will i had it out i replaced the module with the truck one.

and no go..

now im getting a no drip , or ill get some fuel and then it stops..
i dont get it...

i also check fuses and they are good.

i dont know what to do now.
 
#11 ·
You know some (most) TBI trucks have a fuel pump interlock in the form of an oil pressure switch.

Not that it matters, all that will show up if you just check the fuel pressure.
 
#12 ·
yes i did that why im looking els were..
thanks for helping me.. i need to figure this out.

it reads 12psi at tbi inlet.
and i know it was not the pump. they just dont go bad with a engine change.
as it ran when i got the truck. well barely as the #3 piston was toast, but it ran.
but i still checked it.


and like i said it getting to the point were it spits nothing at all..

then it will start dripping again.

theres something causing the injectors not to open all the way i guess..
as when the was dripping i was getting pulses at the harness.
but have not check it when i get nothing at all.

i order a oil sending unit as mine is coming apart.
but i did put the one that came with the truck back on and now my gage seems to be working.
 
#13 ·
just found out some new info...

its about the oil pressure switch.

the engine will still run get fuel if its bad.

its there for a backup of the fp relay.
so if the relay goes bad you will still get power to the pump.

and its not a safety devise were if your in an accident it will not shut off the pump as the senor and relay are parallel .

as with my truck there 3 wires going to it.
thers a power ( in and out pump ) and a gage wire.

and they open about 4 psi .


im going throw each serket to figure out why i have an intermittent fuel droplets and the nothing at all.
 
#14 ·
just found out some new info... its about the oil pressure switch. the engine will still run get fuel if its bad. its there for a backup of the fp relay. so if the relay goes bad you will still get power to the pump. and its not a safety devise were if your in an accident it will not shut off the pump as the senor and relay are parallel . as with my truck there 3 wires going to it. thers a power ( in and out pump ) and a gage wire. and they open about 4 psi . im going throw each serket to figure out why i have an intermittent fuel droplets and the nothing at all.
Hi You ever get it to going right Having the same problem with mine
 
Status
Not open for further replies.
You have insufficient privileges to reply here.
Top