Fuel Pressure Regulator Swap 96 S10 Blazer.

[thomasrn]

Howdy,
Did the fuel pressure regulator swap. The intake manifold had quite a bit of carbon build up, so I soaked everything down in Gas to try and clean it up.

Installed the new fuel pressure regulator, put it all back together again (fuel lines were troublesome). Went to fire it up, cranked and cranked. I even tried priming the air intake with fuel (as i've done before many times). No workey, totally dead. Fuel pressure looks great now! Nowhere near the 60, but I'll take 54 PSI! Left the coolant out as this was just a test.

Couldn't figure out why it wouldn't start. "Oh shoot" forgot to put the fuse back for the ignition system (no spark). Went and gave it another crank. Ka-BOOM! Backfire through the carb. Hmm.. MAP sensor popped out, and a few other items popped out. (I hope I didnt damage the FP regulator from this .

Figured too much fuel, disconnected the fuse in the glovy to the fuel pump. Started cranking again.. The engine turned over, the starter encountered enough resistance to stop dead mid crank. Let go of the key PDQ, Engine moved backwards "KA BANG"! Another backfire.... Tried another quick crank, same thing "KA BANG". (Ka bang is smaller than a KA-BOOM). Hmm... Did I do something stupid like put a poppet in the wrong Cylinder??

Took it all apart again. Everything was in the correct spot. But the air intakes (lower manifold) were filled with quite a bit of gasoline (more than I would have expected - I did not spray that much fuel into the intake, besides that, there would be no way for the fuel that I put there to make it into Cyl #5 and #6 air intakes.). Cleaned out the Gas from all 6 cyl *AIR* intakes as they were "full of gas". I am going to bed to take another stab at it in the morning.

I figure either I flooded it (but I shouldn't be having this problem) from cranking with no spark? Or the Popetts are leaking massive amounts of fuel everywhere? Pretty crazy stuff... It's almost like every cylinder was so full of fuel, that when I cranked the engine, it couldn't due to so much fuel being in cyl. Gas doesn't compress down all that well last I checked.

Any thoughts?

Regards,
------ Robb ------

[metallica21156]

try with the upper intake off and every thing hooked up such as power to the injector, wipe every thing clean and turn the key to prime the system see if you have a leak there and if not then disconnect the wire/plug from the coil and try turning the motor over and have somebody watch for fuel spray. this is a 95 with the CPI right?

[metallica21156]

try with the upper intake off and every thing hooked up such as power to the injector, wipe every thing clean and turn the key to prime the system see if you have a leak there and if not then disconnect the wire/plug from the coil and try turning the motor over and have somebody watch for fuel spray. thats all i can tell you beyond that your on your own. when you have the intake off let the system sit primed for a while and when your ready to prime it run the pump 5-6 times to make sure its primed. then you can leave it and come back later and see if you have any leaks.

[thomasrn]

Originally Posted by metallica21156

try with the upper intake off and every thing hooked up such as power to the injector, wipe every thing clean and turn the key to prime the system see if you have a leak there and if not then disconnect the wire/plug from the coil and try turning the motor over and have somebody watch for fuel spray. this is a 95 with the CPI right?

It's the injection system that came with the car. It uses poppet valves. I heard there was a newer injection system in the 97's that is a little more reliable.

Thanks guys, I'll give the fuel leak trick a try.

Regards,
---- Robb -----

[BlazerLT]

54psi IS TOOO LOW!

YOU NEED 60-66PSI!

[thomasrn]

Originally Posted by BlazerLT

54psi IS TOOO LOW!

YOU NEED 60-66PSI!

When the pump is on, I see 62 PSI. But by the time I run from the inside of the car, to check the Fuel Pressure, I see about 54 PSI. It stays at 54 PSI for about 15 mins, 52-50 PSI for another 45 mins. Later on (8 hours) I see about 40 PSI.

So things are working quite a bit better in terms of the fuel pressure readings.

The results of the 'turn the engine over' with no upper intake manifold are in.

I have a jacobs ignition system, I disconnected the fuse going to it so there was no spark available. If there is a fuel leak, don't want any fires!

Cranked the engine, no visible fuel leaks. I popped the poppet valve from cylinder #2, cranked the engine and YUP there is fuel being sprayed out of the poppet valves. Lookin great that way!

( BTW: I was almost going to head out and grab a new poppet CPI, but when I see it pulsing fuel correctly, it's obviously not the problem) Thanks guys!!!

Previous to all the above:

I reset the computer by pulling all power and fuses for 45 mins. With the car totally together it cranks, but it's acting like as if the firing order is FUBAR. Found out that if I hold the key on it cranks fine for a bit, then stops momentarily almost as if the timing is way off the mark. It's almost like it's firing the cylinder in the middle of a compression cycle. In the past I would let go of the key, the engine would turn back slowly and then backfire through the intake manifold.


What in tarnations did I do that could throw the timing out that far??

Crank position sensor?
Timing Belt gone WAKO?
Mixed up spark plug wire? - Never touched em, but I'll look em over just the same.

Any other ideas?

Regards,
---- Robb ----

[BlazerLT]

It should hold at 60-66psi for longer than that.

You are having pressure bleed off.

[rlith]

You do realize the 96 is not a Batch fired system like the 92-95 CPI? Your injectors have to be placed in the proper order in the plenum system or it's just like not having the proper firing order on the cap...

[thomasrn]

Originally Posted by rlith

You do realize the 96 is not a Batch fired system like the 92-95 CPI? Your injectors have to be placed in the proper order in the plenum system or it's just like not having the proper firing order on the cap...

The wiring to the plenum is 'idiot proof', it's simple a single electical connecter that is KEYED (it only goes one way) that connects all of the injectors at once. I couldn't twist that cable to install it some other way, even if I tried. When I look at the before pictures (before I took it apart), the connector is installed correctly.


The hoses to the poppet valves are 'very brittle', and if I try to bend them to go into some other order, they would probably 'break'.

On the sides of the CPI, I see the cylinder numbering which I would assume tells me which cylinder each hose should be fed into. So I'm running CPI hose #1 over to cyl #1. There are even cylinder numbers imprinted on the lower intake manifold, beside each hole where the poppet valves go. At least I think I did that part right?

Regards,
---- Robb -----

[metallica21156]

any luck? if thats all right then i don't know. you might have gotten a bad regulator. what was the truck doing with the old one?

[rlith]

Originally Posted by thomasrn

The wiring to the plenum is 'idiot proof', it's simple a single electical connecter that is KEYED (it only goes one way) that connects all of the injectors at once. I couldn't twist that cable to install it some other way, even if I tried. When I look at the before pictures (before I took it apart), the connector is installed correctly.


The hoses to the poppet valves are 'very brittle', and if I try to bend them to go into some other order, they would probably 'break'.

On the sides of the CPI, I see the cylinder numbering which I would assume tells me which cylinder each hose should be fed into. So I'm running CPI hose #1 over to cyl #1. There are even cylinder numbers imprinted on the lower intake manifold, beside each hole where the poppet valves go. At least I think I did that part right?

Regards,
---- Robb -----

Actually 96 uses CSFI... I wasn't talking about the electrical, I was talking about the hoses... As long as you followed the markings you should be fine on that part...Now, 2 things you should check again. #1 is there gas in your oil with all the overfuel? 2 have you tried swapping out plugs again?

[thomasrn]

Originally Posted by rlith

Actually 96 uses CSFI... I wasn't talking about the electrical, I was talking about the hoses... As long as you followed the markings you should be fine on that part...Now, 2 things you should check again. #1 is there gas in your oil with all the overfuel? 2 have you tried swapping out plugs again?

IT LIVES! - I finally got it to start, and took it out for a spin!

I disconnected the electricals to the fuel enjectors. Cranked the engine lots and lots and lots to clear out any fuel vapour. Then I re-connected the fuel enjectors up, and cranked it.

I could hear it almost catch..

I then kept cranking, and after quite a bit of it almost running, it fired right back up and ran. Terribly at first. I was able to drive it around town tonight, and it seems to be a bit happier. Not sure how it will be in the morning!

Thanks guys for all your help!

The engine runs and it is not setting any DTC's.

My autotap is still showing some missfires on Cylinder #6 of 177. But I didn't understand what the sensor actually means. So I pulled the sparkplug wire off Cyl #1. Started the engine.

The graph shows Cyl #1 starting at 0 then counting up to 200, then resetting back to 0, then counting back up to 200 (a sawtooth pattern). The engine idled quite nice with no sparkwire on Cyl #1.

Cyl #6 is sitting fairly stable at 177, +/- 5 as the engine runs. I am seeing a fairly 'flat line' that goes up and down. NO SAW TOOTH PATTERN.

It looks like if the cylinder missfires, it adds to the counter. If the cylinder doesn't missfire for a while, it subtracts 1 from the counter. So for Cyl #6 to stay 'stabled' at 177 means it's not missfiring all the time. If anyone knows for sure how to interpret this data, I'd sure like to hear from you.

I pulled Cyl#1 sparkplug, and regapped it from 60 out to 126 (I have a jacobs ignition system, don't try this with a factory coil). Seems to have cut back on missfiring on cylinder #1. So I'll be checking out cylinder #6 in a bit. I am just here waiting for the engine to cool so I can fully tighten #1 and re-gap the rest. Yeah, messing with spark plugs on a hot engine 'is' a no no!

Regards,
----- Robb ----

[rlith]

What you should do temporarily is eliminate the the Jacobs unit and gap normally and see if it goes away... If it does, you may have narrowed it down. And check your oil for gas, with all the fuel dumping you've had, you may have issues with it.