vac line on pressure reg
 

Hi...I'm new to this forum..I've got a 98 4x4 LS that wont run, I've replaced the fuel pump. and I'm now replacing the spider injectors...and I've got a question..when I removed the unit, what I believe to be the pressure regulator on the back of the unit doesn't have a vacuum line going to it. it looks like it has a nipple for one..I've checked Haynes but can't find any thing on it...If it does, where does it hook up??? Thanks for any info anybody has..... Bud

It's inside the plenum, right? See the inside of the throttle body on bottom side. It's IN the vacuum.

The fuel pressure regulator is inside the plenum and is exposed to manifold absolute pressure at all times so it doesn't need a vacuum line.

Unless you need help with an oil change, toss your Haynes manual in the trash ;)
GM factory shop manual is the ONLY way to go.

Thanks Capt Hook, I was stumped, but I didn't think about there being a vacuum in there at all times......appreciate your help..I'll go ahead and put it back together then.. .Bud

Make sure you put oil on the O ring where the injector housing fits through the plenum ;)

98 Blazer wont start again...
 

Hi...It's me again, still stumped, I put the new fuel pump in, put a new injector spider assembly in...fired right up and ran like a charm...drove it about 2 miles and put it in the garage...this morning it won't start..turns over fast and has almost 60 lbs pressure on the rail..it doesn't even act like it wants to start. put a timing light on plug wire and it's getting spark..anybody have any suggestions on what to try next????:icon_hyper: Thanks..Bud

See it if starts when you put a shot of carb cleaner in the air intake. Fuel pressure must be 60psi to 66psi with the key ON, engine OFF, fuel pump running, and must remain above 55psi for 3 to 5 minutes after the pump shuts off. Post your results.

Thanks Hook...I put just plain gas into the intake. and nothing happened.. I'll get some starting fluid tomorrow after church and let you know what it does....Bud

Starting fluid can cause serious damage to a gasoline engine, and to you! One backfire can blow the rocker arm covers clean off the engine.... seen it happen.... and it's not pretty. You're better off using carb cleaner.

If it won't start with the carb cleaner, check for a hot, blue, not orange, rhythmic spark at each plug while cranking. Using a timing light can be deceiving. Spark should easily jump a half inch gap.

98 Blazer wont start again...
 

Capt Hook....I had already bought some starting fluid, before I read your post. and used it.:icon_shrug: didn't seem to hurt anything..but It started right up and ran until the fluid ran out. what do you suggest??? Bud

So..
1. fuel pressure during crank is good

2. Engine runs when primed through intake. ie; spark timed correctly.

So, only thing it seems to be is that injectors arent firing.

And it cant be a fuse because injectors are powered from ECM1 and if it was blown the engine wouldnt run under any condition.
That leaves the harness connector, right?

In post #6 you said fuel pressure was "almost 60psi" (after fuel pump replacement). I'm wondering about fuel pressure actually being too low, and or the accuracy of the gauge you're using; spec is 60psi to 66psi key on, engine off, pump running. Just because the pump is new, doesn't necessarily mean it's good. Might want to double check it, with another gauge if possible.

Another thing to check: As Pettyfog mentioned... the harness connector at the injector housing has 12 very small, very delicate pins and sockets... if they are not lined up perfectly when you tighten the retainer bolt, it can cause a poor connection or an open circuit. Carefully take the connector apart and inspect the pins and sockets, make sure no pins are bent over. Also, with the connector unplugged and the ignition in the RUN position, make sure all of the pink wires show battery voltage.