Metering body gasket trouble

[EJ_74]

Working on a 2000 pickup with the 5.7 Vortec fuel system. New upper intake and MPFI injector assembly.

New engine threw a couple codes the other morning, lean fuel trim on both banks. Looked under the hood and found a vacuum leak between the metering body and upper intake. Thought maybe I didn't get the body seated properly when putting it together. Tried pulling it up some but could see the o-ring was twisted and starting to come off. Took it apart, o-ring fell off and looked like it had got pinched. Put a new one on it but still have an issue.

So I put the gasket on the metering body and lay the intake on top. Upper intake is only like 1/8" above the lower mounting surface. This doesn't really give me enough room to work it down onto the gasket but is still too high up for the intake to lay flat. The same thing happened when I put the intake on the last time, and I just let the bolts pull it down. But I think this might be what caused it to leak. When everything was assembled there was maybe a 3/16" gap between the top of the metering body flange and the bottom of the inner lip of the intake. I compared it to another vortec engine and the gap on that one was smaller. I think my metering body is sitting too low in the intake and not making a good seal.

Been looking at the old and new parts trying to find any differences. Thought maybe the injector bracket was bent or something and got a new ACdelco one. It was identical to the old one. Compared the old and new upper plenums and they seem to be the same height. Can't check the old injectors as I sent them for a core but I remember they looked about the same. Not really sure what else to do other than try to shim the bracket up a little higher. Maybe use a longer bolt too.

Anybody have any tricks, am I missing something?

 

[slow_c1500]

what brand was the mpfi assembly? I know from experience that the eBay ones have a crappy fit. you want GP Sorensen/Standard or Delco

 

[east302]

Did you put a little oil on the o-ring when the intake was seated? It’s been a while, but I think that was in the instructions that came with my Delco MPFI.

Not sure if it helps, but on my 98 the fuel line hold down bracket is about 1/16” (or the thickness of the bracket) higher than the outer edge of intake when torqued to spec.

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[EJ_74]

what brand was the mpfi assembly? I know from experience that the eBay ones have a crappy fit. you want GP Sorensen/Standard or Delco

It's a GB remanufactured unit from Rockauto. Electrical connectors say Delphi on them but I guess the metering body itself could be aftermarket?

Did you put a little oil on the o-ring when the intake was seated? It’s been a while, but I think that was in the instructions that came with my Delco MPFI.

Not sure if it helps, but on my 98 the fuel line hold down bracket is about 1/16” (or the thickness of the bracket) higher than the outer edge of intake when torqued to spec.

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I coated the o-ring with vaseline for lubrication. Thanks for the picture, the gap looks about the same as the other Vortec I have. Not sure why this truck doesn't line up the same

 

[EJ_74]

Any chance someone has a factory or good quality aftermarket injector assembly laying around they wouldn't mind measuring? If I could compare the distance from the mounting tabs to the top of the body maybe something's different.

 

[EJ_74]

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Well I made a spacer out of an old metering body bracket and changed the bolt but later decided against it. In order for the bracket to self-align to the intake like factory it needs to have a little wiggle room. And if the bracket can move, so can the spacer, and I don't like the idea of a piece of metal vibrating around in the intake.

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So I ended up just putting the original bolt back with a couple washers. The thread engagement is a little less and only one side of the bracket is well supported but I used threadlocker and was careful putting it back together.

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It sits up nice and tall now, I felt the o-ring go in good this time. It should run and idle a lot better, no more huge vacuum leak. I did start it yesterday and everything was good but still need to drive it some.