Vortec 5.7 vacuum leak

[slazix54]

I was set to do my fpr and noticed milky oil before taking off anything, since the kit I ordered came with lower gaskets as well I decided to do them. Everything went pretty well although it took a long time.

Now I'm dealing with a vacuum leak, LTFTS pinning at 25, STFTS during startup are at 50 until warmup and drop to 35~ intake psi is at about 5, maf is at about 6. Although previously not having MAF issues If I unplug the MAF it will die, if I leave it unplugged and restart the STFTS will drop to about 8-15 and idles very roughly. I'm assuming these trim numbers are pointing to a fairly large vacuum leak?

I took off the intake plenum after seeing the STFTS dropping when I sprayed alot of carb clean. I ended up finding a twisted and tore up fuel meter body gasket, I reinstalled the old one with a bit of grease and it went on really smooth. But I am still having the same issues.

Besides replacing the gasket or renting a smoke machine I'm not sure what to do.

 

[L31MaxExpress]

You have to lift up on the fuel meter body until it snaps into place.

 

[slazix54]

You have to lift up on the fuel meter body until it snaps into place.

I'll give this a try tomorrow, I definitely didn't feel it snap in, just kinda slid into place.

 

[slazix54]

You have to lift up on the fuel meter body until it snaps into place.

I ended up just getting a new gasket set, I didn't feel a click but I pulled up pretty hard, the plenum was sitting completely flush and the meter body harness plug clips clicked into place.

Same issue :/ I'm really just not sure what I messed up. The truck runs really good for about 10-15 seconds and then all the fuel trim issues start. If I try to drive the truck it will buck and try to die if i accelerate too quickly. Previously I had been dealing with fuel pressure bleed off.

I'm starting to think I might've just gotten unlucky and had my fuel pump die while my truck sat for 4 days during the job.

 

[MikaelT]

I ended up just getting a new gasket set, I didn't feel a click but I pulled up pretty hard, the plenum was sitting completely flush and the meter body harness plug clips clicked into place.

Same issue :/ I'm really just not sure what I messed up. The truck runs really good for about 10-15 seconds and then all the fuel trim issues start. If I try to drive the truck it will buck and try to die if i accelerate too quickly. Previously I had been dealing with fuel pressure bleed off.

I'm starting to think I might've just gotten unlucky and had my fuel pump die while my truck sat for 4 days during the job.

i had the same issue, everytime I opened something to fix it something else broke or started leaking.

1 major stupid thing tho, when I reinstalled my injector connector, one of the pin bent insted of going in, took me for ever to realize.

never managed to reseal the injector connector and the 2 fuel line perfectly either .... ended up just putting some rtv all over the place lol, since the intake is sucking in air, it kinda seal itselfs insted of blowing through like the exaust would.

one thing you can try tho is shimming a litle bit the injector asssembly on the bracket, giving it no choice but to clip fully in the plenum. you should have enough room by the throttle body hole to make the final adjustement.

 

[someotherguy]

I ended up just getting a new gasket set, I didn't feel a click but I pulled up pretty hard, the plenum was sitting completely flush and the meter body harness plug clips clicked into place.

Same issue :/ I'm really just not sure what I messed up. The truck runs really good for about 10-15 seconds and then all the fuel trim issues start. If I try to drive the truck it will buck and try to die if i accelerate too quickly. Previously I had been dealing with fuel pressure bleed off.

I'm starting to think I might've just gotten unlucky and had my fuel pump die while my truck sat for 4 days during the job.

Fuel pressure test is easy and will tell you the story quickly. However, I'll add this - if you're running the original poppet injectors, low fuel pressure won't be the issue. SBC Vortecs running the poppet setup generally won't even start once the pressure gets below the mid 50's.

Richard

 

[Bucknasty]

I was set to do my fpr and noticed milky oil before taking off anything, since the kit I ordered came with lower gaskets as well I decided to do them. Everything went pretty well although it took a long time.

Now I'm dealing with a vacuum leak, LTFTS pinning at 25, STFTS during startup are at 50 until warmup and drop to 35~ intake psi is at about 5, maf is at about 6. Although previously not having MAF issues If I unplug the MAF it will die, if I leave it unplugged and restart the STFTS will drop to about 8-15 and idles very roughly. I'm assuming these trim numbers are pointing to a fairly large vacuum leak?

I took off the intake plenum after seeing the STFTS dropping when I sprayed alot of carb clean. I ended up finding a twisted and tore up fuel meter body gasket, I reinstalled the old one with a bit of grease and it went on really smooth. But I am still having the same issues.

Besides replacing the gasket or renting a smoke machine I'm not sure what to do.

You can make a smoke machine for cheap. I took a pickle jar with metal lid and two pieces of rubber hose one of them that fits tightly into the vacuum line that connects to brake booster and the other one fits into the locking mechanism on bicycle tire pump. Then I drilled holes in metal pickle jar lid that required some effort to push hoses through about 2 inches or so to the inside of lid then hot glued them. Then shove the bigger hose inside the vacuum line leading to brake booster and hook other one to tire pump. Light a piece of scrap paper on fire and drop it in pickle jar then screw jar onto the lid which will smother the fire and start the smoke. Then just pump on the bicycle pump and look for smoke. Once I had the right hoses it took about 10 minutes to make and it has a home in my tool box I have used it countless times over the years and it never disappoints.

 

[slazix54]

Update for anybody doing web searches: ended up being a bad fpr out of the box, delphi brand.