1996 GMC Z71 - 220k - Rough Idle/Hard Start - New to Me

[Shadowmyrock]

Well, I suppose this is as good a place to place an introduction as any.
To start off with, it feels good to be back on a forum, I haven't been on one since I had an LS1 powered F-Body.

Alright, so I just purchased this truck as a fixer to daily driver project. They just don't make them like they used to.
It has the 5.7/350 motor, not sure of the transmission (one problem at a time)

Current big issue is the hard starting, rough idling.
I've done some digging and ordered the MPFI "conversion" just from everything I've seen this HAS to be the root cause of it all.
I averaged 15mpg for 300 miles driving from Brownsville Tx, to Houston Tx, It idles rough, doesn't start right away (one start, rough idle, dies) then fires right up and idles rough, has NO power under acceleration, etc etc etc. All of these seem to align with a failing/failed CSFI.
I have changed the fuel filter and I'm getting ~55psi at the Schrader valve underhood with an almost immediate drop in pressure once the truck shuts off.

So, I plan on replacing that this weekend.

While I'm in there what might be some other things I should look at/into?

I plan on pulling/cleaning all or most sensors, checking the distributor cap/rotor, plugs seemed fine like a motor that's fuel starved (running lean), air filter needs changed.

~Ross

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I know this sounds crazy but I don't know how you posted that so I don't even know how to put a post out there for people to even see what I'm trying to ask but I could use some help but hey I appreciate it if you have the time I appreciate your time
U.S. Marine Veteran
Matt

 

[Erik the Awful]

Probably wouldn't hurt to do plugs/wires/cap/rotor since they are of unknown quantity.

Buy a United Motor Products blue/brass cap and rotor. Anything else is "unknown quality".

More Information for UNITED MOTOR PRODUCTS DCR820X

More Information for UNITED MOTOR PRODUCTS DR820X

 

[96CK]

Does the injector kit come with the upper manifold gasket? If not, you'll need the full set not just the lower.

I ordered a separate kit, but not one that included the lower. It's basically a kit for removing/replacing the upper - it's the Fel-Pro MS 90269 kit. So basically all I'd need are the Intake to head gaskets it looks like.

Consider valve cover gaskets. The newer center-bolt covers seal way better than the perimeter-bolt covers ever did...but as long as you're in there...

Not a bad idea, it'll also give me a chance to look at the valvetrain as well

If you're lucky, your "rear main leak" is either the rear seal on the intake manifold, or the oil pressure sending unit behind the manifold.

Man, that's my hope! That would save me from having to yank a transmission on my back.....

 

[96CK]

Buy a United Motor Products blue/brass cap and rotor. Anything else is "unknown quality".

More Information for UNITED MOTOR PRODUCTS DCR820X

More Information for UNITED MOTOR PRODUCTS DR820X

So, is it safe to say the days of MSD, Accel and the like are gone? Or is this just a good OEM equivalent one for one swap?

 

[Erik the Awful]

The UMP products are superior to the OEM pieces. Everything else has been problematic. Even the AC Delco parts are now chintzy relabeled garbage.

 

[Schurkey]

So, is it safe to say the days of MSD, Accel and the like are gone?

They're not "gone". MSD, for example, is pushing Communist Crap and expecting folks to remember MSD's reputation from a generation ago.
Their TBI distributor cap:

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I bought some extra Accel coil-in-cap distributor cap/rotor kits from Summit when they were "on sale"; made in USA and "so far, so good" but they do seem to be thin plastic.