TampaGuy

Following the fuel pump/lsu R&R, been pluggin' along on this and made some progress. Pulled the rail, replaced the regulator, removed & cleaned the injectors as best I could. Put in new o-rings/sleeves and put it all back together. Pressure shows a bit on the low side @ KOEO (~38), but within spec (~35) w/ engine running @ temp. The injectors appear to be fine. The old seals were actually in decent shape, but I replaced them anyway. I suspect once the PCM adjusts to the changes, it should be ok. For a Z that's been sitting for ~6 yrs w/o being started, it's going about as well as I could hope for.

It was a major pain getting the rail out; it was damn near impossible pulling the harness back out of the way, over the fuel lines, even after removing the tie downs @ the PCM and along the intake. My forearms were plenty bloody from the cowl. Seems like my harness is a lot tighter than normal; there was almost no slack. Going back in was much easier.

Haven't run a scan yet, but will be doing so w/i the next week or so. Do need to R&R both the cat & muffler, so will be looking for those. Am trying to keep it as much stock as possible.

1994-LT1-Eric

I'm in the same boat as you. Mine has sat a couple time for many years. I'll be pulling my fuel tank next for cleaning, maintenance, and replacing EVAP lines after my current task on the manifolds.

Have you tried any seafoam? Also, if you haven't already, try swapping the fuel filter and see if the pressure comes up a little.

Injuneer

When you turn the key to “run” the pump shoul build fuel pressure to at least 40 PSI, and drop very slowly, if at all when the pump shuts off. With the engine idling, pull the vacuum compensation line off the pressure regulator. Target pressure is 43.5 PSI, with the GM acceptable range 41-47 PSI. Reconnect the vacuum line, and rail pressure should drop proportional to intake manifold vacuum, resulting in an 8 to 10 PSI drop (stock cam, less with a more aggressive cam) from the “no vacuum” pressure. System should hold at least 40 PSI out on the road under max load(WOT) at 5,000 RPM.

Unless you have fairly sophisticated equipment, self-cleaning an injector is seldom successful.

Might want to add a “Signature”:

https://www.camaroz28.com/forums/lt1...nature-879835/

TampaGuy

Leaving them sit is a bad move--cost me a tranny--but at least mine was/is in a climate-controlled garage in FL. Everything in the fuel system 'cept the lines, injectors & relay (it tested good, but I have a new spare) is new.

Not a fan of additives in either gas or oil on a 5.7L. Injuneer is right that the "cleaning" I did is no sub for sending them out and having it done right (saw your post on that, Inj), but I wanted to get it running & off to Tim the tranny man before I do much more. When the time comes (& my forearms heal up), rather than cleaning, I'll likely get new injectors. I'm not inclined to even run injector cleaner in the fuel. If you're using 92+ octane religiously...

Additives like Seafoam--so-called "stabilizers"--can do more harm than good in a 5.7L. They're basically drying agents. Stick your finger in some gas. If it dries immed. after removing it, it's good gas; if not, be skeptical (or dump it & get some good gas). I use that stuff (actually, B-12) in my lawnmower, but B&S recommends it if you leave your mower, press. washer, etc. sitting for long periods. While GM likely never considered that we'd leave a Z28 sitting for so long, they don't recommend it at all. Better to follow recommended diags.

Right, 41-47psi. Mine is ~38 @ KOEO.

Shouldn't pressure @ warm idle be in the 31-38 range? I'm getting that, btwn 35-38. After putting everything back together, initial KOEO was ~30, idle @ ~33. After letting it warm up and cycling it a few times, I'm where I am now. Did check the vacuum and did see the corresp. drop in pressure.

Keep in mind, I still haven't had it out of the garage, and still haven't brought it to WOT. W/ the tranny seals blown, not sure how far I'd get.

Injuneer

~38 PSI at priming pump shutoff is low. But the priming number is static, not dynamic, and is typically not high in the 41-47 PSI range.



At warm idle, vacuum line OFF the regulator, end of vacuum line plugged, what was the pressure? 41-47 PSI is correct range. This is important, because the PCM calculates fuel required by assuming a 43.5 PSI differential between the rail (positive) pressure and the intake manifold (negative) pressure. A drop of 8 to 10 PSI for a stock cam at idle would put the pressure with the vacuum line connected to the regulator as low as 31 PSI, or as high as 39 PSI, depending on the "no vacuum" reading.

But you should check the "no vacuum " pressure AT IDLE. That is the measure of the pressure regulator accuracy.

TampaGuy

True, but since pressure is within spec @ warm idle, I'm less concerned about a slightly lower reading @ KOEO.

Well, since you mentioned it & the gauge was still hooked up--and at add'l personal sacrifice to my forearms (why is it that a guy who can only hit 160lbs in a wet wool overcoat has difficulty getting his arm btwn. the cowl & harness?)--I looked @ it again, both by applying vac @ the reg & by blocking the vac line. If I pump vac up to ~15, pressure drops by ~5psi, as would be expected. When I remove the vac pump and block the vac line, it's steady @ 41psi.

I'm using a Standard Ign. reg.--not the pricey Holley adj. reg.--and like most of the garden-variety regs., it rates @ 45psi, so I think I'm good. I can't explain the slightly lower reading @ KOEO, but all things considered...

Pioneer1

Try to be sure your injectors themselves are not leaking. Mine were sticking and flooding my intake.

TampaGuy

Hey Pioneer--saw you're back drivin' down the road, bad clutch notwithstanding. I can move mine, but since the garage is about a 9deg pitch from the street, not sure I'd be able to get it back in. As soon as I do the exhaust, it's off to Tim the tranny man. Have no desire to rebuild a 4L60e--even if I was skilled enuff to do it.

I don't see any evidence of problems w/ the injectors. As I noted, I pulled them, new seals, etc., then scoped them, and can't find any issues. No fuel in the oil. They've only got ~100k on them and I rarely ran it hard, so they should be good for a while. At some point I'll replace 'em, but not until I can rack up some freeway miles--and my forearms heal. For now, it seems to be running reasonably well, despite letting it sit for so long.

Pioneer1

You are probably in good shape injector-wise then. When I pulled mine, 4 would not spray at all, and 4 were pouring gas through them. I built a 'test rig' to flush and backflush under pressure while energizing the solenoid. I spent hours messing with each one until it worked and sprayed a good pattern every time.

I'm not under the delusion that I 'fixed' them- but It got them functioning good enough that the car runs ok and the injectors don't seem to be what's limiting me.

I can drive mine, the clutch will hold and lock up under light throttle driving- it just won't hold if I try to 'get on it'.

My work has been insane last couple weeks. Been a number of days since I touched my car. Maybe I'll get a chance over this weekend.

TampaGuy

Been going over the exhaust, and have decided to first do the cat & crossover w/ the Magnaflow stainless that includes both in a bolt-on solution--no welding, cutting or bending. The cat flange is 3", and since I'll be doing a cat-back, that works out. But I've noticed most of the cat-backs take forever to ship--I suspect they're made/bent once an order comes in--so I'm gonna have 'em swap the cat while they do the tranny and do the cat-back when I get it back.

My question: will I still be able to hook up the stock cat-back in the interim? It's 2.75" pipe, not sure about the flange. Not a major issue if I can't, but it means yet more waiting.

Pioneer1

I'd just wait and do it all at same time.

​​

TampaGuy

If I order it right now, most of the decent cat-back systems wouldn't get here until late April, early May. No sense wasting another month+ twiddling my thumbs, waiting on parts. In the meantime, I can have the tranny done. They already need to pull the cat & crossover to do the tranny, so might as well have them put in the Magnaflow. It hasn't been off in quite a few years, and I sure don't wanna snap any manifold studs doing a magilla gorilla. Let them do it.

I just wonder if the stock cat-back will attach to a 3" flange.

TampaGuy

So I'm still waiting on parts, but today I thought I'd let it run for a while, to let the oil & fluids circ. Everything was looking good, but then I noticed it's almost outta fuel, where there should be ~1/4 tank. I know these things are notorious for low readings, but not that low.

So I get out and --oops!-- there's gas all over the floor. When I applied pressure to the tank, the fuel came pouring out. It's the first time I've seen this. Not sure exactly where the leak(s) is; I'll go out tomorrow, put it under pressure and see if I can pinpoint it, but it looks like I'll be swappin' the tank. Gee, good thing I did a trap door, eh?

It's always something, it seems...

TampaGuy

Looks like maybe I dodged another bullet. Went to trace down the leak(s), and noticed some things. 1. No leak(s) @ KOEO (that would be too easy); must be started and running. 2. When running, it takes a while for the leak(s) to appear--a minute or so. I thought that was odd; if it's the tank, fuel should start leaking as soon as pressure is applied--if not @ KOEO, surely when running. Once it was running for a while, I saw a leak coming from the driver side, which eventually worked over to the pass. side. But no clear indication of a problem w/ the tank itself. Since I hadda do it anyway...

Went ahead and removed the trap door, to evac the fuel. Figured WTH and started it again...and there it was. After a delay, fuel started spurting from the fuel return line, just back from the connection. It leaks down the driver side, under the heat shield and down.

Looks like I need to R&R that line, which I think connects underneath, judging from the tank removal instructions. At least I'm gonna do that before replacing the tank. Not sure what caused that line to start leaking, but I did have some diff. getting it loose when I pulled the old pump assy. They might only sell the entire assy, but that's ok; I still don't need to repl. the lines to the rail. If that fixes the problem, it's far better than yankin' the tank.

Pioneer1

You 'should' be ok on the tank itself unless yours has driven a lot on salted roads.

I had a lot of grief with those fittings as well. I even extended my trap door cut over in that area to get some access. Still had to devise some goofy tools such as a flathead screwdriver bent into a hook-like shape on the end to help get those fittings loose. Waaaay more trouble than they should have been. I have never felt love for those plastic fuel lines. When I bought the car back in 95' I opened the hood and saw the fuel lines and thought- 'there's a problem waiting to happen..'

Guess we can't complain too much- they lasted this long.