Do I have bad fuel injectors or fuel pump on my '92?

[Nacho_ZR1]

So I barely purchased this car a few days ago. I've only driven it pretty hard through gears 1-3 since I've been waiting to do an oil change and tuneup next weekend.

A friend of mine wanted a ride earlier today so I took the car to a very dark quiet street and took off. The car pulled very hard in first gear and began to fishtail around 6500 rpm so I short-shifted into second gear and kept going. Everything was fine until I let off the gas and made a U turn to come back home. The car was idling extremely roughly and it was sluggish to get through the gears. I took her home and let it sit for a few minutes. When I tried starting the car back up, it cranked for at least 10-15 seconds and a big puff of grey smoke came out of the exhaust. I am afraid to take the car for a spin again and not sure what to think. Bad fuel pump or injectors? Am I off base? Not sure if the delaership put in a fresh tank of gas or if it's still the old gas that was from the previous owner.

Not sure what to think but I'm hoping you all have seen this before?

[Paul Workman]

Originally Posted by Nacho_ZR1

Everything was fine until I let off the gas and made a U turn to come back home. The car was idling extremely roughly and it was sluggish to get through the gears. I took her home and let it sit for a few minutes. When I tried starting the car back up, it cranked for at least 10-15 seconds and a big puff of grey smoke came out of the exhaust.

Wow...What is it about Texas anyway? The second car in as many days with a similar tale of woe!

From your description, it sounds more like coolant leaking than it does a fuel delivery problem, e.g, "Everything was fine until I let off the gas..."...coupled with the whitish grey smoke (steam, acutally) is a classic symptom of an Injector Housing (aka "IH") gasket failure. This is not a big deal to fix, but DO NOT crank it again, just yet! There are a couple preliminary things ya need to do to get into the right area, and if it is a coolant (gasket) leak, chances are you may have enough water in one of the cylinders to hydra-lock a piston and wreak some serious damage.

Pull the plugs and see if you have any that are steam cleaned; that is to say it would have much less soot on it than the rest, and of course if it is wet with coolant... There is a coolant passage running between the intake runners of cylinders 1&3 and 2&4 which leaves maybe 1/4" or a smidge less between 15# of coolant pressure and - 10# or so of vacuum; worst case during throttle-closed deceleration from high rpm.

I just happen to have taken a pic of my leak - didn't use one of Jerry's gaskets after porting my top end - was the problem. Notice where coolant has collected on the inside of the runner on number 3 cylinder (primary) runner. Notice that gray-black stuff along the seam (at the 10 o'clock position) extruding into the runner. That, my friend, is some of the gasket that is squirting out, being made of sub-standard material (as it turns out).



BTW, hopefully your coolant is the green glycol type and not the orange colored Dexcool? Our stock head gaskets - all stock gaskets disintegrate in the presence of Dex. Oh, and another thing...You may notice the brass plug to the left of the runner. Should you need to pull the intake plenum, drilling and tapping the IH to accept such a plug will eliminate the need to drain and refill the coolant, whenever the mood strikes to pull the plenum. (Pulling the plenum is a "right of passage" for ZR-1 drivers. Just about everyone has done it once, sooner or later.)

Anyway, if you have a steam cleaned plug, it is a sign of a coolant leak, and chances are it is the IH gasket or maybe even a plenum gasket; not wanting to think "head gasket" just yet.

With all the plugs out, you can tap the starter - just bumping it to slowly turn the crank over. If you have a cylinder full of water, bumping it with the plugs removed will allow the water to escape w/o doing any harm. And, of course, water expelled from a cylinder would confirm you don't have a fuel delivery problem.

A fueling problem can be narrowed down with a leak-down test. You can rent a fuel pressure gauge (or buy one - would be my recommendation) from e.g. AutoZone. Hook the gauge to the Shrader valve on the front of the right-side fuel rail, and without cranking the starter, turn the switch on. The fuel pressure should come up to around 45-50#. Shut off the key, and pressure should not leak down more than a pound or two over a period of a couple minutes. If the pressure holds, then the pump(s) are working and you don't have an injector that is leaking nor a check-valve (in the pumps) leaking either.

Well, this should get you started. Let us know how what you find out, and someone will pick it up from there.

Sorry 'bout your luck. But, you're not alone. And, you are reasonably close to one of the gurus of these cars - Cory Henderson - who can handle anything you may need.

P.

[Nacho_ZR1]

Wow helpful info! My only issue is, I am NOT mechanically inclined whatsoever...yes, I admit it...I can pretty much turn the key in the ignition and shift the gears but other than that, I am useless. I may have to push the car into the garage and wait until next weekend when my friend can come over

[Nacho_ZR1]

UPDATE

So, I had a nice phone conversation with JetJock and am feeling better already :yesnod: I walked out to the car earlier today and it had a very strong fuel smell coming from under the hood. I didn't see anything out of the ordinary but when you look under the car, you can see it is leaking gas! There was about an 8-10 inch diameter puddle where the gas has been dripping all night. I put my finger on the oil pan and it is still dripping fuel slowly.
Blown injectors?

[Pete]

If you have feul dripping off the oil pan check a couple of things

1.pressure ragulater,start the car and pull vacuum hose if you see feul bad regulator

2.make sure the screws are tight the feul line connection at the motor and/or check O-rings

Make sure the MAP vacuum line did not pop off.

The 15 second crank is normal for LT5/ZR-1

Pete

[GTOger]

Yeah, geez what is it about Texas this weekend? (And yeah, Nacho, you're not alone... similar thing happened to me coming home from McKinney to Plano on Thanksgiving. Maybe we can get a multi-car discount if we have to take our ZR1's someplace! LOL...

[GTOger]

Nacho... you and I are having the same problem, I think (see my "oh crud" post). Have you found anything with the fuel leak? Mine was smelling real strong as well this morning but I couldn't find any puddles or wet spots on the car.

[Nacho_ZR1]

Originally Posted by GTOger

Nacho... you and I are having the same problem, I think (see my "oh crud" post). Have you found anything with the fuel leak? Mine was smelling real strong as well this morning but I couldn't find any puddles or wet spots on the car.

LOL it seems we both had the same issues around the same time frame. Jet_Jock has been over at my place this weekend and we definitely think it's something with the injectors/o-rings. Not sure how far away you live from Cedar Hill, but he will be over at my place again next weekend to help finish the car up. You are more than welcome to drop by. Just send me a PM.

We thought it would be a good idea to replace as much as we possibly could while the plenum was off. I have ordered:

-New Delphi injectors from Jon Banner
-Hoses and performance chip from Mark Haibeck
-Starter
-Coil Packs
-Fuel Filer
-Thermostat
-Spark Plugs
-Jerry's gaskets for the plenums, air-horn, etc.
-Coolant sensors
-case of 10w-30 Royal Purple synthetic oil (my buddy is a dealer and gets it at cost)

Been an expensive endeavor so far but it's almost a 20yr old car and i need to make sure she's in tip-top shape. I'm so ready to drive the car again

-Carlos