FormulaReed

Hi all,

I have a 1992 z28 TPI and it's running pretty poorly. I did a fuel pressure test and it seems really low. I did it at the fuel rail and I got 12 psi at prime. I thought that it was suppose to be like 45 psi? Would the car even run with it that low?

Cheers,

Reed

eseibel67

It might sputter but it won't run very long or very well. Pressure should be 40-47 PSI at prime.

1983Chimaera

43.5 nominal, but as said 40-47 is your target window. If you can hear the fuel pump it's unlikely that's the culprit, could be the fuel strainer is clogged, regulator has gone bad, or a stuck injector is bleeding pressure. Does it hold at 12 psi or bleed off?

FormulaReed

It holds 12PSI... but now I have a new issue.

The test port is stuck open, when the car is priming, it's fine but when I turn the car on theres a geyser of gas coming out of the test port. I tried pushing the port up and down but it's stuck or broken. It looks like I can replace it.

The crazy thing is, right before I realized the car was spewing gas, it was running great. Makes me think the regulator is messed up, but I have to fix the test port before I can really figure it out.

FormulaReed

I found a valve to replace the one that had failed after going to like 5 stores.

After I replaced the valve, I replaced to fuel regulator. Car runs better and has good fuel pressure now, but it's running rich. It idles ok, but it when you rev it black smoke comes out of the pipe. It's also down on power.

It seems like I have a bunch of things going on. I'm thinking that the EGR valve has failed, or I have some bad injectors.

I replaced the ADL, but I could not get the idle to set. When I tried to start the car with it unplugged, after leaving a paperclip in for 45 sec. it just died. It would run with the ADL plugged in, but it idels at like 2K when it's cold and 1.2K when it's warmed up.

FormulaReed

I replaced the EGR this morning and it mad a huge difference. It feels much better, it's not stumbling or stalling any more. It's still running rich though. Less black smoke, but still not right.

I OHM tested the injectors and I have 6 that are 16-19 ohm, and 2 that are 6-8. I did the test with the engine hot.

Will 2 bad injectors make it run that rich? It runs the best that it's ever run as long as I have had it, but I would like to get it right. Do you all think that that replacing the injectors will make a big difference?

aliceempire

iTrader: (14)

.double post

aliceempire

iTrader: (14)

[QUOTE=aliceempire;5931339]

Normal resistance is around 16 ohm. I'd double check your finding to be sure I'm not wasting money on injectors. If the same two injectors read low like that then yes, replace them all. Especially if those are multec injectors in there.

86IROC112

[QUOTE=aliceempire;5931340]
Just tested all 8 of my injectors and every one came in at 17 OHMs. Nice and consistent but could I still have a leaky one or two? What exactly does the resistance tell you?

aliceempire

iTrader: (14)

Yes you could still have a leaky injector. The resistance test tells you if the coil inside the injector is shorted or not.

FormulaReed

I retested the injectors and got the same result, so I ordered some injectors from Southbay. It still has the original injectors, so I bet they are due to be replaced.

I got the intake taken off and man, it was really dirty inside so I got that all cleaned up. Getting the intake off was not that hard, but the fuel rail is just killing me.

The bracket that holds the fuel lines on the front of the engine is whats stopping me. I can't for the life of me figure out how to get the bolt that holds it on off. I tried to move the fuel lines around to gain access, but no luck. Any tips on how to remove it? Could I get the injectors off buy splitting the rail and just tilting it up?

Thanks for all the help so far!

aliceempire

iTrader: (14)

The bolt that goes into the intake manifold and holds the rail from jiggling around? Isn't it just a 10mm (or 8mm) bolt head? I think I just used a wrench... sorry, I'm not looking at my car but I don't remember anything being difficult.

FormulaReed

Spending too much time in the sun made the job much harder than it really was. The next day, I took another look at it and 5 minutes later it was off.

I got it and the fuel rail off and found that I had a collection of 3 different types of injectors. Some were original to the car, but it looks like someone went through all the trouble of removing the injectors only to replace 2 of them. Than some one did it again only to replace one. The funny thing is, the ones that tested bad were the replacement ones.

After a few miss steps, including messing up a gasket, not realizing it, putting the whole intake back together only to find a massive air leak when I turned it back on.

It runs much, much better. I had never been able to set the idle correctly but now with the new injectors, EGR valve, fuel pressure regulator and IAC valve, I was able to set it correctly.

I need to replace the spark plugs though. I pulled one and it looked pretty bad from being in the car when it was running so rich. It was still blowing a little black smoke when I fired it up but after taking it for a drive, it did it much less.

I was just going to replace the plugs with platinum AC Delco plugs. Are those still good ones to use? With a stock 305 motor, is there any point in going with a fancy plug like an iridium NGK?

Thanks for all the help! This forum has made fixing my car much easier!

aliceempire

iTrader: (14)

You could use AC platinum's but it'll just cost you more money than coppers. You won't see any benefit using anything more expensive than the factory R45TS plugs. Some one will always debate on this but I've NEVER gained anything on changing spark plugs unless the old ones were bad.