TomP

Hey guys, long time no see! Tried to start my Firebird after 2 years sleep- of course it started right up (with new gas), but it's running rich, even threw code 45.

I have Multec injectors in there, I see now that things have changed- instead of being the hot ticket, Multecs are shorting out and clogging and melting. Would measuring them with a multimeter tell me if they were clogged?

Or, could the injectors are clogged up with varnish/gunk/rust/etc? FPR seemed fine, no gas out of the vacuum port- and if it were bad, I don't think the car would start- right?

The car ran great before I put it away, so that's why I'm thinking it has to do with the gasoline and sitting around doing nothing but waiting.

Thanks!

TomP

Update! Measured two of the Multec injectors' resistance, #1 and #6, both were 11.8 ohms. So definitely shorted coils, probably all are bad, glad my ECM didn't fry up.

Four injectors are leaking. Pressure test:

2:35 = 43 psi
2:37 = 40 psi
2:40 = 34 psi
2:43 = 32 psi = 9 PSI drop in 8 minutes!

When I pinched the return line, pressurized the system, and pinched off the supply line, the system went from 59 PSI to 50 in under a minute, after 3 more minutes it was at 42 PSI.

Question about the fuel regulator though: No fuel leaking into the vacuum hose, which is good. I put my Mityvac and pulled 10" vacuum- it lowered the fuel pressure by 4 psi. Shouldn't it have opened the regulator, and reduced pressure to zero?

And then when I released the vacuum on the regulator, the pressure went back to what it was before I pulled vacuum. I thought the vacuum moved the regulator up (fighting the spring) to cause all the fuel to dump into the return line. No?

(Or is my regulator somehow stuck in down position? [edit] I know it's not completely stuck b/c pressure isn't pegged at 60 psi. But shouldn't pulling a vacuum on it have opened the valve- and all the fuel would've shot out the return, putting pressure to zero?)

Thanks!

Maverick H1L

iTrader: (8)

Resistance spec for the injectors used with the 302 ECM is 10.4 ohms minimum.

If you can get your hands on the proper security torx bit, you can disassemble and clean the plate and the seat in the FPR. Or replace it if you want.

Chances are that the pintles in the injectors are stuck due to fuel gum. Although I couldn't guarantee that a fuel injection cleaning (NOT the crud in the gas tank that NEVER works, I'm talking the stuff that goes directly into the rail and then into the engine) would help, I would tend to think that either sending the injectors to SouthBay or replacing them would help.

:edit: Might also remove the MAF and see if the film is dirty. It won't read right if it is, and that is another thing that can cause a code 45 (I had a code 45 for months before the thing finally spit out a code 33).

TomP

Hi Maverick! Thanks for the response & info. Yes I already have a replacement set from SouthBay on the way. My original injectors (had them in a box) all measured 16.0 ohms, so that was enough for me to replace these Multecs.

Thanks for the info on the MAF film, I'll check it too. Who knows what's got on there just by sitting still all those years. Cars don't like to sit

I have a spare diapraghm and the security torx. Just wondering what should've happened when I pulled a vacuum on the regulator port, with Key On Engine Off, and 42.5 static pressure (pump not running)- I expected the vacuum to have opened the regulator valve a millimeter or so, and "whoosh" all the fuel would drain out the return. No?

RBob

iTrader: (1)

Pulling a vacuum on the FPR will lower the fuel pressure, same as if the engine was providing vacuum. 10" of vacuum will lower the fuel pressure by about 5 psi.

Note that this is with no pinched off fuel lines and the fuel pump running.

Welcome back TomP, haven't seen you here for a while...

RBob.

TomP

Thanks RBob, nice to see some familiar names around here still! Actually I'm glad to see the club is still here too- was a little worried it'd come up "website not found". I haven't seen another thirdgen on the road in a long, long time.

So the vacuum just flexes the diaphragm a bit, but doesn't overcome the spring? That's one strong spring by the way, I was surprised.

Maverick H1L

iTrader: (8)

From what I understand, the vacuum augments the spring pressure to help a lower fuel pressure to push the diaphragm up and away from the seat. So, when you apply vacuum, the fuel pushes up on the spring until X amount of fuel leaves the rail and the spring pressure overcomes both the fuel pressure and the vacuum working against it. At which time, the regulator closes again and no more fuel is allowed to leave the rail.

TomP

The way you worded it though makes me wonder- with key on engine off, first the fuel pressure moved the spring. Then I added vaccuum. If the car was running, both would happen at the same time. I didn't do the "engine running" FPR test, once I found the leaking injectors I stopped. Sounds like I should do the engine running test today.

It was just strange, with the pump not running, to release the vacuum and have the pressure go back up.

TomP

Hey guys, almost forgot to come back and update. Problem solved! The Multec injectors were definitely leaking; when I pulled the rail, the #5 cyl's injector had a drop of fuel oozing from the pintle. I put the ones from Southbay in, the 15lb set on their site, Bosch II's, cut new plenum gaskets (ah, memories) on top of a phone book (so that's what phone books are good for), and put it all back together.

Fuel rail was spotless inside so I didn't even bother to take apart the pressure regulator.

I hotwired the fuel pump until my gauge showed pressure- then unplugged my hotwire- and the gauge was nice and solid, no leakdown this time. So I turned the key and it fired right up! Exhaust smelled nice and clean- just like hot air (instead of unburnt fuel).

And it passed emissions!! Which of course is the best part.

I changed the oil the next day- and it smelt like gas. I measured all the injectors with my meter and they were between 11 and 12 ohms, definitely shorted.

I wonder how long those injectors were leaking (and shorted).

Thanks everyone!

Maverick H1L

iTrader: (8)

For further reference, straight out of the GM service manual, the spec for injector resistance is 10.4 ohms minimum... It's 11.6 for the 7730 system.

Street Lethal

iTrader: (16)

Tom, send them back if not installed yet. I have a set of 28-lb injectors you can have...

Edit: You installed them already, you can have the 28-lb injectors anyway if you want...

Doc91b

iTrader: (1)

If he didnt need them, are those injectors still available?