Well we have been having problems with my moms 87 Z. Its a stock 5.0 We took it to the shop to have them do some diagnostic testing. The 1st injector will need to be replaced. The shop said the injector was blown, dumping fuel into the #1 cylinder which could be causing low compression for that cylinder. I think the raw fuel is also why the cat & muffler were smoking. The fuel pump pressure was also low.

They wanted like 900 to replace 1 injector So it looks like I will be doing it. It doesnt look like it will be too hard. I just did her intake manifold gasket last week so I am pretty familiar with it.

The guy said that 87 had two different style fuel injectors. Any idea on which one I will need? Where is a good place to buy injectors and how much will one run? Any tips on replacing it? Thanks.

 

Well,

You need 19lb/hr injectors, but would suggest you buy a complete set of non-GM's...ala FMS, Accel, etc, for about 225 or so for 8...a OEM injector will run you about 100 each.

Only possible difference for your year would be manufacturer of the injector, Multec or Rochester, but both would be high impedence (about 16-18ohm) as opposed to low (about 12??ohm) injectors.

Fuel pressure could be low due to an open injector, but not sure just one open injector would be much of an issue...do you recall what the PSI was?

Also, if you were dumping fuel in, I'd be thinking about changing oil ASAP, least checking to make sure you're not in the process of "building a bomb"

 

Yeah it looks like i will be buying a set of 8. Would it be a problem if I only replaced one injector though? Maybe he meant there were 2 brands that year. He was probably saying that to worry us a little to let them do it They charged us 80 for a set of plugs.

On the report it says the fuel pressure from the fuel pump was only 40lbs when dead head, and that it should be around 60-80. On the report it also says the compression on the #1 cylinder was 110 while the others were around 135.

I will take your advice about the oil change

 

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Problem with replacing just one, is:
1. No way iot would be matched to the other 7
2: If one failed, then it's very likely that you will be back in ther doing another later
3: With the miles on it now, best to do all 8

Email rich@cruzinperformance.com , he's a standup guy and won't lead you astray, he can advise wheteher to clean/flowmatch what you have (about 100 bucks) or go with new...he also sells Accel, maybe other brands too.

Price is right with him also.

40 lbs with every thing blocked off is low, but as always, might be best if you invest in a FP gauge and do it yourself, before you get stuck with a big bill you don't need. A FP gauge for what you need, would be a 0-60psi, shouldn't run you more than 30 bucks at any discount AP store...also, for another 40 bucks, you can get an injector tester...you need a gauge to work with it, but what it does is fire the injectors, and you mesure the pressure drop of each and compare.

So for less than a c-note, you can verify everything the shop told you...definitely something I'd want to do if I was staring at a $900 bill.

 

Fuel pressure should be around 60-80? I don't think so... 40 doesn't sound too bad at all for a 305. I know some were at 38psi, and others at around 43ish PSI from the factory. I don't think it should be anywhere near 80, or even 60 for that matter.

Compression 110 on that cyl and 135 on the others? I think its time you get a rebuild on that motor.. 135 sounds pretty weak to me.

Anyways, fuel injectors don't look that hard to me either. I haven't done them just yet, and when I do it will be with a different fuel rail (different intake setup), but nevertheless they don't look impossible by any means.

 

I think they are the same ones that SLP sells for a 100 bucks or so...new take outs....if he does go with these, he'll need to reprogram the chip, no doubt

 

The pump should be capable for 60psi, you're thinking of what we set our psi's at...much is returned to the tank via the FPR?AFPR.

Comp is low, but wonder if it's due to washing the cylinders down with fuel...could affect the reading some, could be you're correct, but also have concerns with too many things with one hole...before I pull an engine.

 

Yeah Im new to tpi but I have been learning a lot quick Im pretty sure I can tackle the injectors. What exactly do they do when they flowmatch injectors?

What should the compression be at? The engine has 150,xxx miles on it. It doesnt have all the power it should have thats for sure. It hasnt been running up to par lately though because of an intake manifold leak and now this. Will probably have to replace the cat too.

 

Back with more problems Got the injector fixed and it was running good after that but for the past couple of days the car has been running crappy. It stalls a lot and is choppy at idle and when you accelerate. I think its fuel related. How exactly do I test the fuel pressure? I have a guage so I can do it at home. I also got a new fuel filter. Im hoping its not the fuel pump, I hear those are a pain to replace.

 

Before you change any more parts be sure of what you have working. Check your TPS and IAC to be sure they are in good adjustment.
Heres the link to the tech article :
https://www.thirdgen.org/newdesign/tech/tpimod2.shtml
The IAC may have some junk in it or is stuck after all the parts changing.
Also If it runs ok when first starting (cold) and then gets worse, you may just need a new O2 sensor. With all the extra fuel that was being dumped in, it's probably fouled up pretty good.

There is a "schrader" valve on the passenger side fuel rail for connecting the pressure gauge. you can get one at Autozone or other store for about 20 buck. Tape the gauge to the windshield so you can drive and watch it.