When it rains it pours..... pwr steering pump suckin air emulsion in reservoir, brakes suckin air, but that aint the issue !! Wouldn't start, no spark, dangit. Changed out coil and ign module on the '93 and now got sp. So,ark, hurrah. But, no fuel pressure, crank the motor no start. Son spray ether in intake and it sputters a little. Checked schrader valve, pushed the pin in and it pissed out about 1/3 shot (maybe 10 ml) of fuel. when I changed injectors a while back I'd see a whole bunch of spray and larger volume doing that action. So, low fuel pressure I guess. Why ? When key is turned to run but don't crank the motor, I hear the fuel pump coming on a second, then shuts off, as if its reached its typical startup pressure, but when checked at schrader valve, (yes its a crude measure but I don't have a gauge) very little comes out. So, first inclination is to change the fuel filter, gonna do that when son gets back with filter. If that don't work, can I pull a connector off an injector and check it for volts while cranking ? if so, all I have is a VOM (voltmeter) .
Sheesh, the car was running badass last week, now all hits me at once, must be one of those solar flares, else the Lord lettin me gettin my maintenance done before it turns hot here

 

Checking for codes might help with a solution, and replacement of parts.

http://tech.corvettecentral.com/2011...trouble-codes/

 

Check your fuel pressure. Do not waste your time in replacing the fuel filter at this time. Rent/borrow a fuel pressure gauge because you dancing around changing "this and that" is a waste of time and $$$.

If you get good pressure (36-40 psi) when the key is turned on (engine NOT running)...and it stays...that is great....if the pressure immediately drops like a rock after the 2 second "prime"....then chances are you can have an issue in the fuel tank. Either the check valve in the pump is bad...or the pulsator between the fuel pump and the sending unit is bad...or someone in the past had replaced the pulsator with a rubber hose and it has failed....or you can actually have a hole in the pressure side of the sending unit tubing and it is bleeding off inside the tank because I just fixed one not too long ago that had that problem. You can also have an issue with the fuel injectors you just installed...depending on which ones you installed and some are pieces of junk and fail prematurely.

What year do you have??? Because you can not see the fuel spray on a Corvette...unless it is a cross-fire....and a cross-fire does not have a schrader valve....or you tried to crank the engine when the fuel rails were out to see the fuel spray...which is VERY DANGEROUS.

Not meaning to be a jerk-wad...but if you plan on doing all repairs on your car...you need to have the correct tools to do it. It is like being a lumberjack and trying to cut down trees with a butter knife. Your car requires specific tools and equipment so your diagnostics can be achieved quickly and correctly. I know I do this for a living...but I still have to by tools that do only one thing. Trying to "do with what you have" can be a pointless endeavor.

DUB

 

I agree with DUB. But...you can verify the injector signal with the meter, if you have someone crank the engine. all you want to see is a pulse when cranking. should see no dcv, then battery voltage when ecm grounds the harness. one second is enough to tell.

if you are spraying at the valve you should have enough fuel to start the engine, for several seconds at least. if you have a blue spark, you may have no fuel or too much. you are guessing, as you know, but we can't always have everything we want or need.

add: while you are there may as well check ohms on injectors to see if one is shorted, which should cause all of them to work when the key is ON, at least on the L98.

 

A fuel pressure gauge is one of specialized tools you need to have if you are going to maintain you own car. You don’t use it much but it's invaluable when you need it.

All good info above, I don't think it's a filter either, that would be a flow problem. Once you get a gauge and verify a pressure problem, then you will have justification to pull the tank unit and check it out or do whatever is necessary.

If you have a pressure problem checking injector resistance is a wasted effort. If a injector valve hung up there might be gas in the oil but doubtful. You can check you dip stick. In the mean time check the vacuum line from the FPR to make sure it's dry. Then go out and get a gauge. 

 

its a '93. The injectors are from John at FIC, and I'm assuming they're good since only two years old

yeah yeah, I need a fuel pressure gauge, I know.

But I don't need a thermometer to tell me whether its cold outside or not, I just walk out and feel it, same with the fuel pressure, I got seat of the pants feel for these things, many cars, trucks, RV, harleys over many years & never paid for car repair except tires, I usually hone right in on the problem, call me lucky.

Fuel filter hasn't been changed since I owned it, and I put 80K on the car with relatively little trouble. Its due to be changed. Spark is there so I don't need to use the spare opti in my desk. If that filter is clogged, then no fuel will get through, I had it happen on a 78 olds with a 403 in it, got one full tank of **** gas and the filter in the Qjet clogged and the car wouldn't start, all over a fuel filter. So when my gut instinct says there's not enough fuel pressure and the filter is probably 21 years old, it needs a changin anyway. But I appreciate all your comments, seriously. After I change the filter if it don't run, I'll go up and buy a gauge and add it to the collection

 

At least you are smart enough to ask for advice/help ( many do not)...because your gut may be tricking you...because if your "gut" was right...you would not be posting questions and you would have already fixed it.

The fuel filter should have been REPLACED when NEW injectors when into the engine. But what do I know.

Then if you KNOW what you need...(fuel pressure gauge)...why not go get one???? If not... go to a shop and have them check it. I do it free of charge when I am running a diagnostic...along with my scanner. 5-10 minutes and I am done with a basic check.

The fuel pressure gauge will also allow you with another special tool verify that your fuel injectors are balanced. Ohming out fuel injectors is one easy test...but means nothing at all when it comes to what the fuel injector puts out in a 50 pulse test...and what the ending fuel pressure is when all are tested. If my memory serves me correctly...the injectors have to be within 5 Kpa of each other...or that is what the GM service manual states...if I am not mistaken. I assume nothing. You might be surprised like I have been when I "thought" they were OK...only to find out they were NOT.

YEAH...I would say you are "lucky" also without the correct diagnostic tools. If you keep having problems...you might find that you will need to have specific test equipment to make sure that the data can be received and used for a correct repair procedure. Good luck on reading O2 crosscounts, block learn values, intregrator, IAC vaules MAF gm/sec values and many other data inputs that can direct you to a repair easily...instead of flying my the seat of your pants.

I can relate to changing the fuel filter due to age and possible water in it also. But the reason being...if you find that the fuel pressure is low/bad...and you are replacing the fuel pump in the tank....that would be the time to replace the filter at the same time while the system is down....BECAUSE...I have (in the past) done what you are thinking...ONLY to find that when I went into the fuel tank AFTER replacing the fuel filter...there was so much crap and debris...and the sock was not in good shape at all. I had to remove the new fuel filter due to wanting to blow out the fuel line to make sure it was clean because I was wanting to make sure the system was as good as possible for my customer.....But do as you choose.

I do not need a thermometer either...to tell me if it is hot or cold...but you can not tell me the exact temperature either. Using that philosophy...."guessing" the fuel pressure on a 1982 or a 1984 would make you run in circles for a while....BEEN THERE...DO NOT DO THAT ANY MORE. Engine runs and then begins to "hunt" for a smooth idle ...which was due to low fuel pressure.

I also have a "feel" for things...but I can tell you...that I have been doing this for so long...just like you it appears....I could not tell you the pressure of the fuel system while it is running or being primed when the key is on. I have had engines like yours run at 22 psi...but weren't quite right. My "gut" tells me many things...but I have also come to appreciate my diagnostic tools that can confirm my "gut" or actually prove me wrong and send me down another path of repair to fix the problem.

I am trying to save you TIME...for the long haul...but I guess that you are going to do what you want when you want...which is you choice.

Why GUESS at something... when you can KNOW for a fact..

I wish you the BEST OF LUCK,

DUB

 

I felt the same way on our 93 buick rivera, it wouldn't start. Push schrader valve in with pocket knife, oh I got fuel. NOT enough, went to harbor freight spent 10$ on fuel pressure gauge kit. Low and behold 15lbs. Changed pump good to go. Just saying

 

ok, ok already !! I'll go get a gauge

One more piece of info, don't know if it helps....

The ignition module went out about 5 years ago. Towed her home, got "lucky" with her (she's cute and nice to me) , changed the module and was back on the road till December 2013. Started not wanting to start very easily, like there was a fuel problem, "felt" like water in the gas, and would improve when I put different fuel in. Weather changes can cause condensation, and ethanol in gasoline absolutely sucks baloney. December 22013, would not start, felt like the module again, replaced module and it fired right up, but..... there was something just not quite right about it, would have intermittent misses. 2 weeks ago, would not start. Then brake system started admitting air, and pwr. steering reservoir has air emulsion in it. (new rack, pump 2 years ago. When it rains it pours, like some evil spirit decided to fvck my car, lol. Pulled in garage last week after pleasurable 50 mile ride. went to pull her out to mess with the brakes, wouldn't start, So, I figure the chinese modules are ****, took the module to be tested at auto part store, and it failed so put a new module in, it failed when I took it out for a re-test. got different brand module, and now I have spark at least. Maybe its the opti, lucky I have two spares. I'll check fuel pressure like you all feel strong about, thanks a bunch for your time on this

 

I would put in a GM module...or maybe another that some people may advise on...if proven to be good...and did you apply the siloxane/silica grease under it when you installed it for heat????

make sure that the heat soak plate is also clean...if it is cover with grease and can not shed heat as designed.

DUB

 

check the switch at the bottom of the steering wheel do the wiggle test on all wires mine did the samething the yellow wire is the one that stoped my car from starting I took the switch off and cleand the wires all is good now

 

DUB - yeah, that faux heat sink, aluminum plate with a few fins is a joke and a half, then they bolt it to the front of the head. So, lets see, uhhhh..... those little fins make a big difference, lol. Basically the module is running the temperature of the head. Yeah, I always grease them babies good

Mrcedy, thanks for the tip, I'll check that out.

Went back to auto parts store "A2", they ordered me a new module for 3rd time. Before I walked out with it, I asked..."lets test this on your machine , so we know your module's good". Hooked it up - it failed. So, auto parts store "A2" has a machine that says new modules fail. All along it wasn't the ignition module. *******z. My fault for ***-uming their equipment good, got my money back. almost em-bare-***-ing to ***-ume. I bet they sell more parts that way though. Wasted 3 trips there on modules I thought bad cuz they said so, moral of the story, have them check their new parts on their equipment before walking out with it. I'd go to auto parts store "A1" but they're farther away. Lesson learned. Thanks Mrcedy I'll check it out and thanks DUB. Fuel pressure gauge $35-$50 but my buddy at auto parts store "O" gonna let me rent one for free. Should be warming up here in the next day or two. Meantime, my 67 K20 gets me around. As an aside, it gets 13 mpg with a 350 running a Q-jet and vortec heads, whereas the f250 2004 king ranch I got my daughter for high school, best it could ever get was 12, even with "fuel injection". Ford engineers, well, they must be inhibited somehow. rear axle in the 67 is 4.55, I can tow a garbage truck with that baby )

 

Yepper. When ya get old , experience pays, common sense. Not that I'm sayin yer old.... lol

I know rivs well. At least 95-99 model years, with the factory blowers. Great torque, and great fuel economy, like 28 highway, 24 city. Owned 3 of em and drove em up into the high 100k miles then got most of my money back sellin em. Aerodynamic, handle super well, and I know everything there is to know about that 231 that thinks its a 350 when ya stomp it. I aint much in to numbers, but think its called "L67" and the 4t65E can take a beating with a smaller pulley on the blower, push it up to 11 pounds boost, shorter belt. Too bad the 3.4L DOHC motor didn't have a trans like that available, else they wouln't have had to back off the cam timing. That was a nice piece of equipment killed by internal politics. Oh well, I digress..... Always lookin for a nice blown Riv '99 with low miles, in silver

 

Oh c'mon what ya trying to say..LOL I love the old skool. Thats why i have been driving the real gas guzzler to work. 70 c10 454.. my raditor pooped waiting on ups..

 

Warmed up enough, I changed the fuel filter, all kind of brown crap in there (tank rust, thanks ethanol). Checked pump with inlet to fuel filter not attached, rather ran a hose into a gas can. Turn key on. Yep, pumpin good. Sent son to auto part store to "rent" a gauge for free. psi while cranking = 41 on that gauge, with fuel filter connected, gauge at schrader on rail and pressure holds holds. I'm thinking injectors, I'd saved the multecs in a bag when I changed to the FIC ones. A quick swap to the old ones maybe ...... ??

Spark ? I pulled #4 plug wire (convenient) and put a plug in it and leaned it against exh manif. while son cranked engine. Spark, yep. Weird, I sprayed ether into the intake but no fire up. I never saw an engine with spark before and hit it with ether and it didn't at least make a pop.

Car was running just fine when I pulled it in garage 3 weeks ago. Four days later I go to move it to access cabinet to get a drill out and the dang thing won't start since. arrgh. Is there a simple test for opti ? In other words, can I still see spark at plugs and opti not right ?

 

no codes, but then again I did disconnect the battery. after cranking all I got was a C12. Total mystery to me, I gonna go pull another plug of driver's side bank and look for spark. If there's spark and ether dammit, there's got to be a pop or brief start, no other way about it. when cranking it earlier, it did give a couple ignitions, but very few. Last time it was running, was running well, except.... its was harder to start lately, and would miss a few beats when revved towards 5500 rpm limit. I always suspected the fuel, these oil barons want to sell us water if they can get away with it

 

The opti is the base timing clock or drive, that’s where it starts. Then in turn the low resolution pulse from the opti drives the ECM. The ECM knows from the pulse widths where the crank is and what bank of injectors to drive (or pulse). The ECM also puts out the drive signal which is the 4 volt A/C signal that drives the ICM.

If the opti (optical portion) was not working, there would be no injector drive and no spark. If there was spark off the coil but none (or low) spark at the plugs, then the rotor or cap could be at fault just like a conventional distributor.

That’s if everything is working as designed.

However if the ECM on the 93 is up to it old tricks it could drop out either of the injector or spark drive which would cause engine not to run and could be a intermittent condition possibly influenced by temperature. ECM are known to get flaky if they go tango uniform

 

I went out and cranked it a bunch. For a moment seemed like it wanted to start. Was using the 67 truck as a jumper. But, been careful to not overheat the starter. A couple crackshots like a gunfire, never heard that before. Seemed like she wanted to start but didn't cuz like water in the fuel, but I could be wrong. Added half a gallon of xylene to the tank, will change injectors back to multecs in the morning, that should bleed the fuel rails pretty well

 

Is there any rational basis for, or reasonable expectation, that if there's a problem with one or more fuel injectors on a non-starting 93 C4 vin code P , that changing out the injectors to all good ones, would make that previously non-running vette fire right up ? i.e., is there a hope in hell that by changing injectors my car might start ? Would one bad injector be cause for the vehicle to not start ?

 

It would probably still run if only a couple of injectors were bad. But, did you check for an injector pulse?