Fuel Injector question and information

I have a 1996 Pontiac Trans Am. No crazy mods, engine is all stock besides the Trickflow air intake, but this was an issue even before that add on. Everything else is just suspension upgrades and/or brake upgrades.

Symptoms:
Does not start up anymore on one turn over. Sometimes takes awhile to start up. Sometimes I have to prime the fuel pump several times as it seems like I'm not getting enough fuel to start up the engine. (I hear the fuel pump working everytime however, so I know it's getting fuel.)
Also, while cruising at high speeds, I can heard some sort of "ticking" or "clicking" and it slighty feels like the engine isn't getting enough gas.
Most of the time it only starts to make this noise when I turn on the AC or heater and put the engine under a load. Even when I turn the AC/Heater off, it will continue to make that weird "ticking" noise whenever I'm cruising down the road or slightly giving it a little more gas. If I stomp down hard it will stop. But it will continue again while applying little gas pressure.

What I've done so far:
I have put new injectors in but they are the 19 lbs/hr and were very cheap, but they do work for my car as I got them from SLP.
I've changed wires, changed spark plugs, changed battery, and added a new starter.
Opti was changed but it has been awhile.

What I have been told by a mechanic:
I've taken this thing in to get it checked out (long time ago) and he said there are some misfires in some of the cylinders and that new injectors were needed. Thus the reason why I got new injectors. But the issue remains.

Today I just got a new catalytic converter on the passenger side of the car. The muffler guy told me the only reason why I needed one was because the engine was running rich and it burnt up the inside of the cat.

Could this be fuel injected related?

Are the stock fuel injectors for the 5.7 engine 24 lbs/hr? Should I get those instead?
Why would the car be running rich with wrong injectors anyway? Wouldn't the computer adjust? Or not?
And if the car is running rich, why would it hesitate? Why would it not start up with one turn over? Is it because of too much fuel in the cylinder?

The muffler guy told me, if I don't get it fixed then my catalytic converter will be burnt out again and possibly the more expensive one on the driverside. I don't want that to happen!

This is all I can think of at the moment. Please help if possible.
Thanks.

Sorry to tell ya' bud, but that has all the makings of an opti problem. The ticking you hear are mis-fires. Time to change the opti.

You've got to be kidding me?
You sure it's nothing with the injectors? I know the opti controls timing but would it cause the vehicle to run rich like that? And even not cause it to start up on one or two turn overs?

Yes, the opti can cause your car not to start. I had the same problem a few years ago.

Did you do the opti yourself or did you have someone else do it?
How reliable are those cap and rotor pieces?
I really don't feel like spending $300 just for a new opti when while I do the opti I might as well do the timing chain too.

Did you do the opti yourself or did you have someone else do it?
How reliable are those cap and rotor pieces?
I really don't feel like spending $300 just for a new opti when while I do the opti I might as well do the timing chain too.

Well, that opti went out right after I got the car and before I knew much about cars, so my mechanic did it for me. Full tune up. It was expensive.
If it went out now, I'd do it myself though. I'd probably replace the water pump while its off too.

But if your opti is somewhat new, you might be able to get away with just doing the cap and rotor. But I've never just done a cap and rotor for the opti, so I couldn't tell you if they are any good.

Opti is possible, but, I didn't catch in all that what the fuel pressure is at?

it would be running rich because the fuel isnt burning (due to opti messin up) and no spark igniting the air/fuel in certain cylinders. well i guess it wouldnt be running rich but it has that effect on the exhaust/02 sensor(s) side. and that might be making the computer give less gas to fix the problem of running rich when its not its just not burning gas. make sense? i dont know if thats the problem but it answers your question i guess

Fuel pump check valve is done. One of the first sign of a pump on the way out. On average it probably takes 3 attempts before it will start, correct?

(BTW, SLP injectors are cheap for a reason. They are complete garbage. I had them and unfortunetly turned a few others on to them , well it made me look bad cause all our injectors failed within 5k, some leaked and some fried the solenoid) Also never switch sizes without a tune. Clean the stockers and put them back or if your sure they were messed up check out ebay or I can supply you a stock set I have.

Okay, sorry. Was trying to get back to this sooner but had the Thanksgiving stuff going on.

The Opti was probably done around 50k miles. Can't remember off hand and don't feel like digging through paperwork.
The water pump was also done when that was replaced. So I'm not sure if I would need another water pump seeing as I'm on about 86k now. But then again, I'll get your opinions.

I now kinda understand how the Opti could cause it to not crank correctly and when asked about if it takes 3 times? Not really. Usually on the second try it'll crank right up.
Sometimes if I prime the fuel pump about 2-3 times it'll crank up right away.

I still have the stock fuel injectors, but I'm not sure if they are any good and that comment on those cheap SLP injectors. Yeah, I had to send one back before because it was spraying fuel out the side. It was pretty bad.

I think I'll go ahead and order an MSD opti, not the $500 one because I can't afford that. I'll also get a new timing chain along with the sprockets. And get the 160 degree thermostat, but of course I'll need that Hypertech thing which I'll just have to order later.
Anything else I should try?
I'm thinking I'll just try the fuel injectors last if the opti replacement doesn't work.

I'm thinking I'll just try the fuel injectors last if the opti replacement doesn't work.

Why, FormuaLT1 and I are telling you it sounds like the fuel pump is failing :dunno:

Why not save your time and money and run some pressure checks.

Why, FormuaLT1 and I are telling you it sounds like the fuel pump is failing :dunno:

Why not save your time and money and run some pressure checks.

My fault. The pressure was checked a while back ago. I'm not sure what it registered because I don't have the tools to do that. But the mechanic said it was all good. He thought the injectors were just going bad.
I don't think it's the fuel pump because it's getting too much fuel. But I'm lost in that aspect of the engine and not sure if the pump could cause the engine to run rich.
The last time I did a code check, it registered some miss fires in one of the cylinders. I'm thinking it's only on one side. That would also explain the burn up of the cat on the passenger side and not the driver side one.
Right?

I always say this in general, if you're going to work on a EFI car, you need a fuel pressure gauge and a scanner in your tool box arsenal.

From experience, on my old Buick PA, I pressure tested and flow tested it when I was in fuel systems training. It was in perfect order. A little less than a year later, guess what? I go out, start the car, let warm up for a few minutes while getting my lunch together, come back back out, and bam, just as I get in, it stalls, first time ever. Go to roll it over, and eh eh, no, the pump just abruptly quit.

There is always the chance that it may not be pump. But when you're trying to diagnose a problem on a EFI, computer controlled vehicle, nothing can be assumed. :nono: It needs to be confirmed as not a suspect.

You can get a basic gauge for a reasonable amount (30-50 bucks). I just hate seeing parts shotgunned in the prayer one will hit the problem area.

BTW, I 've heard nice things about the injectors from those guys with blue ovals in their logo :uhoh:

I read up on how to change out the fuel pump.
Man...:banghead:
Sounds like it's going to take just as long if I were to change out the opti and the timing chain. I have to change that timing chain eventually, sometime in the near future. Don't want that thing breaking.

I'll go out and get a fuel pressure gauge, probably today, when I get some oil. If it does register off, or not enough pressure, then what then? Does it just mean the pump isn't working correctly?

Also, if I was to get a pump, what kind should I get? Am I going to have to use that covering that is on the old one? (was getting this info from the shbox.com site)
I'm going to have to go home and read in the repair manual about this mess.

Alot of mechanics will check fuel pressure with vehicle running. See it is within specs and move on. However, this does not mean your pump is not the cause of your issue's cause the pump is suppose to meet the high demand of your vehicle and when the pressure rises and the injectors start pulsing longer and faster, if the pump can not keep up. It will lean out your mixture, raise your exhaust temps and cause missing.

Also, the check valve could not hold pressure but it will appear to be fine under light throttle conditions and idle. I just hope your mechanic gave it a good once over and if not, you should make sure to go over it to make sure it not just functioning but functioning perfectly.

Exactly, neither the fuel pump nor opti are a fun job to do which is why it pays to cover all basis and determine where the problem lies. Your gauge should come with some basic intruction on how to isolate and determine which of the fuel system components is at fault should there be a unacceptable reading found. If not, you know you can get help here :)

Also, Formula has touched on a noteworthy point that sometime at idle or low throttle situation, readings will be normal, and only a road test will pin point the dropoff, however, it sounds like your problem exists at idle and should be readily apparent if ti's in the fuel system.

Exactly, neither the fuel pump nor opti are a fun job to do which is why it pays to cover all basis and determine where the problem lies. Your gauge should come with some basic intruction on how to isolate and determine which of the fuel system components is at fault should there be a unacceptable reading found. If not, you know you can get help here :)

Also, Formula has touched on a noteworthy point that sometime at idle or low throttle situation, readings will be normal, and only a road test will pin point the dropoff, however, it sounds like your problem exists at idle and should be readily apparent if ti's in the fuel system.

See thats the thing. It's not normally at idle. Besides the cranking up part.
When I'm driving...lets say at 1200 RPMs...you can hear that clicking noise sometimes in the engine compartment.
Then while cranking up it can take a second time just to start it up, or waaay too long of turnovers.

Oh, and the blasted Autozone didn't have a fuel pressure gauge. Just great. I'll have to go to another place tomorrow.

Okay, finally got a pressure gauge that works.
And here is the deal...

Pressure when first turning key over: 47 psi

But, pressure drops. It does not stay constant. Isn't it suppose to stay at around 41 or so? It just totally drops to zero (0).

Pressure when at idle: 41 <-- I think, didn't write it down.

Anyway, I kinda figured that if the pressure drops then why not just cycle the pump once, then turn the key back to "off" then just crank it when there is pressure, and this morning it cranked right up. Guess it just means I'm not keeping constant fuel pressure.

I'm thinking about buying some new fuel injectors to start with because these "cheapy" ones I think maybe one cause to the problem as they are not solid metal like the stockers.
What was the regular stock number for the injectors? 24 lbs/sec?
And should I get the Accel Injectors from Summit or get those Ford injectors? Not sure which would be better.

Fuel pump check valve is done. One of the first sign of a pump on the way out. On average it probably takes 3 attempts before it will start, correct?
Alot of mechanics will check fuel pressure with vehicle running. See it is within specs and move on. However, this does not mean your pump is not the cause of your issue's cause the pump is suppose to meet the high demand of your vehicle and when the pressure rises and the injectors start pulsing longer and faster, if the pump can not keep up. It will lean out your mixture, raise your exhaust temps and cause missing.

Also, the check valve could not hold pressure but it will appear to be fine under light throttle conditions and idle. I just hope your mechanic gave it a good once over and if not, you should make sure to go over it to make sure it not just functioning but functioning perfectly.
Thats what your dropping to 0 means.

Sounds like you fuel pump, go ahead and get the injectors because the onse you have are crap but get the pump done aswell.

Thats what your dropping to 0 means.

Gotcha.
Where is the check valve? Is that just part of the fuel pump? Basically just need to get a new fuel pump then?
Yeah, those injectors are garbage too.

Stock fuel injectors? What are the numbers?

How about the Edlebrock pump?

http://store.summitracing.com/egnsearch.asp?Ntt=in+tank+fuel+pumps&N=700+115+4294908153&Ntk=KeywordSearch

Stock injectors are 24lbs.

Gotcha.
Where is the check valve? Is that just part of the fuel pump? Basically just need to get a new fuel pump then?
Yeah, those injectors are garbage too.

Stock fuel injectors? What are the numbers?
Check valve is in the pump. You need to replace the whole pump as you already know and yes the stock injectors are 24.9LB's.

Excellent.
I really appreciate the combined knowledge.
I'll let you know how this job goes. Looks like it's just a matter of getting that fuel tank off and I should be good from there.
Just have to order the parts now. "Cha-Ching"
Autozone wants around $350 for a pump...forget them.

Excellent.
I really appreciate the combined knowledge.
I'll let you know how this job goes. Looks like it's just a matter of getting that fuel tank off and I should be good from there.
Just have to order the parts now. "Cha-Ching"
Autozone wants around $350 for a pump...forget them.
Get a walbro pump off ebay or from from full throttle's site http://cgi.ebay.com/ebaymotors/Walbro-Pump-Install-kit-LT1-LS1-Syclone-Turbo-Buick_W0QQcmdZViewItemQQcategoryZ33555QQihZ006QQit emZ160059699979QQrdZ1QQsspagenameZWDVW . They are great for stock to 600 horsepower engines. Even though the amount of fuel pumped will increase, your regulator will keep the pressure within specs and your PCM will lessen the pulse for any change. They are what all the high performance F-body guys out there run and there is a reason for it..

*whew*
Good thing I read this before I bought my Edlebrock pump.
I'll check that link out when I get home.
Work doesn't like eBay. :nono: Go figure.

BTW, I 've heard nice things about the injectors from those guys with blue ovals in their logo :uhoh:

Yup, my car runs better than it ever did with the Multecs... And a they're a BUNCH cheaper too.

The only downside is they're noiser, but at least they work. :thumbsup:

I use to run 30lb SVO's and now run 42lb SVO's. If you have a modified engine, most likely you won't be hearing the solenoid clicking over the exhaust tone. Ford does make some damn good injectors though.

Yeah, mine is basically stock. Just the simple bolt-on stuff; K&N, underdrive pulleys, SLP cat back, SLP chip, intake baffles removed, 180 thermo, etc.

The car started running odd on occasion a year ago (I only drive it in the summer months) then this spring it was running really crappy. Diagnosed two bad injectors (ohms way off spec) and one marginal. After much research decided to go with the Bosch (Ford) injectors because they were cheaper and lots of "stuff" flying around about how crappy the OEM Multecs (Rochester?) were. This is in a 91 Z.

Have a 95 3.4 liter. This was an interesting thread to read; learned alot. But i have a few questions that i hope are not too dumb; i am just not that knowledgable with the newer vehicles. First the talk of ford injectors in a chevy; i guess that all injectors are interchangeble as long as the fuel ratings are the same? Fit in the hole and electrical connections match? And what in the world is this opti thing we are talking about?







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The resistance and connector are what seperate injectors but much like many things on GM cars. The injectors on TPI's and LT1's are bosch style injectors. They are EV6 type. Which so happens to be what Certain Fords use. SVO just happens to make a excellent injector based on dependablity and fuel atomization in its flow pattern and pintle.

As for what a opti is, it is short for opti-spark which is a distributor used on LT1 and L99 GM engines that measure timing using a optical sensor eye that is drive on a ring that it connected to the camshaft directly via a splined gear.