92GTA

iTrader: (11)

After a 200 mile road trip, my GTA doesn't want to start without cranking over forever first. Stone cold after a week or hot from a gas station fill up, it wants to crank over for like 4-5 whole seconds before firing and stumbling to life. Fuel pressure is good. Maybe spark? I have an LT4 starter with an Optima so it cranks like a champ. The spark plugs only have about 10K miles on them from when I rebuilt the top of my engine a year ago (not valve train, just complete intake). Fuel filter has maybe 40K miles on it, same for the fuel pump. My MSD wires are over 100,000 miles and so is my Crane coil by now. My MAP and TPS have about 55K miles I think.

When the engine starts and is running it's great. The only thing I've been able to notice out of the ordinary since this started happening is a small miss at idle in gear that starts occurring about 5-10 seconds after being at idle at full temp. During cranking it doesn't even sound like it's trying to fire then when it does after 5 seconds, it fires up slow and kinda sputters a bit to get up to idle but this only take a second. Using or not using the gas pedal doesn't seem to make a difference.

I haven't fully rebuilt the distributor since about 140,000 miles, it now has 213,000. The compression tests great still too. This just came out of no where in the middle of the trip.

Any ideas what to check next? I've always tried to replace literally everything over the years. Some things even twice by now to keep one step ahead. The engine has never ever once failed me in anyway until now. I'm parts gathering for a complete mechanical engine rebuild over the winter but need this engine to get me by until my smog in January 2011.

Thanks!

88gta_hiflyer

iTrader: (1)

Have you replaced the fuel injectors?

92GTA

iTrader: (11)

Oh yeah, forgot to mention that. New Accels when I did my distributor.

88gta_hiflyer

iTrader: (1)

What about your ignition module. Have you checked that?

92GTA

iTrader: (11)

Nope, replaced it as part of my distributor rebuild though. Don't even know how to test it lol. I guess it's old enough I could just replace it anyway now.

88gta_hiflyer

iTrader: (1)

I don't know a whole lot about the coil in cap style, mine is external, but I've heard of people having similar problems with those. Maybe someone who knows more about them will chime in and help.

92GTA

iTrader: (11)

Cool, thanks.

92GTA

iTrader: (11)

Well over the weekend I replaced the ignition module with a brand new AC Delco unit and replaced the ignition coil with a Hypertech to replace my old Crane Fireball.

No change I thought there was when the first 5 times I started it it fired right up but then it started doing it again later in the day.

I do have a Holly AFPR I had forgotten about that is going on 70K miles. Maybe that is acting up and giving me an intermittent fuel pressure issue? I have a guage to hook up but when I did before it seemed normal. Idle FP should be around 41 and peak at 45 or 46 when revved right? Average is like 43.5 or something right? I'll have to leave it on longer and be sure that is not the issue.

If it were to be my Accel injectors, wouldn't it take more than just 1 going out to cause an issue like this?

Thanks!

88gta_hiflyer

iTrader: (1)

I would try leaving your fuel pressure gauge hooked up while driving it for a while just to see if you see anything unusual there.

I doubt 1 bad injector would make that much of a difference.

One possibility, could your injectors be leaking? My injectors leak (I can hear them hissing after I shut off the engine while there is still pressure in the fuel lines). My car is hard to start, especially when hot, because of this. It creates a flooded condition but mine will start right away after sitting overnight or if I hold the accelerator to the floor while cranking. I just bought a set of Bosch III's from Southbay but haven't had time to install them yet.

I don't want to tell you to go out and buy a set of injectors but it might be something to look into if you've ruled out all other possibilities. You might want to do a search to verify this, but I think other people have had bad luck with some of the Accel injectors.

92GTA

iTrader: (11)

I'll leave the guage on longer and check for leakdown too then when I can. Funny thing is I already email them about a new set doing some recon for an engine rebuild I'm planning for next January. So considering I planned on new injectors anyway and how many miles I got out of my Accels, I have no problem replacing them.

I bought my Accells years ago right at the end of when people were having problems. Right after I bought my set Accel improved their QC and started including flow test results.

I'll try and do a better fuel system diagnosis in a couple days.

Thanks!

Street Lethal

iTrader: (16)

Sounds like your fuel pump relay is bad. Without the relay, the fuel pump will be triggered through the oil pressure switch when a particular psi is reached, thus the longer than usual starting. Replace the relay, and/or check it's connection....

92GTA

iTrader: (11)

Except I can always here my pump prime the system when the key is turned to the on position and I have verified this with the guage in the rail last week.

I've never replaced it before though so I'm down to doing it just for the sake of it.

92GTA

iTrader: (11)

Ok I busted out the fuel rail gauge and had my GF in the car so I could watch the gauge on prime, running, and after shutoff. The results....

Upon turning the key on, the pressure right away goes right up to 40, stays there a sec until the pump turns off, then BAM, all the way down to 8 in like 1.5 seconds lol.

Then after the engine cranking for like 4-5 seconds to starts, it stumbled to life after being flooded in 1 cylinder or more and the pressure held perfect at idle and increased when revved, etc.

Then after shutting it off, BAM, 1.5 seconds and the pressure went from 41 down to 8 again.

So, a leaky injector? Hell yes! I horribly BAD leaky injector lol.

Tomorrow I am ordering 8 new TPI modified Bosch III injectors for my baby. I'll be going the largest made, 60 or 65lb\hr and tuning accordingly. No sense in buying injectors AGAIN when I go ProCharged in January.

Street Lethal

iTrader: (16)

The ECM will prime, but it looks for RPM reference through the ESC to activate the fuel pump, which gives you a faster start. The oil pressure sensor is a backup when the RPM signal is not being received, and it takes a little longer to build up oil pressure as opposed to RPM which is almost immediate. However, if your losing that much pressure within minutes, then definitely look into the entire fuel system along with the injectors as well; bad regulator, and/or crack in the fuel lines will also cause a drop in pressure....

92GTA

iTrader: (11)

Question then, how can I tell for sure that my Holley AFPR hasn't gone bad? It seems to hold the correct pressure and vacuum increase based on manifold pressure just as it should. That's why I was sure the leak if from an injector.

I'm starting to second guess myself now though and I don't want to replace the injectors just to find the diaphragm in my regulator is jacking up. Any ideas how to know for sure? I'm going to check for fuel leaking from the vacuum line while running and I'll also try adjusting it with the vacuum disconnected to be sure it adjusts correctly too. If all that checks out then it should be just fine still right?

Also I'll go ahead and install a new fuel pump relay anyway since it's only $17.

Alex

92GTA

iTrader: (11)

I just tested the AFPR and there is no gas at all in the vacuum line when running an I can manually do 10psi swings with the adjuster so it seems perfect, no point in fixing what doesn't need to be. I did find out that I had my regulator set to 50psi with no vacuum for the last 6 years lol Now I have it set to about 42 at idle with no vacuum, when I connect the vacuum it dips down to about 37/38. So at least now it increases like it should when WOT for the first time lol. Boy did I bone the initial adjustment 6 years ago lol.

Anyway, so I'm positive it's my injectors. I just found out I can get the new Bosch EV14 saturated injectors in 72lb\hr flavor modified for TPI height and with the EV6 harness connectors.

Now I just have to decide if I'm ready to pony up the $$$ and be totally set for my F1 or just spend like $160 and get my engine running right again. Tough decision because I can totally tune for the 72s and I will need them anyway, I don't want to have to buy injectors twice.

Hmmm, decisions decisions. I'm gonna have to sleep on it.

emmanuel33v

I had the same problem with my 1986 Camaro 350 TPI
I took it to get it diagnosed and what made my car have the hard time starting and low idle sometimes even turned off was the two of my injector o-rings were bad so I had a leak there...try spraying starting fluid in the injectors when car is on and idling and that will right away let you know if thats your problem, if your rpms go up when you spray that you might want to check them o-rings out..

88gta_hiflyer

iTrader: (1)

Alright sounds like you found your problem! Always good to hear success stories.

92GTA

iTrader: (11)

I replaced my injectors today and it helped but I'm still having a fuel leak down problem when the pump stops.

When the I turn the key on without starting the pump kicks in, gets right to the correct pressure, then when the pump stops, it goes down to about 10psi in about 4 seconds.

Same thing happens after I turn the engine off after it has been running.

The injectors are new, the AFPR has no fuel leaking and will adjust higher or lower just fine, there are no fuel leaks anywhere that I can find.

Any ideas what next? The fuel pump is from CarQuest about 3.5 years ago and has about 20K miles on it.

Thanks!

Alex

92GTA

iTrader: (11)

Bump.

The issue is getting worse and I have to crank the engine 5-8 seconds now for it to fire up!

I just want some other opinions before I order a new Walbro 255 pump...

Thanks!

89-bird

Have you tried clamping the return line closed to see if it holds pressure ? My car does this and it is the 2.8 but it will hold pressure when I clamp my return closed . I think something is wrong with the regulator allowing the fuel to bypass the injectors to much so I have problems under load and starting the car . It's like it isn't getting enough fuel .

92GTA

iTrader: (11)

Where is best to clamp it at? All I see are hard lines

89-bird

The rubber flex lines . The return is the smaller one .

IROC212

iTrader: (1)

I have the same problem with mine, turns out the Accel AFPR has a "safety feature" to bleed off pressure when the fuel pump shuts down. Holley may have the same deal. My pressure would drop to 3-4psi after shut down, I clamped off the return line and no drop.

I'm going to put a different regulator on soon, or just wait till I get my HSR on.

92GTA

iTrader: (11)

I crimped the smaller of the lines where they are rubber by the steering box. That seems to have helped.

So what does that mean? Replace the FPR in my fuel rail or my fuel pump?

Thanks!

Alex

John 89 Formula

your fuel pump probably has a bad check valve, allowing the fuel pressure to bleed off faster than it is supposed to.

92GTA

iTrader: (11)

Crap. I guess that's what I get for installing a CarQuest replacement 4 years ago instead of a Walbro.

That sucks. I guess I'll order another pump then...

Thanks!

Alex

89-bird

Not true if he clamped the return and still lost pressure then yes the check valve would be bad or a injector stuck open . If you clamp the return and it holds pressure then you should look at the regulator to see why it isn't holding pressure when it primes and when you shut it off .

92GTA

iTrader: (11)

Thanks for pointing that out before I bought the pump!

I'll hook up my pressure gauge and test. I just installed new injectors about 100 miles ago and they are working great and not leaking so that's one big variable down...

89-bird

Like I said before I have hard starts and the pressure falls on me when I shut it off or after it primes and when I can get to do it I am going to take apart my regulator and see why it isn't holding the pressure like it should .

89-bird

Any updates ?

92GTA

iTrader: (11)

I haven't had time to do another pressure test, my father passed away.

Maybe next week. Thanks for following up!

Alex

89-bird

Sorry to hear about your father .

86White_T/A305

Ill tell you this much from doing my motor build last summer and having the exact same issue slowly build up for longer start up time.When using the cheapy replacement intank pumps,they come with crappy "fuel injection" rubber hose thats its not meant to be submersed in the tank.

As time goes one..and not alot of time mind you.Gas will eat the rubber line and the fuel system will start losing more and more pressure.I did everything you are doing,dist,cap,rotor,wires,coil,module,injectors,esc module,testing check valve,return line,regulator,ecm..all wound down to the damn feed line for the pump in the tank for a $5 piece of hose and 2 clamps.I wasnt thrilled but this is way I now have a dedicated fuel pressure gauge mounted under the hood..it helped alot in checking things out.I also made a access hole to my fuel pump for the ease of changing pumps and the feed line instead of dropping the entire tank since i dont have the tools or garage to remove all that stuff in my driveway.

But atleast now I can say that Im very confident in the rest of the cars fuel system after replacing everything else and doing leak down tests lol.My car now starts within half a crank in the dead winter cold here in canada.No more stumbling to life..and no loss of pressure trying to run wot feeding a 383.Hope that helps you find your issue.there are only so many components to check before your out of options and its the little things that make it seem like a big problem lol.You are probably starring at it in the face too :P

Good luck

89-bird

But if you clamp the return line and pressure doesn't drop then that piece of rubber hose isn't the problem the fuel is bypassing the regulator somehow causeing the pressure to drop off like it is . The regulator port is either dirty causing the regulator not to seal right or the spring is soft and not holding the regulator down enough .

Superkop

I am dealing with the exact same problem and the answer is clear for us...we are loosing prime in the fuel rail and even when our pumps are keyed on to prime and pump up, the rails, lines and injectors are still empty...of fuel that is...don't forget that AIR takes the places of displaced fuel. so we are overcoming a minor air bound symptom of the system loosing its prime. Mine gets better to the point of half a crank and vroom to smooth idle. Shut it down for a few hours and here goes the cranking for eight to ten seconds before it coughs and sputters to life... then idles like $hit until I blast it out a few times and let it run. One variable to you is that I KNOW I have at least one funky injector that clatters as it pops off, so I may only have a bad injector, but I am definitely doing a regulator when these little puppies come out. If the return line is "blocked" and you STILL loose prime, then the problems on the pump side. Check fittings and hose al the way back to the pump plate. (I'd also say injector leaking down, but your are new...) If it does NOT loose prime, the its on the return side...and THAT narrows things down to the regulator leaking back, as there isn't too much beyond that. One question I have is this; are there antisiphon valves in the fuel pump plate? Inline in the system? I don't think so.

irocwagon

update...i suffer as well..mines a little worse...wants starter fluid to crank but then runs fine..have digi fuel pressure guage mounted in car...46-48 without vaccum...41 at idle with...bleeds down pretty quick...around 15 secs i believe.

Superkop

A bleed down that quick is absolutely a leak in the system. Did you replace the regulator? How are your lines heading from the tank to the fuel rail? Your leaking down BAD, and somthing you may need to think about is was this a problem before the new injectors, and if not, you may have a bad injector. Mine goes to 50psi (adjusted with new BBK reg.) KOEO, then at idle it stays at 40-42psi, then on shutdown, stays at right around 40psi for a good 20-30 mins. before a gradual bleed down to about zero the next day. I give it one quick key over to crank for about 2 secs, key it off then go again and she starts in about 2-3secs and runs fine.

92GTA

iTrader: (11)

Update for me...

Turns out it was my fuel pump, I installed RacetronixWalbro GSS340M pump kit. Now when I turn the key off, it bleeds down to about 39psi and just stays there like it should. Starts right up instantly like it used to.

Thanks to those who helped!

Alex

irocwagon

so even making 46 to 48 pressure, its still bad pump possibility,my symptons seem like yours, dand i hate fuel pump swaps,my lt1 car ,pump is mounted on rail,never a problem,im taking volunteers if somebody wants to swap it for me