Camaro Spectre

Okay so I've been playing with this issue now for at least 2 weeks and it has grown tiresome trying to identify a way to fix the problem. I did a HSR with cam/head swap and few other minor things and 24# injectors.

The problem is, the car keeps flooding itself with fuel like none other on start up. It only does it however when the fuel pump relay is hooked up, unhook it and it starts with almost no problem and will drive fine till it starves itself of fuel....you can hook up the relay and it'll run fine as long as you have it started but try and re-start it instantly after shutting the car off with it still attached and again it simply cranks and feeds the car excessive amounts of fuel.

Maybe some of you guys can toss in a little insight as we are at a complete loss ourselves.

86White_T/A305

Hmm only things I can think of to check that is double check the fuel pressure regulator with the relay plugged in..see if your holding pressure aswell and how much pressure you have.Is this the original relay? and is everything associated with it functioning properly,no corroded or melted terminal etc. It could be something stupid sometimes lol.Id check everything over once again and its there isnt any mechanical or electrical failures spotted Id look more into the tune of the chip for your 24lbs injectors during crank.Also make sure you dont have any leaky injectors..those are very sneaky aswell for flooding our nicely built motors :S Keep us posted

cronsformula350

I've just done a stealth ram swap and installed some gm, .028 thick head gaskts for more compression, and my car also, cranks a lot longer, then finally starts with the 24# SVO injectors, I run 14* base timing and 38 PSI of fuel pressure because those were the best results with a motor in GM High tech, so I copied his tune, and it works well, but I may try higher fuel pressure, and more timing, OR I may try my Rochester 22lb per hour injectors, because they are supposed to be good for 450 HP according to TPIs, so yeah.

What do you think?

Camaro Spectre

Well we tinkered around some more with it and listened to it a bit more and the problem still persists but we think we have simply found our way of bypassing the problem temporarily until we can figure out what the problem is.

What it is is with the relay plugged in its tripping the injectors wide open with the key turned on and just opening the flood gates, but as soon as you can get the car started with it unhooked and hook it back up the injectors pulsate just fine like they are supposed to and aren't wide open as when first trying to start it. Thats what really has us puzzled. But yes the relay is the original(as far as i know) and there is no damage to the terminals.

So what we are going to try doing at this time is making the relay a toggled switch for the time being until we can find another way of fixing the problem so i can have the relay plugged in once more. As for the tune, thats something i have to work on myself as there isn't a place around for over 200 miles to do it.

91interceptorZ

iTrader: (3)

Do you have the fuel lines hooked up correctly??

Camaro Spectre

Pretty sure, even made sure of it when doing the whole swap before attaching the braided lines by putting my finger over the openings and identifying the one feeding the fuel.

Camaro Spectre

Well after taking a few moments time to examine it a bit more thoroughly i noticed the vacuum for the AFPR had came loose enough at some point prior to the engine starts that it would possibly not be drawing vacuum. Could that small problem really cause such a big problem to cause the over fueling?

cronsformula350

No, a V8 can run with a lot of fuel in the chambers, it takes a whole lot more than just having no vaccum attatched to the regulator, something else's wrong

customblackbird

iTrader: (15)

just thought id chime in, im gona be doin a HSR 383 with patriot aluminum heads, comp cams XFI 280 cam and all the goodies... i went with SVo 30lb injectors... this is for cronsformula350 those 24lb SVo injectors ur using... arent really 24lb, they are about 26lb when compared to GM injectors. ford rates there injectors at a lower PSI like 37.5, when GM rates there injectors at 43.5psi. So at GM pressure your 24lb are actually like 26ish. I kno this bc i went with my SVO 30lb knowing that i really had a 32lb injector when i run it at GM pressure. so you running it at 38psi is making it a 24lb injector, if u raise it higher u will be increasing the flow rate to basically a 26lb. Also the tune in the ECm will counter your increased fuel pressure by lowering the pulse width of the injectors if you raise the fuel pressure and not in the chip, the O2 sensor will read the increased fuel and cause the ECm to compensate with shorter pulse widths. so basically dont raise the pressure unless u tune it for it.

also i dont care who tells you wat but a 22lb injector can not support 450hp. even at 50psi it wont support it. you would need at least a 24lb at higher pressures like 48-50psi. my 30lb aka 32lb will only support 500-550hp.

camaro spectre, not sure how the fuel relay is causing this.... did u install a higher flowing pump? all the relay does is switch the fuel pump on causing pressure in the line. i would think your fuel pressure is off bc if the vacume line is off watev u set it at is not accurate. since yours is a 91 u dont have a cold start injector, so your cold start is programed into the ECM which adds extra fuel via the 8 injectors. if youve upgraded to the 24lb injectors over your stock 22lb and installed a HSR your gona have to tune that to your combo... esp bc you did a cam and head swap.

my dads 305tpi 86 TA had head porting, cam swap, and 24lb boschIII injectors installed, it runs like COMPLETE $HIT on start up... i mean wants to stall bucks snorts, u cant even drive the thing untill it hits operating temp, this is due to the increased injectors from the stock 19lb to 24lbs and not changing the tune. when warmed it runs alot better but gets alil hairy in the upper RPMs.

set your pressure again correctly, and tune it. should clear up ur probs

Camaro Spectre

Yeah see thats how we are not sure of it either as its got us puzzled. We know that the rail and injectors are building up pressure and keeping the pressure and not leaking it out but we cannot figure out for the life of us how come we cannot get it to start with the relay attached. When we un-plug the relay after simply using it briefly we can get it to start with a little help from the throttle, however when we try and start it up with the relay still attached to no avail she will not start, it simply floods it with fuel. Take the relay off after it floods and crank crank crank with full throttle and you'll sometimes be lucky enough to get it to fire over.

So we are still trying to chase down this bug as the vacuum being loose was not the problem. Could it be the IAT? We used the IAT sensor off the 89 instead of trying to use one off the 305 or a 350 SD car (is there really any difference between any of these IAT sensors? If there is i would think it would be between the MAF/SD instead of 305/350)

As for fuel pump it is a higher flowing one i had installed about a year ago when the stock one ate the dirt. Had no problems with it when i was running the 305 however.

If anybody has any ideas it would be great. The only problem right now is getting it to start with the pump relay attached, otherwise getting it to idle (althought a bit high atm) and rev isn't much of a problem as that really comes up once tune is in order.

Camaro Spectre

Played a little bit more today and watched the fuel pressure. The relay is not technically the source of the problem it is simply the supplier to the problem. As long as I do not attempt and crank the rail keeps a steady pressure of 40 PSI however the moment i start cranking it that pressure declines rapidly to 0 as it floods the engine.

Not sure what or where to check for the solution to that problem.

customblackbird

iTrader: (15)

so when u turn the key the fuel rails basically dump the fuel into the engine... i would think then that ur injectors could be an issue. since they shouldnt dump all the fuel but pulse. inorder for the fuel rails to dump all the fuel that would mean the something isnt stopping the fuel going out into the engine and that something isnt allowing fuel to get into the fuel rails. you could have a 2 part problem. if the fuel dumps out of the fuel rails and the rails dont fill up with fuel constantly then u might have a pump issue or a fuel line kinked or bent etc.

the pump should turn on once the key is turned to the on positon and not the run position. there should be a pump whine from the back of the car... this is the pump turning on to prime the fuel rails up to pressure for startup. does yours still do this? those are the only real things inline to cause the issue... besides the fuel regulator and the ECM.

is there an electrical short or bad connection with the pump relay?

86White_T/A305

ive mentioned this before to another person who was chasing fuel issues.Check the fuel pressure regulator diaphram for pin hole leaks.Its cost me a good 355 motor by the time i found it after flooding the motor tme and time again.

Before i found it i was trying higher press,injectors,timing,vacuum lines,tried re-seating the fuel rails and injectors making sure no leaks were present..drove me nuts lol.

the relay wont be the cause of the problem..if anything its helping point you in the direction of it.

New2Chevy

iTrader: (11)

Sounds like a fuel pressure issue to me, too. I'd get the highest quality regulator money can buy. Worth it.

Camaro Spectre

Well I had brain storm after playing with it a bit and checked for grounded harness.....wasn't grounded anywhere. So I kinda thought a little bit about what could cause the issue as it all worked soundly when i stopped driving it to prepare/pull/drop engines, so it didn't make sense why it would have went sour in the month time period the swap happened.

Then i thought of pulling the ecm and replacing it. Problem solved with that simple fix. Not sure why the ecm would have taken a bite while it sat for the month so I'm just going to attribute it to the vast quantity of lightning strikes this summer in the area.

Thanks for the help tho fellas, now i can actually begin tuning it.

New2Chevy

iTrader: (11)

Best wishes on your project, bro.

Camaro Spectre

Thought I'd give a quick update/ask for some opinions.

Car runs, runs good. Got it to where it would stay running and be able to drive (albeit not efficiently) and then took it for some dyno tune time. The numbers i got back from the dyno however were very depressing in my opinion. 259/272 at the wheels on the final pull. That seems extremely low to me given the mods. (see sig). But there were also some minor problems that i have since corrected and I think these could have been some detrimental factors to the numbers.

The problems at Dyno time
- Throttle blades sticking, car wouldn't come below 1600rpm (changed throttle body now, idles at 800-1000)
- Exhaust manifold gasket was completely gone by the final pull(fixed at home)
- Horrible vibration from the rear, believe to be driveshaft (fixing)

So I'm thinking there is still a lot left in the tune to bring the numbers up, and that by fixing a few of the problems that had occurred on the dyno i have put a few more ponies back to the ground. Opinions? Thoughts? Especially from you fellow stealthram owners.

cronsformula350

how much base timing did you run? And what was your total advance? Albeit stupid, I ran 17* base timing in my 13second iroc, and it ran like a bat out of hell. The power increase can be rather dramatic, if your not used to it.

But what was yours? Did you do anything to the timing when it was on the dyno?

Camaro Spectre

8* Base with 34* total Timing.

The car has absolutely no problems holding its own on the streets its just that the numbers seem so low for the mods considering a stock L98 with HSR swap makes same rwhp numbers as I do. Hence why wondering if there is a lot of room left in the tune (but doesn't appear that way to myself, but maybe there is), or the if the afflicted problems themselves limited the number and kept it below its "true" number. Really expected to see closer to 300rwhp out of the setup.

Hence why I am asking for opinions/help and sharing the dyno graph for other HSR owners to chime in.

89_RS

Did you check the fuel pump relay with a volt/ohm meter? If your fuel pressure is going to 0psi on startup, chances are that you are losing power to the pump somewhere.

Burnout91

I think something in the fuel system, electrical system or something mechanical is wrong:https://www.thirdgen.org/forums/tpi/...-350-lays.html

Bill

Camaro Spectre

Thank You burnout91 for opinion. Was looking for somebody like yourself or Orr to respond as its your guys information on the stealths that i can take the most from.

I am running 43.5 psi, and I'd have to double check again to be sure but my a/f is at 15 at the bottom end and strays into the mid 12s on the top end. So I think there is bit more that can be squeezed out in the tune seeing as how before on the dyno it wouldn't Idle low due to throttle blades sticking (new throttle body has since changed that and I idle nice and low once again & has no hesitation like it did with the old one catching)



I think that with the throttle body changed and the header gasket (aka exhaust gasket) replaced since it was completely blown out on that final dyno pull that my numbers have came up a little to possibly around 270/280 instead of the 259/272 that the graph shows. Is that a reasonable assumption?

The car holds its own very well on the street including putting 3/4 a car & still pulling away on a 04 Mach 1 in little under an 1/8th mile. The same car my 00 T/A managed to pull 1 1/4 car on in the same distance.


Also I should add that the cam is currently only operating on .492 lift as I am using 1.5s.