racerx520

iTrader: (1)

i have been having problems with keeping my 350 tpi running for almost a year now. i can tell that its all fuel related, that much i know. since figuring it out to that extent, i found my my 24lb svo injectors were overpowering the car since apparently svo runs at 35psi and tpi runs at 41. so i bought 24lb injectors from southbay.

i installed the injectors and it worked great all last summer. this spring i took it out and it was running worse than ever....wont idle, wont rev without choking, and would backfire everytime you tried revving.

today i replaced the fuel pressure reg with an afpr from southbay. without any adjusting it seemed to run decently, so i put on the harbor freight fuel pressure gauge and found it was at about 30psi....way lower than it should be. i took off the vacuum line and didnt move. i followed the directions for adjusting the fuel pressure on the package southbay sent and the pressure didnt move at all. however it began running worse as i tried adjusting the pressure higher - even though the gauge didnt move. (i found the stock FPR from 1987 was dryrotted and passing fuel through the diaphragm, and the engine was sucking fuel through the intake from the FPR)

i'm not sure if my gauge is messed up or if it could be the PROM that was written by "tuned performance" when he was here. i put on a matco OBD I scanner and certain things never changed which were odd. it showed the car never came out of open loop, the coolant temp never moved from 66 degrees, and also showed the timing at 22 degrees advanced, although the timing light was at 10 degrees advanced (recommended there by tuned performance), as well as showing the pulse width of the injectors at 0.00. certain values on the OBD I scanner i'm unsure of, like the O2 voltage or the MAF values and what they should be at.

I'm going to try and get get a better fuel pressure gauge incase my 2 brand new ones are somehow defective, and maybe looking into a new prom, but i'm not too sure where to go from here.

1MeanZ

iTrader: (9)

I'd start with a coolant temp sensor if I were you. If it's really reading 66* all the time it might be bad. Put a new one in and try that.

I can tell you right now there are probably multiple things wrong, and you've had your hands in this a lot and some of the things you say don't make any sense. This will be tremendously difficult to properly troubleshoot over the internet...

racerx520

iTrader: (1)

I had built the motor 2 years ago and put it in. I did put a brand new coolant sensor in, not saying it can't be bad, it would be par for the course at napa. I remembered my father has a 88 corvette he's trying to sell, I'll try the scanner and gauge on that too and see what it comes up saying.
I'm not too sure how much I trust the work of tuned performance right now though with the computer work

What are some of the things that don't make sense by the way?

tealman92

When is the last time your fuel pump,sock and filter were changed?

1MeanZ

iTrader: (9)

1. SVO injectors are very good, I would have never changed them out. They will flow more at higher fuel pressure, but you can compensate for that in the PROM by recalculating the flow rate at higher pressure.
2. Standard fuel pressure is not 41 psi, it's 45-47 with the vacuum line unhooked on every thirdgen I've worked with.
3. The fact that it ran fine last year and then when you got it out this spring it acted up tells me something else is wrong now. Something changed.
4. None of your fuel pressure data from when you installed the new pressure regulator makes any sense. Your gage is junk, the regulator is junk, your pump is junk, or all 3 are junk. Get a good gage and try again (if you get another gage from Harbor Freight, don't bother posting what it says.) Even backed all the way off I've never seen an adjustable regulator get that low.
5. the PROM has nothing to do with your fuel pressure, get that fixed before you blame tunedperformance.
6. your temp readout on the scanner being static at 66 degrees means the CTS is bad, or the scanner connection was no good. you can check a coolant temp sensor by just checking resistance across both terminals with a volt meter. You can find resistance vs temperature tables online with a google search. If the CTS is bad, i assure you it will run poorly.
7. the amount you set the base timing to is completely unrelated to the 22* you saw on teh scanner. The scanner is displaying the commanded spark advance by the ECM, the ECM has no idea where you set the base timing. Tunedperformance has the base timing in your tune set to 10*, so you must leave the base timing there unless you are going to change it in the tune.
8. I don't remember what maf values should be at idle, but O2 mV should cross over the .450mV mark. Could swing as wide as .300-.600mV during idle.
9. if the car ran good and now all of a sudden doesn't, it's not the PROM. The PROM wont cause the car to all of a sudden act up. From what you've stated on here you have major fuel pressure issues and the CTS is bad.

Bob88GTA

iTrader: (2)

racerx520

iTrader: (1)

Thanks guys this is super helpful. The fuel pump was changed about 5-6 years ago, filter about 3 years ago. The sock was with the pump. It hasn't been a daily driver for about 4-5 years. I'm comparing the information from my car to the corvette later today, and I'll try to hunt down a better fuel pressure gauge.
I didn't mean to sound like I was blaming tuned performance, the first prom I had written by someone was totally messed up so I wasn't sure if this could be a similar issue, this is the first time I've had a scanner to put on the car since my aldl cable / computer combo didn't work out for some reason.
And yes I kinda figured the gauge was incorrect somewhere since I don't think these cars can even run at 30psi. I still have the svo injectors, you think they're better than the 24lb Bosch? I didn't want to flood the motor with too much fuel since I read that the 24lb svo injectors at 41 psi actually calculate on a flow table to 26 lbs

racerx520

iTrader: (1)

Alright, so this is what I found today: the corvettes pressure shows up at 35 psi, so it moved the gauge, with the vacuum off it jumped to 45psi, so I think the gauge is correct unfortunately.

I did notice that the needle stayed steady on the corvette, my car it bounces between 25-35 so I figured it was about 30. So a problem too is the gauge needle bouncing.

The Matco scanner worked fine, turns out I'm an idiot and never reset it from when it was used on the corvette last, so it was setup for that car. May have been a problem too.

racerx520

iTrader: (1)

Not too sure of what to make of the fuel pressure bouncing on.my car like it is, all I know is that it can't be right. I have heard some people say a problem with these cars could be the pulsator. Not sure if it could be that in my case or not. Are they included on the sender when replacing the fuel pump now? If so it has a new-er one

tealman92

More then likely you have a pump related problem. Its been in the car for 5-6 years regaurdless if its been driven or not they fail. The other thing that it could be is a leak between the pump and the hardline in the tank this will cause the problems you describe. If your regulator is new and your maxing at 30 psi then you need to go back down the fuel line. Next will be filter then tank.

racerx520

iTrader: (1)

I was afraid it could be the pump. Such a pain to do when I had access to a lift, may have to pay to have it done I guess. Thanks guys, I looked at my records and did the fuel filter last year with the engine. I don't see any leaks on the ground. However I haven't been hearing a strong humm from the pump when I turn the key to the on position lately.

racerx520

iTrader: (1)

Is this kinda indicative of the pump failing. I know most people (myself included) would have thought that if the pump was bad, it would just not work, not put out less pressure but still operate

1MeanZ

iTrader: (9)

I've never had a pulsator on a pump fail, so I don't know how that manifests itself. The pulsation could be caused by the regulator as well, so keep an eye out for that. I generally don't use adjustable regulators because frankly, if the injectors are sized properly to the engine an adjustable regulator shouldn't be needed. Plus, I've had adjustable regulator housings not have the proper radius on the ID and rub a hole in the diaphragm causing a failure. If your regulator isn't using the factory diaphragm and spring, that could be part of your problem.

racerx520

iTrader: (1)

It looks like the factory spring and diaphragm, it's through south bay. Could a small vacuum leak do this too? I can't find any sufficient ones anywhere under the hood.

Where should I be going next on this you think?

SbFormula

1MeanZ

iTrader: (9)

Next thing I'd do is measure the voltage going to the fuel pump. If it's getting good power, and your fuel filter is new, and your regulator isn't messed up, i'd put a pump in it. With the regulator vacuum reference unplugged it should make a solid 45psi. If it won't do that you've gota problem.

I have no data to support this, and I realize I'm troubleshooting this over the internet, but my gut doesn't feel good about the regulator. I'm not in any way throwing cold water on South Bay. I don't like the pressure fluctuation you're seeing, and in my opinion the regulator is the most likely cause of that.

racerx520

iTrader: (1)

ok, maybe i'll see if i can get a new diaphragm and replace the stock one with the afpr one of these days, i wont have much time coming up to do that anytime very soon though.

i put the scanner back on and entered the correct VIN info and it worked this time. here are some readings i got, incase you guys are interested at all (in italic are the corvette readings which i took yesterday, closest thing to this motor i have to this car - bold are my car)

O2 volts .31-.68 .62-.76
(new sensor)

Integrator 147 126-132

MAF 10 G/S 10 G/S

Coolant Temp 208 F 177 F

MAT 84-122 F (over some time) 075 F
(I dont know what this is)

RPM 775-850 1050

KNK Signal No No

EGR D/C 000% 000%
(i have egr delete)

Inj. P/W 2.6 ms 1.7 ms

Prom ID 4131 7861

Trouble code 42 34
(I have no check engine light on though)

O2 Cross 000-007 006

TPS .52v

racerx520

iTrader: (1)

also, does it matter a whole lot if when i turn the key to the ON position, i hear the fuel pump turn on for a second, but it doesnt continue to buzz for the about 3-4 seconds like it used to. that was another occurrence which just appeared this spring.

Bob88GTA

iTrader: (2)

see red

Bob88GTA

iTrader: (2)

FP should buzz when key turned to "on" for approx 2 sec. Turn key "off" then back to "on" it may buzz once again if pressure in rail is not full.

bigal55

iTrader: (1)

If you still suspect the fuel pressure regulator, pinch off the return line to the tank. If you still don't get good pressure and the pump is running, the pulsator is probably the problem. This, of course, is predicated on the fact that the fuel filter is good and no lines are plugged or kinked from the tank to the fuel rail. HTH!

racerx520

iTrader: (1)

Pinched off line and checked pressure, was still around 30 psi and bouncing both with the vacuum on and vacuum off. The pressure dropped from 30 to 10 almost immediately after turning off key (return still pinched) but held at 10psi

bigal55

iTrader: (1)

If you want to run the pump more than the 2 sec. prime, follow this picture and jumper the fuel pump to ground at the ALDL. HTH1

bigal55

iTrader: (1)

After reading through this thread again and hearing that the fuel pressure didn't change when you pinched off the return line, (BTW, that was fast!) I believe your problem is the pulsator. My reasoning is the bouncing pressure and low pressure when dead ended. The purpose of the pulsator is to reduce or eliminate pressure spikes (pulses) in the fuel system. Other threads I read have shown the pulsator to be the problem when the pump runs but doesn't build pressure. Sorry, but I think you will have to drop the tank. GL!

racerx520

iTrader: (1)

Ok, I had read a couple threads where inadequate pressure wound up being the pulsator too. Was hoping i wouldn't have to drop the tank, but hopefully i can find someone with a lift I can borrow, not sure how possible it is to do on my back in the driveway.

This time when I turned on the car in the garage and stood outside of it I heard the pump run, it ran for the appropriate time, however it just isn't very loud in the car for some reason. Not sure if that would be the pulsator too.

And yes, i don't have work until 6p tonight so I had time to run out to the garage and mess with the car lol.

1MeanZ

iTrader: (9)

This stuff is why I'm a strong advocate of cutting the fuel pump access panel! Haters gonna hate!!

racerx520

iTrader: (1)

I just hate cutting holes in cars lol. Do all the other numbers above from the scanner seem about within correct tolerance? I was wondering about the injector pulse width being 1 ms longer than the stock vette's too. Not sure what are good numbers on there, and apparently the code 42 is from disconnecting the wire when checking the timing yesterday

racerx520

iTrader: (1)

Was doing a search on pulsators, we're they only on tpi cars? I saw a thread saying they weren't on 5.0L cars which is what was in here, but that 5.0L was a tpi also. I think the thread I saw was talking about carb motors.

Steve Mack

iTrader: (5)

I agree with 1meanZ,cut the access panel.

racerx520

iTrader: (1)

Just wanted to make sure on where to go from here.....replace the pump and pulsator and report back?

bigal55

iTrader: (1)

If you look at your log, you will see your int at 147 (way lean) so the ECM is adding fuel to try to correct the lean condition, thus the wider pw. At least that is what I think is happening. Lean condition due to low fuel pressure caused by faulty pulsator.

racerx520

iTrader: (1)

Oh ok, that would make sense then how you describe it. The scanner has a light for rich and lean and it bounces between lights as I was described it should if it has a correct balance of rich/lean mixture.

I may have been on this site for a very long time and have done a lot of work to the car (under supervision of course) but I clearly still don't know much about mechanic work

racerx520

iTrader: (1)

I was just wondering. For my setup (listed below) is a stock fuel pump good, or should I upgrade to a performance pump? I see there are no performance pulsators. If you think I should upgrade the pump, which one do you guys recommend?

Gm crate 350
Summit aluminum heads
Crane 2032 cam
Accel base manifold
Slp runners
24lb Bosch injectors
Afpr
Tuned prom
Hooked headers (egr delete too)
Electronic cutout
Cool air intake
And can't forget about the airfoil

racerx520

iTrader: (1)

Any thoughts on more of a performance, higher pumping fuel pump?

1MeanZ

iTrader: (9)

walbro 255

racerx520

iTrader: (1)

Is that going to be too much for my mild setup?

Also, havery November 4th reserved at a friend if a friend's shop to drop the tank. Only guy I could find with a lift I could use.


I also wanted to thank youn guys for all your help with my build, I would never have been able to get even this far if not for this site and its members

TPI

Just a little sea story here.. But, I had the same issue with my T/A. Fuel pressure was
reading correctly, it primed correctly with no signs of failing. The car barely idled, and
under load it shuddered and barely limped around the street. After doing the whole troubleshoot
song and dance.. I decided to drop the rear axle,
pull the tank and inspect. Nothing overly obvious, but you don't go
through the hassle of pulling the tank without just replacing the pump
and sock anyway.

Buttoned it up, the car screamed! Whether the pump/impellor was varnished,
or it was just failing.. Ill never know. Guess it doesn't matter. I won't say not to
cut a access panel, but I will say it is easier than you think to yank the tank.
Mind you, it is intimidating for the uninitiated.

racerx520

iTrader: (1)

I have pulled the tank once before with a lift. I don't know if i can get the car up high enough with jacks.

Btw, if I replace the pump with the aftermarket one, would I still need the pulsator? I have read it wasn't on tbi cars but on tpi, so not sure of the car won't run without it

racerx520

iTrader: (1)

hmm....so i spent money on refurbished injectors for basically no reason? thats a bummer.

racerx520

iTrader: (1)

i know its been a long time since i posted. i finally got over to my friend-of-a-friend's house to use his lift (i dont know how anyone does this on the ground, this tank had to be on a huge angle). I replaced the pump, sender, pulsator, and filter. i started it up, had great pressure (45 w/ vacuum on, and 55 w/ vacuum off) so i may have a little fine tuning there, but i'll take it. the pressure evened out and isnt jumping all over. the car is finally reactive when it hit the gas, was able to get a really really nice burnout when leaving the house, too bad it was just one tire. now that the fuel issues are fixed, just need to replace the LSD lol.


THANKS AGAIN EVERYONE FOR YOUR HELP