Problem

85 iroc with a 350 rebuilt motor as described with 305tpi and new promm

the 350 motor---- crank is new,stock, and 10/10 turned, 4" plus .040 bore, with flat top high compression pistons, stock stroke, rv cam 4 valve relief, 305 heads planed for approx. 10.5:1 compression ratio, .010, hypertech dist, .048 gap, msd wires 5 ohms, bosch 24lb injectors, adjustable fuel pressure regulator, ed wright fastchip.com promm chip, slp 1 5/8" headers.

at startup my fuel pressure gauge is reading 48 psi s (book says 35 to 45 psi at startup) and the regulator is backed off 100% so i am attacking the fuel pressure diaphram and spring that is allowing the pressure at startup to be so high.

so my guess is to put a new fuel pressure reg in it and than put my adj fuel pressure reg back on and i should get my pressure down at startup...

so am i right.......i have read in other threads here i should have changed the knock sensor.....2 what a 350 knock sensor? and why......i cannot get this motor to idle yet, i also have 52mm throttle body pulled screens on maf and air foil for a calculated 790cfm but ed wright has reprogrammed the chip for this and injectors and cam.......... can any1 tell me how i can tune this in........... i am pulling my hair out.............thanks alot..... .......

 

You need a scantool to see what the IAC counts are for the idle. It should be around 20 counts.

Did Ed Wright just burn you a chip or did he take readings to make sure that it is doing what it is supposed to be doing. I went to www.fasterproms.com and that is what we did to get it perfectly tuned in. No one is good enough to do it right the first time. I send them feedback of everything the ECM sees and they keep burning till it is nuts on.

 

o.k. but i am over pressure at startup so how does my iac matter at this point if my pressure at startup is so high.

i just gave ed all that i have done with the car and he burned it. he will work with me and burn more to tune it in, i get about 2 more burns before i got2 start paying him again.

any1 know about the knock sensor, i read the computer will advance timing which we are not 2 yet since she is running so rich at this elevated pressure

 

Wow. Fasterproms does it till you are satisfied with the chip or there is no more mods to make. On difficult cases, you borrow their DIACOM unit and take readings so you can email them the data. They send you another chip that is more tuned to your readings instead of your impressions.

KS has nothing to do with what you are describing. KS will retard the timing till it doesn't hear knocking. As long as there is no knock, the KS will do nothing and you probably aren't getting any knock at idle unless your motor is really shot and the bearings are worn.

Get another fuel pressure gauge and see if it is really high or what. If you have set the adjustment all the way out, you should be lower than that. If not, you have a problem. When it runs, what is the pressure? You do have the feed hose disconnected when youare taking pressure readings, right?

 

actually i have the fuel pressure gauge hooked right up to my fuel line and than i just hook up the fuel pressure regulator and turn the key.........this gives me a startup reading of 48psi with the adj fuel pressure bell housing screw all out applying no pressure to the regulator.........

so today i am going to change the regulator to see if that will bring my startup pressure down to like 35psi..........i hope

right now from what i have read the fuel pump elevates the fuel line pressure to 50psi and i am getting 48..................

so i think maybe my diaphram is shot on the regulator, it is a guess.......

 

It sounds like your reading this after the initial ignition on primer cycle. I believe your supposed to read it when the engine is running. I believe you will get a higher reading after priming because none of the injectors are open during this cycle.

 

i got the part i believe the diaphram is broken and i cannot disconnect the feed line and have my fuel pressure gauge tell me what is going on......the doctor is going 2 work ................i'll let you know how the surgery goes........

 

If the diaphragm is broken there would be gas in the vacuum line.
The line at the base of the regulator is the return line, the feed line is on the front end of the passenger side fuel rail. Fuel pressure should be taken at the shrader valve near the passenger side fuel rail near the regulator.

I've modified mine, (it's not at an angle anymore,) but you can see the return line, and the shrader valve.


Regulator Picture

 

Now that he pointed it out, where are you taking fuel pressure and how? Did you have a seperate plumbing set to take care of that or what? He is right that it should be taken at the fuel rail and not before.

I would think that you would notice that the diaphragm is broken when you take off the hose to get a reading at WOT.

 

so,
here we go, i put the new fuel pressure regulator in and fire her up and play with the throttle, we come up at 48psi and than we come back down 2 37psi, but she wont turn over because we have been running so rich... so tomarrow i will pull plugs clean um up and i think i am in business.......................

 

37 is a little too low.

 

i am on the schrader valve with my guage and i think ill keep it hooked up why not, the nice thing here now is to see the guage come up and back down. we have also disconnected the return line and are dumping it into a water bottle ....reason maybe it is clogged from something we did put a new motor in......anyways just to eliminate the return line as a possible problem for now and to get her to turn over.........but as i said she wont fire with us putting the carb starter to her.........so we ponder for 30 seconds and decide as follows........

so since we have been running way to rich resolving this problem............. we think the plugs are real wet right now........... from all that xtra gas we were pushing in with that high fuel pressure.

so i called it quits last night 7pm started on it at 5, and will clean the plugs tonight, hopefully i'll have good news.

 

Did you unplug the vac line at the regulator when you took your reading (you should). In your post you said you have a RV cam, 24 lb injecotrs, 52mm T/B. You have way too much fuel going into that engine, more then the components can handle. Although the excess fuel isn't going to give you high pressure at startup it sure could be the problem of trying to get it to idle correctly. Try to stick the stock PROM back in (for TPI) and see what it does for your idle (it will narrow the pulse width of the injectors). Sounds like your pulse width is not setup correctly and dumping too much fuel at idle and that is why it won't idle. You really don't need a custom prom for the cam/heads you have installed. It might even help to put the stock 19lb injectors back in with the stock PROM.

 

well i am not convinced yet that i cannot get her to idle out nice.

she sounded mean at throttle position up but way 2 rich, now we have a fuel pressure reg that works.

i have bumped the air to 790cfm from i think 570cfm stock, so more air, more compression, more fire, more gas, new promm.......

i could be way off here but 24lb injectors are being run by people on this site and on others and these can go to 80lbs of pressure.......

i hope i did not overdo it with the injectors and thanks for the heads up.

 

Similar to post on thirdgen message board. Problem solved.
FUEL PRESSURE 2 high on satrtup