racerx520

iTrader: (1)

hey guys, been having some problems with my t/a since doing a motor swap. I got it running pretty well since, but now my problem is that it hardly stays running while trying to warm up. if i floor it while its idling it pops and such in the exhaust. i checked everything and went to check the fuel pressure, and found it to be around 35psi while running. not sure if this is an FPR problem or something worse, like the fuel pump. hoping someone here can help point me in the right direction on where to go next. i had a few problems with the fpr already and had to install my 28y.o. one from my 305 motor since the new one wasnt holding pressure. since then, i put in 24lb bosche injectors from southbay. (although they have a pentagon like a chrysler symbol on them?) i replaced my 24lb svo injectors cuz apparently they run at 26.2 lbs at the psi our cars run at.

last summer when i checked my psi, it was at 40psi, and that was with the current fpr in there too.



any help is greatly appreciated. thanks guys

racerx520

iTrader: (1)

Nothing? Again?

aliceempire

iTrader: (14)

I didn't know anyone here was at your beck and call.....but.....was your fuel pressure reading taken with the engine running and vacuum line installed? Or was it running and vacuum line disconnected? The reading with it disconnected is fairly irrelevent, the pressure you want it 43.5ish with the vacuum line off the regulator and preferably capped at the plenum. Problems warming up is more likely a problem in the CTS circuit. Did you test the sensor or wiring?.....checking "evrything" isn't very descriptive.

racerx520

iTrader: (1)

was never intended to sound like anyone was at my beck and call. each time i ask for suggestions on fuel issues i dont get any responses. i have waited for nearly 7 months on a post to get one response.
but yes, the engine was running, no the vacuum lines were not disconnected. i'm not sure what the cts circuit is so i have not checked it. however i have also let the engine warm up fully with the fuel gauge still on and it did not go above 35psi. i'm going to try the gauge on my father's 88 vette to see if maybe the gauge is at fault, but it is brand new. my fear is that the problem is the fuel pump (which was replaced like 6-7 years ago) because it is such a pita. thanks for any help

aliceempire

iTrader: (14)

35 psi with the regulator hooked up to vacuum is probably normal. Pull the line and cap it at the plenum. Then recheck it. PSI will pop up into the 40's since there will be no vacuum to work against the spring in the regulator. I doubt the gauge is wrong. I don't think fuel pressure is a problem.

The CTS is your coolant temprature sensor. It's covered a lot on the boards...please search...and here are troubleshooting guides for codes that will give info on it even though you have no code. http://chevythunder.com/cts_diagnostics.htm
http://chevythunder.com/cts_diagnostic_pg2.htm

Also search for 'won't run while cold' type threads, it's kinda common, they may have more info than I can give.

racerx520

iTrader: (1)

thank you for the info, greatly appreciated.

when i checked the pressure last summer i thought it was at 40 psi without disconnecting any vacuum lines, i'll have to double check the troubleshooting page i was on for the injector leak down. thanks again

aliceempire

iTrader: (14)

If it was 40's with the vacuum line hooked up it was probably set too high OR the engine was pulling poor vacuum (or a vacuum leak) at the time you tested it. Not a bad idea to retest it correctly just to know where you're at.

racerx520

iTrader: (1)

ok thanks

racerx520

iTrader: (1)

today i ordered up a new AFPR from southbay. I'm hoping this helps the issue, if not, it was atleast something on the list for me to purchase for the car anyway. I tried the pressure gauge on the car with it not running, since that would in theory be at 41psi since the vacuum has nothing to do with it at that point. I hit the key multiple times to prime it, and it never went above 35psi. i'm hoping it wont be a fuel pump issue, if it were, would that be a problem where the pressure would drop, or would it just cease completely?

aliceempire

iTrader: (14)

I've had pumps that couldn't provide enough pressure. More often I've had them just stop working. You could've tested the regulator by pinching the return line and seeing if pressure goes up.

racerx520

iTrader: (1)

I'll give that a try tomorrow. The afpr was something on my list to do anyway. I took the car out today and it kept trying to stall while at low rpms and taking off from a stop. It would run ok at high rpms. It kept backfiring in the headers. I had the timing set right last year before I put it away for the winter so I doubt it moved. Also going to pull plugs, hopefully shouldn't be dirty with only like 300 miles on a brand new built motor.