Any ideas what this can be???? HELP..

MY 85 GT · 07-13-2008

Ok i put in a Phelioc spacer...i put in a fuel pressure gauge...also put in a fuel pressure Regulator....And STILL have a stumble and now i actually can see the gauge drop pressure...it does it in 1st and 2nd gear under a load...giving it gas but here is the funny thing it doesnt do it all the time seems like it does it when cold...When its warmed up it might do it a litttle once in a blue moon....I have the pressure set at like 5 ish i bought a cheaper regulator it seems not to adjust very well....I need to buy a better one...But still i see the fuel gauge drop then stumble what could be wrong....

02whtstanggt · 07-13-2008

my guess is a bad fuel pump. since the problem was present before the regulator was replaced and is still there after the new regulator. try a new pump since a mechanical pump shouldn't be that expensive even if it's not the problem at least you'll know the pump is working properly.

MY 85 GT · 07-13-2008

Quote:

Originally Posted by 02whtstanggt

my guess is a bad fuel pump. since the problem was present before the regulator was replaced and is still there after the new regulator. try a new pump since a mechanical pump shouldn't be that expensive even if it's not the problem at least you'll know the pump is working properly.

Thaks for the info im going toward maybe a bad pump but it didnt do this until i did the Exhaust lol....i had the pump for 3 months never did this stumble until about a week ago...I still need to vent the gas somehow...either thru a vented gas cap or unplugging the return line that the shop plugged up....Im lost.....

heavy metal · 07-13-2008

It may just be a venting problem,try the gas cap first.The 3 month old Carter pump should still be fine.

MY 85 GT · 07-13-2008

Quote:

Originally Posted by heavy metal

It may just be a venting problem,try the gas cap first.The 3 month old Carter pump should still be fine.

Yeah before i put a regulator on..i was running 6 psi like they said it would...I put a reg on because i felt it was too much pressure for the needle and seats....Edelbrock recommends 5-5.5 so thats were i have it...If it was a bad pump or weak i think it wouldnt be putting out 6 psi...Now on to venting i wonder why that would cause a problem some cars arent vented? are they all? I mean yeah it is kinda weird how it didnt do this before the whole exhaust system was installed...but he did change alot took all the emissions stuff off ..I had the return line opened with a filter on it ...He closed it..I dont know if im coming or going ...ive tried alot of different things im lost....LOL

heavy metal · 07-13-2008

Put the filter back on ther return line and let it breath.I am running a holley red pump,6 psi,no regulater on my 79 5.0,Edelbrock carb,no problems.

MY 85 GT · 07-13-2008

Quote:

Originally Posted by heavy metal

Put the filter back on ther return line and let it breath.I am running a holley red pump,6 psi,no regulater on my 79 5.0,Edelbrock carb,no problems.

Ok thats easy to do...so do you think i shouldnt regulate it??? or leave it at 5-5.5 psi...Or should i let it go to 6 psi....

heavy metal · 07-13-2008

I would try it with out the regulater and see what that does.

MY 85 GT · 07-13-2008

Quote:

Originally Posted by heavy metal

I would try it with out the regulater and see what that does.

I did it seemed ok put the car was warmed up and it seems not to do it as much as when its cold...Im going to call edelbrock tomorrow to see what they say...maybe i can run it with the 6psi maybe they can point me in the right direction...I am going to vent it tho im sure that cant hurt...

02whtstanggt · 07-13-2008

Just going over in my head you said that the pressure guage dropped when it stumbled. Maybe the guage dropped due to rpm. I would vent the tank like Heavy Metal said as built up pressure can throw things off. However the stumble may not be solved by the venting. Have you tried adjusting the carb. Your stumble maybe an accelerator pump adjustment. Hope you get it figured out.

heavy metal · 07-13-2008

Hope it works out good for you.Holler if i can help any.

MY 85 GT · 07-14-2008

Quote:

Originally Posted by heavy metal

Hope it works out good for you.Holler if i can help any.

Thanks i will if i cant figure this out.....

MY 85 GT · 07-14-2008

Quote:

Originally Posted by 02whtstanggt

Just going over in my head you said that the pressure guage dropped when it stumbled. Maybe the guage dropped due to rpm. I would vent the tank like Heavy Metal said as built up pressure can throw things off. However the stumble may not be solved by the venting. Have you tried adjusting the carb. Your stumble maybe an accelerator pump adjustment. Hope you get it figured out.

Yeah i am going to vent the tank with either a vented gas cap or opening that line again...When it stimbles the rpm doesnt jump it feels like a bad spark plug wire for that short secong but now that i have the fuel Pressure gauge i actually saw it jump when it dod the stumble...It might be an accelerator pump the carb isnt that old maybe 3 months old i know you can adjust the pump shot i have it all the way down in the 3rd hole closet to the intake...wonder if i should move it into the middle?

02whtstanggt · 07-14-2008

Did the stumble start when you replaced the carb? The Edelbrock carb that I had needed different jets and rods as well as adjusting the acc. pump. Try playing around with the carb to see if it gets better. The rejetting kits for the carb have great instructions. Moving the acc. pump rod up might be the fix. Try it and let me know how it responds.

84 predator mus · 07-14-2008

if your carb has an electronic choke it might need adjusted as well. usually after a carb breaks in a little the choke will need to be adjusted. just something else to look at