fuel pressure problems

[guruofdirt]

Just put a Baker pro-cam fuel pump 9351 on my 602 crate engine and running e85 had a cv pump that i borrowed that was running too much fuel pressure 10 to 11lbs. at idle put this 1 on today and now gauge is fluctuating from 2 to 10lbs. and have to idel carb.up for it to run but doesnt sound right and throttle when i rev it is sluggish idle down and its rough idling and almost cuts off.Any help would be appreciated been battling fule problems for 2 weeks and cant see if setup is getting closer.Oh and ethanol % is 87.

[Matt49]

Let it run for a few minutes with the breather off and see if you see fuel dripping or running out of any of the carb nozzles. If this is a Holley carb and you're getting 10 pounds of fuel pressure, you're probably blowing the needle valves open and flooding the bowls. Fuel dripping from the nozzle would be an indication of that and the symptoms you're describing sound like the motor is getting way too much fuel. After you shut it off, pop the sight plugs from the bowls (have a rag or something ready). If fuel pours out, that's likely your problem.
10 PSI is too much for a Holley needle valve. 7 PSI is about the max it will stay closed. Run a regulator, set it to 6 PSI, and go racing.

[guruofdirt]

Matt 49 you think carb. is screwed up from the pump that was pumping the 10 to 11lbs. at idle and the baker pump i just put on it fluctuating from 2 to 10 lbs. is alright, need to swap carbs. and see I have my gauge on fuel log end of carb. where return line would go?

[50j]

Mechanical pumps will bounce the fuel pressure gauge at low speed. Rev it up a little bit and it'll smooth out. If you have a fuel log and can run a return line, you could put a bypass on the BACK of the fuel log and have the right set up. E-85 will usually need around 7.5 psi to keep up wide open.

[Matt49]

High fuel pressure won't "screw up" the carb it just won't allow the needles to close properly.
Based on what you are describing, I think the motor is getting too much fuel. Question is why?
First let's figure out if it is even getting too much fuel. Pull the breather and see if you can see fuel dripping from the nozzles at idle. When you shut it off, pull the bowl sight plugs and see if fuel runs out. You should just get a few drops; more than that and something is wrong.
If it is getting too much fuel (and your bowl heights are set correctly), it is usually because a needle valve is failing to close which can happen for a number of reasons.
1) Could be a piece of debris stuck in the valve (it doesn't take much)
2) Could have a sunk float
3) Could be getting too much fuel pressure not allowing the needle to close

I can tell you from experience on a Holley that at 9PSI that it won't run right. We had a 650 and at 9PSI the needles would not stay closed and it always ran rich. This was on gas but the needle valve doesn't know the difference. Pressure is pressure.

[guruofdirt]

High fuel pressure won't "screw up" the carb it just won't allow the needles to close properly.Based on what you are describing, I think the motor is getting too much fuel. Question is why?First let's figure out if it is even getting too much fuel. Pull the breather and see if you can see fuel dripping from the nozzles at idle. When you shut it off, pull the bowl sight plugs and see if fuel runs out. You should just get a few drops; more than that and something is wrong.If it is getting too much fuel (and your bowl heights are set correctly), it is usually because a needle valve is failing to close which can happen for a number of reasons.1) Could be a piece of debris stuck in the valve (it doesn't take much)2) Could have a sunk float3) Could be getting too much fuel pressure not allowing the needle to closeI can tell you from experience on a Holley that at 9PSI that it won't run right. We had a 650 and at 9PSI the needles would not stay closed and it always ran rich. This was on gas but the needle valve doesn't know the difference. Pressure is pressure.

OK thx guys going to shop and try and figure this out I first thought when fuel pressure gauge was fluctuating from 2 to 10lbs. fuel pump may be bad. And this is a 650 too.thx,Andy

[guruofdirt]

Thx guys for all ur help got it figured out i think may have gotten some air in line fired it off let it run til operating temp. at 2k fuel pressure picked up and is steady at 7 1/2 to 8 now adjusted floats to level where fuel is barely seeping thru threads of plug idled her back down and she runs good loaded it up and took it to track and ran bout 15 laps and ran great wide open throttle all way around and found setup is very close also. So hopefully tomorrow night will have a much better experience other than the frustration of foul running engine.

[dirty white boy]

hope you get'er right for saturday night guru!!