Won't idle

[chadwinters]

My 2000 S10 Xtreme with cammed 350 V8, new Holley 750, S10 Parts fuel pressure reg. w/return runs VERY rich, has trouble at idle in and out of gear; but RUNS at higher Rpm. I added a fuel pres. guage and adjusted the pressure down to 3 lbs, and adj. floats, and idle mix with little change. Don't think there's any vacume leaks. Does the "orifice" outlet connect to the carb or the return? Maybe I've got it backwards. Any Help?

[grimpuppy]

Look down in the carb while it is idling and see if fuel is pouring out. (use a flashlight not a lighter http://www.s10v8.com/images/smilies/icon_razz.gif ) If so I would say your regulator is hooked up wrong. Got any pics of how the reg and inlet to the carb is setup?

[Melonhead]

What is the vacuum level at idle? What power valve do you have installed? http://www.s10v8.com/images/smilies/icon_biggrin.gif

[chadwinters]

I've looked down the front two and don't really see anything. I can hear it though. I don't have a vacume guage. It has plenty. The heads and intake were flow matched and the carb set up by the engine builder. It ran good until we put it in the S10. I haven't checked the rear float levels or the power valve. I didn't want to take it apart. I do want to get the right hookup on the pressure regulator. The outlet with the orifice is connected to the carb, and the open outlet is connected to the tank return.

[grim_reaper888]

well if yours is right, then i hooked mine up backwards.

[oncearacer52]

You need to get that fuel pressure up to about 5 lbs. and I don't think you need any kind of orifice on the outlet to the carb. Your idle circuit is probably to rich. I would want to know just exactly what this guy did to "setup your carb". There are many things that will cause an engine to not idle, but you say it is to rich so I would look to the carb idle circuit.

[Scotty_S-15]

On 2008-02-20 16:56, oncearacer52 wrote:

You need to get that fuel pressure up to about 5 lbs. and I don't think you need any kind of orifice on the outlet to the carb. Your idle circuit is probably to rich. I would want to know just exactly what this guy did to "setup your carb". There are many things that will cause an engine to not idle, but you say it is to rich so I would look to the carb idle circuit.



I'm thinking all of that. But puzzled because if you have the orifice facing the carb, then you'd expect it to run poorly at speed for lack of gas. http://www.s10v8.com/images/smilies/icon_confused.gif But yeah, I'd think the orifice is for the return line.

.............. And like Oncearacer said, could be lots of little things wrong with the carb setup. But before anyone can even begin to diagnose the problem, it'd be best to hook up a vacuum gauge, and also share with us all the "intimate" details of the cam. DP or vac. secondary Holley? Also things like where the timing is at idle, and how many RPMs it's idling at would help.

.............. Most common problem with something with a serious cam, is that to get it to idle, the throttle plates are open beyond the idle range. There are some fixes for that.

[Ryoung68]

The way you have the regulator hooked up it is regulating the return and not the fuel pressure to the carb. Reverse the oriface connector to the return line side and put the regulated output with the pressure gauge to the carb side. Then remeasure and adjust the float and idle.

[chadwinters]

OK I changed the lines, reset the float levels and it runs a whole lot better; but still won't idle when hot. One plug cracked and most gas fouled, so I'm doin complete tune-up. Runnin 38 degrees advance and 195 thermostat may have too much heat on intake and causing it to percolate. Could be the sound in the carb I've been hearing. Changing to 160 help cool intake. I will repost the results when done. Thanks for the help.

[Melonhead]

On 2008-02-25 10:04, chadwinters wrote:

Runnin 38 degrees advance. Could be the sound in the carb I've been hearing.





Is that timing total or initail??? The sound you are hearing may be detonation. Cheap gas, heat, and high timing is a bad mix.

[chadwinters]

Engine builder recommended 38 degrees total with mechanical advance coming in at 1000 RPM. These Vortec heads realy respond to this timing. With the 2800 stall, it is reponsive.

[Melonhead]

OK, Good for me. The engine would be better with a 180 thermostat. http://www.s10v8.com/images/smilies/icon_biggrin.gif

[chadwinters]

Engine came with a 160 and it took forever to warm up on cold days. I put a 180 in it and then a 195. It warms up now and stays at 195, but won't idle. I have put the 160 back in, will check how it runs after I do the tune-up and switch to the 180 if it needs it. Thanks

[chadwinters]

Did the tune-up and 160 thermostat. Now that the fuel pressure is under control, it runs great. Slow warming up, so maybe the 180 is in order. Thanks all.

[peasej406]

By the sounds of your issues you are detonating the engine at idle.

[peasej406]

Nevermind....