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Old 09-05-2010, 05:36 PM   #1
Join Date: Sep 2010
Posts: 1
Lightbulb No Idle no matter what

5.7 2 Barrel carb will not hold an Idle, the only way i could get it to the slip was to restrict the air intake by Half, which gets me a stumbled Idle but then of course i get no Rpms over 2900, this has been a three year battle and as far as the fuel additives and tricks I have tryed them all, has anyone had this sort of problem and if so what types of remedy have been used i have re built the carb twice and am now looking at new carb options or even a fuel injection set up for next year, just trying to salvage the season for now any Ideas??? WTF

BilgeRatRod is offline   Reply With Quote
Old 09-06-2010, 12:34 AM   #2

Join Date: Jun 2008
Location: B.C. canada
Posts: 265
Cool carb

have you check for a leaky carb base gasket sounds like a vacuum leak ????check with a hose you will hear it suck air in???

cunuck is offline   Reply With Quote
Old 09-07-2010, 02:01 AM   #3
Join Date: Jun 2009
Posts: 83

If you have to put you hand over the carbie to suck the fuel in, it may be a blockage in the system, a weak fuel pump (if you could set up a temporary tank and supply pump straight to your carbie) this may help point the direction of your problem 1 the carbie 2 some other part before the carbie. If your fuel pump is electric you may have a intermittent Volt drop at the pump caused by a bad/damaged/corroded supply cable
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Old 09-07-2010, 01:15 PM   #4
Lt. JG
Join Date: Oct 2009
Location: Montreal, Quebec
Posts: 16

I had the exact same proble 2 weeks ago. I have 5.0L, 2 barrrel Mercarbs and I could start the engine with no problem and even keep it running at 2500 RPM and above. By depressing the choke plate manually, I could maintain idle. But by itself, at idle it would stall. Can you keep the engine running at higher RPM's. If so, than I suspect a dirty carb...again! Obviously, if your gas is dirty, the carb will continue to get clogged and the idle ports are quite small so it doesn't take much to block them. That was my problem...dirty carb. But then you did say that you've had this problem for 3 years??

If you can't keep the engine running at higher RPM's neither, then maybe you have a fuel pump problem.

You didn't say if you have twin engines but I would consider switching carbs on the engines to see if the problem follows the carb or stays with the engine.

My 2 cents!

rtw_ca is offline   Reply With Quote
Old 09-22-2010, 02:31 AM   #5
Lt. JG
Join Date: Oct 2009
Location: Atlanta, GA
Posts: 16

I have recently had a similar problem, 1997 5.7 2brl mercarb, wont idle, after running for about 15-20 minutes the engine wouldn't run hardly at all, lost power and had a couple backfires trying to get it to rev. I have a rough idle, but it is getting better. Rebuilt carb, new intake gaskets, new water/fuel separator. Runs great on the muffs in the driveway, but I haven't had a chance to get back to the lake. I have added startron fuel treatment, was pretty sure the E-10 I get at the gas station went bad (didnt know about the problems with it when I got gas). I keep siphoning out gas and adding new, hoping I am getting any possible water out of the tank. Have you solved your problems yet? I am hoping it was just bad gas, or maybe a clogged vent line, which I have yet to check.
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