Only runs with full choke. Where to look next? (1 Viewer)

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I'm working on a 77 FJ40, everything stock 2F engine. This cruiser has under gone a restoration for the last couple of years, so it running for the first time in a while. Everything has been gone thru and carb was rebuilt. I pull the choke all the way out and it starts good. Let it warm up a bit and start pushing the choke in. As soon as the butterfly valve starts to move, the idle drops and the engine dies. I have put thread sealant on all fittings in the intake manifold, tightened the intake manifold bolts, remove carb and cleaned all the mounting surfaces. I have had someone who knows a lot more about carb adjustments do the adjustments and he has said the adjustments are where the should be. I checked the vacuum at full choke and its 16.5. Can't check any lower then that cause the engine dies. I'm stuck on what to look at next.

Mark
 
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if ICS is working, then you'll need to find where the vacuum is leaking(sucking in unmetered air, causing havoc with the air/fuel ratio and bypassing the metering devices of the carb). this can be tricky sometimes, but what worked for me was spraying short shots of staring fluid at the various interfaces of the carb to manifold, manifold to head and at each of the vacuum control devices found thru-out the system. trick is to shoot your short shot and wait for about 2-3 seconds and listen for a change in idle quality- not speed increase or decrease so much as overall quality. there is a lag from the time the spray is shot and the time the engine reacts. once you find you leak, verify it by waiting and respraying and if you get the same result a few times over at any given spot, that it where your leak is. It can be a bad gasket, cracked or warpped manifold, cracked carb, or bad vacuum doohickey...
 
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I have also checked that. I pulled the idle solenoid off my 78 and stuck it on there. Nothing changed.

if the wiring harness of rig in question isn't letting 12 volts thru the wires to the solenoid, it won't matter how many known good ones you swap in. I had a loose wire give me some trouble cutting out at stops one drive home a few weeks ago. after panic subsided, I found the loose wire to the solenoid connector and viola.
 
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I had a leak between the carb and insulator, but since removing them all and cleaning, that seems to be taken care of.
 
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I think the intake manifold and exhaust manifold are not a matched set. If I remember correctly, my father got a different intake cause the original was cracked and welded a couple times. Do or should you machine the mounting surfaces of both manifolds? I can't remember if they were even or not. Would this possibly cause enough of a leak to cause the issue?
 
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I had a leak between the carb and insulator, but since removing them all and cleaning, that seems to be taken care of.
run a baseline lean drop carb adjust; check all vacuum lines and doohickies. I had a vcv near the dizzy must have cracked on the inside give me hell tracking down the leak. No reaction from starter fluid, all dialed in at the carb and diz, valve adjustments twice, still had low vac. pulle doff each component one by one and capped lines to them and fired rig up at each step and eventually I got to that one vsv that when all the lines to it were capped, I got my vacuum back. swap in a known good one and on I went. if your ICS is working and the passage isn't clogged, the carb is baselined and the timing is right, if there aren't any vacuum leaks and the compression is good, it'll run without choke.
 
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I think the intake manifold and exhaust manifold are not a matched set. If I remember correctly, my father got a different intake cause the original was cracked and welded a couple times. Do or should you machine the mounting surfaces of both manifolds? I can't remember if they were even or not. Would this possibly cause enough of a leak to cause the issue?

a mismatched set will not seal easily. they should be assembled together with new gaskets between the intake and exhaust, and the assembled set should be machined at the sealing surface to the head. the manifolds can be a big headache, but with enough research and proper planning, and a good machinist, you'll only have to deal with it every 25-30 years. any corners cut will shorten that timeframe exponentially. it's the type of thing you try to only do once.
 
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I won't be able to give any updates on things I tried or found for a week. This cruiser is at my parents house and I'm only able to work on it on Friday or Saturday nights. Just trying to get some ideas for the next time I head over there.
 
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I would want to see 16.5 at 600 rpms. do you know if it has a cam? what elevation are you? how many rpms is you high idle? it should idle 600 with 16.5"- I'll bet the vacuum drops as the revs taper off. if everything else is alright(no leaks, timing, comp, baseline, ics) it will run. any chance any of the circuits of the carb got some gunk in em during the shuffling? if the idle control circuit is clogged afetr the solenoid, a working solenoid won't do anything. did any of the screws around the base of carb get turned? if the idle speed screw is backed all the way out and the idle mix is turned in too far, it won't idle as well. My suggestions previous were all based upon all things having worked ok before...try this: welding glove and piece of cardboard big enough to cover the air horn and with a hole just big enough for the air cleaner stud to stick thru. fire truck up with choke and fast idle and cover air horn of carb(choke it out). if the revs increase before it dies or bogs down, there is unmetered air getting in. if it bogs and dies, stop looking for a vacuum leak; start looking for reasons fuel wouldn't make it thru the idle circuit. may have gunk caught in carb circuits blocking idle path. Also make sure the fuel is only half way up the sight glass...doubt you are flooded, but hey...
 
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I had the same condition on my 78/40 years ago. I did not find any obvious vacuum leaks so I decided to pull the carb for a rebuild. Once the carb was off, I could see the bottom of the intake manifold was cracked in several places where it mates to the exhaust manifold. I took it to my Uncle's welding shop and he grinded it out then welded it up. Reinstalled it, rebuilt the carb and runs like new for the past 14 years.
Figured it was a huge vacuum leak and had to compensate by adding fuel (choke). You may want to check the intake manifold.
 
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If you have a good idle with choke pulled and it starves for fuel without it- you have--1. a vacuum leak(large), 2. a plugged up idle circuit in the carb,
vacuum at idle(Without any choke, and 650 RPM) should be ~16"Hg--any thing less -- you have a leak. if you have this 16 " then fuel is not getting to the venturies(meaning the fuel circuit is restricted)(this is assuming you have a 1/2 full float bowl)
 

Racer65

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When I checked my vacuum recently it was 18.

Check the check valve at your brake booster. Air should only pass through in one direction, or you'd get a vacuum leak.
 

Racer65

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On a '77 you should have tons of vacuum lines. Are you sure none is leaking? I'd change them all with Silicone lines.
 
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The intake is not cracked below the carb, plus we installed that steel block off plate between the intake and exhaust. All the vacuum lines were replaced with new vacuum tubing. The hose going to the brake booster is where I hooked up my vacuum gage, so that tells me it's probably not the check valve on the booster. The fuel gage on the carb is a little above half full.
 

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