2F dieseling at shut off.

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1979 2f when I turn the key to off it runs wild a bit then shakes to a stop. For the last few months I've been shutting it off in gear and letting the clutch out to stop the beast. Only does this when fully warmed up. Seems to be getting worse. Fuel solenoid is wired to ignition switch and clicks. Timing BB is at bottom of window. Points dizzy w/big cap. It may be running backwards during the dieseling, I keep forgetting to check.
 

mattressking

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Make sure the o-ring on the fuel cut solenoid isn't torn/broken or missing. What changed between not dieseling and dieseling? Usually its a poorly setup carb/vacuum leak or busted fuel cut solenoid.

1. Start by verifying timing is at 7* with a timing light, with vac lines disconnected from dizzy at an idle under 900rpms.
2. Ensure you have 18-22inHg at idle. Subtract 1inHg per 1k ft of elevation.
3. If all passes, do a lean drop; Set idle speed to 690rpms, using mixture screw, turn CCW to richen mixture, blip throttle 2-3 times to reset. If idle raises, use idle speed screw to reduce back to 690rpms. Repeat until mixture screw no longer raises idle above 690rpms. Turn mixture screw CW to lean idle out to +/- 650rpms.

You mention it's a '79. Do you have a 1 or 2 wire ICS?
 
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Ok thanks. I just bought a multitester with a tach so I can do the lean idle drop next weekend. I desmogged this engine more than 30 years ago. Has a non usa carb with one wire ICS. At that time I went to the points dizzy as well. Currently idles at 20 inHg vaccuum and compression is from 158-170. It started the dieseling about mid-summer. With no roof, this is a summertime vehicle so that gives me the winter to send one of my 3 asains to one of the carb gurus if needed.
 
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Could the deposits be caused by the 'gasp' 64.00 chinacarb? It actually runs well with it. Idle is good accelerates well, and last summer when I got it back on the road it didn't do the dieseling thing at first. It crept up on me. Honestly the carb was just a bandaid so I could drive around in my jalopy over the summer. When I desmogged it I bought a factory new non usa carb from spector. The rusty very rusty 55 went into deep storage in the deep woods and I robbed that nice carb for an fj 60 desmog. Later sold the 60 and put a 1977 carb that needed rebuild on the 55. I also have 2 fj 60 carbs that might be just fine. Just that they have a lot of 'stuff' on them that I don't think I need.
 
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Oh, and I put the solenoid from my '77 carb on the Chinacarb, don't recall o ring problems but wasn't looking. They both 'click.
 
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Had trouble with solenoid stuff in the past.

Don't underestimate the inexpensive Chinese carb. Everyone makes such a big deal about carbs, but, it is not much more sophisticated than having a home with a working toilet - is it clean, or does it leak? Aside from the whole, who messed with the settings without knowing better kind of issues.

However, I got a minitruck with a carb that has no idle-cut-solenoid - only diesels when it is dirty inside the engine and it is hot outside. Solenoids are more of a security device than a necessary engine component.

The big problem that no one has yet to address is the engine is probably firing at a crank/degree moment based on cylinder pressures instead of when the plug tells it to. Living with a light knock for too long seems very doable on these motors. It will run just fine with a clutch-shut-down; I managed to ignore the problem thru my life with two F motors on an early 70's 40. Hard to say how bad the damage was, but, it didn't stop me from driving.
 
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Thank you Grayscale. The carb does work just fine. I will check the ICS today or swap it out. Might not be too easy to get it running hot since it is 28 degrees this morning and no roof or doors, well you get it. When this 55 was a total rust bucket it was driven about 2 miles each year, then shut off. Snow chains on all four corners year 'round. Maybe the 24 years of short trips carboned it up. I will make an effort to dump some seafoam in the fuel and drive it long and hard next summer. Still thinking about sending one of these carbs out 'just because'. I know there are several carb folks here to pick from. I'd love to get some input on who to send it to, and should I send the '77 or one of the FJ 60 type?
 
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I'd bet that more than half of a chance that it has nothing to do with the carb, but the valve stem seals are leaking. It not only makes the intake port kinda restricted, it fouls the plugs quick. Hence the hard cold start, and the can't-stop-it-when-hot - glowing plugs or valve surfaces is what I'm saying is the likely problem.

These motors fire up easy above about 20 deg. F. if the ignition is proper, and that the gas in the bowl isn't older than a couple of weeks - my LC is running below factory specs for vacuum (age and altitude), and that you have a fine touch with the choke. BTW, I never tap the throttle before I engage the starter - the starter can create enough vacuum to start the fuel 'circuits' in the carb, and the fast-idle automatically pushes the carb's pump-plunger for unmixed gas. The last thing you want is a big old drop of unmixed gas puddling up on the floor and surfaces of the intake manifold, that is bound to make carbon deposits.
 

kudzugypsy

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i hope more people chime in on this thread. i know a lot of us younger owners have grown up exclusively with EFI that we never really had to "know anything" about and carbs require some understanding to dial in/maintain. i would suspect that a lot of owners have/will have similar issues - i know i have with the dieseling after shut off, esp after a longish summer drive - i figured it could be several factors.
 

pb4ugo

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There are many reasons for dieseling. What do the plugs look like? Are they showing sign of getting excessively hot? When you turn the engine off an fuel air mixture could be ignited by a hot plug. You mention the timing bb is at the bottom of the window which I believe indicates the timing is advanced past spec. Typically dieseling is from hot spots in the cylder. Carbon build up can increase the compression ratio, advanced timing creates more heat. then running lower octane fuel, will all contribute to the issue. Does this engine ever see faster speeds or higher rpms for any length of time? Maybe a different heat range plug might help too. Sometimes a good flogging can blow the carbon off the top of the pistons too, but that's up to you.
 
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I have been flogging it at 50 plus mph last summer when I could, but I live on a 58 sq mile island of narrow winding roads with only four or five good straightaways. The county has been generous and posted these few areas with a 40 mph speed limit unlike most of the roads which are 35.... Add to this it has factory 3.70 gears and 33" tires so it's idling at 30 :). Very hilly here so at least it gets wound out pretty good on the hills in second and third. When I first dragged this fj 55 out of my woods last year and mounted new sheet metal on it #5 plug would foul routinely. It got better and better with miles. So did the compression. It increased an average over 30 lbs after getting it licensed and hitting the road. #5 stopped fouling too. But I haven't looked at the plugs since this diesel thing started. The 2f has 198,000 miles on it, the last 120,000 by me. When this week of unseasonal freezing temps ends maybe I can take a spin, get it up to temp and do some experimenting with timing, spark plugs, premium gas and anything else we come up with. I will still need my ear flap hat.

Foyota rear quarter.jpg
 
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It has excellent compression and vaccuum as stated earlier, and no smoke from the tailpipe either. It has not used any oil in the 2000 miles since I ressurected it. I am interested in looking at the plugs again. I may well learn something from their condition.
 
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The very high compression is a good sign. The vacuum is a good sign. I wouldn't rule-out a vacuum leak as the source of heat (lean fuel, not leaking valves or rings). However, these things are designed to oil the valve stems by having some pass past the seals, and if they are original, they have probably suffered from age alone; it wouldn't take much deterioration to make them a bit too oily. Every 2F head I've torn into needed valve stem seals.

Love the pics of the FJ-Fifty-Ford on the island.
 
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Can the seals be replaced with the head on? I can picture at TDC the valves would be safe from falling into the abyss. Sounds like a pita though. Other names for my jalopy are the FJord, the FJfordy, the FJ 47 (body year), the Blue Bomber, and the Sow's Ear. I do like the 'FJ Fifty-Ford' too. Good one Grayscale.
 
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mattressking

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If you have good compression, I wouldn't stress about the valve seals, if you were blowing cylinder pressure through them you'd see it in the compression numbers. If they are consistently oily it's a separate issue but not causing the dieseling immediately. Definitely fix, but again, not causing the dieseling. Fresh plugs and gapped to .032 to start.

Go into the carb, check o-ring on solenoid. It may click but the o-ring may be shot or missing. If it's in good shape, clicks reliably and sharply, then take top hat off and remove the venturi/emulsifiers. I have witnessed first-hand the cheap $60 carbs dropping their emulsifier tubes, which is another good possibility for dieseling. Your dieseling issues are carb related if you have greater than 18-19inHg at sea level, unless you have a terrible tune on the carb.

Then do a quality lean drop once the engine is hot. What is timing set at? Since its desmogged/no smog equipment - set to 7* and a max of 10*. Better quality fuel helps here but listen for pinging if you opt to raise timing. Run another lean drop any time you change anything when warm and check vacuum at idle. Make sure needle is steady indicating good valve adjustment. Any fluctuation should be noted and mentioned. If consistently shaking, do a quality valve adjustment per Toyota Service Manual.
 
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If you have good compression, I wouldn't stress about the valve seals, if you were blowing cylinder pressure through them you'd see it in the compression numbers. If they are consistently oily it's a separate issue but not causing the dieseling immediately. Definitely fix, but again, not causing the dieseling. Fresh plugs and gapped to .032 to start.

Valve stem seals have nothing to do with pressure from the combustion chamber. That pressure is held by the valves themselves. Valve seats (on the head), is that what you mean?
 
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Can the seals be replaced with the head on?
Yes, but, it is trickier than just a manual. Kinda tricky by the 40 booster and firewall with a lever-type spring compression tool (home-brew compresses the spring farther which is important). It is plenty covered in this forum. Don't loose your valve keepers down any holes in the head, stuff rags in them. Also, like $5 a pop, so what $60. Money well spent, but, it took a full day because I'm slow. I'll be happy wrenching about anything if the bottoms of my shoes are actually touching the floor.

You can get a 'bore scope' for your phone and look in the spark plug holes, or so I'm told. However, if you pull the intake/exhaust you can see the top of the valves.
 

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