Help identify problem stall, stalls, stalling

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studawg

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Help identify problem, 78 Fj40 stall, stalls, stalling

1978 2F, stock except im missing the air pump, charcoal can, and vsv valve, and probably a couple other things, EGR is in tact, air line going from vsv to air injection line is capped/plugged, (see red hose with half a spark plug sticking out of it, I didnt do that) The truck is currently running rich, (black smoke out of exhaust). There is a vacuum port near the top of the carb (see pic)that is open with no line coming out of it.

It cranks up from cold with full choke and then I back down to half choke and it idles smoothly for 10-15 minutes. As soon as I take choke off fully, it bogs down and stalls with in 15-20 seconds.

After driving for 30-45 minutes in 95degree weather, then shutting off for 10 minutes, then driving again, it started cutting off when i came up to a stoplight and engaged clutch to go in to neutral and apply brakes. It would then crank back up but anytime I slowed down, I would have to left-foot brake and apply throttle to keep it from stalling.

:confused: Does anyone have any suggestions for procedures, plan of attack, culprits, etc.....or simple fixes :bounce:?????

pics below.....
 
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I am sure you have a vacuum hose nightmare based on your description. Most of the items that have been eliminated have vacuum running to them which makes you wonder how the lines were re routed once they were removed. I would study up on the various threads regarding desmog as well as the desmog diagrams under the tech links, determine what systems are salvageable and you want to continue running vs which you should properly eliminate and how to re route the vac hoses. It is complex but after a bit of reading and looking at the pictures and diagrams it starts to make sense.

I would find a replacement charcoal canister since there is no good reason not to run the evap system. If you decide to do away completely with the air injection I would remove the rail and cap the ports in the head. Obviously your path forward is dependent on your local smog laws and if you need to have the systems intact.
 
Thanks, all good points. My plan is to return it to 100% stock, with all the smog components intact and working. SC has no smog laws, but I want it all original and stock. I have the 1978 emissions repair manual on the way.
 
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Sorry forgot to attach pics :bang:
smog pic 1.jpg
smog pic 2.jpg
 
So here is a pic of the engine side of the carb. According to SOR, my carb doesnt match up with any of the ones it lists. Only one port around the idle mixture screw, engine side, and 3 ports on the front. The diagram in the 1978 emissions system manual shows 3 ports on the engine side. It is showing an advancer port and an EGR port and a TP port. I have to figure out what carb I have.
engine side carb.jpg
 
Anyone????
 
So here is a pic of the engine side of the carb. According to SOR, my carb doesnt match up with any of the ones it lists. Only one port around the idle mixture screw, engine side, and 3 ports on the front. The diagram in the 1978 emissions system manual shows 3 ports on the engine side. It is showing an advancer port and an EGR port and a TP port. I have to figure out what carb I have.

The best way to know what carb you have is from the production date stamp on the top of the carb on the front facing side adjacent to the fuel line. It will be coded # A ## where the 1st # is the year, A-L denotes the month where A=Jan, B=Feb etc, the last two #'s denote the day of the month the carb was made. Example mine is 5 L 24 for Christmas Eve 1975 ('76 model year carb)

Just reading your posts, I agree with the vacuum investigation but would also make sure your idle solenoid is operating correctly when the key is turned to the ON position. Also helps to give some background regarding the issue and when it started, i.e. have you always had to engage the choke to establish idle or is this a recent development?

If the IS works and you find steady strong vacuum, you may find that its time for a rebuild. Consider pulling the air horn off the carb to see if the fuel bowl is clean. If you have stuff floating in there you will definitely want to consider going through a rebuild. Good luck.
 
Has it ran good before this and this is something new? I'm willing to bet that you have a vacuum leak somewhere. Take a can of starter fluid and, with the motor running, start squirting around various places: carburetor, intact manifold, vacuum lines. Your motor will rev a bit higher when/if you hit a leak.
 
Take some of the guesswork out, mount a vacuum gauge. I found that the vacuum gauge was so useful that I put one in my dash.
Check your timing too.
 
My carb date code is 5 G 25, so July 25, 1975. However, according to the pics oof carbs on SOR, it doesnt match up, and it doesnt match with the diagrams in the 1978 2F emissions repair manual. This carb has 3 ports at the top, front side, around the date stamp. So I am having a hard time routing the vacuum lines when I cant find anything that matches it.

I tested the idle solenoid by unplugging and plugging it back in with the key on and it clicks, so it works.

I just got this Cruiser so I have no frame of reference of how it ran before. Before I bought it, it sat for a good period of time and was not run very much. I have changed the oil and run about 3/4 quarters of a tank of premium, ethanol-free gas through it, with about a half a can of Seafoam in the tank and half a can in the crankcase.
 
I would suggest you get a vacuum gage and figure out if you have a vaccum problem. I believe there are a couple good threads in the FAQ under carbs that discuss in detail using vaccum to tune the carb. I connected my gage by removing the line at the brake booster and attaching there. If your vaccum is weak or unstable then you know you have a leak to chase. Using the carb cleaner to chase worked for me.

I was looking back at the pic you attached. First up, I can't tell where the line coming off the Power Valve (PV) on the top of the carb is going. Since it sounds like you have a 75 carb on your '78 truck you will need to set up the carb like a 75, i.e. the PV on 75-76 gets vacuum from the manifold, not internally. Without vacuum to that port, your PV will always be open and you will be running really rich. I could not get a good idle setting up my 76 until I closed the PV with vacuum. Chase that line coming off the PV and see if it is coming direcly from the intake or other source below the throttle plate on the carb. Second, I don't recognize the port to the left of the PV adjacent to the fuel line that appears to be open. Just means I don't have one on my 76 and I dont have enough knowledge of all the nuances and changes through the years on the Aisin carbs. Is that a cap that I just cant see, if not check to see if you are loosing vacuum there. Sounds like you have a 78 emissions diagram, where is that line supposed to go, or does it even show up?

attachment.php
 
Mustard, which is the line for the power valve?
 
89cruiserfj62 said:
Mustard, which is the line for the power valve?

It's the single line coming off the top front of the air horn where the line comes across the bracket with the three ports. It's just to the right of the open one asked about previously.
 
Yes it goes to a port on top of the bracket, out the bottom of the bracket and into the gas filter. The gas filter only has one port, and of course my 78 emissions manual shows a filter with 2. Might that gas filter be plugged up? As I said, this truck sat for a while without being driven.
 
>>After driving for 30-45 minutes in 95degree weather, then shutting off for 10 minutes, then driving again, it started cutting off when i came up to a stoplight and engaged clutch to go in to neutral and apply brakes. It would then crank back up but anytime I slowed down, I would have to left-foot brake and apply throttle to keep it from stalling.

I have a completely stock '78 (fresh carb rebuild, all emissions stuff intact and working) that does this, too. I installed an electric fuel pump in line with the OEM pump, and when it starts sputtering, I turn it on, and the engine recovers and does not stall. Otherwise, like clockwork, the engine stalls about 45 seconds after you start it (after sitting parked, hot). I have battled this for years, and the Evap canister is the only thing I have not studied closely. I wish I could help you, but I can only sympathize.
 
According to the manual, the things that I dont have are the VSV, VCV, ABV, Air pump, charcoal can, and the outer vent control valve. But my carb doesnt have the same ports as the carb in the manual so I wouldnt know how to hook it up even if I had all the components. I want to make this thing as stock as possible, but dont know how to go about doing it exactly. My weird carb is the problem.
 
89cruiserfj62 said:
According to the manual, the things that I dont have are the VSV, VCV, ABV, Air pump, charcoal can, and the outer vent control valve. But my carb doesnt have the same ports as the carb in the manual so I wouldnt know how to hook it up even if I had all the components. I want to make this thing as stock as possible, but dont know how to go about doing it exactly. My weird carb is the problem.

Do your emission laws where you live still effect the vehicle or is having the original setup personal preference? If so you can post WTB in the classified and probably score most of the items over time from other members that are desmogging or doing an engine swap. Otherwise you may consider a properly executed desmogging, there are good threads in both the 40 & 60 sections.

I still think job 1 is to figure out your current idle issues. Have you been able to read your vacuum at low rpms? If you have steady vacuum at 18 Hg or better then the issue is else where. If your vacuum drops or is erratic as you drop down to 650 rpms then the hunt is on for the leak. From what you described it sounds like a large vacuum leak.

Solve the idle issues them move on to the emission setup.
 
Ok thanks Mustard. SC has no emissions laws that Im aware of, :) , but I want to get it completely stock with everything in working order as personal preference. Im kind of a purist.

I didnt know if I was just fighting an uphill battle by trying to fix the idle problem before having all the emissions intact.
 

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