Newbie- FJ40 stalls only when I floor it

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This is my first post but I've been lurking around here for a half year or so and can't seem to find an answer to a question. My 77 FJ40 w/ 2F engine stalls only when I floor it- hot or cold, and then only when under power. With the clutch in, the engine revs just fine. I have put in a new fuel filter and pump, timed the engine, new points, plugs, etc. It ran fine for the first six months I had the truck, then one day this started. Any ideas??? Thanks!
 
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tk - I'm a newb as well, but had some idle problems recently that brought out the gurus to help me resolve the issue. The first thing Jim will want to see is pics of the carb and dizzy. Everyone will be interested in how the vac lines are connected, check the year of the carb (I have a 78 desmog with a 76 carb), and note anything that may be connected wrong as far as linkages.

I would also like to see some pics of your truck if you wouldn't mind sharing.

Welcome to mud!
 

John McVicker

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So it revs fine in the driveway ? even up to 2500-3000rpms ? You only have a problem 'under load' as in driving at say 30-40 mph & then stalls when floored trying to increase speed ? How about that same situtation & you ease up to speed. No problems ?

What carb do you have ? Just trying to get a clearer understanding of the problem. Right now I would look at the carb for soultions.

John
 
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Wow- rapid replies!

So it revs fine in the driveway ? even up to 2500-3000rpms ? Yes, it does fine and idles perfectly!

You only have a problem 'under load' as in driving at say 30-40 mph & then stalls when floored trying to increase speed ? Exactly

How about that same situtation & you ease up to speed. No problems ? Right again!!! John- You must have ESP

I have a stock carb, I'm not sure what year- and I don't know how to find out!

Bama- Will try to post pics later
 

John McVicker

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Also check to ensure you have a solid ground where your igniter is bolted. Points or pointles dist ? And do you have a condenser inside your dist. ?

John
 
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It has no igniter. The "points" are the Mel's conversion avaialble from JT Outfitters so no condenser.
 
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Make sure the accelerator pump in the carb is working. Remove the air cleaner, look down in the carb bowl and open the throttle. You should see a stream of gas squirt down the bowl.
 
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I think you may have hit on the problem. The pump plunger hardly even moves when I depress the accelerator. There is no obvious gas stream either. It just so happens that I have a carb rebuild kit on hand and will try replacing the pump plunger assembly. I hope I don't have to take the whole carb off though. Do you know if I have to?

TK Hughes
 

Pighead

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Before you take the top off to replace the plunger, examine the linkage very carefully. Perhaps if you open and close the throttle (engine OFF) while watching all the linkage, you can find if it is hung up somewhere, or you lost one of those little clips...I'd think it's sorta rare to have an accel pump suddenly fail internally. And if you say the plunger is hardly moving, I'd have to guess linkage first. Pictures might help here...



I think you may have hit on the problem. The pump plunger hardly even moves when I depress the accelerator. There is no obvious gas stream either. It just so happens that I have a carb rebuild kit on hand and will try replacing the pump plunger assembly. I hope I don't have to take the whole carb off though. Do you know if I have to?

TK Hughes
 

John McVicker

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I think you may have hit on the problem. The pump plunger hardly even moves when I depress the accelerator. There is no obvious gas stream either. It just so happens that I have a carb rebuild kit on hand and will try replacing the pump plunger assembly. I hope I don't have to take the whole carb off though. Do you know if I have to?

TK Hughes

TK

Don't be afraid to take off your carb. 4 nuts & some linkage & it's off. Then you can spray clean & blow out the lines pretty darn good. Putting it on/off is pretty self intitutaive. You'll be able to figure it out.

John
 

fjwagon

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Next time it dies check the fuel level on the site glass located in front of carb. If you do carb rebuild take lots of pics. Good Luck.

I think you may have hit on the problem. The pump plunger hardly even moves when I depress the accelerator. There is no obvious gas stream either. It just so happens that I have a carb rebuild kit on hand and will try replacing the pump plunger assembly. I hope I don't have to take the whole carb off though. Do you know if I have to?

TK Hughes
 
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tk - Do you have a mechanical fuel pump or has it been converted to electric? If it is the latter, you may need to make sure it is pumping and you have gas to the carb when checking for the gas stream. Just a thought.
 
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Okay- I removed the carb top (the old pump plumger was barely moving) and replaced the plunger, needle valve, cleaned everything up, and put it back together (you can just remove the top to replace the plunger!). Started right up, test drove and nothing much has changed. Still hesitates (stalls) when I hard accelerate, and a new wrinkle- seems to have less power in 4th gear going up hill. One other thing I didn't add is that we are at 9000' altitude, but, when I first got the truck up here it worked ok! Could the thing be running too lean? Thanks for all of your comments.

TK Hughes
 
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Okay- I removed the carb top (the old pump plumger was barely moving) and replaced the plunger, needle valve, cleaned everything up, and put it back together (you can just remove the top to replace the plunger!). Started right up, test drove and nothing much has changed. Still hesitates (stalls) when I hard accelerate, and a new wrinkle- seems to have less power in 4th gear going up hill. One other thing I didn't add is that we are at 9000' altitude, but, when I first got the truck up here it worked ok! Could the thing be running too lean? Thanks for all of your comments.

TK Hughes
Unless you have changed the jets and put in ones that are too small, it will not be too lean - you have less air, so it would be too rich. If it was fine before, this is not your problem. If the new plunger is still hardly moving, then Pighead is probably right - check your linkages.
 

John McVicker

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Linkages look fine visually. Now, whether they are linked correctly???

TK

Easy enough to check. Have a helper sit behind the wheel & floor the gas feed. Then you move the linkage under the hood by hand & see if you get additional movement. You should not.

How about the stream of gas now after replacing the acc. pump. Strong or is it still weak ? You have got to have a strong visiable stream. If you don't have a strong stream, that's the 1st thing you must fix. And it may be your solution.

John
 
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I should have checked the gas stream after replacing the plunger (suggested a couple of times by John and sepr2). Now that I have, after the fact, when I push on the accelerator, there is still no visible stream............duh. I am not sure what the next step is and what to check. You guys have a lot of patience and I really appreciate the advice for a rookie !

TK Hughes
 

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