Stalling issues (fuel line mixup?)

[ducktapeguy]

Does anyone have a diagram of how the lines are connected to the carburator?
Just picked up a 75 FJ40 and I'm having some stalling issues. It's got a stock 2F engine and 2bbl carb. The carb looks like this one

http://www.sor.com/sor/cat042-carbp...retion&descriptionpg.ctx=Page 042 Carburetion

At lower speeds, the engine runs fine, but as soon as I hit 3rd or 4th gear, it seems as if the engine is starving for fuel, to the point of stalling. If I let off the gas and shift into neutral, it'll pick up again, but as soon as I try and speed up, it starts stalling. I suspect maybe the fuel lines are connected wrong? If you look at the SECOND diagram on this page

http://www.sor.com/sor/cat042.tam?xax=13523&page.ctx=cat042.tam

The fuel pump is connected to part #144 & #145, which looks like a banjo bolt, and the return line is connected to fitting #143. Is this how it's supposed to be connected? I doesn't look like the small opening on the bolt would be capable of supplying enough fuel to the carb during operation.

A littlre more background info on the vehicle. The engine and carb has been rebuilt by the PO fairly recently, so I dont' suspect a problem there. The fuel pump pressure is within spec (3 - 5 lbs). The egr valve was plugged up and the piping cut, I don't know if this contributes to the problem or not? No visible vacuum leaks that I can see. One thing i notice, if you rev the engine at high rpms while looking at the fuel level in the bowl, you can see the fuel level start to drop in both the bowl and the fuel filter. The PO said if you clamp the return line to the gas tank, then the problem goes away, but i haven't tried it. Also, there was a 22 gallon auxillary tank installed and removed at some point, so there seem to be some extraneous fuel lines and stuff. Thanks for any advice you can give.

 

[Pighead]

Sounds suspiciously like a clogged fuel filter.

 

[ducktapeguy]

Fuel filter is new, so I didn't really suspect it. Also, the gas tank is relatively new, with new sending unit, so if there's a pre-filter in there somewhere, it should be ok. One other possibility I was thinking of was a clogged vent tube from the gas tank? I'm not too familiar with the FJ40's yet, but don't most fuel systems have a vent to prevent a vacuum in the tank? I have two different FJ40 manuals, but neither have the fuel system layout diagrams that I need.

 

[largenfirm]

Fuel filter is new, so I didn't really suspect it. Also, the gas tank is relatively new, with new sending unit, so if there's a pre-filter in there somewhere, it should be ok. One other possibility I was thinking of was a clogged vent tube from the gas tank? I'm not too familiar with the FJ40's yet, but don't most fuel systems have a vent to prevent a vacuum in the tank? I have two different FJ40 manuals, but neither have the fuel system layout diagrams that I need.

Run it without the gas cap to diagnose clogged vent.

Kirk

Sounds like a weak fuel pump, to me...

 

[Pighead]

The fuel return line, if working properly, will "pressurize" the gas tank. I often get the little outward whoosh when I uncap to refill.
If you can see the fuel level (in the porthole) going low as the revs increase, I think you have delivery issues. Check the hardlines for rust and crud inside. Some guys blow air through those lines to clear them out.
It's pretty hard to mix up the delivery and return lines, sounds like you have that part right. Do you have one of those clear fuel filters with the replaceable elements? I find mine useful when eyeballing fuel flow.

 

[ducktapeguy]

Thanks for all the responses, I didn't expect to get any before tonight. I'll check it without the gas cap to see if it's working.

Sounds like a weak fuel pump, to me...

Is it possible for the fuel pump to be weak and still give a decent reading? Is there any other way to test under some sort of load?

The fuel return line, if working properly, will "pressurize" the gas tank. I often get the little outward whoosh when I uncap to refill.
If you can see the fuel level (in the porthole) going low as the revs increase, I think you have delivery issues. Check the hardlines for rust and crud inside. Some guys blow air through those lines to clear them out.
It's pretty hard to mix up the delivery and return lines, sounds like you have that part right. Do you have one of those clear fuel filters with the replaceable elements? I find mine useful when eyeballing fuel flow.

I'll check the lines, and probably disonnect the fuel line to see how much fuel flow I'm getting. The fuel and delivery lines are connected with short lenghts of rubber hoses to the nipple fittings, so I guess in my case it is fairly easy to get those two mixed up. Is the delivery line supposed to go through the banjo bolt, or should it go through the larger fitting? I've never seen a carb like that, but this is my first time working on a toyota.

On a related note, does anyone have a picture of their carb setup without the air cleaner attached? I've been trying to find a clear picture of a stock setup, but most of them don't show what I'm looking for. Right now I'm having trouble putting the air filter housing back on, the fuel delivery hose is sticking out too far and interfering with the inlet. It's the straight connection that is causing the problem (part#143 in the above link), it looks like the PO put an adapter in there that sticks out farther than normal. Should there be an 90 degree bend in there to clear the housing?

 

[Pighead]

That's never a good sign...I want to know more.
Since "The engine and carb has been rebuilt by the PO fairly recently, so I dont' suspect a problem there. "...how long have you had this rig? Has it ever run right?
And the gas tank is new? Plastic tank or steel?
I think there's a spec in FSM for how many liters a fuel pump should pump in a given time.
Have you ever had that air cleaner on there before?

The fuel and delivery lines are connected with short lenghts of rubber hoses to the nipple fittings,

 

[gladly]

so you have fuel to banjo bolt, return from straight fitting, right?

if so, I think that you've got it backwards, when I was installing my aisin I hooked it up:

banjo bolt to return line, fuel to front of carb.

(as a result of my inqiries online, and peeking under the hood of a few local cruisers) it seemed backwards to me, too, but fuel delivery hasn't been one of my problems since.
picture here: http://tinypic.com/view/?pic=jka77q I already had it posted like this from another post, so disregard the circled bit, (unless you're wondering where to hook up your power valve
something that I did which helped me figure out some other things is to use a clear hose for the return line, something heat+fuel resistant, but see through. then it's pretty clear whether you're getting enough fuel, even if you just do this temporarily until you get it running smoothly

 

[Pin_Head]

Banjo is the return line. The front facing fitting is the inlet.

 

[Poser]

... the gas tank is relatively new....

To the truck(as in USED), or NEW as in a NEW OEM steel tank?


Did you do the work or the PO?


I have seen a few trucks act this way when there is a restriction in the tank to the fuel pickup...starving the pump....


I removed one tank that sounded like a box of legos it had so much crap in it...




Good luck!


-Steve

 

[ducktapeguy]

FIXED! Thanks for all the help. The problem was a fuel line mixup. The delivery line was going to the banjo bolt, and not giving enough fuel at the higher rpms. After a quick switch, everything seems to be working great, just took it for a drive and it drives smooth (as smooth as a FJ40 can get)

Just to answer a few of the questions, the tank is an relatively new aftermarket polyethylene tank. I have the original steel tank, also a 22 gallon auxillary tank (not installed). I think the tank was replaced because of a few pinhole leaks, I might weld it up and coat the inside or I might just junk it.

Also, I haven't done any work on the cruiser yet, this is actually the very first thing I've looked at. I just picked it up a couple days ago. Right now I'm just going over everything, making a list of what I need to do before i jump in and tear everything apart. The PO did most of the work himself, I think he did a pretty good job on most things, but he was fixing the mistakes of the PO before him, so there are a few things that need replacing and rework. Still need to switch out the fitting on the carb to allow the air cleaner to fit back on.

I'll be asking a lot more questions in the future once I get started on the restoration. Right now I'm shopping different companies pricing out all the parts I'm going to need.

 

[projektdotnet]

caongrats....welcome to MUD