Missing Vacuum Hose = Carb Problem (1981)

Vaulter09 · 01-07-07, 12:20 AM

Hey Ya'll, First post here! I'm gonna start out with my most pressing issue at the moment.

Background: 1981 FJ40 that has a problem cutting out at higher RPM's

It has recently been brought to my attention that I am missing a vacuum hose on my carb. I didnt really notice it because that was how it was when I bought it. I always thought that this little nob looked out of place. I am having a problem figuring where it should connect too due to all the smog stuff.

I was hoping that someone with a little more experience and knowledge than me could help identify the other end.
-Matt

AATLAS1X · 01-07-07, 12:44 AM

That is the A/C idle up if I remember correctly.

Best,

Shane

Vaulter09 · 01-07-07, 12:51 AM

As strange as it sounds, the guy that pointed it out to me sucked on it which in turn revved the engine up. Dont know if that helps.

AATLAS1X · 01-07-07, 01:08 AM

Quote:

Originally Posted by Vaulter09

As strange as it sounds, the guy that pointed it out to me sucked on it which in turn revved the engine up. Dont know if that helps.

As it should, when the A/C is turned on it opens a VSV and pulls vacuum to that and raises the idle up.

Vaulter09 · 01-07-07, 01:35 AM

umm only problem with that diagnosis is that I do not have A/C in my rig...

AATLAS1X · 01-07-07, 04:01 AM

Quote:

Originally Posted by Vaulter09

umm only problem with that diagnosis is that I do not have A/C in my rig...

Then A/C was removed or the carb replaced. No matter what one it has nothing to do with a running issue that you have.

Shane

spotcruiser · 01-07-07, 08:11 AM

Cutting out may be a fuel delivery problem at higher RPM. Change your fuel filter. Clean the small screen on the input to the carb (take care not to damage it). You may also have a fuel pump that is failing.

If you are going to keep all of the smog tubing/eqpt, get one of the OEM smog manuals for your truck. They're really very good.

Stop in at the monthly meeting this Tuesday.

http://seattlecruiserheads.com/

Pin_Head · 01-07-07, 11:28 AM

It depends on what you mean by "cutting out at high RPM". If it starts missing above a certain RPM while sitting in your driveway, it is most likely an ignition problem. If you mean it cuts out when you floor it in 4th gear going up hill, then this is more like fuel starvation.

dougm's · 01-07-07, 01:49 PM

I don't know if it is relavent but my fj60 has the same carb setup I think (84). On mine that diaphram vac hose goes to a sloenoid o the side of the washer fluid reservior and then that has a vac hose that goes to side attachment on the large vac line that goes to the brake booster. Hope that makes sense. In other words that vacum comes from the intake manifold connection that goes to the brake booster and has a small L shaped side vac tube on it. Then goes to the mystery solenoid net to the waher fluid reservior then to that diaphram that has no connection to it right now. Good luck. Doug

jjhancock · 01-07-07, 02:59 PM

Cutting out at high rpm is a little vague, although it sounds strikingly familiar... My 81 did the same thing until I bypassed the EGR. Runs like a champ now.

spotcruiser · 01-07-07, 03:52 PM

Quote:

Originally Posted by jjhancock

Cutting out at high rpm is a little vague, although it sounds strikingly familiar... My 81 did the same thing until I bypassed the EGR. Runs like a champ now.

I won't say that it can't be causing a problem, but normally you won't notice the EGR at RPMs above idle. When the EGR causes a problem, the engine will be very rough at idle because the EGR valve is open and shouldn't be. The valve is normally open above idle when the engine is warmed up.

Vaulter09 · 01-07-07, 08:20 PM

Thanks DougM, I'm gonna take that direction and see if I can find what you are refering too. If not...then its back to the drawing board.

Is there a resource like a diagram that will show where the hoses should run?

spotcruiser · 01-07-07, 08:29 PM

Quote:

Originally Posted by Vaulter09

Is there a resource like a diagram that will show where the hoses should run?

The original diagram under the hood (if still there) or an OEM smog manual (still available and very detailed).

Vaulter09 · 04-16-07, 01:20 AM

Soo it took something unfortunate for me to figure out the problem. The gas pump was the cause of all my issues, not the carb. Ends up the pump was pushing .5 lbs of pressure instead of the normal 3 lbs. With that replaced, she is back running strong!