FJ60 vapor lock or over heating??

[joey.w]

So...The wife and I drove up to Freeport ME from Boston yesterday in my 86 60. The trip up was hot and bumper to bumper slow moving traffic -truck ran great!! On the way back some where round
the NH border I noticed a slight loss of power going up hills this was followed by mild to sever bucking like no gas was getting into the carb for a few seconds if I stepped on the throttle to hard ? Ths went on for over an hour causing me to drive in the breakdown lane at 30mph. It did this once in May driving back from Uxbridge on the Pike. I let the truck sit for a 1/2 hr in Bedford NH and the rest of the ride was fine? Any ideas on what this is and how I can fix the problem ???

 

[tucson_sailors]

Cheap vapor lock check

The vapor canister in the engine compartment has two hoses that can be swapped temporarily (or forever depending on your state emissions rules) that will vent the pressure from the tank directly out, rather than through the vapor canister.

I've been having the same issues, and I've tried all of the easy things I could find on the board - change fuel filter, swap the vapor canister hoses, bypass the EGR valve, and its gotten better, but just this morning I felt the "buck" feeling in normal driving, in 80 degree weather. So I'm still working on it, but the changes above made a BIG difference in my experience.

Good luck, and hopefully some of the cruiser gods will reply, rather than "search the threads".

Glenn in Tucson

 

[joey.w]

Thanks Glenn !!

 

[tclark]

I had the same issues, tried the same fixes--ended up installing a new carb(Trollhole) and it nows runs like a top.

 

[tucson_sailors]

Another datum

Its raining buckets and in the 70's here, and I had it happen again on the way home. Noticed that it seems to be happening when the gas tank is 1/2 full or less. Pulled into a gas station and brought the tank to 7/8's, and odd behavior stopped.

No conclusions yet - its a thought, not defnitive one way or the other. Could also have been stopping the vehicle and restarting it. Otherwise I'm going to think vacuum leak - gotta search for the dizzy vacuum issues, see if there is anything on those threads that is similar.

Glenn in Tucson

 

[High Desert]

Its raining buckets and in the 70's here, and I had it happen again on the way home. Noticed that it seems to be happening when the gas tank is 1/2 full or less. Pulled into a gas station and brought the tank to 7/8's, and odd behavior stopped.

No conclusions yet - its a thought, not defnitive one way or the other. Could also have been stopping the vehicle and restarting it. Otherwise I'm going to think vacuum leak - gotta search for the dizzy vacuum issues, see if there is anything on those threads that is similar.

Glenn in Tucson

This sounds like a fuel pump going out.

 

[tucson_sailors]

Fuel pump

Hmm, I had replaced that back in 2008, but it wasn't an OEM pump. I'll see about ordering a good one and see if that makes any difference. Seems like the classic FJ60 stutter though, and don't want to just replace parts unless I'm pretty sure. Any idea of how I can test the fuel pump for an intermittent issue?

Glenn

 

[dorcom]

Happened to me years ago a few times and only up hill (I live in San Francisco)
Cause: When the venting system creates a to large vacuum in the tank.
Why: Hmmm?
Quick Solution: Open your filler tank cap and you 'll hear a brief air sucking in sound.
thereafter problem is gone.

 

[tucson_sailors]

Fuel vent

Happened to me years ago a few times and only up hill (I live in San Francisco)
Cause: When the venting system creates a to large vacuum in the tank.
Why: Hmmm?
Quick Solution: Open your filler tank cap and you 'll hear a brief air sucking in sound.
thereafter problem is gone.

Thought it might have been the opposite - fuel tank pressure due to heat, so I swapped the hoses on the charcoal canister to provide venting on the tank. I did check to see if I had a pressure condition when I stopped at the gas station, and didn't hear a whoosh for either pressure build up or vacuum.

Glenn

 

[Benjaman]

So...The wife and I drove up to Freeport ME from Boston yesterday in my 86 60. The trip up was hot and bumper to bumper slow moving traffic -truck ran great!! On the way back some where round
the NH border I noticed a slight loss of power going up hills this was followed by mild to sever bucking like no gas was getting into the carb for a few seconds if I stepped on the throttle to hard ? Ths went on for over an hour causing me to drive in the breakdown lane at 30mph. It did this once in May driving back from Uxbridge on the Pike. I let the truck sit for a 1/2 hr in Bedford NH and the rest of the ride was fine? Any ideas on what this is and how I can fix the problem ???

Next time it happens, hook up a timing light and see if the mark is jumping around. If it is, Remove the rust from the advance weights and see if that helps.

 

[dorcom]

Glenn

The venting system sucks the gasy air out of the tank (EPA)
When the vacuum is to high the (old fashioned) fuel pump will no longer be able
to pump enough fuel since the vacuum wants to pull back the gas.
Try (careful!) drive with tank lid not really closed. You'll see the problem will not
occur!

Rob

 

[joey.w]

Holy reply !! my fuel pump is only a few years old- In ten years I have replaced it 3 times-this one was brand new. I'll try the cap not quite on thing! But the power loss followed by the bucking only happens going up hill with increased load and only after 2 or three hrs of driving in hot weather?

 

[High Desert]

Last time I read up on it...you were suppose to here the gas tank go Whoosh when you took off the cap.

do you smell gas under the hood?
the ethanol literally melted the soft rubber hoses off of my charcoal canister after a year of using it (Oregon has 10% ethanol in all fuel(yes you can buy it with out ethanol but it's $.60 up more per gal)

I smelled gas and it ran crappy, I replaced the hoses with fuel line. My rig is stock except I have by-passed the egr due to surging at all speeds at all times (4 years ago)

 

[lcolon]

You might also check the wire for the fuel cutoff solenoid... I was having similar issues, and it turned out that this wire was cracked. I replaced it and have not have a problem since.

 

[tucson_sailors]

Probable fix?

I swapped out the emissions control computer this weekend on advice from another mudder, and have not noticed any further "bucking/stumbling" issues. Since one of the things that it controls is the idle cutoff, I'm wondering if the idle solenoid was getting spurious signals from the emissions box.

Here is another thread on this with the part # - I got mine from a 86 60 parts rig, $50.00 local. Dunno if thats a good price or not, but I've had 2 days of driving without the stutter, and feel thats worth the price.

https://forum.ih8mud.com/60-series-...xed-my-stumbling-hesitation-but-now-no-c.html

Glenn in Tucson

 

[Sacto60]

Happened to me in the middle of the AZ desert N of the grand canyon. Felt like I was on Mars. Hot as hell, long steep grades and truck was loaded up w/ gear. And then the same symptoms. Awful bucking and loss of power. Shop in Page, UT said it was vapor lock and changed out the fuel filter. Haven't had problem since.

 

[yoshi]

it looks like the carburator need service also check the gas filter

 

[TheJackRabbit]

All that is way to complicated. Do what I do. Take the cap off the tank filler pipe and hold a match to see if anything is coming out. Better yet, have Curly do it.

-Moe Howard

 

[tucson_sailors]

Fuel filter

Had actually replaced the fuel filter 2x before I changed the emissions computer. Helped for a while, but always returned. Old filters were not clogged. Had also performed the "poor mans vented cap" by swapping the lines to the purge charcoal canister in the engine bay, so I wouldn't have too much pressure in the tank. Issue still recurred after these intial steps.

I had also replaced the PCV valve and gasket in the back of the passenger side of the engine the same time I replaced the computer, so my admittedly shotgun approach could have found something else. I also replaced the dizzy vacuum line as I thought it might have had some cracking issues. I had blocked the EGR without any improvement, and replaced a large number of the vacuum hoses in and around the carb also without success earlier. The next step was the emissions box/PCV/dizzy line. BTW, the dizzy line is 5mm, the other vacuum lines at 3.5mm. VW/Audi/Mercedes shops should have this if you can't find a shop that specializes in Asian.

Been driving all over town and no recurrence of the stumbling issue so far - will keep posted. 100+ temps during the day, so if it was vapor lock would expect it to recur pretty quickly. And I do happen to have a working carb fan.

Glenn in Tucson

 

[Elbert]

the "carb fan" is suppose to help address vapor lock issues. You may need to make sure its working.