On a road trip and disabled, need some vacuum advance help! (1 Viewer)

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Aug 9, 2015
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Location
San Diego, CA
So I just had my '87 FJ60 carb rebuilt and all vac lines and some pressurized lines replaced by Dependable Carburetor. Was running better than ever, could actually cruise at 75+. Accidentally shut the car off on the freeway going to LA, and now there is a huge bucking hesitation at around 2000 RPM when you're trying to take off, and it's lost all its power over 3K, if I can get it over 3K. It whistles when the power bog happens and maybe above. Can't even accelerate downhill over 60mph. I found 1 hose that had popped off the Denso unit by the carb labeled R P Q. Low end big is a little better now, but still quits acccelerating at 3K rpm. I'm a long freeway ride from home here. Looking for common advance vac lines etc.

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Fuel starvation?
Try an okie rebuild on the carburetor, could have a particle in a passage.
 
I had a similar whistling sound a long time ago, above 2500 rpm & caused hesitation. Turned out I had a bad egr valve. Replaced it with a used one and it went away. Do you have a vacuum routing diagram? If not, i'd get one and check, re-check, then check again every fn vacuum line on the truck. Sorry, just my only $0.02.
 
Vacuum hoses shouldn't just pop off, unless the wrong size was used. There are a few lines that vent to atmosphere. Make sure you double check that.they look like they should attach to a port somewhere, but don't.

A few more pics around the engine bay would help us spot any potential problems.
 
sounds like a vacuum leak, check base of carb...and all vacuum connections
 
I had a similar whistling sound a long time ago, above 2500 rpm & caused hesitation. Turned out I had a bad egr valve. Replaced it with a used one and it went away. Do you have a vacuum routing diagram? If not, i'd get one and check, re-check, then check again every fn vacuum line on the truck. Sorry, just my only $0.02.

If it is the egr you might free it up by hitting it with a hammer several times with engine running at idle to get the carbon loose inside it. Immediately afterward take the cover off your air cleaner and see if you have bits of carbon int the bottom of the air cleaner around the air filter.

When my egr acted up ...the motor wouldn't start or would stall at idle. I had to to this on a few occasions until my problem went away.
 
I'm thinking it's the EGR as well. The latest be that had come off its pipe is the one I'm pointing to with pliers in the pic. At lower rpm it was blowing out air, then after a certain amount of revs it became a vacuum. It feeds the bottom of the denso unit in the pic. I'm thinking I fixed the wayward hose, but now that valve is funky...?
 
That part in your pic is the EGR vacuum modulator. You really want the 2F Emissions Manual to troubleshoot your EGR. Look for any post by Spike Strip or gregnash and a link to a PDF will be in their sig line.Attached are a couple of highlights from that awful but indispensable publication.

You can try and disable the EGR for the time being - if it solves your problem it will tell you whether it's the culprit, and unless it's stuck open disabling it will make your truck driveable.

Pull the line that runs from the EGR vacuum modulator (port Q in your pic) down to the top of the EGR valve, and plug it with a screw (unless you've got a golf tee lying around). Then, swap the two vac lines that run to the distributor vacuum advance. You should end up with the one with the VTV (valve) attached to the outer diaphragm (further from the dist).

Listen for pinging under load and if you've got room in your tank run premium until you sort this out. Some people run with their EGR bypassed for years and love it, others only last a few minutes. It can result in a very lean condition. Results vary based on what's going on with the EGR. Regardless, you'll have to get it working right before your next CA smog test.

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Thanks so much for the in depth answer. I got those FSM downloads earlier, and I'll try this swap tonight. Do I pull and plug the EGR modulator end of the hose or pull and plug the EGR valve end of that hose?

Whole thing just got rebuilt and re-hosed a couple days before the trip. Some hoses are loose a bit and I'm sure there's one popped off in there somewhere.
 
I have left the line attached to the modulator Q port on the one side, and then plugged the open end. Then I added a short hose to the open nipple on top of the EGR valve, and plugged it, too. That may be unnecessary, since you're really just trying to prevent the modulator from applying vac to the valve.

There's also the VSV for EGR with three vac lines - I have not touched that though some cap those lines too.

From the picture you posted, it looks like the vac lines are new. So there is a very good chance that your problem is just a loose or misrouted hose and not a failing smog component. That's the hope, at least.

Search "EGR" if you haven't already and you'll find a lot of threads about troubleshooting and/or bypassing the EGR. Different approaches and results for different people but it's pretty simple to try.
 
Yes they are new. As mention in the post I had the carb fully rebuilt a couple days before and all new vac lines put on. It ran better than ever till the engine was shut off at top speed. The issue was immediately there upon restart. I'm looking for which other fitting popped off besides the egr modulator connection to the egr valve that I found and reattached. I'm sure it's as easy as reconnecting 1 line. Not sure what else carried high air pressure like that one does.
 
As a roadside fix, if your EGR valve itself is stuck open, remove it and tap the valve shut with a hammer. Then, reinstall the valve, and remove and plug the actuating line. This way, the EGR will be closed, not leak, and stay closed, until you effect a proper repair.
 
Update- carb shop tells me that even though it happened all at once when the ignition was shut off at speed, that it's a clogged catalytic to blame. Same cat was there 4 days ago when they rebuilt and tuned the carb....
 

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