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Questions and Answers

Toyota Landcruiser Milage Concerns

Q. Hi Vincent. Let me say first how much your articles have helped me in my attempt to understand and work on my 1987 Toyota Landcruiser. I've gotten some real seat-of-the-pants results by following your instructions on troubleshooting such problems as a faulty coil. This FJ60 truck has a 4.2 liter carbureted engine with a 4-speed manual transmission and 159,000 miles.

Toyota Landcruiser Milage Concerns

The previous owner replaced the exhaust manifold with a stainless steel Tri-Y header. But it looks like he found a way to keep almost all of the emission controls intact, including some custom exhaust work connecting the EGR. The only thing that no longer works is the original heat riser, which is gone, and the hot air tube that goes into the air intake assembly and furnishes hot air before the engine warms up.

When I purchased the truck, it got 10 mpg. It went to 11 or 12 mpg after I paid for a tune-up. Since then, I've done a number of things in an attempt to reach the 14 to 16 mpg range, which is what several vintage Landcruiser specialists tell me I should be able to get from a well-tuned stock vehicle. The original EPA rating is 11-17 mpg.

The work includes, not necessarily in order of when I did the job:

  1. A new coil, after the old one failed the specs during an ohmmeter test.
  2. A new alternator, after the old one failed to charge the battery, and a new battery.
  3. New spark plugs and plug wires, the old wires were dated 1992.
  4. New distributor cap and rotor, this model has electronic ignition.
  5. New fuel filter.
  6. New K&N air filter.
  7. All new vacuum hoses, after finding numerous breaks in the old ones, including a new PCV grommet.
  8. Rebuilt carburetor tuned for mixed street and highway driving by a Landcruiser carburetor specialist.
  9. New manifold gasket and milling to the intake manifold and header after developing a header leak.
  10. A fluid heat riser kit installed at the same time as the header work.
  11. Synthetic gear oil for the transmission, differential and transfer case.

The truck has far more power as a result of this work, with much better acceleration and responsiveness across the board, from a dead stop to highway speeds. But my fuel economy has stalled at about 13 mpg in mixed driving, with slightly better figures on the highway alone.

Here are some of the other problems/symptoms that remain:

  1. The engine idles high after warming up, doing 1,000 to 1,100 rpm instead of 650. But when I turn it off, go into a store for 15 or 20 minutes or so, then return, it will run at 650 rpm for several minutes before slowly shooting back up again.

  2. The gas tank exhibited a noticeably high vacuum whenever I pulled off the gas cap to refuel. This has diminished from a pronounced whoosh to a smaller hiss since I replaced the vacuum hoses. A previous test of the evaporative emissions control system suggested that I might have some problems there, possibly with a stuck vent in the gas cap and with a valve between the charcoal canister and the carburetor, but it does seem better with the new hoses.

  3. My No. 1 and No. 6 spark plugs look great, with a slight tan haze on the electrodes. But Nos. 2-5 have a relatively thick coating of carburetor on powder indicating that they are running rich. Thankfully, they are not oily at all. The firing order could offer a clue here: 1 and 6 are followed by the others, giving me a good, bad, bad, good, bad, bad cycle.

  4. I discovered a broken port in the BVSV unit that links to, I think, the distributor vacuum advance. It may also have some impact on the EGR valve which does move when I apply vacuum to the diaphragm as a test. Whoever broke it attempted a repair with what looks like a ball-point pen cartridge, but I'd be surprised if it produces the kind of vacuum that's needed.

  5. My catalytic converter appears to be the original model. It is rusted in spots, as is the O2 sensor. I tried giving it a good bang with my palm to see if I could produce a rattle. But it's still so solidly mounted that it didn't move, and it didn't rattle. When I replaced the exhaust pipe and muffler recently, however, I discovered that they were ¼-inch smaller in diameter than they should have been. So I sized back up to 2 inches expecting to see some change in performance. But I was disappointed. No difference at all despite the removal of that restriction.

  6. Even after replacing the alternator, my voltmeter continues to dip below 12 volts occasionally when I have the windshield wiper, turn signal, lights and heater on. But since replacing the coil, it no longer plunges so low that the engine stalls or threatens to stall.

Other changes include swapping out the knobby, off-road tires for a more fuel-economy friendly set of highway Yokohamas. But I didn't get any improvement in mpg here, though my ride and handling are much, much better.

Right now, I'm reluctant to make any adjustments to a carburetor that was rebuilt by an expert, tested on a well-tuned Landcruiser of the same vintage and then retested with an engine analyzer. I've always heard that you should get everything else right first, then dial in the idle speed and mixture settings if you need to.

I am, however, trying to figure out how to adjust the ignition timing without messing around with the carburetor first. I'm thinking of running the truck up to temperature, then letting it sit until it cools enough to get back down into the proper rpm range. I'm hoping it will hold until I can make what should be a relatively quick adjustment.

I have a valve adjustment on the list, too.That should help in some fashion. But what I'm really concerned about are the emission controls and, possibly, the catalytic converter. I've got a Toyota EC troubleshooting manual on order. I just got a MityVac. And that's where I'll be checking and hoping to find some fixable problems for the next couple of weekends.

There's no way, of course, I can change the basic fact that this is a heavy, not very aerodynamic, non-fuel injected truck. And I'm not expecting miracles. But every little gain in mpg helps in a case like this. So whatever guidance you can provide would be very much appreciated.

Mark

A. There was a recall on the fuel tanks in the 1980 to 1990 Toyota Landcruisers with the 2F and 3F-E engines due to high pressure buildup in the fuel tanks. If the recall was done, there should be a label affixed to the firewall next to the brake booster. If not it either fell off or the recall wasn't done. I would check into it. The new Fuel Tank is part number 04001-03160 and the Fuel Tank Service Kit is part number 04001-04160.

Setting the timing is easy.

  1. Connect a timing light to the engine.
  2. Start the engine and run it at idle. Idle should be no more than 650 rpm, adjust as necessary.
  3. Slowly turn the distributor until the timing ball and the pointer, when illuminated by the timing light, line up which indicates 7° BTDC.
  4. Tighten the distributor lock down bolt and ensure that timing is still within spec.

Also, make sure the hoses to the vacuum advance and vacuum retard are not crossed.

Toyota Landcruiser Milage Concerns

I would also recommend using NGK spark plug BPR4EY (Stock number 2128) gapped to 0.032". You'll find that they do make a big difference.

Everything else, replacing the BVSV, setting the ignition timing, etc...should be done before going to the carburetor. That is the last thing to get adjusted.

From the carbon buildup on the middle four spark plugs I would say the carburetor is running a little too rich. Lacking a proper four gas emissions tester, I would turn the mixture screw in a ¼ or ½ turn in.

The catalytic converter can be test with a vacuum gauge. See Engine Testing With A Vacuum Gauge

When all is said and done you may have to resign yourself to the fact that 13 mpg is the best you're going to get out of it. You may be able to get another 1 or 2 mpg by changing your driving habits.

Additional Information provided courtesy of AllDATA

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