Lose of power on highway

[HossRig]

Hello,

Recently I have purchased a 1991 land cruiser (3fe). I was driving on my trip last weekend about 500 miles. At about 200 miles in on the highway I felt like I lost power and the car started slowing down by itself. I pulled over and checked the coolant it was somewhat low so I topped it off and let the car sit for about an hour. I got back on the road and after about another hour I had the same thing and pulled over to let it cool down. I then finally made it home after going about 50 the rest of the way.

Since being back i haven't had the problem driving around the city but I haven't driven for more than about 30 mins. I am thinking I might have a bad radiator or thermostat and its causing my car to overheat on the highway. Has anyone had something similar happen and what was the problem?

 

[Malleus]

I've driven a lot of Land Cruisers over the years, but I've never heard of one getting tired because it was hot.

A couple of questions:
1. You opened a hot radiator and filled it? How did that work out?
2. You think your engine overheated, but you didnt' say anythign abotu the temperature gauge. Did you see a high engine temperature, or do you have a reason to suspect the gauge doesn't work?

As to the engine power failure, I'd look at a fuel related problem first. However, we're going to need a lot more information about the truck and its history to get anywhere fast.

 

[HossRig]

I refilled the coolant after letting it cool down. The temperature gauge was a little over half way at the time of the problem. I ran the heat on full blast after the second time and didnt encounter the problem for the rest of the trip.

 

[Malleus]

Gotcha. I'd be inclined to look at the fuel system, although it may be counterintuitive.

The fuel system consists of several engine coolant related relays:
» a water temperature switch (for EFI) (89428-60020) which is NLA
» a water temperature sensor (for EFI) (89422-20010) which is available

either or both of which could be causing your problem, which, again, sounds like a fuel loss problem, based on what you've described.

There is also a circuit opening relay (for EFI) (85910-30050), which controls whether the fuel pump gets power or not, which may also be a source of concern.

You can test all these components off the truck, to determine whether they are functioning properly or not. Details are in the service manual. If you don't have one, check out the Resources forum, 80 series section.

I can't be definitive, without more information, but this is where I would start, if it was me.

May some of the 3FE sages (@jonheld) can chime in.

 

[jonheld]

Hello,

Recently I have purchased a 1991 land cruiser (3fe). I was driving on my trip last weekend about 500 miles. At about 200 miles in on the highway I felt like I lost power and the car started slowing down by itself. I pulled over and checked the coolant it was somewhat low so I topped it off and let the car sit for about an hour. I got back on the road and after about another hour I had the same thing and pulled over to let it cool down. I then finally made it home after going about 50 the rest of the way.

Since being back i haven't had the problem driving around the city but I haven't driven for more than about 30 mins. I am thinking I might have a bad radiator or thermostat and its causing my car to overheat on the highway. Has anyone had something similar happen and what was the problem?

There is a pre-filter on the fuel pump that should be changed every 100K miles or so. When it gets clogged, the truck will behave normally for the first hour or so of highway driving.
As the fuel in the tank warms, the pre-filter will start to collapse on itself under load, blocking the fuel intake to the pump. Shutting down the engine allows the filter to regain its shape and fuel starts flowing again...until it collapses when the motor is under load.

The fuel pump can be accessed through the removable panel on the floor under the second row seats. You'll want to spend some time cleaning the top of the tank to prevent the 35 years of crap from falling in.
The picture below shows most of the parts that you will need along with a side by side of the old pre-filter next to a new one.
I would add a pair of 90430-12026 (metal gaskets for the fuel line banjo bolt).
Since this truck is 35 years old, I would replace all soft parts.
The small metal clip on the left is what holds the filter in place as you will destroy the old one taking it off.

This is an exploded view of the fuel pump assembly.

 

[Malleus]

Definitely get that clip. If you don't, it'll be the "golden screw" that holds up the repair.

 

[GORDA91]

There is a pre-filter on the fuel pump that should be changed every 100K miles or so. When it gets clogged, the truck will behave normally for the first hour or so of highway driving.
As the fuel in the tank warms, the pre-filter will start to collapse on itself under load, blocking the fuel intake to the pump. Shutting down the engine allows the filter to regain its shape and fuel starts flowing again...until it collapses when the motor is under load.

The fuel pump can be accessed through the removable panel on the floor under the second row seats. You'll want to spend some time cleaning the top of the tank to prevent the 35 years of crap from falling in.
The picture below shows most of the parts that you will need along with a side by side of the old pre-filter next to a new one.
I would add a pair of 90430-12026 (metal gaskets for the fuel line banjo bolt).
Since this truck is 35 years old, I would replace all soft parts.
The small metal clip on the left is what holds the filter in place as you will destroy the old one taking it off.

View attachment 4089279

This is an exploded view of the fuel pump assembly.

View attachment 4089285

Not a difficult job. Did this on my 91 about 1.5. yrs ago.

 

[GORDA91]

As JH said, the top of the tank will be really dirty

 

[steve578]

I purchased a 1991 last week. I started having similar symptoms and plan to change out the prefilter. It appears that 23217-11010 has been discontinued. Any alternative part number suggestions before buying a random aftermarket pre-filter?

RockAuto's aftermarket offering.

More Information for AUTOBEST F239S

***Edit*** After pulling codes (24, 31, 51), my issue appears to be the air flow meter.

 

[steve578]

I replaced the air flow meter with a junkyard Camry unit. I am still having the same symptoms but now only have code 51. Funny enough the original AFM ohm’ed out okay per the FSM procedure.

I guess the next step is to purchase some feeler gauges and test the tps?