Random Power Loss

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radd5

Joined
Mar 17, 2004
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Northern Virginia/Fairfax
I'm getting random power loss on my FJ62. It can happen when it's cold or warm. I replaced the MAF sensor last week that seems to have diminished the effect, but the engine still stumbles. The power loss can last a few moments to 20 seconds. It's been a chronic symptom since the engine was put in the vehicle 5 years ago.

My temperature sending unit failed last year (a short). I'm thinking of going through the wiring harness and checking all the wires. Does anyone have any experience at trouble shooting electrical problems that can advise where to start?

Thanks guys for all the support!
 
If you don't have an FSM, get one. Go through the EFI section and check the trouble shooting charts, and start testing sensors.

Check for engine codes (there is a link in the FAQ section on how to do this, or detailed in the FSM), that may give you lead in the right direction.
 
Charcoal Canister

The FSM indicates a clogged charcoal canister:
1. I blew into the tank pipe and I can hear air coming out of somewhere but niether of the other two pipes (FSM indicates that no air should come out of anything)
2. I blew air into the purge pipe and air came out the bottom (FSM inidcates that no air should come out of the can).

Do you think a bad charcoal canister would cause the intermittent power loss?
 
I don't know much about the canister, so can't really say......
My first thoughts are that it could be fuel delivery (canister could play into this I suppose) or electrical/sensor. I wonder if an "intermittent" vacuum leak could case similar symptoms.

Can you fill in more on the symptoms? Does it stall out? Fall back to idle? Hold rpm, but loose the power to push farther? Does you get any issues at idle? Cruising? Only with a decent load on the engine? Does it only do this when warm, or also when it is warming up?

You need spark, fuel and air to keep the engine running right. The spark and fuel systems I don't have a lot of firsthand experience with.. hopefully someone else will chime in with some things to check. On the air side (well fuel metering really), you have the air flow meter, the throttle position sensor and the related wiring. I'd be checking the condition of the connectors, and performing the sensor checks detailed in the FSM.

Did you check for engine codes?
 
Runs excellent but ...

The FJ62 really runs great. Fires right up, idles perfectly, gets ~13 mpg around town, has plenty of power, except when....

On my commute to work 14 miles one way, I will usually get a brief power loss. It is always when I'm asking for power (accelerating). It doesn't stall it just feels like the engine is choking (as in not enough fuel). I back off on the gas and the rpm falls to idle with no problem. I can often pump the accelerator and it will finally clear up (and that's what if feels like...like a blockage cleared). If the accelerator pumping doesn't work, i'll pull over and put it in neutral and give it as much gas as possible to get the rpms up as high and as for long as possible until the "clog" clears. Once it clears it runs great again.

I've checked the fuel pump (per the FSM) and it was fine. Replaced the MAF senor (and that helped). I'm following you advise (thank you very much) in using the FSM diagnostics. No service code errors. I'm starting with the EC side first. I'll take the CC to work tomorrow to try to clean with compressed air. I'm thinking of just replacing the FPR because I don't have all the equipment to test the darn thing. I'll move onto the FI sensors next...

Any advise is much appreciated.
 
If it seems like it's failing to respond to the accelerator, I'd start by looking at the throttle position sensor (check connector and run the tests with a multimeter). Failing that, the fuel delivery, and maybe back to the air flow meter.

Paging Crazy 8s, paging Crazy 8s...
 
Well you are in the ballpark that's for sure....it is LACK of fuel rather its a filter, or the sock in the tank.

You really need a fuel pressure tester and they are cheap enough. I will provide a link in a few minutes. Usually if the FPR is bad its bad.

I am sure you changed the fuel filter. The charcoal canister I don't think would cause this but I could be wrong.

Here is what I would do in the order.

Get some seafoam run it through the pvc. Use a coke bottle(plastic) and cut it in half. Ok once the bottle is cut in half fill the cut portion half way up. Pull the pvc off with the hose, start the motor with someone helping and let the engine vaccum pull the seafoam....it only takes a few seconds. Also why you are there check the condion of the PVC valve itself. It will hurl white smoke for some time but that is normal. Whats left of the seafoam dump it in the tank.

Get the fuel pressure tested! Rather you do it or shop does it. You can do it at the filter. I would do it on the tank side....really makes no difference. I have even did it on the cold start injector spot once.... I think it was. You want to test the fuel pressure with and without vacuum per FSM. If you find the fuel pressure is good, the sock is ok in the tank, the seafoam done jack s***(usually the seafoam takes time before you noticed it helped anyway) I think you need to look at the injectors.....one or more maybe dirty as hell. I have only heard of a fuel pressure damper going bad once so. You could go by the local auto crap store and order a FPR and once you put it on and no change take it back.....I have done stuff like that many times.

Hell try even blowing out sections the fuel lines...you never know.

I have a 2 month old fuel filter if you need it....those little suckers are $$$
 
I almost forgot.....These intakes get realllll dirty on a 62 along with the EGR'S It would not hurt to pull it and check them both. I know when you look at the intake its looks like much work at first glance....its not really. I also have injectors that a fellow has never paid for....some new some used all in good shape....only if you need them and this guy does not pay up.

I also forgot to ask you...did you install the TPS per the FSM? I am sure you did but there is some people that would just slap it on there. Simple things like the air filter could be over looked. If you need a phone call my phone line is always open....just pm me for the #. It is sometimes hard to diagnose a rig via the internet.
I have one of these...its awesome even if its from Harbor Freight.

Harbor Freight Tools - Quality Tools at the Lowest Prices

Trust me.....you need the kit. This thing will pay for itself in one use:beer:
 
Last edited:
RockDoc said:
If it seems like it's failing to respond to the accelerator, I'd start by looking at the throttle position sensor (check connector and run the tests with a multimeter). Failing that, the fuel delivery, and maybe back to the air flow meter.

Paging Crazy 8s, paging Crazy 8s...
Click to expand...
Unless it is dirty wouldn't the Air Flow meter throw a code?
 
I'll check the TPS

The MAF doesn't throw a code. I did check it per the FSM and it was out of spec (I replaced it with a Python Injection). I'll check the TSP (throttle position sensor...right??).

I feel it's a wiring issue. There is nothing consistent. It can happen at any time in my commute (from the time I start from the moment I pull into the garage 30 minutes later). I really should have replaced the wiring harness when I had the chance.

In any case it's due for a new air filter and I'll clean out the intake while I'm at it.
 
radd5 said:
The MAF doesn't throw a code. I did check it per the FSM and it was out of spec (I replaced it with a Python Injection).
Click to expand...

You're talking about the vane (flap style) AFM, right? (ala this) You put in an aftermarket one? Or is this some kind of a MAF kit that replaces the AFM?
 
gotcha, right TPS is throttle position sensor.
 
Oh my....I forgot. There is a wire for the hot side of the fuel pump in the drivers rear quarter panel..... It goes bad ALOT! And that would explain why its not consistent. Like hit a bump or it gets wiggled around

radd5 said:
The MAF doesn't throw a code. I did check it per the FSM and it was out of spec (I replaced it with a Python Injection). I'll check the TSP (throttle position sensor...right??).

I feel it's a wiring issue. There is nothing consistent. It can happen at any time in my commute (from the time I start from the moment I pull into the garage 30 minutes later). I really should have replaced the wiring harness when I had the chance.

In any case it's due for a new air filter and I'll clean out the intake while I'm at it.
Click to expand...
 
ha doc..can you give him the color of that wire for the fuel pump? I bet that is what it is. It happends to so many mudders
 
My FSM is at home (I'm at school), and the OP has one. ;)

radd5, have a look at the wiring diagrams in the fold outs at the back of the FSM, you should be able to find the right wire color code, and pull off the trim panel by your jack/toolkit/rear window washer and access the wiring in the bottom of the quarter panel (or is the offending bit under the truck?)
 
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