MAF failure? Random stalling issue (1 Viewer)

[Reuben K]

1999 lx470 253k. Few weeks ago I left for church and about 200 yards from my house my cruiser stumbled, bucked and died. Restarted but then stalled again. Eventually it just cranked and wouldn’t start. I pulled it home and all looked fine under the hood and no codes showed on my scanner. It felt similar to when the MAF failed on my old Nissan, and I had a can of MAF cleaner on hand so I removed and cleaned it. Boom. Started right up, drove it round the block. Figured it was on its way out better to replace it before it totally died, so I went and got a new one from local store. Installed new maf and drove fine.
Fast forward to today, I went to leave my job, and it died when I put it in park. Didn’t want to restart, got it started and it didn’t want to rev, and would die when I shifted to drive. I had the old MAF still in the truck, the one I had cleaned, and I thought what the heck and swapped it with the new one. Boom. Started up and drove home fine. What gives? New part is junk, old is good just needed cleaned? Maybe the connector is the issue and wiring is spotty? I’ve driven it a few hundred miles since the first time it had this issue, and no problems.

 

[Trapper50cal]

A worsening failing fuel pump would act the same or at least similar. When and where you succeeded in starting it could just be anecdotal.
Or failing EFI relay.

 

[Reuben K]

A worsening failing fuel pump would act the same or at least similar. When and where you succeeded in starting it could just be anecdotal.
Or failing EFI relay.

Hmmm interesting. I’ll do some research into this Just seem weird that cleaning/changing the MAF would seem to fix it.

 

[Trapper50cal]

I agree just trying to help think outside the box. Mine had completely random episodes of crank/no start as well as a few "stalls-while-running" and then it would just temporarily "fix itself" and work again. But it got progressively worse until it finally pooped the bed.

 

[Reuben K]

I agree just trying to help think outside the box. Mine had completely random episodes of crank/no start as well as a few "stalls-while-running" and then it would just temporarily "fix itself" and work again. But it got progressively worse until it finally pooped the bed.

Ah interesting! My first thought was fuel pump. I guess if it keeps getting worse I’ll go that route

 

[Privateer383]

Yep, I went down that trail in my '98 LC100- MAF, fuel filter, etc etc. Turned out it was a INTERMITTENT fuel pump failure. Pump was "ok" whenever I tested it, but I was unable to test it during it's very brief intermittent failures (because I was driving it!). Spent a lot of money on unnecessary fixes. If you don't have maintenance records showing a fuel pump replacement in the recent past (normal service life of pump), I recommend replacing the fuel pump with Toyota or at least OEM quality component.

 

[2001LC]

Warning: It is the vapor of gasoline, that is highly combustible. So use the greatest care. No sparks, ambers, cigarettes, open flames, etc. with below test.

Best: Use OEM fuel system and sensors parts. Not some cheap aftermarket, which are giving us problems.


Fuel pump failing, are often intermittent start no start:

One trick/test is to pull fuel line from fuel filter, during event (crank no start). Turn IG key off. Pull fuel line from fuel filter. If fuel pump was working, fuel will blow out as pressure in fuel line & rail released. If not working, fuel dribbles' out at best. The reason for this: Fuel pressure is bleed off the fuel rail while cranking. Without fuel pressure/flow being supplied/pumped adequately during cranking to start (build pressure in fuel rail), pressure fails to build back up.

We can also run a line from filter to catch can and crank (turn key to start). To see if fuel flows and how much.

But keep in mind, these fuel pump cam be intermittent, and may happen to pump as you crank during test. They may even, flow but at reduced GPM/PSI.

We also see bad gas clogging fuel sock and filter. This may show as high LTFT (lean fuel ratio mixture). Watch fuel trims may yield clues of.

Squeeze the green clip to release fuel line from filter. This one doesn't show, the white plastic bracket, that hold fuel line to fuel filter bracket. Fuel line needs pulled from white bracket first.

Bad gasoline, from old steel storage tanks. Are causing issues. Lean fuel mixture, yields clues.

MAF can, give much the same symptoms Or may show as rich fuel mixture.
MAF, are very sensitive instrument. Replacing old MAF, isn't a bad idea as a PM. I'm see improvements, in fuel trims & MPG doing so. Make sure to disconnect battery negative clamp first, before disconnecting MAF. Reconnect battery when done, but no sooner than 20 minutes.

This MAF bad on, burned up BK1 CAT fast. Luckily CAT BK2 did ignite.