2nd Gen 4Runner Stumbles and Dies

[Von Hayek]

Hey Guys,

I'm trying to help some friend with a '95 4Runner who live 700 miles from me.

Their truck stumbles and dies routinely. No CEL right now, but they had one fixed previously (I don't know what CEL it was) and the stumbling really started afterward. Their mechanic has suggested a problem with catalytic converter, but I cannot see how that would cause this kind of problem.

I suspect a problem in the fuel system, maybe clogged fuel pump pre-filter, or faulty fuel pump. I asked my friend for a description of conditions when this happens, and here is the reply:

"It hardly ever doesn't happen - weather does not matter, and the check engine light does not come on (anymore). The car will run fine, but then the engine will sound like it is starting to struggle (stumble?). And then very quickly, the car slows, loses power until it just stops. There are times when it stumbles and then regains, but it is only a matter of time. If you put it in neutral and pump the gas for a bit, it helps, but to me is seems temporary and still weak after that. The remedy that works every time I discovered (and this is probably very relevant), is to pull over, turn it off and back on again immediately. It ALWAYS starts fine then, even if it is only off for a split second. But it might only be 5 mins or 20 mins before the problem occurs again. For example, last night I drove a mile to, and a mile back from the theatre where Meghan's play is. I had to pull over once on the way there and once on the way back"

Any suggestions before they throw in the towel? They are in Portsmouth, NH if anyone knows a good Toyota mechanic up there.

Thanks as always.

 

[2ndGenToyotaFan]

Have them check the codes again, not all codes will cause the light to come on.

Off-Road.Com - Toyota Tech - Diagnostic Trouble Codes

 

[Offroads4x4]

You could try this idea.

Sounds like the Cats going out. It gets warm than runs rough. Have them check it by unbolting it at the front of the Cat. Than run it around a bit to see if that helps.

JM2C

 

[eiknoll]

Check Fuel system

I had a carburetored vehicle that I had to keep shutting off the engine while driving it late at night to get to where I could stop to check out the problem. The fuel line had decomposed and plugged the fuel filter. Shutting off the engine allowed the gunk to fall away from the filter enough to let fuel through for a while until it would plug again. It usually will seem like you have no power when accelerating. I'd check fuel system.

 

[Devil's Slide Doug]

If it is indeed a fuel issue this will only cost you a paperclip to diagnose. My truck was recently doing this and it turned out the Circuit opening relay (fuel pump relay) was bad. Mine was water damaged and when it would get hot (or when electrical accessories such as the in cab fan was turned on the slight voltage drop would open the relay) the engine would die from lack of fuel. It is easy to rule out the function of the relay (and confirm the fuel pump is OK) by jumping the B+ and Fp ports in the engine diagnostic plug. 4 crawler has some info and piks about this.
Toyota 4Runner and Pickup: Cheap Tricks
In my case, the jumper cured my trucks problem and allowed me to drive it until the new relay was installed. The relay is located above the ecu on the passenger side kick panel/a-pillar (behind the glove box which needs to be removed).