Fuel delivery issue, 3fe idles(somewhat rough) no go. (1 Viewer)

[masong]

My 92 Fj80 left us stranded today, first time ever. Had it towed back to the shop, where I was able to limp it in, barely, and left it to warm up. As it has been pretty damn cold (0 degrees last night)here in Montana the last few days and I have yet to put any gas drying agents in the fuel for the year I figured that is the first step. I didn't spend much time on the side of the road looking under the hood but I'm pretty sure its a fuel delivery problem.

It idles rough, but starts fine. If you give it any throttle in Park/Neutral or Drive it pretty much dies. The only way I could move it was to start it, and while the idle was still high, drop it in gear and not touch the throttle, idling along until it stalled, then restart.

Upon reading my FSM it looks like the fuel pressure regulator has a vacuum operated flow mechanism that will be the first thing I check after verifying that the fuel is not suffering from icing. Do these cause a no go situation if the vacuum line failed? seems unlikely.
Next I was going to check the fuel filter and replace it.
And Lastly the Fuel pump, although proper testing before hand seems prudent.

Anything I'm missing? It certainly seems to me like a fuel issue but I may be missing something. IIRC any sensors going wonky would lead the ECU to default to rich which is not the apparent issue.
Also, no codes, no CEL, Volt meter was nominal, engine temp at normal, car had been running and driving all morning.

Any tips appreciated,

Mason

 

[ScottMac]

Check the fuel sock filter in gas tank. Access is under left rear seat.

 

[Camino]

You did not say how many miles. At 210,000 our 92 needed a new charcol canister. Do you have a suction when removing fuel cap?

 

[masong]

You did not say how many miles. At 210,000 our 92 needed a new charcol canister. Do you have a suction when removing fuel cap?

Similar mileage, 207k. Yes, suction at the cap when fueling, or anytime, I just removed the cap and it did the same.

 

[jonheld]

Look at the simple things first. Check the intake plenum for cracks. If it is torn or cracked due to age/cold weather it will exhibit similar symptoms.

 

[Camino]

I bought a plastic canister for $35.00 (search to find out part number). It took a little modification at the bracket but it fixed the problem.

 

[Camino]

Found it. GM VC120

 

[masong]

Found it. GM VC120

By your response I assume that having suction at the gas cap is bad? This car has always had that, as did my previous fj80. I thought that was typical.

Also, I'm getting no fuel pump response when B+ and FP are jumped in check connector. So I feel like thats the likely culprit. Seems likely as it just quit like most fuel pumps I've experienced. So...silly question, Do I spring for the Toyota pump? or do I got for a NAPA bosch model? I was going to do a new fuel sock and inline filter at the same time which seem like OEM is the best option here.

As an aside, This check connector seems to have been covered in some sort of grease? is that a factory application? Haven't seen that on my other toyotas.

 

[masong]

Oops, Fuel pump does run when jumped... which led me to try something not directly fuel related. The AFM. If I disconnect the AFM wiring harness it will run, at a high idle, but obviously dies when throttle is applied. It will not currently run beyond initial starting if the AFM is connected. So guess I need to test the AFM thoroughly.

 

[Camino]

Do you mean mass air flow?

 

[Camino]

I'm not a genius but, if the fuel tank can' t vent, as the fuel is sucked from the tank, it becomes more and more difficult to pump (because an ever increasing vacum is created in tank). It may appear to be starving for fuel. Take the cap off and swoosh air is pulled into tank. Instead of replacing charcol canister, try squirting wd40 or jb80 into each tube on the canister, let it set then repeat each day for a few days. Then blow with air hose and see if the check valve is freed up. I just replaced mine with vc120. To answer the question, no, you should not have a vacume in fuel tank.

 

[masong]

I'm not a genius but, if the fuel tank can' t vent, as the fuel is sucked from the tank, it becomes more and more difficult to pump (because an ever increasing vacum is created in tank). It may appear to be starving for fuel. Take the cap off and swoosh air is pulled into tank. Instead of replacing charcol canister, try squirting wd40 or jb80 into each tube on the canister, let it set then repeat each day for a few days. Then blow with air hose and see if the check valve is freed up. I just replaced mine with vc120. To answer the question, no, you should not have a vacume in fuel tank.

It would stand to reason though that if you vent the tank at the gas cap the vacuum would be released and the problem should be resolved temporarily. Does not seem to change my situation.

Also update on AFM testing. Tests normal with exception of E2-THA (temp sensitive) which read slightly low on resistance 1.7k ohm which is still with in the spec of the next temp range above.

Tested the Circuit Opening Relay and that tested normal.

Still won't run when AFM is connected, will idle high when AFM is disconnected.

Camino, Yes FSM calls the mass air flow a Air Flow Meter.

 

[SUMMIT CRUISERS]

I vote for bad fuel (water in it) and/or fuel filter plugged. If not, then fuel sock replacement and lastly fuel pump.

 

[LS1FJ40]

Agreed on the bad fuel.

 

[masong]

I'm skeptical on the bad fuel, it had been running for days on that tank of fuel and it was running good, then it wasn't, and its been sitting in a heated garage for over 24hrs now so the water would have thawed. I don't doubt the fuel filter, and or fuel pump sock may be a issue. The issue so far seems more like a short some where.

 

[jonheld]

Do you mean mass air flow?

3FE has an AFM not MAF.

 

[jonheld]

Still won't run when AFM is connected, will idle high when AFM is disconnected.

This is not supposed to happen. With the AFM disconnected there is no ground path for the fuel pump logic once the starter motor stops cranking.
Without the AFM, the engine should fire while cranking and die once the key is released from the start position.

 

[jonheld]

This is not supposed to happen. With the AFM disconnected there is no ground path for the fuel pump logic once the starter motor stops cranking.
Without the AFM, the engine should fire while cranking and die once the key is released from the start position.

Unless you left the jumper in the check connector from B+ to FP????

 

[jwilber]

The suction in the tank is not normal but I don't think that it's your problem. Mine has had it for awhile and not affected drivability as if yet. You need to check your plenum tube like john said. Its the tube going from the air cleaner to the intake. Any little crack or hole will affect the way your rig runs. A good size crack will do exactly what you are experiencing like john said.... start small

 

[masong]

The suction in the tank is not normal but I don't think that it's your problem. Mine has had it for awhile and not affected drivability as if yet. You need to check your plenum tube like john said. Its the tube going from the air cleaner to the intake. Any little crack or hole will affect the way your rig runs. A good size crack will do exactly what you are experiencing like john said.... start small

Intake tube is solid. No cracks at all, no leaks, at least not big enough to prevent from running. The last 3fe I owned had a terrible intake tube that I had gorilla taped and such to keep tight, seemed to work fine. Can't see any vacuum leak culprit areas.

Got a friend coming by today with a 3fe so I can swap out the AFM and see if that changes the situation.