91 FJ80 Intermittent Starting Issue (1 Viewer)

[seatosummit]

Hi All-

I have a 91 FJ80 that has developed a starting hesitation. It first emerged about three months ago and has seems to have worsened gradually to the point that now nearly every start seems to require about 10 seconds of cranking.

What I know:

• The starter is good (with new contacts) and is properly rotating the flywheel
• The Check Engine Light (CEL) is reliably illuminated when the ignition is in the "on" position
• Though it has an alarm system that is no longer in use, removing the "immobilizer" relay causes the starter to not engage, seemingly ruling out the possibility that the immobilizer relay was wired to interrupt the fuel pump
• After 10-15 seconds, it will start
• Once it starts, an immediate attempt at restarting will always work within 2-5 seconds (normal time)
• Once started, the 3FE will run smoothly and accelerate without hesitation. This includes long drives in below freezing conditions. This makes me think the fuel pump is properly functioning.
• My battery and starter won't last forever

My questions:

• If it was a bad ECU relay, I would be without CEL in "on" position, yes?
• Do these symptoms align with a bad Circuit Opening Relay? Part #?

Thanks for any help on this, Guys.

Austin

 

[goranvolvo]

did you check crank sensor inside distributor

 

[seatosummit]

Hi @goranvolovo, no I didn't think to look there as I haven't noticed any symptoms that I would normally attribute to bad (or missing) feedback to the ECU. It runs perfectly once it starts, and hasn't stalled, idled poorly, hesitated or guzzled fuel--well that last bit is a lie, but no more than normal...

I suppose its worth a check though.

 

[SUMMIT CRUISERS]

Here's what fixed my son's 92. Not sure if the symptoms are exactly the same.

Intermittent Starting Problem Solved

 

[mct75]

On mine, the cold start injector is borderline mandatory, even in ~60 degree weather. Additionally, there's a fuel pressure VSV that improves starting. With those two things not working, mine would have to crank for an embarrassing amount of time, but restart without much trouble.

 

[seatosummit]

Here's what fixed my son's 92. Not sure if the symptoms are exactly the same.

Intermittent Starting Problem Solved

Thanks, @SUMMIT CRUISERS, I tightened my fuel damper screw last year, and I just popped the cap off to confirm that it is still tight. Perhaps something has failed internally though?

 

[seatosummit]

On mine, the cold start injector is borderline mandatory, even in ~60 degree weather. Additionally, there's a fuel pressure VSV that improves starting. With those two things not working, mine would have to crank for an embarrassing amount of time, but restart without much trouble.

That sounds like a good component to clean regardless. I'll pull it and give it a clean later today. Thanks.

Interesting addition, I just drove to work (10 miles) and its 60F outside. Started with little hesitation at my house, but upon arrival to work, was not quick to turn over when I attempted a warm restart.

 

[tacoma2002]

Before you try starting it cycle the key from the Lock position to the ON position about 3 times. When you cycle to the ON let it sit in that position for about 5 seconds. After you do this 3 times attempt to start the vehicle.

Sounds like the fuel pump is losing prime. If the vehicle starts after this method then you know the check valve on the pump has gone bad and is allowing fuel to back flow into the tank.

 

[seatosummit]

OK, so I have gone through a removed the old alarm system to reduce complexity in the wiring harness. I took the opportunity to also inspect the circuit opening relay (COR) behind the kick panel on DS. Cranking the engine causes the relay to palpably actuate, which I believe is normal behavior. The relay opens about 2 seconds after the vehicle stops which I believe is triggered by the AFM recognizing there is not longer air being pulled into the manifold.

The likelihood of ECU or COR sporadic failure seems diminished too because the issue only appears when I am starting and never when running. Agreed?

Before you try starting it cycle the key from the Lock position to the ON position about 3 times. When you cycle to the ON let it sit in that position for about 5 seconds. After you do this 3 times attempt to start the vehicle.

Sounds like the fuel pump is losing prime. If the vehicle starts after this method then you know the check valve on the pump has gone bad and is allowing fuel to back flow into the tank.

I will try this method exactly as described and report back, but my suspicion is that it will lead to an increase in number of successful starts, as this aligns with a troubleshooting method I have stumbled upon via trial and error.

@tacoma2002, is the check valve located at the pump, or closer (hopefully) to the fuel rail?

Thanks for all your feedback, guys.

Austin

 

[tacoma2002]

The check valve is built into the pump itself. This means if the valve is bad your pump will need replaced. There is an access panel underneath the 2nd row seats that will allow you to remove the pump without dropping the tank (if it comes to that).

 

[seatosummit]

The check valve is built into the pump itself. This means if the valve is bad your pump will need replaced. There is an access panel underneath the 2nd row seats that will allow you to remove the pump without dropping the tank (if it comes to that).

Bummer, so I feared. Its likely worth checking fuel pressure at the rail before I pull it all apart, right? I haven't seen a nice location to hook up a gauge, however...

Have you personally ever replaced a pump in your 80? OEM or after market?

Thanks

 

[tacoma2002]

Unfortunately the check valve does not directly effect running PSI. It only prevents the fuel from seeping back into the tank. It sounds essentially like you're having to "prime" the system before it'll start.

I have.

Unfortunately the tank had a considerable amount of trash in it that lead to the pump demise. I wasn't comfortable with only cleaning from the top so I went ahead and dropped the tank and cleaned it thoroughly.

I replaced it with a after market unit and have been running well for several thousand miles.

FWIW I've never used a new OEM pump in anything. I've used Airtex and Spectra brand pumps with good results. Actually went through an Airtex pump testing facility once in my Auto Parts sales days. Pretty neat.

 

[SUMMIT CRUISERS]

@seatosummit read through my link that I posted. It explains where to tap in for the fuel pressure gauge and it also explains how the fuel pressure readings can drop with the adjustment of the fuel damper screw. Just FYI, I changed out probably 3 fuel pumps (under lifetime warranty) before I found the real culprit, the damper.

 

[Formulaonehd]

Bummer, so I feared. Its likely worth checking fuel pressure at the rail before I pull it all apart, right? I haven't seen a nice location to hook up a gauge, however...

Have you personally ever replaced a pump in your 80? OEM or after market?

Thanks

Same problem I had in my 93 , it was a clogged fuel pump and filter catch , funny enough a bottle of fuel cleaner actually fixed the issue as it sat in a garage for 3 years without being started!!

 

[sea bass]

I replaced my 92 fuel pump with a denso from amazon for 90$ denso 951-0012

 

[seatosummit]

@seatosummit read through my link that I posted. It explains where to tap in for the fuel pressure gauge and it also explains how the fuel pressure readings can drop with the adjustment of the fuel damper screw. Just FYI, I changed out probably 3 fuel pumps (under lifetime warranty) before I found the real culprit, the damper.

I will see about getting a pressure gauge from my local parts store.

Can you confirm that the part# you listed (#2327031080) in your thread fit on your 3FE? Where did you source it?

Thanks,

Austin

 

[seatosummit]

Same problem I had in my 93 , it was a clogged fuel pump and filter catch , funny enough a bottle of fuel cleaner actually fixed the issue as it sat in a garage for 3 years without being started!!

I love easy fixes! Wish I had 3 years of downtime as a potential cause.

 

[seatosummit]

I replaced my 92 fuel pump with a denso from amazon for 90$ denso 951-0012

Thanks, @sea bass good to have a part number for the denso unit. May pull the trigger on this or an Airtex or Spectra unit if I find the damper is not faulty.

 

[jonheld]

Personally, I would replace the fuel pressure damper with a new one. It is a small pressure vessel that serves to absorb the pressure fluctuations in the fuel rail as the 2 sets of injectors fire. Over time the membrane will fail. Tightening the screw will do nothing.
The fuel pressure regulator is another culprit on the fuel rail with a diaphragm that fails over time. These items are over 25 years old now. They have served you well.

 

[SUMMIT CRUISERS]

I will see about getting a pressure gauge from my local parts store.

Can you confirm that the part# you listed (#2327031080) in your thread fit on your 3FE? Where did you source it?

Thanks,

Austin

I originally sourced from @cruiserdan @ American Toyota but since his retirement from the parts industry and move from ABQ to SLC I source online at:
DAMPER ASSY, FUEL PRESSURE PULSATION. FUEL INJECTION SYSTEM for 1992 TOYOTA LAND CRUISER. #2320746010
If you haven't changed your FPR and fuel sock/strainer, I would order and install it as well. The FPR is on the front side of the rail and as @jonheld mentioned "These items are over 25 years old now. They have served you well" and are really just a ticking time bomb which will cause you issues down the road.