FJ62 Starts after letting fuel pressurize

[JAX 1988 FJ62]

I’ve been chasing down the cause of my occasional hard start issue and I think I’m finally onto something.

What I’ve noticed is that when I jump the f+ and B terminals, and turn the ignition to “on” and let the fuel pump run about 10 seconds, the car will start right away. If I have the terminals jumped, and try to start it (without letting the pump run a few seconds) it will turn over many times before finally starting.

Does this sound like a weak fuel pump, or potentially a clogged fuel filter? I’ve already checked or replaced the cold start injector, fuel pressure regulator and the coolant temp sensor/connector.

Once started, the truck runs perfectly. No issues at all.

Thanks for the insight!

 

[SteveH]

I would check to see how fast the fuel pressure drops off upon engine shutdown. Most vehicles maintain pressure for this reason.

Also, some vehicles have a check valve (somewhere in the system) that maintains pressure. I don't know if an FJ62 does, but if so, it's the first place I'd look. This check valve was located in the fuel pump assembly on a Ford Taurus that suffered from this. I replaced the entire fuel pump assembly (because it was cheap) and it fixed the problem.

 

[cruisermatt]

Have you had an actual fuel pressure gauge on it when doing all these tests to verify your theory?

 

[Spook50]

Have you had an actual fuel pressure gauge on it when doing all these tests to verify your theory?

That's what led to me diagnosing my fuel pump (well, lack of power to it) problem that caused my engine to quit on Christmas two years ago. Invaluable for troubleshooting on a 3FE.

 

[JAX 1988 FJ62]

Have you had an actual fuel pressure gauge on it when doing all these tests to verify your theory?

Matt, is there a write up on where to tap into the fuel line and test? I’m happy to get or rent one and perform the tests and prevent just throwing parts at the rig. Thanks!

 

[cruisermatt]

Matt, is there a write up on where to tap into the fuel line and test? I’m happy to get or rent one and perform the tests and prevent just throwing parts at the rig. Thanks!

Not that I am aware of. We have a 62 here with some issues maybe I can do a little write-up.

 

[JAX 1988 FJ62]

Not that I am aware of. We have a 62 here with some issues maybe I can do a little write-up.

That would be amazing! Thank you!

 

[Spook50]

Matt, is there a write up on where to tap into the fuel line and test? I’m happy to get or rent one and perform the tests and prevent just throwing parts at the rig. Thanks!

When I rented a fuel pressure gauge it came with a special banjo bolt that would install in place of the one on the fuel rail where the cold start injector hard line attaches. The "special" bolt had a quick disconnect that the gauge would connect to so you could even run the engine with the gauge connected.

 

[Paullus]

Did you check to see if the fuel pressure regulator is leaking fuel from the vacuum port. I had that happen on another vehicle and it was only 1 drop every 10 seconds. I had to tap the vacuum line to get fuel to come out.

 

[YooperCruiser]

Easiest place to put a fuel pressure gauge is at the cold start injector with this 4Runner banjo bolt from Fuel Pressure Bolt Kit 22RE Fuel rail - https://www.lceperformance.com/Fuel-Pressure-Bolt-Kit-22RE-Fuel-rail-p/1093076.htm

 

[Spook50]

Easiest place to put a fuel pressure gauge is at the cold start injector with this 4Runner banjo bolt from Fuel Pressure Bolt Kit 22RE Fuel rail - https://www.lceperformance.com/Fuel-Pressure-Bolt-Kit-22RE-Fuel-rail-p/1093076.htm

View attachment 3636950

Looks like that could be used on either the injector or (if you wanted to keep it somewhat tucked back for a remote connection to an in-cab gauge) on the fuel rail itself.

Is this in your Cruiser? Curious why the humongous bonding wire connected near your EGR inlet, and did you just put a freeze plug in the inlet for an EGR delete?

 

[JAX 1988 FJ62]

Easiest place to put a fuel pressure gauge is at the cold start injector with this 4Runner banjo bolt from Fuel Pressure Bolt Kit 22RE Fuel rail - https://www.lceperformance.com/Fuel-Pressure-Bolt-Kit-22RE-Fuel-rail-p/1093076.htm

View attachment 3636950

Great info and thank you for the link and picture. Is there a recommended generic fuel pressure gauge that would mount to that banjo bolt?

How does that compare to the fuel pressure test kits you can rent or buy for around $50 at harbor freight? I assume you’ll still need the specific banjo bolt anyway?

Thanks!

 

[JAX 1988 FJ62]

I rented a fuel pressure gauge. Results below:

- Checked fuel pressure per the FSM
- With the service wire jumping the +B and FP terminals, I get 40psi.
- With the motor running, I have 42psi
- with the motor running and the vacuum line on the VPR disconnected, I have 49psi
- 10 min after shutting down, I still have 37psi

That all appears to be in the right range.

What would cause the “extended cranking” time before starting if I don’t let the fuel pump prime for about 8-10 seconds. When I do that, it fires up in about 2 seconds.

 

[diesellibrarian]

From the Factory Service Manual diagnostic chart:

These are all very general, but each worth investigating. It wouldn't hurt to start with a full tune-up (valve adjustment, timing, plugs, wires, cap and rotor, etc.) and a really thorough hunt for vacuum leaks. A lot of the EFI and ignition components are easily diagnosed with a multimeter, assuming you have a copy of the FSM to guide you.