Electrical help! (1 Viewer)

[Alan Jones]

My fault. Meant no start. Replaced fusible links, no change. Pulled fuel pump relay and cleaned points, no change. At this point, it cranks fine, and fires up, but dies within seconds. I can keep it running for a short time if i feather the throttle. Pulled EFI Main and that relay is warm. Normal?? How do I test that four prong relay?

 

[Mandrake]

Have you checked for an air leak between the MAF and the head? The electrical thing was odd, but if it consistently starts and idles, but dies as soon as you tickle the pedal, that says to me that you're getting unmetered air from somewhere.

 

[Mandrake]

Your MAF could also just have gone tits up. Not very common, but not impossible.

 

[blkprj80]

96 FJ80: On the way home earlier this week, dash lights go a bit crazy ... Newer battery, newer starter, and alternator. ...

When you replaced your alternator, what did you use? There is a lot of remanufactured junk out there. Just because someone said it was good don't make it good. Don't trust it.

 

[Alan Jones]

Rebuilt by a VERY reliable local shop.

 

[Alan Jones]

So now I am chasing a fuel problem I suspect. It cranks and runs for about three seconds before stalling out. I checked the fuel pump relay and it checks out. How do I check the fuel pump resistor? If that is not it, I have read on here that I can access the fuel pump through the rear floor. Is there a way to test it prior to digging in? I am now wondering if the electrical issue was related to a fuel devliery issue like the pump or resistor dying in transit...

 

[blkprj80]

I liked your original idea that it might be a bad ground somewhere.
Check the back of the engine to the firewall ground strap.
Check that ground wire from the battery negative to the fender.
Measure things that "should be ground" while it's running and when it stalls. Your throttle body should always be zero volts with respect to the battery negative terminal. Is it? Measure other things, alternator, engine block, etc.

I don't see how you could get a light show in the dash, kill a headlight, and now have a bad fuel system.

Do you have a good multimeter?

 

[Alan Jones]

Okay, following your advice, back to the drawing board. Ground from battery negative to fender is solidly grounded. Checked it like 10 times. Going to check the back ground strap now. When you say the throttle body should be zero with respect to the battery, you mean testing for a positive read on the body of the throttle body, etc.? Be back in 10 minutes...

 

[blkprj80]

Yes, measure voltage with your meter. You're looking for a wire or connection that isn't passing current, therefore has a voltage drop across it.

Anything that should be zero volts should be zero volts. Use the battery minus terminal as your reference. If you measure 6V somewhere it shouldn't be, track it down.

 

[Alan Jones]

Ground strap is solidly grounded. Throttle body, block grounded. My thoughts were that if something in the fuel delivery system went out, perhaps a surge would send the dash into fits and blow the headlights as they are on some common fuses. I am retesting the fuel pump relay and may have the issue. According to the FSM, relay pins 1 and 5 should show continuity and pins 3 and 5 should show continuity. Pins 3 and 5 show solid continuity for me, but pins 1 and 5 do not with a reading on continuity setting of 84. Sound like the relay is bad?

 

[Alan Jones]

Alright, replaced fuel pump relay and no change. Any thoughts from those with more experience? Baffled and need help!

 

[gummycarbs]

Alright, replaced fuel pump relay and no change.

So what is the current state? No start? Or start and then dies?

Is the "Christmas tree" still going on? i.e. low voltage warning light (red light by the voltmeter), AT/P, and other lights coming on?

 

[SmokingRocks]

Fuel pump relay

 

[SmokingRocks]

What did you fiddle with or replace before this symptom presented itself?

I have had a fuel pump relay take a dump on my face at the same time I was chasing down another issue. It was extremely frustrating, the FPR passed all the bench test yet it was still bad.

You can bypass the fpr and ‘Hotwire the pump. OTHERs can tell you how

 

[Alan Jones]

Starts and dies immediately. I can throttle it for a few seconds to keep i running but it will die immediately when I get off the throttle. I replaced the FPR tonight to no avail. And no more crazy dash lights. No CEL, no AT/P, no voltage warning light.

 

[Alan Jones]

Starts and dies immediately. I can throttle it for a few seconds to keep i running but it will die immediately when I get off the throttle. I replaced the FPR tonight to no avail. And no more crazy dash lights. No CEL, no AT/P, no voltage warning light.

 

[Alan Jones]

I believe there to be an electrical failure somewhere within the fuel system. Any, any, any advice lady accepted. I'd like to get her running tonight!

 

[clx16]

You've replaced the fuel pump relay but are you sure the fuel pump is not giving up the ghost? Haven't experienced it on a toyota but I have had a ford that has some of those symptoms when it was dying.

 

[Alan Jones]

How do I test the fuel pump itself? I tried using the diagnosis connector in the engine compartment but there doesn't seem to be a connector in the Fp position.

 

[clx16]

Unless you have a fuel pressure gauge you might start with using the multimeter at the fuel pump to make sure you are getting the power back there. You can also verify the ground is good there and your positive lead is good also. I am pretty sure the Land Cruiser shuts off the pump after a few seconds if it doesn't detect the vehicle running, this could be done through the relay. I am not smart enough to put money on that. If it is true you will see the voltage jump and then when the relay cuts off it will drop and it may not be an indication of If you have a fuel pressure gauge or someone to lend you one, then I believe the fuel pressure test port for most toyotas is near the fuel filter.