Electrically Sick 75 FJ40

[Clyde-2]

Took my cruiser out last nite, everything had been working great.
Engine backfired and blew the fuse tied into the ignition system.
Replaced fuse, went to dads, Mr. Gasket electric fuel pump started
clicking real hard and engine started running rough. Fuel pump finally
quit clicking and engine smoothed out. Took off from dads and fuel
pump started clicking again, stranded me, got it home, no clicks from
pump, turned on running lights, they started flickering, turned on head
lights and fuse at ignition blew again, it's a 20amp. Think I have 2 problems
at the same time. Elec. pump is a MR Gasker 12s and is new. Alternator
is old and probably needs to be replaced. Any help from the gallery would
be appreciated.

 

[ian]

I feel your pain. I've owned two 40's.. each with serious electrical problems they day I bought them. Usually the fault of PO. I'll be starting a rewire in a few weeks.. I'll be sure to take pics and write something up when I'm done.

I haven't heard of over supply being much of a problem or blowing fuses.. your reg should take care of this anyway... blown fuses are usually a short somewhere. However, a constant cutting in and out on a high draw circuit *could* lead to a blown fuse. Think of the startup draw from an inductive motor... Did your lights flicker right before the ignition circuit fuse blows? Probably just a side effect of shorting. What I'm getting at is I don't really think it's your alternator.

Anyway. Your fuel pump may be "clicking" due to cut in/out of supply voltage. Start into this with assumption that it's fine and that you're simply having an electrical problem.

Troubleshooting in order of simplicity:

1.) Check leads from battery. Give each a good yank. Check other side of each lead. My friend's volvo had a corroded secondary lead from the battery. The result.. rig wouldn't start. Also a "clicking" from a relay on the ignition circuit . There was a tiny bit of voltage making it through the corrosion. Started yanking on leads and it poppped off.. aha!

2.) Play the intermittent short game. Some fuses have quite a few components hanging off them and numerous of places for the harness to ground out. Trace the fuse you've been blowing (ignition). Disconnect battery. Pull fuse. Hook ohm meter up between the load side of that circuit on the fuse block. Ground meter to a *known good* chassis ground (like the ground side of the fuse block). Find ohm setting that clearly shows difference from ground. Start wiggling wires until meter shows little/no resistance (or if you're lucky, you have one that chirps @ ~0 or fluctuation).

3.) Failed fuel pump? There's a chance it's failing and causing a ground fault. I'd contact the manufacturer before going too far with this (i.e. start into step 4 before replacing it). A well engineered component should fail open.

4.) As a last resort, go get your alternator tested. If you have some extra cash, this might be a good time to replace the mechanical voltage regulator as well. Search the forums.. someone found a solid state (no points) regulator @ napa that works well.

 

[Clyde-2]

Ian...appreciate the detailed advice!! I think the fuel problem is because there is no
back flow preventer or check valve on the electric fuel pump. Have found out the the
elec. fuel pump is made for pushing fuel and not pulling it. Going to install check valve
in line and see if that helps.

Highly likely that something is grounding out. There is lots of "christmas tree" wiring
on my 40 and it's time to clean some of it up. Coil is brand new, alternator, not sure.
All I know is when I loaded it down my turning on the head lights it cause the fuse to
blow and the whole system went down. Have Haynes as well as Toyota repair manuals
and will get the multi meter out tonite and see if I can diagnose my patient.

thank......mike

 

[sherwood]

turned on head
lights and fuse at ignition blew again, it's a 20amp. Think I have 2 problems
at the same time.

'Trying to follow you here. My '75 FJ-40 schematic does not show an "ignition fuse". The five 20Amp fuses are for Headlights, Heater, Stop lights, Wiper, and Lighter. The "Engine" fuse is shown as 15Amps. Which fuse was it ?

Instead of "2 problems", maybe think of one problem that is common to two symptoms.

John

Also, where does the fuel pump splice in to the wiring ?

 

[Clyde-2]

The fuse is/was a 25a installed by the PO. It ties into the main harness that comes out of the firewall and heads toward the batt,coil, etc. When this fuse blows, the entire vehicle goes dead. I'm almost certain that the electric fuel pump clicking is a gas flow problem.
It clicks when it is not moving fuel. Going to install a check valve and see if that helps.Fuel pump is tied into ignition circuit, it will start running when the key is in the "on" position prior to actually activating the starter.
Just not sure if the electrical problem is related or not. With engine running in park and
only park lights on, everything was fine. Turned on head lights, lights began to flicker, and then fuse blew, entire system went down.

 

[Pin_Head]

It isn't the ignition circuit, because it is not fused as noted by Sherwood. It is a short that is downstream from the fuse that blows. Maybe the PO wired the fuel pump into the circuit that blows a fuse. It is also possible that addition of the fuel pump overloads the circuit, so you might want to consider running a separate fused circuit. Fuel pumps make noise when they aren't pumping normally, so I would suspct that the fuel line may be plugged causing it to work harder.
To find the short, start by disconnecting each of the devices that are fed by the circuit. If it still blows, then the short is in the wire. To find it, you will have to trace each wire. Look at places where the wire passes through the body or rubs against metal. It is a PITA.

 

[ian]

Use ammeter to determine draw without the headlights on (sounds like it's over 15 amps). Determine what components are drawing at that time and add up maximum combined load. If the estimated and actual load differ by much, you've got a short (or failed component).

 

[Clyde-2]

What circuit could it be on that when blown causes the entire vehicle the electrically
shut down? Appreciate you guys help!!

 

[Bennett]

have you checked your frame to motor ground strap?

make sure the connections are clean... it is often overlooked and poor grounding causes all kinds of crap.

The engine is basically suspended in rubber and that ground is important. I saw a cruiser backfiirng throuhg the carb and running like a model T... soon as we jumped a battery cable from the frame to the motor she smoothed right out.
PS check the battery ground cable for clean connection as well. sometimes it is just simple things that are hard to find.

 

[Clyde-2]

Haven't checked the strap, not sure where it is. have verified that the neg on the battery is adequately grounded.

 

[ian]

What circuit could it be on that when blown causes the entire vehicle the electrically shut down? Appreciate you guys help!!

Your ignition coil is on this circuit. No ignition coil, no spark, no combustion, no run. This is why people like to add a hidden switch to the circuit. Engine turns over but won't run. Throws theives for a loop.

 

[Clyde-2]

Good point Bennett...........my FJ has been sitting for 5 years and have already discovered numerous elec. connections that are coated with that white stuff/corrosion. Battery to frame cable is new, but attachment point on frame may need some wire brush action.

 

[Clyde-2]

Your ignition coil is on this circuit. No ignition coil, no spark, no combustion, no run. This is why people like to add a hidden switch to the circuit. Engine turns over but won't run. Throws theives for a loop.

When I mean electrically shut down, I mean no lights, no nothing, dead. It's like throwing the main disconnect for the whole rig when that fuse blows.

 

[ian]

That's odd. I think it would behoove you to work your way through the spaghetti and draw up a schematic. There's a good chance the PO has done some naughty things.

 

[Clyde-2]

Yeah, was afraid somebody was gonna suggest that.
Have been thinking about possible solutions and causes since last nite. Couldn't sleep.
Haven't got crap done at work today. Am ready to go home and figure
it out. Think I'm becoming obsessed!!

 

[Pin_Head]

You are going to have to figure out how the PO wired it up. Download the schematic (78 will be close) from the tech links section. Start following the large white wire with blue stripe that runs from the battery to the amp meter and then to the ignition key and fuse block. Look for taps into this wire or any wiring that does not look original. Is the fuse that is blowing in the original fuse block If so, then the wiring problem is downstream from this fuse. Normally the lights and engine are on separate fused circuits, so there should be no interplay between these circuits. If the fuse blows, it is a short or overload and not a bad ground.

 

[Clyde-2]

Fuses in fuse block inside are fine........fuse under hood is the culprit. When I replace it,
everything is back to normal, at least for a while till it blows again.

 

[3_puppies]

Does 75 have a fusible link off the battery? mine went bad in my 79 and it started blowing fuses under the hood by the blower motor and elsewhere.

 

[ian]

Follow Pin_Head's advice and look for splice prior to interior fuse block. Check interior fuse block for defeated fuses (you know.. the special foil / bullet casing ones).

I still think you're looking for a short.. grab a meter and get to work.

 

[Pin_Head]

Fuses in fuse block inside are fine........fuse under hood is the culprit. When I replace it,
everything is back to normal, at least for a while till it blows again.

Sounds like the PO added a complete new circuit with a fuse. Where does this circuit connect (to the large white wire?) and where does it go.

Does 75 have a fusible link off the battery? mine went bad in my 79 and it started blowing fuses under the hood by the blower motor and elsewhere.

'79 and up are different. They use the fusible link as a shunt for the amp meter and when the link goes bad the fuses to the amp meter blow to protect the meter.