Juan

iTrader: (28)

All of a sudden the 15A engine fuse started blowing. The car had to be towed ($$$) home because of this and not being able to fix it bugs me. I ended up with a small pile of blown 15A fuses and a towtruck bill. What runs on that same line that can cause that specific fuse to blow? The car is an '87 TII.

HAILERS

It feeds the Circuit opening relay and the fuel pump and the Main Relay.

HAILERS

Its the fifteen amp fuse in this jpg feeding the Main Relay/ Circuit Opening Relay/Fuel Pump/. Maybe a fuel cut switch is shorting out that you installed?

WAYNE88N/A

Always track down a short by isolating the bad dude (or bad wire dudette)...

Luckily, there's not much to this circuit...Unless you've added some things...And if you did, the simple act of overloading the circuit may be blowing the fuse...Depends on how fast she's blowing...

Here's what I would do if mine was blowing:
1) disconnect the plug from the back of the alt
2) disconnect the circuit opening relay (pull the plug)
3) insert fuse...If it blows, you have a wiring problem in the alt voltage reg/excitation circuit wiring (I'd look near the plug for chaffing against the water pump housing or front housing), the power circuit wiring for the fuel pump/circuit opening relay, or the main relay (or wiring going to it) is bad.

Isolate those three down to find the gremlin...

If it doesn't blow, reconnect the alt back plug and try again. If it blows, your alt volt reg is bad...

Disconnect the fuel pump plug at the left aft strut tower...

Reconnect the circuit opening relay. It if blows now, you've got a short in the wiring to the fuel pump connector, or the circuit opening relay...If it doesn't blow...

Reconnect the fuel pump connector...If it blows now, you probably have a bad fuel pump...

Juan

iTrader: (28)

I have a fuel pump kill switch installed but the fuse still blew after removing the switch.

Thanks HAILERS and WAYNE88N/A, I'll try to track down the gremlin today and I'll report back what I find.

dreadseb

I had this same problem and took your advise to test it with the relay out and now the fuse hasn't blown yet. Does this relay only run the fuel pump or other stuff too.

Could I just leave the relay disconnected since it works like this.

NZConvertible

Yay for three year old threads...

The fuel pump will not work with the relay disconnected unless someone's butched the wiring.

HAILERS

Yeah. What is meant by that. Is the car running with that relay out?? Or is the fuse just not blowing and the car is resting in the driveway?

The relay is just a safety device and also supplies power to the fuel pump....on a normal car.

dreadseb

Yeah the wiring was slightly butched, as I wired in a fuel disconnect switch wired direct into the pump. So thats the main reason itll work with the relay out.

So can I leave the fuel pump running like this or should I try to work something about.

benfer

jump the fuse with a paperclip and look for smoke.

NZConvertible

A switch at the pump shouldn't allow the pump to run without the relay because the power comes from the relay. Something else must've been done to bypass the relay.

No because the circuit opening relay is a safety device. It kills the pump's power when the engine stalls, like in an accident.

HAILERS

Ah. It makes sense now. Most likely the problem is a dead short in the wire from the relay to the fuel pump. That Blue wire is probably dead shorted at the fuel pumps plug.
But there's other possibilities. That Blue wire from the relay also passes thru a connector near the pilots left foot area. A plug with a designator X-13. It''s a big seventeen pin/socket plug. If you have not been working in that area, then that's an unlikely suspect.

The Engine fuse also powers the Main Relay but that can't be the problem since the car runs with the Circuit Opening Relay out and the Main still in place.

I guess the relay itself might be shorted internally. Maybe.

dreadseb

Yeah, my switch is whats causing the short then because I have a switch wired from key voltage to the pump so thats what is causing the fuse to pop. I personally don't have a problem with it being this way and keeping the relay unplugged if it's just a safety issue, ill just bolt my trusty old fire extinguisher to the floor just in case.

NZConvertible

You're assuming you're going to be conscious and mobile after a crash bad enough to cause a fuel leak?

dreadseb

Yeah, that and few other things like not getting in a bad crash and if I do crash it better be big enough damage to hurt me bad enough to knock me out it should be bad enough to destroy my battery thereby shutting off the fuel pump.

londonmazda

iTrader: (2)

... any luck?

HAILERS

On most every post on a Thread, you'll find the date and time that post was made. It's located at the top left of each post. Such as the very first post made by the original poster on this thread has 09-30-04 as the date. Then later on post number 15, the date of his post was 02-28-07.

Just a little FYI. Nothing more, nothing less.

londonmazda

iTrader: (2)

I am aware. but people still use this forum 4 years later :p thanks tho.