Fuel Pump Fuse keeps blowing


coojo81480
04-20-2008, 04:35 PM
I am new here and need some help with my 93 ford escort. I am currently having problems with it blowing the fuse that runs my fuel pump. I am guessing it is being caused by a bare wire some place touching the body and causing the short. I am not sure what all is on this circuit and would be helpfull if I knew what all was on it or what else might cause it to blow the fuse. Also there was a recall for a relay for the fuel pump that I already had serviced but it didn't seem to help the problem but may have made it worse because it doesn't last as long before it blows out again. If anyone can help by telling me where to find a wire diagram or what else could cause the fuse to blow on that circuit it would be very helpfull. Thanks in advance.

Selectron
04-20-2008, 09:23 PM
Hi, welcome to the forum. The electrical circuits differ between models, so we know it's a '93 but which model?

coojo81480
04-20-2008, 09:38 PM
It is a 1993 Ford Escort 1.9 L 4 cylinder, 4 door with hatch back style trunk

AzTumbleweed
04-21-2008, 08:57 AM
Disconnect the fuel pump and see if the fuse still blows. If it doesn't then the fuel pump is shorted.

Selectron
04-21-2008, 10:57 AM
I don't have a diagram for the '93 1.9L, but the diagrams in the autozone.com vehicle repair guide for the Escort should enable you trace the circuit.

This is the list of wiring diagrams (http://www.autozone.com/az/cds/en_us/0900823d/80/13/c8/c5/0900823d8013c8c5/repairInfoPages.htm), and Fig.7 (http://www.autozone.com/images/cds/gif/large/0900823d8013c8cc.gif) and Fig.13 (http://www.autozone.com/images/cds/gif/large/0900823d8013c8d2.gif) on that list would appear to be relevant.

I assume it's the 30A Fuel Injection Fuse that's blowing. On the first diagram you can see that the fuse feeds the fuel injectors plus various other items via the switched contacts of the EEC power relay, so a short-circuit in those items or the associated wiring could cause the problem.

On the second diagram, three circuits are shown - yours will be the one at the bottom left (labelled '1991-95') which shows the path from fuse to fuel pump via the switched contacts of the Fuel Pump Relay, so the problem could equally be a short-circuit in that section.

coojo81480
04-23-2008, 10:03 PM
I don't have a diagram for the '93 1.9L, but the diagrams in the autozone.com vehicle repair guide for the Escort should enable you trace the circuit.

This is the list of wiring diagrams (http://www.autozone.com/az/cds/en_us/0900823d/80/13/c8/c5/0900823d8013c8c5/repairInfoPages.htm), and Fig.7 (http://www.autozone.com/images/cds/gif/large/0900823d8013c8cc.gif) and Fig.13 (http://www.autozone.com/images/cds/gif/large/0900823d8013c8d2.gif) on that list would appear to be relevant.

I assume it's the 30A Fuel Injection Fuse that's blowing. On the first diagram you can see that the fuse feeds the fuel injectors plus various other items via the switched contacts of the EEC power relay, so a short-circuit in those items or the associated wiring could cause the problem.

On the second diagram, three circuits are shown - yours will be the one at the bottom left (labelled '1991-95') which shows the path from fuse to fuel pump via the switched contacts of the Fuel Pump Relay, so the problem could equally be a short-circuit in that section.

Thanks I think the fig.13 link is the one I am needing because it does have the fuse link that keeps blowing out. Doesn't look like much on the circuit so not sure what would cause it other than a bad fuel pump but I would think would go bad and not run...not blow out the fuse. I guess I will have to hunt along the wires and see if there are any spots where they may have melted or rubed through to the wire and causing it to short. I know I have to remove the back seat to get to the wires going to the pump but not quite sure where else in the car they run to get to the front. I wouldn't think disconnecting the fuel pump and seeing if it blows out would work since the circuit would be broken at the pump. Also I have installed a remote start for my car that I don't use anymore because the remote broke so I don't know if something in that area could cause it to short out...sound like a possibility?

Selectron
04-24-2008, 08:13 AM
... Doesn't look like much on the circuit so not sure what would cause it other than a bad fuel pump...
Unfortunately, I think you have more to consider than just the pump and its associated wiring. The Autozone diagrams don't always show the full picture so I had a look at the Ford diagrams for the '95 1.9L (see below). The fuel pump circuit and the wire colours correspond to those on the Autozone diagram for the '93 so I think there's a good chance these '95 diagrams will apply to your vehicle.

Diagram 24-1 shows the fuel pump circuit, but you will see that there is also a tap off the fuse which exits the diagram at the point which I've marked 'Point A'.

That leads off to diagram 24-2, where it runs clean across the page without connecting to anything and exits the diagram at 'Point X'.

Now pick up Point X on diagram 24-3 and there's a path through the switched contacts of the PCM Power Relay, which leads back to Point K on diagram 24-1.

From Point K, there are two connections into the PCM plus one to the Fuel Pump Relay coil but there's also another path which exits the diagram at the point which I've marked 'Point B'.

That leads to diagram 24-2, where it feeds the four fuel injectors, IAC valve, EGR valve, Evap valve and MAF sensor, but then there's another feed which exits at the point which I've marked 'Point C', leading to the ignition system on diagram 21-3.

I've marked that as 'Point D' - the PCM Power Relay switched contacts are shown again, as are the two connections into the PCM but we've already seen those - the only new item there is the feed into the Ignition Control Module.

It's a bit awkward to follow because it's spread across four diagrams, but that appears to be everything that's fed from the same fuse as the fuel pump. You can also see that there's no particular reason to suspect your fuel pump above anything else - the problem could be in any of those other circuits.

I assume the fault is still intermittent - if so then that makes fault-finding much more difficult - it would be a lot easier to locate if it was a constant short-circuit.

I don't know what the wiring for your remote starter consists of so I don't know if it would be likely to be a factor in this, but if you installed it yourself and know where the unit and the connections are located, and if you don't plan on using it again then I'd remove it and see if that makes a difference - it may not, but it's a whole lot easier than tracing through that list of components and wires, looking for an intermittent fault.

Diagram 24-1 (http://i180.photobucket.com/albums/x64/Selectron/Escort/Diagram-24-1.png)
Diagram 24-2 (http://i180.photobucket.com/albums/x64/Selectron/Escort/Diagram-24-2.png)
Diagram 24-3 (http://i180.photobucket.com/albums/x64/Selectron/Escort/Diagram-24-3.png)
Diagram 21-3 (http://i180.photobucket.com/albums/x64/Selectron/Escort/Diagram-21-3.png)

tripletdaddy
04-25-2008, 12:55 AM
It wasn't that clear to me if this happens once in awhile or the fuses blow as soon as they are put in. If the former, than obviously testing will have to wait until the short ocurrs. Either way, you could do a continuity test to ground on your hot wires (fuse pulled of course, testing for voltage wouldn't hurt where not sure if there's no power) and start disconnecting components that Selectron listed until you no longer have ZERO resistance. If you have no continuity to ground and an open circuit, then similarly you will have to narrow down where the break is. You need to keep in mind that you will normally have some resistance measured through the components, even only 5 to 10 ohms with some of those components possibly.

What Aztumbleweed was saying is, if you disconnect the fuel pump and IT is the problem, the fuse won't blow. If it still blows, then it's not the pump, but everything but the pump. It STILL could be the wiring TO the pump, just not the pump. This could be tested with continuity to ground instead of blowing fuses over and over. I would try to isolate the two legs of the circuit so that you are only testing the fuel pump side, then the other. Then I would test for continuity to ground with ZERO ohms just to the fuel pump circuit. If zero then problem is there, if not, then test the side with the engine components. For bad pump, next disconnect pump connection at pump and test wiring again for Zero. Yes, then wiring, No, then pump. Test AT pump side, of connector for continuity to ground. It should be Zero if pump is source of short to ground. Wiring to tank may have been pinched or frayed around tank maybe or wiring from fuse box to pump connector with wear maybe. Good luck.

thesandmanisme
10-18-2008, 04:56 PM
I cant even locate where the pump relay or the pump fuse is located. can u tell me?

rhandwor
10-18-2008, 06:42 PM
For test purposes you can make up a test wire with a 20 amp inline fuse.
They sell these at the parts store hook it up to the pump motor if it blows the fuse install a new pump. Otherwise either rewire it or find the problem. Always use a wire loom and use wire ties. Coat all splice connections with silicon.
Use a good quality crimp connector. Clink on the links and follow the diagrams.

dieselscout80
11-13-2008, 08:47 PM
I have a 1995 Ford Escort 1.9L Auto (about 90K miles on it) and it keeps blowing the 30 amp fuel injection fuse as soon as the key is turned on.

I have replaced the fuel pump relays.

I have tested the ohm reading of the injectors.

I have pulled/disconnected the fuel pump connectors (fuse still blows).

All wiring looks good.

Replaced the ECM/EEC/PCM still blows the fuse.

The ignition switch behind the key switch looks good.

The Haynes diagrams show a diode, but Ford say there isn't one.

Here is a link to where I have been trying to test it.
http://www.feoa.net/modules.php?name=Forums&file=viewtopic&p=514797#514797

Does anyone have any ideas?

rhandwor
11-13-2008, 09:40 PM
I would unplug the wiring at the computer and ohm to each injector. You should get full continuity then touch one end to a ground and touch each wire
If it gives you a reading the wire is touching something. Ohm each injector and check for one out of range. Touch two wires close to each other for a bleed. I would pull the harness and visually inspect it untape it. I think you have a wiring problem.

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