97 Escort blows the 30 amp fuel injection fuse
 

My 97 Escort recently started blowing the 30 amp fuel injection fusable link when accelerating hard. These fuses aren't cheap.

It runs fine otherwise. Any ideas?

I think the fuel pump may be shot. When you accelerate hard the pump seems to pull to many amps.
Look at this:
Good luck!

When the fuse blows the pump stops because the fuse powers the fuel pump relay so no voltage goes to the pump. A new fuse and all is wll again for a while. The video assumes the car won't start due to a questionable fuel pump.

Is there a way to test the current draw of the pump?

I thought the fuel pump always worked the same and the excess is returned to the gas tank. Shouldn't the current draw stay the same no matter how hard the car accelerates?

The Alt/Gen internal regulator is circuit protected on that 30. How long during a hard thrttle till it pops? If quickly, you might unplug the connector and see if it still blows...

It takes maybe 5 seconds of hard throttle to blow the 30 amp. I took the alternator off and had it tested. I'm told it's ok.

If the fuel pump was bad, wouldn't the 20 amp fuel pump fuse blow instead of the 30 amp?

I won't comment here since you are in good hands with Hayapower and bluewind.
It's always nice to see the light come on upstairs when you start asking good questions.

That 30 link protects the Alt reg,,, and feeds the CCRM for the internal PCM power relay (load side), which when closed,, also controls the fuel pump relay (relay coil side 12v~ PCM in charge of grounding to close relay) within the CCRM,, as well as control for the cooling fan.

Most of the engine controls are fed through the 30 link with the injectors and IAC direct through the closed PCM power relay. The MAF, EVAP can, EVR, EVAP sensor IMRC all pull through the 30 link. If the fuel pump was to overload, it 'should' blow the 20.

Now you're scaring me. Almost anything could be going wrong from what it sounds like.

Would it prove useful to gently drive the car to the parts store and have them read the codes?

A local mechanic suggested putting in a larger link and see what fails. He was serious. That does not sound like a plan to me. I'm hoping to avoid a potential fire. It was also suggested that a frayed wire could be the problem. I haven't found any yet but I would expect a frayed wire to cause the link to either blow instantly or intermittantly. This problem is both predictable and repeatable.

twj:
Electricals are not my forte but I have some experience. Hayapower really knows the circuits.
Here is what I would do based on my experience: This is an old car and therefore it is possible that the charging system is on the fritz. (Hayapower says the 30amp is protecting the voltage regulator) So check the charging system, including a load test for the battery. Make sure the battery poles are clean and all ground connections are good.
Trouble with the charging system can manifest itself in mysterious ways.

While you are under the hood check all connectors for dirt and corrosion crud, and check the wires for chafed insulation. Wiggle the harnesses while idling the engine.

(I wonder what Hanky would do if the light upstairs starts flickering?)

I haven't found any bad wires or poor connections yet but I have found a few dried out, cracked and broken vacuum hoses. The engine should run smoother once it is fixed.

Someone suggested a bad throttle position sensor or crank shaft position sensor. I have no idea how to test them and would rather not just start replacing parts hoping to find a bad one.

Am I barking up the wrong tree?

The light is starting to come on . but dimly.
Since you can't remove the items all fed by that fuse,there is possibly an alternative and that would be to splice a 20 amp fuse into the feed for the supplied items and maybe you might get lucky if one of them blows only their individual fuse. It's a bit of work .but it would rule out the various sensors and items if done maybe two at a time. If only the 30 amp fuse still blows you will know it's not one of the things you provided with a separate fuse.
What do you think?

Fix the cracked hoses. I bet it makes a difference. As for testing the sensors: look for Youtubes on" Testing a _______". Richpin, Ericthecarguy, ScottyKilmer and a few more do a great job explaining thes things.


Hanky's idea of splicing a lower amp fuse in for various circuits makes sense to me. I would look what the typical amperage would be for individual circuits. 20 amp might not be sensitive enough. It's a process of elimination.

I would hope that if the problem is blowing a 30 amp fuse a 20 should certainly be sensitive enough to blow before the 30.
It's a lot of work to do this, but with limited equipment to work with maybe someone can come up with a shorter procedure without so much work.

After trying to figure out which wire goes where and anything else I could do, I have decided to leave an automatically resetting circuit breaker in place for now and try to drive the car moderately. We've been driving it for a week this way with no problems. If the breaker trips the car can be restarted within 30 seconds. This is no longer an open road vehicle so it seems to be a workable solution for now. Should the problem worsen the culprit might become more readily noticable.

I hope.

As you know two and a half heads are better than one and maybe I can provide the half head.
Since you state the problem occurs on hard acceleration, just what takes place on hard acceleration?
The engine torques and moves. Usually it lifts up in the front. Could you try stepping on the gas in drive with the foot brake applied and see if you can create the problem of making the fuse blow? If so, all you need to do after that is watch what wiring moves /gets close to possibly something hot and you might be able to create the problem with the vehicle in park idling. That might get you even closer to the problem, if, that is what might be happening. It might be worth a shot , try it and let us know if it helped .

The alternator failed yesterday. It won't charge at all. I'm replacing it today. Let's hope that this was the real problem all along.

I also just picked up another Escort, a 1998 ZX2. I'm the second owner and went to work with the original owner two weeks after she bought it. She has taken great care of it and I think that I will be enjoying it for some time.