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Unread 04-11-2005, 10:05 AM   #1
BRad704
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91 YJ Fuel Problem... any thoughts?

My 91 4.0L just quit going down the interstate one day. I've tried an new pump, filter, strainer, relay and it keeps blowing the fuel system ecu fuse. the only other thing I can think of is a bad ground or shorted out power lead.

Does anyone know a way to find/isolate these elec problems?

I've been on ramps in teh driveway for 3 weeks and cant take it any more!!!!

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Unread 04-11-2005, 10:27 AM   #2
jdjonesdr
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You need to do a search...

This has been covered many times on the jeepforum.
Your problem is probably electrical, and very possibly the ignition module under the wiper water bottle on the left front fender.
Look at your tachometer when your turning the engine over. Does the tach needle bounce up and down a little? If it doesn't, the module is giving you headaches. You may want to try to find one in a junkyard somewhere that you can plug in and try.
Also, if it's the module, you can sometimes push the vacumn advance lever back and forth a few times, and if you hear a faint clicking noise, you may be able to get the module to fire again.
Hope that helps. This advice comes from personal experience. Same thing happened to me
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Unread 04-11-2005, 03:40 PM   #3
wasaw
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Racefan318, we had the same problem when we first purchased our '91 YJ. We checked all the wiring in the fuel electrical system, per the schematic. Ending up finding that the wires coming up from the O2 sensor, from the downtube on the exhaust pipe were shorting out aginst the block. Simple fix: replaced and shielded the four wires. Good luck !!!
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Unread 04-12-2005, 07:07 AM   #4
BRad704
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Quote:
Originally Posted by jdjonesdr
This has been covered many times on the jeepforum.
Your problem is probably electrical, and very possibly the ignition module under the wiper water bottle on the left front fender.

So the ignition module will cause the fuel system to cut out? I am not getting presssure to the fuel rail.


Wassaw, were did you find the schematic for the wiring?
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Unread 04-12-2005, 08:58 AM   #5
wasaw
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I used the Chilton Jeep Wrangler/YJ 1987-94 Repair Manuel, Chilton #8535. I had to take the schematic to work and blow it up on the copier so thjat I could read it (getting older). The Haynes Repair Manual 1987-2000, # 50030, also has decent schematics. When blown up, I like the Chilton better. BTW racefan, I found my short purely by luck. .
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Unread 04-12-2005, 09:20 AM   #6
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I guess its time to buy a book.

Luck doesnt usually run on my side lately.
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Unread 04-25-2005, 02:57 PM   #7
BRad704
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turns out that wasaw was completely right, down to which wire was burnt up.

for what ever reason the four wires from the O2 sensor ran up beside the exhaust manifold and block without any cover onthem. So now that wire has been replaced and run out of the way of the exhaust.

4 weeks, a fuel filter, fuel pump, fuel strainer, fuel relay, 2 maxi fuses and 12 hours of labor later... the problem was resolved with a piece of wire I already had in my garage.

oh yeah... Haynes wiring diagrams suck. I'm an engineer and they still suck.
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