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fuel pump wires? FOUND PROBLEM.........NEED ECU ASAP!!!!


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the orange wires with a black tracer that plug into the resistor by the egr solenoid i believe are power to the fuel pump. I'm not positive on this but i know my pump wouldnt run without these connected. theres also a green wire along that same harness that was cut on mine and the pump wouldnt run till it was reconnected. these wires were from an 89 xj though

 

i hope this helps a little bit. i know its kind of vague but hey i tried.

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oh that kinda helps, but i just need to know which wire is pos. and where the ground is.. iam only gonna run a on/off switch for power..

That may not be the best of ideas. In case of a wreck etc you don't want your fuel pump running after the engine is off. At least make the switch large and easy to reach in case you get trapped in the cab and you smell something burning. I know how you Texas boys like your BBQ's, but I don't think you want to be the main entree :D !

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Where are you trying to connect in, in the engine compartment or back by the tank?

 

The black wire coming out of the fuel pump assembly is the ground. The heavier wire going in (I think orange is the correct colour for your year but not all years were the same) is for the fuel pump, and the third wire (violet in 1988 IIRC) is for the fuel level sender.

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well it still won't start, i just put new spark plugs in.. all it does is crank.. but no start.. i saw three blue relays on the passenger side of the engine bay.. what are they to? what else may mess up if it gets wet? i hope its not the distributor but iam sure that didnt get wet

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Slow down and approach it logically. I saw your other post about tossing in ECUs and "stuff" because you don't "think" you have spark. That's no way to trouble-shoot a problem.

 

Do you have spark, or not? Easy check -- pull the wire off a plug, hold it in well-insulated pliers near any bolt on the engine (or near the tip of the spark plug), and have someone crank over the engine. If you get a big, fat, blue flame -- you have ignition. No flame -- no ignition.

 

If you don't have ignition, try checking the CPS -- or just replace it, since the test isn't 100% reliable. There's a resistance spec for it, but the spec is for "warm engine." I'm still trying to figure out how to warm up an engine that won't start ...

 

If you have spark but no start, then you wonder about fuel. If you don't hear the fuel pump running for a few seconds when you first turn on the key, it probably isn't getting power. Crawl under the chassis, unplug it (there's a connector about a foot away from where the wires go into the tank), and check for current on the big, fat wire.

 

If the fuel pump has power and runs, pump it up 'til it stops, turn it off, then push the button on the Schrader valve on the fuel rail. (Put a jar or a large absorbant cloth in front to catch the gasoline.) If you get a good squirt, you have fuel pressure. No squirt = no pressure.

 

If you're not sure about the fuel, just pour a small amount of straight gasoline into the mouth of the throttle body. Not a lot, just a spalssh. Crank it over. If you have decent spark, it should start and rev for a couple of seconds on the fumes from that splash. If it won't start at all, go back to checking for spark.

 

Do NOT just start throwing parts at it ... unless you have deep pockets and enjoy self-flaggelation.

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thanks for the heads up eagle..

iam about to get a cps for it..

 

but i think today after work iam gonna check and see about fuel pressure.. since i put the fuel pump on a switch i turned it on then tried cranking the truck i heard the fuel pump goin but it sounded like it stayed on instead of "priming" then getting quiet.. my friend says the fuel pump stays on like that all the time i just can't hear it because the truck is running

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If it is on a switch it will stay on constantly. The prime/ then off is part of the ECU, which is no longer controlling the pump. The pump is just a motor, power&ground= running. Lose one and it shuts off. When the truck is running the pump runs contantly, you just don't hear it.

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I was thinking you just took the ecu wire and threw a switch in it sorry about that but yeah what he said :agree: yeahthat.gif . Just a quick thought though would it flood the motor if left on to long before the engine turns over??? I would think so but the injector don't fire till the comp says to right. Maybe i am nuts :nuts: i just realized it can't flood if the injector doesnt open.

 

Cole

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The cps is very sesitive when it comes to any thing that touches it like water sand ect. ect. just don't drop that bolt in th bellhousing also you can slit the new cps holes so next time the bolts only have to loosen. I think Pete has a pic of it done or search the forum i seen it before.

 

Cole

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well i found the probelm...

 

i put a new CPS on today and it still didnt start... so as i was about to go in i decided to take my ECU off and check it out.. i unbolted it.. uncliped it and handed it to my friend... he turned it over to look at it and TONS of water poured out of the plug holes... so my ECU was a swimming pool.. and now i know ... that was the problem haha..

 

does anyone on here have a 4.0 5spd ECU??? i need it quite badly and quickly... iam doin my clutch friday night after work.. and wanna be able to drive home and to work monday

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I'm heading to the 'yard tomorrow...I can look for one for ya if you want. Last time I got one (was a couple years ago), it was around $10.

 

Does it have to be from a 5 spd? You can't swing a dead cat without hitting a billion 4.0/AW4's, but the manuals are sparse (not to say there aren't any, though...)

 

Jeff

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