Some ideas to get the K5 running?

The 90 deg connector on the OP switch is NOT factory.
If I remember correctly the factory sender is much smaller but much more $$$$.
SO everyone uses the parts house version. Always makes for a fun trip to lowes with a bunch of parts test fitting brass connectors.
If you have to go this route, I recommend using a 135 degree or backwards 45 it will clear much nicer.

As stated if OP switch goes out FP shuts down thinking there is no Oil pressure.

Quick dirty test for spark, is just to dump a smidge of gas or spray some ether into the TB while you crank on it. That should eliminate the question of fuel supply.
 
Alright, got two of us to work on it tonight... some new information to add to the fire. I've got the fuel pump working, know the fuel filter isn't clogged, and the lines are not blocked. The injectors are getting gas because I watched them spray gas into the throttle body. Here's the issue: if I dump gas into the throttle body and it's just sitting on top of the butterfly valve, it will fire up. If I don't do that and just try to start it regularly, I can watch the injectors spray... but it won't fire up. Can the injector tips be clogged just enough to not let it get enough gas to fire, but clean enough to spray? It seems like even if they were spraying a little bit, it would combust enough for the engine to run. This really stumped me... especially since the issue happened while I was driving the K5. Any ideas?
 
336wheeler said:
Alright, got two of us to work on it tonight... some new information to add to the fire. I've got the fuel pump working, know the fuel filter isn't clogged, and the lines are not blocked. The injectors are getting gas because I watched them spray gas into the throttle body. Here's the issue: if I dump gas into the throttle body and it's just sitting on top of the butterfly valve, it will fire up. If I don't do that and just try to start it regularly, I can watch the injectors spray... but it won't fire up. Can the injector tips be clogged just enough to not let it get enough gas to fire, but clean enough to spray? It seems like even if they were spraying a little bit, it would combust enough for the engine to run. This really stumped me... especially since the issue happened while I was driving the K5. Any ideas?
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I'd be tempted to look at the plugs at this point.
 
I got one of my buddies that owns a shop to come over, and what we found out is that on both the old and new fuel pump (the old fuel pump still works I found out), both pumps will run when straight wired to a 12v battery charger, but once inside the tank, they won't do anything. That is the problem. We tried every combination we could think of for getting it to run inside the tank, but then I was messing around with the float on the old pump and when the float registered that the tank was empty, the fuel pump ran. It's like something is backwards about the fuel pump, both the old and new. Has anyone ever ran across this? As a last resort, I'll figure out a way to put an external pump on there.
 
I have no idea. If you are getting everything from the gas tank through the injectors, you should be running. It sounds like something with the plugs, instead of the pump. Cap, rotor, wires and plugs all good? I have nothing else to offer at this point.
 
The other night the injectors were spraying. Now they aren't doing anything, and the fuel pump is acting like its backwards. It's the weirdest problem I've ever seen... I'm waiting to hear back on somebody else to see if they've ever ran across it too. I have no idea about this.
 
You've gotten some wiring screwed up at this point. Remember, you've got one wire coming down the framerail for the pump positive. The other is for the fuel level sending unit. The pump grounds to the chassis.
 
There is no way to get the wiring disoriented back there; remember that the harness back there is sort of keyed... it only orients one way. And plus, I haven't changed any of the wiring back there. I get 9v back there.. is that low enough to make it act weird? Oh by the way.. that ground on the chassis doesn't really effect how it works. The pump has sort of a double ground; one in the harness and one going to the frame rail.
 
A more condensed version of the problem is this: I can straight wire both of my fuel pumps and they work fine outside of the tank. I can put them in the tank (and straight wire them), and neither of them work. The float on the old pump was weird.. if I lifted it up about an inch, the pump cut off (outside the tank). I haven't tried that with the new pump, but when I straight wire it and it's in the tank, I can't hear it running. I even took the gas lines off and straight wired it... it should've been shooting gas out. It almost seems like it shouldn't even be able to happen.. but it has. Is there something about the inside of the tank that can affect a pump's ability to work? By the way, it does have gas in the tank... haha.
 
Only thing i could think of would be that somehow the wiring gets shorted when installed in the tank somehow?
 
I've put the new pump in twice.. the first time it didn't run in the tank so I pulled it out and tested it, and it works outside the tank, so I put in back in... still doesn't work inside the tank. It's the weirdest problem I've ever heard of anybody running into... I'm not sure what's up with it. About the wiring being shorted, I don't think it could happen twice. I'm pretty sure both pumps are in working order, its just that they don't work inside the tank. It's definitely some of my weird luck.
 
Is the tank grounded to the chassis well? Could the fuel level sending unit be acting as a ground? You've got some funky resistance getting in there somewhere, and it sounds like a high resistance ground. Are you sure the wires inside the tank are good?
 
I'm going to try to just hook the pump (positive) up and ground it to the chassis only, and see if it runs. I'm thinking that the sending unit is somehow not letting the pump run.
 
The pump will almost always run outside of the tank because there is no load on it. Most bad pumps will even run without a load. You've got too much resistance in the pump circuit, fix that and go from there. Until you do that you're really just wasting time playing with the pumps. Get 12 volts back to the pumps and less than .4 ohms resistance on the ground, and see where that puts you.
 
^ yep.

Basically the pump can turn ll day with no head pressure on it, but it doesnt have enough umph to actually pump fluid.

Then again, at 9V it probably wont.

Answer #1 you have to get 12 (or real darn close) to the pump and an electrically good ground .

Before you do this all your testing is for naugt
 
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