Some ideas to get the K5 running?

336wheeler

Well-Known Member
Joined
Sep 9, 2006
Location
Boone
Well I was hoping to make the fun caravan this weekend, but the K5 isn't wanting to cooperate with me. I was driving it and it just cut off. I couldn't start it back up so I waited about 30 minutes and tried it again... it maybe ran for a minute. Since then, I haven't gotten it to fire back up. I don't want to believe that it jumped time, although I'm starting to think it has. It is getting fire to the plugs, so I don't believe the distributor is the problem. I believe the fuel filter and fuel pump to be in working order also. Any ideas? I was hoping that it didn't jump time... because that would definitely mean I don't have enough time to fix it by this weekend. By the way, its an '87 with a TBI 350.
 
do you hear the fuel pump gut on when you turn on the key? if you spray ether or poor gas in the throttle body will it start?

if the fuel pump kicks on, you could maybe see how much fuel/pressure youre getting to the TB...

id say that its a fuel/timing issue if your getting spark
 
Are the injectors spraying fuel while your trying to start the engine??Did the check engine light come on??Can you hear the fuel pump working when you turn the engine over??

It should backfire thru the Tb if it's jumped time.
 
A 350 isn't going to jump time. If it does, you've got big problems, bud! It sounds like the fuel pump's dead. The relay is on the firewall. It has a random wire with a spade connector hanging off it, if memory serves me. This is the relay bypass terminal. Jump +12v to that and see if you can hear the fuel pump running. If it does, then the relay's probably bad. If it doesn't, then get under the truck with a meter.

The fuel pump connector is along the DS framerail. Two wires. Disconnect that and check for voltage when you've got the relay bypassed. This can be done with the ignition off, BTW, as long as you take the +12v off the battery directly.

If you have voltage at the connector, then plug it up and try again. It may have just been dirty, but more than likely it's the pump. Don't waste the money on a complete sending unit, it won't take you any longer to just change the pump. Unless, of course, your fuel gauge isn't working either. Get the pump, it should come with the o-ring for the sending unit. Also get the little sock filter that goes on the pickup tube. I believe it's sold seperately.

Drop the tank. It's much easier to do if you remove the bumper. Hopefully, you don't have a full tank. With gas prices what they are, I'm sure you're like me and just putting in $20 when you need it! If it's full, syphon off as much as you can. Clean off the crud and find the notches on the retainer ring. You have to unthread that with a punch and a hammer. You should really use a brass punch to avoid any chance of creating sparks. Bad juju, y'know? Once the sending unit's out, the rest of the procedure should be fairly apparent. Installation is the reverse of removal! :D
 
NC is the best repair manual ever. Thanks guys; I was wanting to believe it was the fuel pump over a timing problem. That lockring that you have to punch off, is there a tab that needs to be folded down? I was looking at it and it looks like I have to push down a tab before it'll want to spin. External fuel pumps > internal fuel pumps.
 
I don't remember folding down any tab. It should only move about 15° or so before it pops off. Make sure you clean all the crap from around it before you take it off. You don't want that in your tank. I'm guessing you've already got the tank down? If so, Damn! That was quick!
 
Haha, the previous owner cut a hole in the floorboard above the fuel tank, so it's pretty quick access to it. They left the hole there, but I made a little hinged door to go over it with seals. It's pretty trick.
 
Btw, dumbass me didn't even think to shoot some ether in the throttle body. Fired up for a few seconds once I did that, so it was definitely the fuel pump. I'm trying to get a new one in tomorrow in order for the CTB ride this weekend.
 
do you have my old truck?
i used a TORCH :cool:
 
Got a new one going in tomorrow, removal of the old fuel pump was a breeze thanks to the hole in the floorboard. If you want to make your life easier in the future, just go ahead and cut yourself one, haha.
 
Well I put the new fuel pump in, but it still wasn't wanting to cooperate. I believe it to be a wiring issue because I can't hear that the pump is turning on when I turn the key on. Catfishblues mentioned something about the fuel pump relay... any ideas?
 
I had a bad Hall Effect Switch in my S10 distributor once that was TBI also, basically the switch tells the injectors to pulse when your cranking over the engine. Pull your air cleaner and have someone crank the engine if there not squirting thats prob your problem.
 
Catfish, following those wires on the DS framerail end up into a harness.. which ends up into two connectors. Both of the connectors end up going back into the firewall, which I suppose then goes to the ignition. Where's the relay there? I did check the fuses.
 
My relay is hanging on the firewall, I believe. I'll try to verify that this afternoon. But I remember it being on the passenger side. It's got a random red wire hanging off it that doesn't go anywhere. That's the test terminal.
 
I just dealt with a very similar issue. Engine turned over just fine, no spray from the injectors while cranking. Dumped fuel, started right up. It turned out to be a bad connection on a failing oil pressure switch on my 87 Jimmy 5.7/TBI. This is the switch behind the distributor ($5.99), not the sending unit near the exhaust manifold on the driver's side ($25.00). Autozone's computer did not state a difference in the computer, that's why the prices are there. I couldn't find any way to test it, so just replaced it. Runs like a champ now.
 
SarasotaUSMC, for a while I investigated what you were talking about (that switch on the back of the distributor.. there are two side-by-side?), but then I also thought that if it was that, I should be able to hear the fuel pump running when I turn the key on, which isn't happening. I just looked at the TBI wiring diagram for the fuel pump and it shows the fuel pump relay... but I have no clue where it actually is on the vehicle. According to it, it should also be in the same wiring as the fuel filter? This problem eludes me... and my K5 won't run...
 
336wheeler said:
SarasotaUSMC, for a while I investigated what you were talking about (that switch on the back of the distributor.. there are two side-by-side?), but then I also thought that if it was that, I should be able to hear the fuel pump running when I turn the key on, which isn't happening. I just looked at the TBI wiring diagram for the fuel pump and it shows the fuel pump relay... but I have no clue where it actually is on the vehicle. According to it, it should also be in the same wiring as the fuel filter? This problem eludes me... and my K5 won't run...
Click to expand...

What wiring for the fuel filter? I didn't think that was a powered device! Seriously, though, the relay should be just hanging out under the hood, probably on or near the firewall.
 
Fuel pump relay is on the firewall, passenger side towards the middle.

fuelpumprelay.jpg


There is a way to bypass the relay and direct wire it, I never figured it out, but you should be able to find the info on either CK5 or Pirate.

My fuel pump didn't run every time I turned the key on prior to fixing the oil pressure switch. Now it does. I didn't think they should have been related, but who knows.

Fuel filter is on the passenger side, inside frame rail. There's no power that goes to it.
 
336wheeler said:
SarasotaUSMC, for a while I investigated what you were talking about (that switch on the back of the distributor.. there are two side-by-side?), but then I also thought that if it was that, I should be able to hear the fuel pump running when I turn the key on, which isn't happening. I just looked at the TBI wiring diagram for the fuel pump and it shows the fuel pump relay... but I have no clue where it actually is on the vehicle. According to it, it should also be in the same wiring as the fuel filter? This problem eludes me... and my K5 won't run...
Click to expand...

Not the connections on the distributor itself. If you get back there, disconnect those two connectors that you are talking about, directly underneath to the rear is the oil pressure switch. It looks very similar to temp sending guage and has a two wire connector on it. I'd take a pic of that too, but would have climb back into the engine bay to do it.
 
Sweetness. Thanks guys - yeah, there are no wires on the fuel filter, which is why the diagram sort of confused me in the first place. Thanks for the pictures man.
 
I found it.. but I'm guessing you have to pull the distributor to replace it? It's in a very inconvenient location to work on, haha. I couldn't really get a wrench or a socket with an extension on it.
 
I was able to get to it without removing the dizzy. It was a real PITA though.

Also, not sure if it was stock or something that the PO did, but it was plumbed up to a 90 deg elbow coming out of the block, and it broke off while trying to get it out. The broken part came out easily enough with an EZ Out, but just added to the frustration of trying to find a replacement. As I said in a post above, this part isn't really identified in any of the parts stores computers.

Try making sure the connection is good before you start to take it out. Mine was a bad connection causing the bulk of the problem, but the switch was going bad too.

Good luck with it. If you replace it, I hope it solves your problem.
 
sarasotausmc said:
Fuel pump relay is on the firewall, passenger side towards the middle.



There is a way to bypass the relay and direct wire it, I never figured it out, but you should be able to find the info on either CK5 or Pirate.

My fuel pump didn't run every time I turned the key on prior to fixing the oil pressure switch. Now it does. I didn't think they should have been related, but who knows.

Fuel filter is on the passenger side, inside frame rail. There's no power that goes to it.
Click to expand...

There is a red wire dangling from the relay. It is connected to the Normally Closed tab on the relay. If you run +12v directly from the battery to this wire, it will bypass the relay and turn on the pump, assuming it's good. The reason it wouldn't run when the OP switch was bad is because the computer doesn't want you siezing up the motor if you run out of oil. I believe it shuts down the spark and FP circuits if it detects low oil pressure. I believe if you have spark, then the switch is good. The Chilton's manual goes into good detail on this situation.
 
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