Truck runs...but won't restart

[Konabear]

I inherited a 1987 R10 from my uncle in January. I drove it from TX to WA without any issues (except a weak heater), but now I'm having a problem. About a month ago I drove the truck for ten minutes and shut it down. It wouldn't restart. The engine cranked fine, but no combustion. I've been looking through the forums and have been able to get it to start and run. This is what is going on.
When I open the door, the interior lights do not come on. When I turn the key to the RUN position the fuel gauge doesn't move, the fuel pump does not come on, and the check engine light is not illuminated.
I've replaced the fuel relay. When I run power directly to the red wire on the fuel relay bundle I can hear the fuel pump run. After that I can start the truck and it continues to run. I've disconnected the fuel pump relay and the truck continues to run so I believe the oil pressure switch is working. However, when I shut the truck off it won't restart without running power directly to the test wire for the fuel pump.
Any suggestions?

 

[82sbshortbed]

I like the mechanical fuel pump myself. Cheap and easy to replace. That's what I use too many things go wrong with electric pumps. If you don't have fuel injection I don't see the need for one. Jmo.

 

[Konabear]

Second question.
I found a trouble shooting chart in the service manual (chart A-1 in section 3) for when the service engine soon light does not come on with the key in the accessory position.
Step 1- does the engine start? No
Step 2- Is the continuous battery fuse and ECM fuse OK? I checked the ECM fuse on the panel to the right of the emergency brake. Where do I find the continuous battery fuse?

I'll move on to step 3 after I check the battery fuse. For step 3 it says to disconnect the ECM and check the grounds on CKT 340 and 439. Where is the ECM located?

In the past I've taken my cars to a mechanic so this is pretty new to me, but I'm taking my time to learn how.

 

[Konabear]

I like the mechanical fuel pump myself. Cheap and easy to replace. That's what I use too many things go wrong with electric pumps. If you don't have fuel injection I don't see the need for one. Jmo.

The engine is fuel injected (TBI) and has dual fuel tanks with an electric pump in each tank. I found paperwork showing my uncle had both pumps replaced three years ago.

 

[Backfoot100]

Ok, you gotta clear some stuff up. What are you trying to accomplish with the key to the ACC position?
It'll never run in ACC. ACC is to power accessories like the radio without powering the ignition system. Its designed that way. Or is your terminology for Accessory something other than Accessory.

The gauges, pump and relay won't power up until you turn the key to RUN. Then START will crank the engine, after it starts, it stays in RUN keeping everything energized and running.

 

[Konabear]

Ok, you gotta clear some stuff up. What are you trying to accomplish with the key to the ACC position?
It'll never run in ACC. ACC is to power accessories like the radio without powering the ignition system. Its designed that way. Or is your terminology for Accessory something other than Accessory.

The gauges, pump and relay won't power up until you turn the key to RUN. Then START will crank the engine, after it starts, it stays in RUN keeping everything energized and running.

Bad terminology on my part. With the key in RUN, the pump doesn't run, the fuel gauge doesn't work, and the Service Engine Soon light is not on. I'll edit my original post. Thanks for the point out.

 

[Frankenchevy]

Did you check for 12vdc at firewall junction?

 

[75gmck25]

The feed to the fuel gauge runs through the dash switch for the tanks. If you get no reading in either position, something is disconnected. With TBI I'm not sure what happens if the solenoid under the truck has no power, but that may also power the fuel pumps.

Bruce

 

[Rusty Nail]

I've disconnected the fuel pump relay and the truck continues to run so I believe the oil pressure switch is working.

Wait.
What?



Weak heater huh?

In a Chevrolet?

UNHEARD OF

Next time you duplicate the issue, you could flop down and rap on the gas tank with a rubber matter or similar a couple of times to find out if the issue persists.

Outside of that? Gonna need some pictures of your supposed "87R10". Underhood pics too!

 

[Bextreme04]

The fact that none of the lights come on and you have no pump and no dome lights tells me you most likely have a bad battery fusible link. As others have said, check for battery voltage at the firewall junction block. It is a twin post black block on the firewall above the engine. Standing at the front of the truck looking at the firewall, you should have 12v from the terminal on the left to ground. If not, you probably have a broken wire or melted fusible link. That wire runs directly down to the starter to provide continuous power to the fuse block.

 

[Konabear]

The fact that none of the lights come on and you have no pump and no dome lights tells me you most likely have a bad battery fusible link. As others have said, check for battery voltage at the firewall junction block. It is a twin post black block on the firewall above the engine. Standing at the front of the truck looking at the firewall, you should have 12v from the terminal on the left to ground. If not, you probably have a broken wire or melted fusible link. That wire runs directly down to the starter to provide continuous power to the fuse block.

I will check this on the weekend. If the fusible link is melted would I still be able to start the truck the way I am starting it now? Basically priming the engine via the red test wire on the fuel pump relay.
I did install a new starter in March.

 

[Konabear]

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I installed a new ignition coil. This is what the wires coming from the top look like. I can not find the other end of the broken wire, but the truck runs with it like this. I’m going to try to find the wiring diagram, but in the mean time does anyone know what that wire does?

 

[dvdswan]

I would also look at the ignition switch on the column.