Fuel pump gets no signal to run

[P8riot0366]

I just (3 months ago) installed a Walbro pump and hotwire kit, new 60# injectors, and TT chip. I also replaced the oil cooler hoses and put in a new Optima red top battery.

For some reason, the fuel pump won't run when the key is turned. When I put a power probe to it, it runs and charges the rails, but the car won't start.

The engine harness is butchered, thank to the previous owner.

I get tach activity when it cranks and it will try to start with starter fluid in the intake.

I have the service manual and traced some wires, and here is what I've discovered so far:

The oil pressure sensor is not on the car and the sending unit has been jumpered.

The pink/black wire has been cut and spliced to bypass the fuel pump relay.

The wire then goes to the brown wire of the injector harness and is spliced into a red wire that goes to the ignition slot on the fuse block.

The car ran until I installed the stuff listed above, and had a stereo installed. In fact it ran until I parked it in the driveway to look at why it was running rough. There it sits. I have been wrestling with this issue for months now.

I'm not an electrical guy, but I know how to use a multimeter and power probe, kinda-sorta read the wiring diagrams.

I had seen some drawings posted in these forums (now gone for some reason) that seemed to address the connectors and what to test for, but the weather wouldn't cooperate to let me troubleshoot until recently.

I have searched these forums to find information and have found some things that have allowed me to eliminate some causes, but I still can't find the root cause.

Any suggestions would be greatly appreciated.

 

[turbo89]

I just (3 months ago) installed a Walbro pump and hotwire kit, new 60# injectors, and TT chip. I also replaced the oil cooler hoses and put in a new Optima red top battery.

For some reason, the fuel pump won't run when the key is turned. When I put a power probe to it, it runs and charges the rails, but the car won't start.

The engine harness is butchered, thank to the previous owner.

I get tach activity when it cranks and it will try to start with starter fluid in the intake.

I have the service manual and traced some wires, and here is what I've discovered so far:

The oil pressure sensor is not on the car and the sending unit has been jumpered.

The pink/black wire has been cut and spliced to bypass the fuel pump relay.

The wire then goes to the brown wire of the injector harness and is spliced into a red wire that goes to the ignition slot on the fuse block.

The car ran until I installed the stuff listed above, and had a stereo installed. In fact it ran until I parked it in the driveway to look at why it was running rough. There it sits. I have been wrestling with this issue for months now.

I'm not an electrical guy, but I know how to use a multimeter and power probe, kinda-sorta read the wiring diagrams.

I had seen some drawings posted in these forums (now gone for some reason) that seemed to address the connectors and what to test for, but the weather wouldn't cooperate to let me troubleshoot until recently.

I have searched these forums to find information and have found some things that have allowed me to eliminate some causes, but I still can't find the root cause.

Any suggestions would be greatly appreciated.

The first thing I would do .. is UNDO all the splices and rig work with the jumpering and put it back to stock configuration .. from there the troubleshooting is super simple
with all the splicing and wiring debacle .. you don't know where to even start to diagnose .

 

[P8riot0366]

The problem is that there looks to be wires missing. I am trying to find a replacement harness, but that's a battle all in itself. I figure that if I can get a stock harness, then I can figure it out a lot more easily as you say.

Plus, the oil pressure sensor isn't even on the car., so there's nothing to plug the sending unit into.

 

[~JM~]

Wiring diagrams: http://www.gnttype.org/techarea/electrical/wiring.html

IF... The wiring harness was original... I would say that the fuel pump relay on the passenger side fender was probably bad.

The original starting circuit energizes the pump for 2 seconds when you initially turn the ignition key. This pressurizes the fuel rail for the engine start. If the fuel pump relay fails to make up & start the pump, the fuel pump will start after cranking the engine enough to build 4psi oil pressure.

Good luck. Electrical problems are the most frustrating to resolve.

 

[GNRick]

Check your fuel pressure with a gauge. If you didn't mess with any wires under the hood then maybe the hose came off the pump inside the tank or the hose clamp is loose. Sounds like you were able to get the pump to run.

 

[HighMileage]

You mention that the engine harness is butchered. I'd start by getting a replacement. Check Caspers electronics.

As far as getting the pump to run,I eliminated all of the complication.

My Hotwire runs from the alternator...to the Hotwire fuse on the back...to a switch hidden inside the car...to the pump. That simple.

No relays,no complication and a piece of cake to troubleshoot if need be. ....and there hasn't been a need.

 

[P8riot0366]

You mention that the engine harness is butchered. I'd start by getting a replacement. Check Caspers electronics.

As far as getting the pump to run,I eliminated all of the complication.

My Hotwire runs from the alternator...to the Hotwire fuse on the back...to a switch hidden inside the car...to the pump. That simple.

No relays,no complication and a piece of cake to troubleshoot if need be. ....and there hasn't been a need.

I have a replacement harness coming from a seller on eBay who pulled it from another '87. After it gets here next week, I'll swap it in and see where I stand. I counted no fewer than 8 splices and 5 cut wires on the current harness. The replacement is supposed to be tested and complete. Fingers crossed.

You mention a switch in the car. Do you turn it on every time you drive and then off when you stop? What happens if you forget to turn it off? Can that burn out the pump?

Thanks for the reply and I look forward to getting back on the road soon, I hope.

 

[HighMileage]

You mention a switch in the car. Do you turn it on every time you drive and then off when you stop? What happens if you forget to turn it off? Can that burn out the pump?

Thanks for the reply and I look forward to getting back on the road soon, I hope.

You don't forget to turn the switch off. I shut the switch off first,then the ignition. I trained myself/got in the habit of doing it that way.

It's sort of like a shut-down checklist in an airplane. There is a procedure to be followed.

(The switch also makes for an excellent theft deterrent. There should be many on these cars)