Fuel pump no power

[Alex240z]

Hello. My name is Alex. 
 

Just to let you guys know that I’m very new with cars and this is my very first project car so please bear with me.

i have a 1977 Datsun 280z that has no fuel going to the engine. I figured it was the pump itself not working so I had it replaced. However, after that, it continued to not work. I’ve been searching online for some solution however I still can’t seem to figure out what’s the problem. Here are some things I’ve tried.

 

So my engine doesn’t start and while it cranks there is no volts coming to the fuel pump. I tried to look for my fuel pump relay and most people say it’s under the driver side for a 1977. However, in my case, it’s not in there but in the engine bay right next to the battery. I’ve looked at the relays and they seem okay. I can send photos if you guys request. Another thing I checked out was the afm and it seemed perfectly fine too. I test I read online was to try starting the car and open the afm flap to see if the pump would start but it didn’t so I believe it might have something to do with the relays. 
 

please any help would be amazing. 

[Zed Head]

You've left out the connections between some good details.  When did you measure voltage to the pump and where did you measure it?  And how?

When you say "no fuel to the engine" do you mean the fuel filter or the injector rail or the injectors not opening?  Sounds like you're convinced that the fuel pump is not getting power but it's not clear.

The simplest way to check your issue is to disconnect the small yellow wire from the starter solenoid then turn the key to Start.  The fuel pump should run but the engine will not crank.  Usually you can hear the pump run from the driver's seat.  You can do this to measure fuel pressure and flow also.

Also, how long have you had the car?  And when did it last run?  Check your fusible links.  Use a meter and make sure everything has power that should.

Edited May 17, 2020 by Zed Head

[Alex240z]

14 minutes ago, Zed Head said:

You've left out the connections between some good details.  When did you measure voltage to the pump and where did you measure it?  And how?

When you say "no fuel to the engine" do you mean the fuel filter or the injector rail or the injectors not opening?  Sounds like you're convinced that the fuel pump is not getting power but it's not clear.

The simplest way to check your issue is to disconnect the small yellow wire from the starter solenoid then turn the key to Start.  The fuel pump should run but the engine will not crank.  Usually you can hear the pump run from the driver's seat.  You can do this to measure fuel pressure and flow also.

Also, how long have you had the car?  And when did it last run?  Check your fusible links.  Use a meter and make sure everything has power that should.

I couldn’t measure the Exact voltage to the fuel pump because I do not have a tool that can do it although I should go and get one. I have a small sensor that detects whether there is power in a wire. I put that next to the wire that goes to the fuel pump and it didn’t go off. This is while the engine is cranking.  

I opened the line right after the fuel filter and while I try to start the car no fuel is coming out of it. 

I had this car for about a month now. It was last registered in 1990 and from what the guy told me who I bought it off it didn’t run for at least two years. 
 

I checked the links and they were good. I’ll try your method and let you know what I get. Thanks.

[Alex240z]

Here are a photo of the relays. I’m not sure if they look good.

[Zed Head]

31 minutes ago, Alexg280z said:

I have a small sensor that detects whether there is power in a wire. I put that next to the wire that goes to the fuel pump and it didn’t go off. This is while the engine is cranking.  

I opened the line right after the fuel filter and while I try to start the car no fuel is coming out of it. 

I think that that type of sensor works from AC current.  The alternation creates a magnetic field that can drive the sensor.  i don't know if they work with DC.  I know they don't if there's no current flow.

You should get a meter,  you can get a cheap one at Harbor Freight for about $6, I think.  You really need a meter to measure resistance and voltage.  There is a whole series of tests that you can run to diagnose your problem.  I'm going to guess that the fuel pump is bad and/or the tank is clogged.  Did you drain any fuel from the tank to see what's in it?  You don't want to pump a bunch of bad fuel in to the system anyway.

https://www.harborfreight.com/7-Function-Digital-Multimeter-63759.html

https://www.classiczcars.com/files/file/32-efi-book-1980/

 

Edited May 17, 2020 by Zed Head

[Zed Head]

Forgot to say, with a meter you can also measure power right there at your relay plug.  That will tell you if the relay is getting power or not.  If there is power there you can jump the pins to do what the relay would do.

[zclocks]

Hi Alex, 

Congratulations on your first project. First I think we should back up and see what year you have. I have a 75  and 75-77 FI was much the same. 

The FI manual you need is the 1980 version as there are changes. In 78 the FI relays were located under the hood according to the FI manual and they show 4 on the schematic just like in your photo . Are you sure the car is a 77? Did you look at the production date on the jam of the drivers door? If this is a very late 77 it might have the newer 78 relay upgrade. Maybe some one of the 77-78 owner could chime in?

Look at the items I've enclosed and if you have the 4 relays then the schematic could help you track down the wiring, it's for a 78. I have seen both FI manuals somewhere free to down load , but if not I have copies of both you can have. It's almost essential to get a Datsun 280z Service manual as it is really the best for an owner to have.

[SteveJ]

I this case the build date is everything. I'm guessing the build date is 9/77 or later. The plate in the door jamb should tell you if it hasn't been removed or damaged.

[Alex240z]

2 hours ago, zclocks said:

Hi Alex, 

Congratulations on your first project. First I think we should back up and see what year you have. I have a 75  and 75-77 FI was much the same. 

The FI manual you need is the 1980 version as there are changes. In 78 the FI relays were located under the hood according to the FI manual and they show 4 on the schematic just like in your photo . Are you sure the car is a 77? Did you look at the production date on the jam of the drivers door? If this is a very late 77 it might have the newer 78 relay upgrade. Maybe some one of the 77-78 owner could chime in?

Look at the items I've enclosed and if you have the 4 relays then the schematic could help you track down the wiring, it's for a 78. I have seen both FI manuals somewhere free to down load , but if not I have copies of both you can have. It's almost essential to get a Datsun 280z Service manual as it is really the best for an owner to have.

 

 

Yeah that relay under the drivers side dash doesn’t exist for me. I tried looking for it under there but it’s just not nor is there the two wires supposed to connect to it. I checked the old pump and connected it to a 12V battery and it worked fine and blew all the oil out of it. But when I installed it back into the car and tried starting it I got nothing. I checked all four fuses and I got electrical signals from them and from the relays and fuses in the engine bay. My theory is that the wire got cut somewhere along the passenger side so my priority is the check the connection under the passenger seat with a dmm and see what’s going on. When I get the chance I’ll let you guys know the exact year. Thanks.

[Yarb]

Trying to chime in here on the location of the FP relay. I have a 78 280 manufacture date 1/78. By chance did you happen to check behind the passenger seat. It’s mounted to the rear of the seat support with the harness running over to a grommet above the pump assembly. Worth taking a look. 

[Alex240z]

The car is a 4/78 btw

[SteveJ]

20 minutes ago, Alexg280z said:

The car is a 4/78 btw

That would make it a 78.