fuel pump troubleshooting

[ethanrover98]

Hello all,
Need some help...........I am stuck at work and have limited time to search. I drove to work this morning and the truck ran great (98 D1, 202,000miles). Shut the truck off and came back about 15 minutes later and started it up and it began to sputter and would barely idle (like it was running out of gas). Now it won't start at all........

Things that I've checked:

-fuses under the hood and under the dash

-I have spark

-the pump does not cycle on (prime) when you turn the key

-checked the wires and connectors at the pump for the obvious

Need to know:

-which wires on both connectors to check for power at the pump

-location of the fuel pump relay

-does a bad crank position sensor prevent power to the pump

-anything else that you guys would recommend checking

As always....thank you for your help!!!!!!!!

 

[ethanrover98]

Any thoughts?? I am stuck at work!!!!

 

[Lake_Bueller]

Hello all,
Need to know:

-which wires on both connectors to check for power at the pump

-location of the fuel pump relay

-does a bad crank position sensor prevent power to the pump

-anything else that you guys would recommend checking

As always....thank you for your help!!!!!!!!

1) Sorry, don't know

2) It's the black box on the passenger fender. It's about the size of a pack of cigarettes.

3) Don't think so but not sure.

4) Fuel pressure?

 

[Mongo]

check for fuel pressure at the rail..it could be as simple a clogged fuel filter

 

[justinhaaga]

sounds like fuel pump to me. check fuel pressure, also go listen to it in the rear. hear if its coming on and if sounds OK.

 

[ethanrover98]

bump for some more help........

I want to put 12 volts to the pump and need to know which pins to energize. Also, I only see 5 volts at the pump with the key on or off!! How much voltage should I see going into the pump?

Also, I took the relay apart and energized each of the 3 coils with 6 volts (didn't know how much to use) and the all worked great??!!

Any thoughts for more troubleshooting would be greatly appreciated.........

I did check the fuses under the hood and under the dash which were good......

 

[peter sherman]

There are a million threads on this
I think hot wire is white purple

 

[xutpuu]

Make sure you know its the pump before you replace it. I replaced my pump only to learn that it was a faulty relay. Could have saved $400!!

 

[ethanrover98]

I bet there is a million threads, but as I stated in my original post I was at work and could not spend too much time searching the internet..........now that I am home and don't need a quick answer I will search................

 

[peter sherman]

well check the white & purple for voltage
if 12v then its more that likely da pump
if no the trace from the pump forword

 

[floridarover]

If you need a pump contact Trevor with Rovah Farm. Good deals. Good guy to deal with.

 

[ethanrover98]

Thanks for the pump contact, but......................

I still need some help and here is the data from my latest troubleshooting which makes no sense to me:

-I am getting 12v at the harness connector

-I put 12v to the pump (with an external power supply) and the pump works

-I hook the connector back up AND.........NOTHING

Any ideas would be greatly appreciated............I am in the process of hot wiring the pump to get home, but I really want to fix it......thanks in advance.......

 

[Joey]

Relay in the passenger foot well.

 

[peter sherman]

pump load might be the issue.

by the way I have done several chevy pumps with no issues.

 

[ethanrover98]

Relay in the footwell???? It is a 98 D1........I thought that the only relay was the mutifunction relay under the bonnet????

 

[peter sherman]

If your getting 12v at the pump not sure how the relay is a suspect
pump load is the likely issue if you have 12v to the pump. For 60 bucks I would just through one in there anyway.

 

[ethanrover98]

Thanks, Pete.............I assume you mean do a rebuild with a new motor.......

The only thing that bothers me is that I can make the pump work with an external 12v supply.......

I am getting ready to jumper the plug on the harness to the pump.......maybe I have an issue with the harness connector......

 

[peter sherman]

yes but look at the amps in your jumper if its more that the fuse on the pump this might be the issue. thats why I said load earlier.

 

[ethanrover98]

I agree with your theory, but is there a way to check the pump with a multimeter to kinda prove out the theory? I am driving around now with the external power source hooked to the pump and I am going to change the pump tomorrow, but curiosity is getting the best of me..........thanks for the help........once again this site has proven invaluable and the good news is in 202,000 miles and 8 years of ownership my truck has only been towed once............all thanks to this great group of folks.........

 

[peter sherman]

you can but you'll need a small probe & another one to plug into the harness
ground the ground the complete with the multimeter