I just bought this truck. Started right up when I put a battery in it. I let it run for ~ 10 minutes, then I moved it about 30 feet to a different spot. When I tried starting it after it spun over fine but no start.

I put a pressure gauge on and it was reading 20 psi. So I bought and installed a new Delphi FG0085 pump, and had to replace the line from the pump to the filter as it fell apart. I also put in a new filter. So now I was thinking I would be all set but nope, turn key, whirr 2 seconds only comes up to 20 psi?! Jump out solenoid to see if it will get any higher, nope 20 that's it. It holds pressure forever after turning the key off. I did a resistance test and get 2.1 ohms on the pump. I measured the voltage at the pump connector and I get full battery voltage (12.6) I used my fluke meter set to amps inline and jumped the solenoid out and I get only 1.5A. So using ohms law, volts equals R x I. I get 3.15 volts. Something doesn't add up here!

I forgot to add, I noticed the battery was losing a charge overnight. I tested in line with my fluke and it seems I have a 2.5a constant draw with everything off

Please help
TIA
Eric

 

Pump low pressure probably due to the low voltage. I'd suggest you find the electrical issue, then persue the fuel issue if you still have it.

 

Thanks for the reply,
The weird thing is, I measured full battery voltage right at the plug on the fuel pump end. But based on the amp reading it seems like there must be a voltage drop somewhere.

 

Well, one is going to be the other, in other words in this case the voltage will drop with current. Voltmeter reads difference of potential, so if you have (ex.) 12 volts at the pump, and 2 amps (ex.) you have 12 volts at 2 amps at the pump. If the pump isn't producing enough pressure, and in your case, it isn't, AND the current isn't excessive , then in my opinion, you have pump issue. If the current is high, and no pressure, you have a restriction. Just my opinion.

 

Well I had time to work on the truck over the weekend.Turns out the reason the pump wasn't putting out the right pressure was a bad ground.

Ohm's law, Current = voltage divided by resistance. With the 2.1 ohm reading. IF the pump was actually seeing the 12 volts it SHOULD have been drawing ~5.7 amps. So first thing I did was take a motorcycle battery and connected it directly to the pump. The pump put out 62 psi. So then I made a long jumper and connected the jumper to the battery ground on one end and the ground side of the pump, Then a jumper from the power side of the plug and voilla! 62 psi. Good and bad. I Probably Didn't need a new pump DAM! So I ran a 14 gauge wire directly from the connector to the ground side of the battery. I could have just connected it to the frame but Now there is no question on the ground.

Hopefully this will help someone else in the future.