truck not running / fuel pump not working / priming while turing the key

[mechjames]

alright, i was pulling into a parking lot then all of a sudden the truck stalled out.

i have spark, and i can run it a bit on carb cleaner, so i know its firing alright

i'm not hearing the pump prime while i turn the key to on. although since i did the sending unit i haven't really heard the pump at all, and its driven fine for a couple weeks (probably because i never used to fill it up, and when i did the first full, it fully lubricated the pump)

so i've swapped relays for the fuel pump and i've checked fuses. i'm going to try and test the pump to a 12 v source and see if it runs.

i did do some heavy off roading about 3 days ago but the truck has driven fine up to this point.

i'm not out of gas either. just went with a jerry can and put some in.

no specific check engine codes for the fuel system come up, just my usual EGR problems and the camshaft sensor that i have to fix soon. 214 and 336.


If the pump runs with a 12 v source on it, what could it be? I don't really want to run a toggle switch, thats just cheesy.

i also forgot to mention that i've run out of gas before and i know the pump gets a little noisy when that happens, and i think if the pump seized, it would have been noisy again. also i've tried banging on the tank (well skid plate anyway)

 

[btexpress]

Just for kicks, check the inertia switch above the RF passenger foot area, pull the carpet back and see if the connector is pulled off a little, this can cause no fuel pump issues. Sometimes, depending on how active a passenger might be with the feet and how the wiring is routed to this switch, it can actually become disconnected.

 

[mechjames]

i've checked the interia switch. forgot to mention that in my above post.

my fuel pump voltage is 9.6V, with a battery voltage of 11.5V with ignition on, not crank. I'm getting power to the pump, but i'm still going to run power manually to the pump to see if it works. if not, then i guess i will have to drop the tank. Its possible one of the two spade clips on the fuel pump connector inside the tank came off.

 

[mechjames]

what i don't understand is why there is voltage even after the fuel pump usually stops priming. this 9.6V reading was taken just while the key was in the on position. usually when i switch it to the on position it just cranks and stops, like normal, and then after the motor starts the fuel pump will be on continiously.

so why is there 9.6V reading at the connector even after the 1-2 prime cycle the PCM sends out?

 

[mechjames]

alright, i hooked up the pump to my 10 amp battery charger and give it a 12V source. There is a little hum coming from the pump, like its jammed. It isn't doing anything, and the truck won't run.

Banging on the tank didn't help, because of the skidplate Going to pull that off then band on the tank a bit.

Any other things i should try guys?

 

[manaen]

sounds like you need to bite the bullet and drop the tank. Take a multimeter and test the resistance between the ground lead and the power lead to the pump. if it is good it will have a resistance reading, if it is bad it will either have no reading or a very low resistance reading (close to 0 ohms)

 

[Limited Ex]

You say you did the sending unit, is it possible that you stirred up crud in the tank and it is now clogging the fuel filter?

 

[mechjames]

i'll try the resistance thing.

when i changed the sending unit, it was a few weeks ago, and i put a new strainer on the pump. and its not the fuel filter, because the pump doesn't work whatsoever. all i get is a click when i give the pump 12 DC power. I'm trying to unjamb it, and i'm working on dropping the skidplate.

i've also tried giving it reverse polarty to positive polarity back and forth. it seems like it might be working, but still just a little tick.

 

[mechjames]

sounds like you need to bite the bullet and drop the tank. Take a multimeter and test the resistance between the ground lead and the power lead to the pump. if it is good it will have a resistance reading, if it is bad it will either have no reading or a very low resistance reading (close to 0 ohms)

what sort of resistance reading should i be looking for?

 

[manaen]

I'm not sure that there is a published spec, however like I said if you get infinity then the motor is bad, if you get close to 0ohms the motor has a hard short. Anything in the middle is open for enterpretation. It's just a quick test before you drop your tank.

 

[mechjames]

yea, i'm getting 0.8 - 1.6 ohms

 

[manaen]

well thats not very telling, sounds like you need to pull the tank :scratch:

 

[mechjames]

the motor sounds like its shot or stuck. when its close to 0 ohms like that its like a hard short.

plus all it does when i give it power is click.

 

[mechjames]

alright slapping in a new pump today. i don't want to reuse the old one, because it just failed while i was driving, and i don't want it to fail if i'm out in the middle of nowhere somewhere!

 

[manaen]

for the work involved and the money for a new pump it is well worth the investment to not reuse the old part

 

[mechjames]

ack, fuel pump died again today. it started whining a week ago and it finally kicked the bucket today.

for a bit, it wasn't working at all, and it wasn't priming. after a few hits, it primes a bit, but just makes the motor sputter, and doesn't start. runs on starter fluid tho. sometimes you can hear it prime, and u can hear it come on constantly while cranking over, but it isn't pumping any fuel.

the new strainer i put in is clogged to ****, i think someone put something in my tank, which clogged the strainer, which then overheated the pump. 3rd time i've dropped the tank in a month theres also a bunch of white crap sitting at the bottom of the tank.

good thing i can still exchange it

 

[manaen]

was there a lot of dirt in the tank ? seems strange that the new pump would have died already. But I guess stranger things have happened, that's what warranties are for.

 

[mechjames]

the tank was clean this time, no dirt, but i changed the fuel filter this time. I'm thinking the filter would have been clogged so bad that it was putting pressure on the pump somehow.

I cut it open and it was all dark black inside. But before that, with the leftover gas from the filter, i drained it into a cup from the end that goes to the engine, and it was full of dirt and the gas was like coming out black. So, yea, it was also putting a lot of crap into my engine.

Should be alright though. I'll monitor the loudness of the pump for the next few weeks.