Fuel pump no start question

jeffster · September 1, 2005

Ok, I posted a topic recently about my 2k Silverado 1500 with 4.8L that recently started having starting problems. At first I was leaning toward the Passlock system since it eventually started after fooling around with the locks.

Anyway, last week it wouldn't start and hasn't started since. I finally had time tonight to look at it and I checked the regulator vacuum line and it was completely dry. I then climbed under our 01 Suburban and listened to the pump when the ignition was on and can definitely hear it. I did the same under the Silverado and it was completely silent. Ok, with my half-witted mechanical skills, I would make the diagnosis that the fuel pump is bad.

However, does the Passlock system prevent the fuel pump from operating at all if it is in an active alarm state?

I really don't want to spend the money and time changing the pump if it is the retarded security system that is just preventing the pump from turning on.

Thanks all!

-Jeff

asilverblazer · September 1, 2005

Passlock when activated does preven fuel delivery, I believe by cutting the pump. Is the key you are using original/factory? If it is not that could be the problem. Using the remote "arms" it and it "unarms" it.

Bish · September 1, 2005

Not sure about the passlock disabling the fuel pump.

One way you could test it is to have somebody turn the key to run (do not start) and then rap on the bottom of the fuel tank with a rubber mallet within the first couple seconds of turning the key. Many times the pump will come to life long enough to get it to a shop. If it does work, just don't shut it off if you don't have to.

Good Luck

jeffster · September 1, 2005

Thanks for the replies guys. Yes the key I am using is my original. I have tried my other original key as well, but no go.

I'll give the mallet trick a try tonight and see what happens. Fortunately, the shop isn't too far from my house. However, if I can determine if it is the fuel pump, I'll change it myself. I hate giving money to dealers.

Thanks,

-Jeff

MR1911 · September 1, 2005

This is not half-witted at all, some pumps make more noise than others , but you can hear it still if its working . As to passlock is your batt up to snuff ?, check to make sure it at full charge some times a low batt will cause the bcm to do strange things, aslo check cables for good ground and or conection to batt. Just for the heck of it disconect the batt for say 10 min and see if resetting the truck helps. If you do wind up needing a pump go to ebay new pumps are a quarter of the dealer price, I just did mine the other day in my 2k sierra for $100.Good luck

jeffster · September 1, 2005

Thanks MR1911. Yeah, the battery is still showing green and holding a good charge. I did actually try disconnecting the battery for about an hour last week and it did not seem to help. I think I'll go ahead and check on Ebay for a fuel pump like you suggested.

I also checked the ECM fuses last night, as I found a couple of postings relating to similar situations where the ECMB fuse blew, but it looks good and I replaced it with a spare just to be sure, but no go.

Anyway, thanks for the thoughts!

-Jeff

Mattt · September 2, 2005

Ive had the same problem with a fuel pump that doesnt turn on. Its not necessarily the pump. It could be the connector that goes to the pump.

Check out Carter Fuel pump on the internet. On their website, they have a write up about how the terminals in the fuel pump connector burn and short out.

My truck does this exact thing. I never know when its not going to start. To fix it, I reach up to the connector on top of the tank, disconnect the wire, hook it back up and 99% of the time, my fuel pump turns on after that.

You might check your wiring up there before ponying up the $400+ for a factory fuel pump. There are 4 connectors, look to see if one of them looks darker than the other 3. Thats the sign to look for.

firefighteremt3100 · September 4, 2005

Thanks MR1911. Yeah, the battery is still showing green and holding a good charge. I did actually try disconnecting the battery for about an hour last week and it did not seem to help. I think I'll go ahead and check on Ebay for a fuel pump like you suggested.

I also checked the ECM fuses last night, as I found a couple of postings relating to similar situations where the ECMB fuse blew, but it looks good and I replaced it with a spare just to be sure, but no go.

Anyway, thanks for the thoughts!

-Jeff

<{POST_SNAPBACK}>

On a side note, don't rely on the "green" light/bubble/whatever you want to call it. That green dot is only for the cell/cells below itself, not the whole battery. It can show green, but still be dead.

GM-Tech · September 4, 2005

However, does the Passlock system prevent the fuel pump from operating at all if it is in an active alarm state?

Passlock disables fuel by simply not pulsing the injectors. It does not do anything with the fuel pump.

And the keys are nothing special. You could go get a 50 cent K-mart key and as long it turns the lock, the theft system will not prevent starting. PassLOCK security systems are all within the lock assembly. PassKEY systems have a special key. Some have a visible resistor chip, others have a transponder in the key head. You have PassLOCK.

jeffster · September 6, 2005

Thanks again gang. Also, GM-Tech, that was exactly what I wanted to know about Passlock, so thanks.

I'll also check out the wiring to the pump. It sucks just having my truck sitting in the driveway looking pretty. We went camping over the weekend, and I definitely can't fit as much in the Suburban as the truck. I had to get extra creative with packing.

I'll follow up as I find out new info...

Thanks!

-Jeff

Black Bart · September 7, 2005

I know this is probably a silly question, but have you

checked your fuses and voltage going to the pump?

jeffster · September 7, 2005

Black Bart,

Yes I have checked the fuses. I have NOT, however, checked the connectors and voltage to the pump itself (yet, anyway). Thanks for the thoughts, and hopefully I'll get some time to work on this next week some more before I have to leave on another business trip...

Thanks,

-Jeff

Adrenaline Addict · September 13, 2005

I am not sure but I have worked on cars with relays in a box under the hood which sometimes conntrol the feul pump and go bad. You should be able to swap one of the existing ones for a moment. If nothin works, the pump might just be bad. In my experience many feul pumps go bad. Not too bad to fix though.

jeffster · October 11, 2005

Ok gang, I finally got time to change my fuel pump. Pulled the bed off the truck, and changed the pump out. Pretty simple actually. However, it still wouldn't start and the pump wouldn't produce any sound. Turned out to be the stupid relay. I could have sworn I swapped relays already, but I guess I didn't after all. Oh well, the pump was an easy change and at least now I know it is done and I don't need to worry about it.

Thanks for all the help, I appreciate it!

-Jeff

gmcjoe · October 11, 2005

Ok gang, I finally got time to change my fuel pump. Pulled the bed off the truck, and changed the pump out. Pretty simple actually. However, it still wouldn't start and the pump wouldn't produce any sound. Turned out to be the stupid relay. I could have sworn I swapped relays already, but I guess I didn't after all. Oh well, the pump was an easy change and at least now I know it is done and I don't need to worry about it.

Thanks for all the help, I appreciate it!

-Jeff

<{POST_SNAPBACK}>

That is pretty uncommon. Before I swapped out my fuel pump a few weeks back (145K miles on my 2000 GMC) I checked the relay and it was fine.

The pump usually always goes out before the relay.

Glad you're back on the road at least