Seems simple but it's strange: New Battery and starter, turns over strong and hard but will not start.

Symptoms:
-Only starts when jumped
-Fuel Pump sounds weak
-Pump sounds strong as new when jumped
-Pump occasionally doesn't turn on at all

It has new plugs and wires and I've replaced the pump relay. I'd have thought the pump was bad but with a jump, the pump runs loud and strong and starts right up. I don't have $200 to blow on a new pump if it's not needed. Any ideas? I need to get to work!

would like to know did the truck run properly when is jump i mean engin stay running or stall after 2 ou 3 sec ...


theft module relurn ?

Truck runs fine afterwards with no struggling or hesitation. If I turn it off its possible I'll need a jump to get going again but as usual, with a jump it starts right up. Has only ever cut off while driving once. Other than that it runs great with a small miss but been that way for a long time.

Maybe I should start testing the voltage going to the pump. Any hints as to how to do this would be extremely helpful. I'm going to take a wild guess that maybe enough power is not reaching the relay unless jumped.
FYI: This Tahoe has 307k miles and is still a champ! :biggrin:

i mean you have remplaced battery and starter this not hard at all

you need to look at this firstcuz vehicul running well before and what not working 1e think crank

they have fuse box under hood look about maxyfuse #6 know if the fuse are good or not
poor connection on
if there good, look at ignition sw
about red wire d5 behind ignition sw d5 looking bTTERY VOLTAGE ! ? good or not !

in the fuse box they have starter relay is there you jum them ?? starter relay voltage good ? or not ?

Thanks for helping out - The battery is new (1 month old) and starter was replaced approx 3 months ago. Both work so well that when I crank it the truck rocks with as it spins :iceslolan.


Tonight:
I'll check the fuse
Then I'll try to look at that d5 wire for damage (does it have D5 marked on it? Switch is where key goes in correct?)
Not sure how to check relay voltage but I did swap it with another with no results. I'll try those again too.

Before you dig too far, I'd check for loose/bad connections. Sounds as if you're not getting full voltage due to a bad ground or loose power supply.

Thanks iroc, that makes alot of sense. I was starting to suspect the harness was the culprit. I'm now seeing VERY erratic behavior with the gas gauge. It's bouncing all over the place and even makes complete circles. That gas hand behavior stops when the tank is nearly full.

I'll try to lower the tank a little and make sure the connector and wires are all secure. I'll try to get that tonight and send updates. Any more advice you or anyone gives is always helpful :D

Thanks iroc, that makes alot of sense. I was starting to suspect the harness was the culprit. I'm now seeing VERY erratic behavior with the gas gauge. It's bouncing all over the place and even makes complete circles. That gas hand behavior stops when the tank is nearly full.

I'll try to lower the tank a little and make sure the connector and wires are all secure. I'll try to get that tonight and send updates. Any more advice you or anyone gives is always helpful :D

because you own a old vehicle make sure the fuel tank grounding wires are clean and secure....remove wire brush the mounting point on the frame rail....remember electricity needs a good ground as well as a good feed,,,this trips many an auto repairer.....

Thanks for the tip. I'll check the grounds at both ends. I'm attempting this tonight if possible because I was forced to put it off till now.

I hate to jump in here, but Ive seen this dozens of times. New battery- corroded cables. Bolt bottomed out in battery-tight, but cables loose and bad contacts.

I'm starting from the top and working down. I've purchased replacement cables. There was some wear of course so I'll be posting my results.

Thanks all for the steady flow of advice.

Update: I played around with the battery posts and saw some changes. Separated the two positive leads going to the side post and placed the one running to the pump relay on the top post and re-mounted the other to the side post. I was able to start the truck twice on my own after a couple of tries. The pump seems to get stronger (it sounds the way it does when getting a jump) after cranking a few times. I didn't let it run those 2 times it started because I wanted to prove to myself that it was working but didn't get it started again and I smelled the gas from under the hood. I'm guessing I may have gotten the plugs wet??? I will finish by splicing the wires today and attaching to new connectors for the posts. If ANYONE wants to add to this, please do! I'll post updates again after tonight's attempt.