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Beefy
New User
Jul 13, 2009, 7:43 AM
Post #1 of 3
(1956 views)
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Fuel Pump not engaging
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The fuel pump or fuel pump relay is causing me some grief on my 5.7L 98 GMC 2500 2wd pickup.
I recently replaced the fuel pump relay because I suspected it was causing my truck to randomly stall. It has been doing so for the past few weeks, but now I am not so sure that was the problem. The fuel pump itself isn't very old either... I got a brand new one about 4 months ago. It has been working fine ever since the stalling problem.
The problem I was having before was a mixture of two different scenarios. One scenario would be driving on the highway, and then it would just randomly stall. At that point I would put it in neutral, shut it off, and then start it back up again. 95% of the time the restart would be successful. The other 5% I would have to shut it off a couple times, and then restart it until it finally worked. The second scenario I would be parked, the truck would be running, and I would shift to D or R, and then it would stall. In this case, I would shut it off and try again. About 80% of the time, the fuel pump would engage, and the truck would start. The other 20%, the fuel pump wouldn't engage at all, and the truck would not start until about 10 tries later.
Today was a completely different story. The fuel pump completely failed to engage this time. No matter how many times I tried, it would not run this time. I tried banging on the tank really hard, I tried messing with the relay, I wiggled the wires on top of the fuel pump in hopes of a bad connection... NOTHING. I eventually had to get the truck towed back home.
Now here I am... completely confused as to what is happening with my truck.
One thing I noticed that was different this time was the Fuel Gauge. It is maxed out to the fullest without any change no matter what I do. I turn the key on, it is maxed out, I turn it off, it is still maxed out. This leads me to believe that there is no connection whatsoever to the fuel pump.
I am open to all suggestions that may help me track down the actual cause of this. Thanks.
(This post was edited by Beefy on Jul 13, 2009, 7:46 AM)
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Loren Champlain Sr
Veteran
/ Moderator
Jul 13, 2009, 11:12 AM
Post #2 of 3
(1945 views)
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Re: Fuel Pump not engaging
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Beefy; The first thing to do would be to check fuel pump pressure. These Vortec engines are very picky regarding pressure. If it is less than 55psi, they usually won't start. If you have no fuel pressure, then you'll need to check the fuse, relay, and power at the pump. Some of wire connectors have been upgraded. The new pump probably had the new connector supplied with it. Or, at least should have. Have you replaced the fuel filter? A plugged filter can burn up a pump. Only use factory GM fuel pumps. The aftermarket types just don't last.
Loren
SW Washington
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Hammer Time
Ultimate Carjunky
/ Moderator
Jul 13, 2009, 11:59 AM
Post #3 of 3
(1940 views)
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Re: Fuel Pump not engaging
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That connector that Loren mentioned is very important. They have a known problem with those connectors that can cause repeated fuel pump failures and intermittent fuel pressure problems.
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