97 Chev Wrecker Problem

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Oklacarcollecto

Oklacarcollecto

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Guys I could use a little imput here.

I have a 1997 Chevrolet 1 ton cab and chassis wrecker with a 5.7 Vortec in it and it won't start.

It is a fuel problem.
I can't hear the pump running and I have checked the following.
Fuses beside the left door by on dash panel.
All fuses in the master block where the relays are under the hood.
5 pin fuel pump relay changed with a known good one.
Due to back problems I can't get under the truck but a friend checked the plug on the fuel tank and all looked good.
Checked for any damaged wiring and found none.
It will start with either very easily so it is definately a fuel issue.

Here is the history on the truck. I bought it 5 years ago but have barley used it in the last 2 years since I bought the rollback. It ran fine but has set about 4 months without being started.
Is there anything I may have overlooked?
I have already ordered the new fuel pump just because I had ran out of ideas.
 
Most vehicles with fuel infection have a sensor that shuts off the fuel pump when the vehicle is hit in the rear. Doesn't take much of a jolt to trip them and I have seen it happen more than once. Try to find it and reset it. It's usually a small black box with a red or yellow button for reset purposes and is mounted in the rear of the vehicle. On the other hand the fuel pump could be gummed up from sitting. :toothy10:
 
grumpuscreature said:
Most vehicles with fuel infection have a sensor that shuts off the fuel pump when the vehicle is hit in the rear. Doesn't take much of a jolt to trip them and I have seen it happen more than once. Try to find it and reset it. It's usually a small black box with a red or yellow button for reset purposes and is mounted in the rear of the vehicle. On the other hand the fuel pump could be gummed up from sitting. :toothy10:
Click to expand...

That had crossed my mind but I didn't follow up on it since the truck is a cab and chassis from the factory.

Thanks, I will look into this idea further.

Other Ideas guys or gals?
 
Not hearing the fuel pump run is the biggest thing. Ford is the only one I know of who puts the interia switch on the vehicles (though I may be wrong). The new pump should come with the new pigtail to update the connector for the pump to harness. I know you said your friend checked this and all is fine, but these things have a habit of loosening up and burning out the pump. The new one is a more positive lock, meaning no more loosening.
You also said the truck had been sitting for four months. That long of time sitting with an electric pump can be bad news. Remember that it's a little electrical motor in there that is prone to moist in the tank. A little corrosion and it's history.
 
I have swapped out two pumps in a 97 and 98 full size Vortec. One thing I figured out is that just because you hear it kick on doesn't mean it is putting out enough. The two I swapped out would power up and had the G.M. fuel pump humming sound but would get hot and kick off while cranking. A buddy of mine had a Snap-On scan tool and it showed the presssure was low. An A.S.E. tech at a local dealer told me they have a thermal protection and the e.c.m. will cut power off to the pump while cranking if pressure drops. I don't know it this helps you but that's what I went through at work 2 days in a row.
 
Try tapping on the bottom of the fuel tank while some one cranks the engine over. I work on a large GM fleet and most of the time when you don't get a 2 second run on the pump when you turn the key on, the armarture is likely stuck. slapping the bottom of the tank will get most likely get it started. I have done this twice when some one had broken down, shoulda seen the look on their face when the vehicle started. this usually only happens when you shut the vehicle off and go to restart it. if it starts after doing this, replace your pump and strainer. most of the time the sending unit is worn out also by the time the pump goes bad.
 
There should be a schrader valve under the hood on the fuel line somewhere. Place a pressure gauge on it and it'll let you know what ya got.
 
Banging on the bottom of the tank works quite often, but not forever, so be sure to change the pump as previously stated. Look to see if you have a test wire that will bypass the pump relay. You can apply voltage directly to this and see if maybe you have a pressure regulator, or sensor, or even a relay problem. My $.02
 
Finally got around to fixing this truck.

When the tank was removed and then the pump removed we found that the black rubber type of wrap that went around the pump itself had nearly turned to a jelly. It had slid down and was covering most of the pick up screen.

We bench tested the old pump after removing the screen and jelly and it works fine and the pressure is great at 77 psi unrestricted to the pressure gauge.
Since I had already bought a new pump we went ahead and installed it.
 
good to hear you got it repaired. I would have replaced the pump also considering the trouble you went through and the age of vehicle. Thanks for posting this info might be helpful for the next head-scracther.
 
grumpuscreature said:
Most vehicles with fuel infection have a sensor that shuts off the fuel pump when the vehicle is hit in the rear. Doesn't take much of a jolt to trip them and I have seen it happen more than once. Try to find it and reset it. It's usually a small black box with a red or yellow button for reset purposes and is mounted in the rear of the vehicle. On the other hand the fuel pump could be gummed up from sitting. :toothy10:
Click to expand...

Agreed and replace filter, but I was thinking emergency shut off button too!8)

Sorry wrote too late!
 
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