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whchris

gm fuel pump

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whchris

OK here's the story a few months ago the 1996 gmc 1500 just died while driving wouldn't start waited for the tow truck and it started right up so it got taken buy the tow to the shop anyways after AAA it only cost me like 15 bucks the thing uses more gas than that any way and the check engine light was on so figured i get it checked out see if that was what caused the stall it sat at the shop for 2 months and all they did was a diagnostics and tell me the #5 cyl was dead after the 2 months i went and got it and drove it daily until last wednesday it stalled twice while idling in the drive way and once backing out so i parked it and took the blazer went later and the truck wouldn't start at all no fuel pump noise so i changed it truck ran like a champ got about 12 miles away from home and it started to make a wining noise from the tank area and the truck would only idle so i shut it off clicked to cycle the fuel pump twice and started the truck runs great for 5-10 minuets and does the same thing my question is is this a pump problem or does it sound like a vacuum leak?

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perry

may want to check the connector on top of the gas tank. make sure there isnt any corroded or loose wires. just something to look at :D . hope you get it figured out. let us know what you find.

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Sparky

Hey Chris.

A little off topic, but now that yer almost mobile you should stop over. I have a few new tractors since you were here last and a nice new garage to tinker in.

Mike.....

PS...Sorry but I have no advice on the truck

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whchris

that's alright mike when i am fully mobile and can afford the gas ill stop by,(i got laid off in December but it looks like I've just about squeezed my way into the local 42) you should also think about coming up here some time you never saw the first power king but i got two of them now he he and the wheel horses are doing good too i think I'm gonna keep two of everything two wheel horses two power kings two cub cadets and all but one craftsman went to the scrapper

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TT

Chris,

You might also want to check the fuel pump relay. I don't know GM's so I can't tell you where to find it.

I'm assuming it's an in-tank pump, correct?

It actually sounds like the pump is losing it's prime, or the pick-up/screen is loose or clogged.

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chevelletown

Have you changed the fuel filter? It should be in line along the frame.

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nylyon

These are just guesses on my part since I don't know GM's. It sounds like the computer is going into limp mode. That is when it detects a component failure and sets on the minimal setting. In other vehicles, these components can be the CPS (Crank Position Sensor), or a cam sensor. Since it's a 1996, it should have an OBDII connector. If the check engine light is on, get the codes read. Many auto parts stores like Autozone will read the codes for free, even reset your MIL if you would like. Let us know what the codes are and go from there.

It could still be a fuel pump issue too. When you replaced it was it a new pump or used? You could always run a new wire to the pump and install a new relay on the ACC side of the key to be sure you don't have a wiring problem as well.

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whchris

new pump, this is number five in the last two years two were bad eggs from nappa and this is the first non nappa pump (advanced auto parts pump) it is in tank im gonna try to disconnect the battery tommrow as well as replace the relay and filtter the filter is olny two months old though yes the pump is in tank cleaned the terminals when i put it in being an electrical apprentice its kind of a habbit to clean all termanals also redid the ground straight to the neg on the battery the same with every other ground ive run into

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nylyon

If you can, get the codes read before you disconnect the battery, it will reset the computer and clear the codes.

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illinilefttackle

new pump, this is number five in the last two years two were bad eggs from nappa and this is the first non nappa pump (advanced auto parts pump) it is in tank im gonna try to disconnect the battery tommrow as well as replace the relay and filtter the filter is olny two months old though yes the pump is in tank cleaned the terminals when i put it in being an electrical apprentice its kind of a habbit to clean all termanals also redid the ground straight to the neg on the battery the same with every other ground ive run into

Whcris-My daughter has a 1996 GMC pickup-she was going thru a fuel pump a year-until I was given some advice by an experienced parts counter guy-he said that the repair community has found that you must replace the wire harness that goes from the pump to the sending unit (within the tank) you can't tell by looking but the wires develop very high resistance burning out new pumps prematurely.

I replaced it and now have gone 3 yrs on replaced pump.

Don't know if it could be causing your present problem, but it very well could be-AL

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whchris

the code reader says it runs rich caused by #5 having 3lbs of compression piston looks fine with the fiberoptic scope and once i get a few more projects done shell be in the work zone to get the heads rebuilt i will try changeing the wires that go from the sending unit to the pump i didnt look too intensly but are those pluged in to the top of the sending unit or do they pass through it? im really looking into getting a high psi frame rail pump and extending the hose that the in tank pump connects to putting a strainer on it and a filter before and after the pump any one know if this will work with this system?

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illinilefttackle

the code reader says it runs rich caused by #5 having 3lbs of compression piston looks fine with the fiberoptic scope and once i get a few more projects done shell be in the work zone to get the heads rebuilt i will try changeing the wires that go from the sending unit to the pump i didnt look too intensly but are those pluged in to the top of the sending unit or do they pass through it? im really looking into getting a high psi frame rail pump and extending the hose that the in tank pump connects to putting a strainer on it and a filter before and after the pump any one know if this will work with this system?

Whcris- I went thru the same thought processes that you did- I have been told that a frame pump would not work-the wires I spoke of are located in the sending unit-when you take it out of the tank-they run from the pump itself to the bottom of the sending unit-they are immersed in gas thats why they go bad,are you replacing the fuel sock too? -if this is the VORTEC system-it requires above 60 lbs pressure just to start-whereas general GM systems only require 30 lbs. Good luck-I know how frustrating this can be-AL

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whchris

not really sure what youy mean about fuel sock unless its that foam like thing that goes over the pump in that case yes and yes its a vortec im off to the parts store now to see what i can get

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illinilefttackle

not really sure what youy mean about fuel sock unless its that foam like thing that goes over the pump in that case yes and yes its a vortec im off to the parts store now to see what i can get

Whcris-I dug thru my receipts for parts-and found the part # for the wiring harness= NAPA

NFP

888536 they highly reccommend replacing this on the vortecs-COST $9.99

Hope this helps-AL

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whchris

now ya tell me my local napa could find the part so i settled for a new sending unit well its probably needed anyways

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whchris

any one got a good tip for removing the rusted on fuel lines from the sending unit??

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whchris

never mind i disconnected the lines up at the filter and unin for the two and cut them off the old sending unit and brought them too the vice with the heat and pb blaster they came right off

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