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New k5 member. Need help with Fuel pump issue

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Alky350

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Just bought my 1989 Chevy k5 blazer last night. Had to tow it home because the fuel pump won't prime. By bypassing the relay I was able to get the pump to come on. The fuel filter and the relay have been replaced and not sure what else to check. I hear the relay clicking when I turn the key. The motor Will run if i spray the tbi with starter fluid. Any idea what other things I should check?
 
Keeps flashing 12. Should the service engine light stay on with the key turned to the on position?
 
Will the engine run with the relay bypassed?

If the fuel pump will run but you don't get pressure, then either the pump is bad in the tank, or the regulator on the tbi is stuck wide open.
Oops, or the fuel filter is stopped up.
Oops again, you said you replace it.
The pump in the tank can run without pumping if its bad.

Of course, you might be out of gas.........Never trust the gauge in situations like this.
 
I unscrewed the two lines going to the tbi and bypassed the relay again but no fuel came out. I hear the pump running though and the tank is full. So you think it's a bad pump??
 
Well, if the pump runs and it don't pump..............

Double check the filter again. Easier than the pump.
But, there is a short piece of hose that connects the output of the pump its self to the connection on the outside, and if it comes off the pump will just circulate the fuel inside the tank with none coming out.

Sounds like what has happened to you.

If so, then you have the choice of dropping the tank, or cutting a small door in the bed to replace the pump through.

It seems that most of the guys here drop the tank, but they are used to working under the truck and have lots of jacks and stuff to do it with.

As I have posted here before, a mechanic friend of mine quotes two prices for replacing the pump.
One for dropping the tank, and less for the door.

He has the measurements for where to cut the door for most every truck or blazer type he works on, and does a pretty neat job of making a small door to cover the hole.

Double check the filter and all lines first, but if not, then its the pump.
 
I Removed the filter and bypassed the relay. Fuel came out.....but still wondering why it won't prime when I turn the key. Hooked everything back up but left the tbi lines off. Bypassed relay again a small about of fuel came out but then stopped while the pump was still running.
 
You should have had a lot of fuel come out when you disconnected the filter.
If you did but did not get any after the filter, then something may be wrong with your new filter.

But it sounds like a bad pump.
The pump does not run continuously when you turn the key on. It runs long enough to fill the system then cuts off.
It only runs all the time when the engine is running.

Get someone to help, take the line off the filter again, and put your finger over it. Have someone jumper the relay.
You should get probably 20lbs or so of pressure. I suspect that you will barely feel any.
That hose I mentioned inside the tank not only can come off, it can also get a hole in it.
In that case, it will let some gas come out with no backpressure, but if there is even a small amount of restriction, like the filter, it all just runs out the hole back into the tank.

We have had several folks here who fought for days with poor running engines only to find that there was not enough pressure to give a good spray.
And in several of those cases it was that little piece of hose in the tank.
 
Thanks for the help guys. A 3 inch hose from the pump to the fuel pump assembly was all it was. It's running now. I ended up cutting an access port to get it done quicker. Again thank you!!!
 
Fantastic. That was sure what it sounded like.
Be warned, that piece of hose has to be made of something that can withstand constant immersion in gas both inside and out.

Couple of guys here have replaced it, but I don't know exactly what they used. Personally, if the pump has a good amount of age on it, I would just replace the whole thing.
 
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