Fuel Pump? 87 k5 tbi

[crazedyak]

I've been working on the Blazer for over a year in what might be safely called the slowest build in history. Been having problems with the ignition that I finally solved when I upgraded to MSD Dizzy, Ignition Coil and Taylor wires. Much better starts and she ran great.... until this morning.

First off ZERO CODES. My engine started sputtering at a red light. A tap on the gas pedal got rid of it for a minute. Then the light turned green and halfway through the light the Blazer dies. I coast off to the side to clear the roadway. Sit there for a second wondering what happened while scratching my head.

Turn it over a few times and starts back up. Seems fine, so i wait a minute to make sure no cut off while I'm out of traffic. Get about a mile down the road and it dies again. Same symptoms. Starts up a few minutes later and I finally get to work and park it.

I went out at lunch and began looking around for any possible disconnected wires, or issues and found nothing. The I notice the Fuel Pressure Gauge says 7.5, not the normal 10. The gas gauge says half full, and is not pegged out like it would for a bad ground in the fuel sender (had that happen before).

Several weeks ago I upgraded to -6 AN Stainless Braided Hoses from the Fuel Filter to the TBI and rebuilt the TBI with new gaskets, installed rebuilt Injectors, put in a new TPS and IAC. All cables are connected and all vacuum hoses are new. I check three times to be sure with the manual by my side, and the engine has been going along GREAT until today.

So given what I see and know... I am assuming my Fuel Pump is going bad. Any ideas of what I could possibly be missing?

I'd like to drive it home today, but hitchhiking could be fun... maybe.

 

[shady]

the rubber intank hose connecting the pump to the fuel line sounds like it cracked. pumps probly good. but might as well replace it while your in the tank. I had the same thing happen on my 88 burb

 

[dyeager535]

If the fuel pressure gauge is working correctly, then I think you are probably on the right track.

I'd probably just check to make sure the pump is getting 12V at the tank connector first (it's easy) to make sure there isn't some kind of ground issue or something.

Able to test fuel pressure at the tank side of the fuel filter? I would just want to make sure the pump is putting out that pressure before dropping the tank.

Additionally, if the problem IS in the tank, it might just be the hose from pump to sending unit, although yours doesn't sound quite like others I've heard that have this common problem with the hose rupturing.

 

[shady]

some just crack. others desinegrate,, like mine I just listened for the pump and heard it running, but had no fuel.

 

[dyeager535]

What I recall seeming to be a commonality for the split fuel hose was that when you gave it any sort of gas, it would stumble and/or die.

I don't discount what you are saying, with a small crack what has been explained could be an issue with a split hose, as-is only getting slightly better than 50% of fuel OP should be.

I'd just hate to drop the tank to find out that something got in the hose from the AN conversion or anything else along those lines.

In-tank is the most likely location of the problem, no doubt. Just not a lot of fun to drop.

 

[crazedyak]

I cranked her up this morning with zero issues, but after she broke down this morning the was engine dying when I give it a little gas. It cleared up after a few start attempts.

Well there is one positive to dropping the tank. I've been wanting to put in an access door to the fuel sender in the bed floor.

I'll check voltage first, as I have my multimeter in the console right now.

Appreciate the help.

 

[travis565]

im having similar issues i just made a post about to. i already have the access door on my truck luckily. im going to try the same thing. does yours have a missfire when this happens?

 

[crazedyak]

Okay issue resolved... Bad fuel pump, also found a crimp in the fuel sender ground where it was caught between the tank and the frame. I went ahead and cut out the crimp. I had to drop the tank... but I did get the access hole I wanted cut for future tank issues.


I cut the access panel 14 inches front to back and 18 inches side to side. I laid the tape measure down for reference if anyone stumbles upon this and wants to make their own. Measurements done for you. The Center of the Sender is in the dead center of the bed (on mine at least)

I'm using this method to seal it back up.
http://coloradok5.com/forums/showpost.php?p=2747130&postcount=42

 

[eagle mark]

The I notice the Fuel Pressure Gauge says 7.5, not the normal 10.

10 will run, but if you ever want it to run good? Get 13 PSI...

What is it now with issue fixed?

 

[crazedyak]

As soon as I cranked it up the PSI was at 11.5. I do have a AFPR so I'll try to up it some to get to 13.

I drank entirely too much yesterday at a all you can eat and drink oyster fest... maybe I'll get to it today after I have a few more cups of coffee.