93 sonoma, 4.3L TBI motor. the fuel pump runs and there is fuel in the tank, but will not start. plugs have been replaced and fuel is fresh. any leads? when gas is poured into the TBI it runs but only for a min. this is my neighbor's truck so sorry about being short on details, but i know nothing about it. i told him to check fuses and am going to see him monday so any things to look for would be good. the ECM can't reset itself after sitting for that long, can it? it has been running every once in a while during this time but not far. sorry not a blazer but all are the same pile anyways, right?

 

First check to make sure the fuel filter isn't clogged up. Second check the fuel pump relay to make sure the run side is working, Third, check to trouble codes. I have to ask though have YOU physically seen fuel being sprayed out of the injectors?And always remember just cause you can hear a littlwe whir, doesn't mean its pumping gas.

 

no fuel getting to injectors or injectors not letting fuel out, whatever. will pass on the clogged filter as an idea. thanks, will reply later with diagnosis

 

I would change the filter due to the age of the gas in the tank... the filter will not pass water.
Put a fuel pressure gauge on the rail and "see" whats going on with the pressure.

 

the older Blazers with 4.3's and TBI equipped don't have a fuel rail, the pressure tester goes down under the frame, we have to take the fuel filter line and screw a fitting onto it and connect the tester that way. TBI's have a line going to each side of the upper unit to supply fuel evenly to both injectors, so one tester will not work there.
BUT, if theres no check engine codes and the filter doesn't fix the problem its either the pump or the relay.
If it was in my front yard, I'd change the filter, replace the relay, and if that didn't work I'd yank the tank

 

good evening, thanks for the posts, neighbor is in the process of removing the fuel filter for replacement. no fuel flow at the tbi so can assume it is blocked filter or line. fuel pump seems to work well, but tank probably needs to be cleaned out. I love the smell of KEROSENE in the morning!! Will keep posted and again, thanks!

 

You can test fuel pressure on the TBI motors at the throttle body. I have done it on more than one occasion.

One line (larger) is the feed from the pump while the other (smaller) is the return to the tank. To test pressure here, you will need an adapter fitting to plumb inline with the feed line, but it definitely is possible.

A TBI motor requires 8-10 psi of fuel pressure. The filter is the first place I would look as well, but if you are getting no fuel to the throttle body, the filter would have to be plugged solid...

 

swartlkk....your telling me that for 30 years I've been doing it the hard way? So much for my dad being the smartest man I knew.


THANKS MAN from now on I don't have to get grass on my back side testing fuel pressure

 

You just need the proper add on test port fitting for your gauge or put a special fitting in to allow for a mechanical gauge at the TBI itself.

THIS is what I plan on putting on the TBI unit for the new engine I will be putting into my K5. Then I'll install a 0-15psi mechanical gauge.

Here is what Actron sells as an add-on test port - TBI `T` Fitting 0180-000-1320. The nice thing about the adapter fitting is that it goes between the hard line and the fitting into the back of the throttle body. What I plan on using replaces the fitting on the back of the throttle body since I just want to have a mechanical gauge.

In your defense (and your dad's), it is far more common to remove the fuel filter and install the add on port at that location.

 

I have a fuel pump pressure test kit here that has all the fittings, but it doesn't say anywhere in there instructions about hooking up to a TBI, but it has a fitting that will plug into the large line just fine, I just tried it to see if it'd work and its a hellofa lot easier than crawling under a 89 S-10.
My dad was a 26 year MM in the Navy, so anything having to do with engines or A/C units he was about the best I could ever find, but when it came to fuel injection I remember he bought a lot of books