1991 Chevy S10 Blazer 4WD 4.3 liter 6 cly Vin "Z" TBI Will not start

phoenixssn702

1991 Chevy S10 Blazer (Taho) 4WD 4.3 liter 6 pistons Vin "Z" TBI 13lbs pressure fuel pump Delphi CFE0115. (This is NOT the HP pump that most models have)

Truck stopped as if it ran out of fuel when braking to a stop sign. Will not start. Turn key, SE Light is on but not flashing codes. Will crank but not start.

Did a code check and 12 code only (normal). Check all fuses ok. Had this problem before in 2006 and it was the fuel pump.

Replaced FP Relay, inline fuel filter, and fuel pump. Checked all leads for power and ground per GM TS chart, OK. Pump runs two seconds and cuts off as normal ITO. Crank, will not start. Fuel pump lines were marked and set back in exact place. Grounds were cleaned bright and set back tight. Wiring is correct: Pink line is sender and reads 0-97 ohms to ground. New pump is Gray line and reads 4 Ohms coil to ground. Does a bad Oil Pressure Switch prevent a start up as it sends a failure to the ECM and prevents startup?

Will test or replace Oil Pressure Switch next, then MAP Sensor, then Distrubator ICM next. Distrubator is new replaced Oct 2016.

What can this be, that I am missing? Seems simple like a missing ground somewhere. I do not suspect the ECM because the relay recieves the two second command. I cannot smell fuel in the injectors (TBI 220 unit). Remove battery ground which should reset ECM.

Need help as I have no other xport and no money to tow to dealer. I really need to get this fixed.

Thank you very much for any help, Gene........

phoenixssn702

The problem has been fixed.

First, I forgot to say that I had to do a hull cut in the cab to access the FP. I could not remove the gas tank by myself or pay the cost. Anywhere from 450 to 700 dollars just for that, and then a 30 min. job to actually replace the FP. I also did a rebuild of the cutout so that in the future, I can pull the hatch in 10 min. It is sealed with screws to prevent gas vapors (which should not exist) and exhaust blow back into the people space.

The next problem was a burned out ICM in the distributor. I got a next high tech lifetime warranty replacement from Auto Zone last October and it worked fine during the winter until last week when it hit 98 degrees outside. When I got it, I should have stripped down the ICM and checked the heat sink and re-did it properly. I did not, and payed for it later. When I pulled out the ICM, it was in fact burned up and the heat sink was missing about 40 percent heat sink compound coverage. It looks like they made it with two drops on the ends and tightened it down leaving open gaps and bubbles. Dried out completely hard.

I replaced a new warranty ICM and did a proper MIL-SPEC heat sink compound procedure.

That means using a razor blade as a squeegee and spreading a good layer on with no bubbles. First you must clean both metal surfaces with a greenie pad and follow up with acetone pads to remove any greese and fingerprints. Then usie a high tech heat compound like Arctic-3 Silver or the new TG-7 Diamond compound that has better heat transfer. The white silicon is OK only if you apply it as noted here. There must be on bubbles and when you secure the screws tight, there should be a fine bead of compound oozing from all sides. Not much but just enough to see a clean white edge.

Put it all back together and the engine turned on the first try. The engine tested perfectly, no leaks, and runs with new power and very quite. I may replace the two TBI fuel injectors later since they have over 250K miles on them. An easy 20 min fix.

So, new fuel pump, hull access hatch cut, fuel filter, fuel relay and ICM.

Thanks for reading this, I left this up for others to see.

Gene MD