so surfing the inet to find a solution to my problem of my truck not starting most of the time i found a TSB issued by Chevy about our 1st gen blazers and i have seen Many threads open up about hard/ no start problems and no one has mentioned this bulletin. So for those who are dropping the tank and about to replace the fuel pump be sure to look at the pulsator as well because thats a lot of work to drop the take and then have to do it again to replace the pulsator



GM has issued a Technical Service Bulletin about a similar issue in older Chevy/GMC trucks. Due to the addition of higher concentrations of ethanol in gasoline, these vehicle experience an issue with the fuel pulsator.



Please refer to the information below:



File In Section: 6E Engine Fuel & Emission

Bulletin No.: 66-63-09

Date: April, 1997

Subject:
Engine Hard Start or No Start (Replace Fuel Pump Pulsator)



Models:
1992-96 Chevrolet
and GMC Trucks
1992-96 Oldsmobile Bravada
with Gasoline Engines



Condition

Some owners may report their engine is hard to start or will not start.

Cause

The fuel delivery system may have low or no pressure due to a ruptured fuel pump pulsator. The pulsator is the flexible connector between the fuel pump and the metal fuel line in the tank. This rupture appears as a tear in the pulsator openings and is the result of exposure to gasoline containing a high percentage of ethanol.

Correction

Follow the Strategy Based Diagnostic Steps for the reported symptoms. If diagnosis reveals low or no fuel system pressure, and the fuel pump is identified as a possible cause, follow the service procedure for, On-Vehicle Service, Fuel Pump, in the appropriate Truck Service Manual. Before replacing the fuel pump, inspect the pulsator for signs of tears or leaks. If the pulsator is damaged, replace it with P/N 25175836 and re-test the fuel system for normal pressure. This pulsator is made of Viton which is resistant to Ethanol content fuels. P/N 25175836 replaces P/N 25094266 for trucks. This change will appear in GMSPO parts catalogs as they are revised.

 

Wish I found this earlier...about to take my tank out again! Should have just put the damn rubber hose that came with the new pump

Also while your in there inspect the intank wiring...my ground for pump was all burnt up, I soldered directly and bypassed the in tank connector

I prob fixed a non cause problem when the pulsator was bad...the old pump spun up during a bench test

The only aparent symtoms was lil to no fuel pressure @ the test port on the engine it just bubbled out mildly

94 4.3 4x4 blazer

 

I bought a new fuel pump for my blazer and used the new hose that came with it and my truck would not run , I took the tank back out and put the pulsator back in and it fired right up . The hose was supposed to replace the pulsator or maybe some models don't have a pulsator .